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Colorado Division of Wildlife
Wildlife Research Report
July 1998

JOB PROGRESS REPORT

state of

Colorado

cost center 3430

Project No.

W-153-R-11

Mammals Program

Work Package No.

__0_6_6-2______

Preble's Meadow Jumping Mouse

conservation
Task No.

:

Preble's Meadow Jumping Mouse

conservation
Period Covered:
Author:

July 1, 1997 -

June 30, 1998

Tanya Shenk

ABSTRACT
A draft conservation plan, entitled 'Conservation Assessment and
Preliminary Conservation Strategy for Preble's Meadow Jumping Mouse (Zapus
hudsonius preblei)' was completed and submitted to the .USFWS on January 9,
1998 during the Open Comment Period for the Proposed Listing of Preble's
meadow jumping mouse as endangered. The conservation plan was divided into
two parts. The first part, a conservation assessment summarized and evaluated
available information on the taxonomy, distribution, and ecology of z. h.
preblei and identified potential threats to the conservation of the mouse.
The second part, a preliminary conservation strategy outlines the goals and
objectives of a conservation strategy for z. h. preblei and summarized
prioritized research needs to provide necessary information to develop sound
conservation strategies. From this list of prioritized research needs two
study plans were completed and research begun on both starting in May 1998.
These research plans are designed to investigate (1) temporal and spatial
variation in the demography of Preble's meadow jumping mouse and (2) habitat
use and distribution of Preble's meadow jumping mouse in Larimer and Weld
Counties, Colorado.

��3

Preble's Meadow Jumping Mouse Conservation Plan
Tanya Shenk

P.H.

OBJECTIVE

Develop and implement a conservation plan for Preble's meadow jumping mouse in
Colorado.

SEGMENT OBJECTIVES
1.

Complete a literature search for all known, relevant information to
develop a conservation plan for Preble's meadow jumping mouse.

2.

Complete an inventory of current research being conducted on Preble's
meadow jumping mouse.

3.

Evaluate known information on Preble's meadow jumping mouse in the
context of providing information necessary to develop sound strategies
for conservation of Preble's meadow jumping mouse.

4.

Define and prioritize needed research components to develop sound
strategies for conservation of Preble's meadow jumping mouse.

s.

Begin study design for research to address a high priority need to
develop sound strategies for conservation of Preble's meadow jumping
mouse.

6.

Complete a draft conservation plan for Preble's meadow jumping mouse.

RESULTS AND DISCUSSIQH
1.

Complete a literature search for all known, relevant information to
develop a conservation plan for Preble's meadow jumping mouse.
A literature search was completed, the information was summarized
and presented in the draft conservation plan (see Appendix A).

2.

Complete an inventory of current research being conducted on Preble's
meadow jumping mouse.
There are four research projects being conducted on z. h. preblei,
with a fifth planned to begin spring of 1998 (Table 1). Each of these
projects is designed to provide further information on the ecology or
demography of Preble's meadow jumping mouse. However, if research
methodologies were standardized and coordinated across all the projects,
comparability and quality of the data would be greatly enhanced. Such a
coordinated effort would maximize data quantity, quality, and
comparability over varying conditions throughout the range of z. h.
preblei in the most effective and efficient way possible. Comparable
information gained across the ecological range of z. h. preblei would
then provide more useful information to develop sound management
strategies for conservation of the mouse.
To achieve such a coordinated research effort all project leaders
must agree to follow data collection protocols, establish 'ownership' of
data and future publications, and work cooperatively to share equipment
and technical assistance during peak data collection periods. To
facilitate such a mutual effort will require the participation of all

�4

project leaders conducting field studies of z. h. preblei as well as
cooperative investigators, and specialized data analysts with expertise
in the study design, analysis, and interpretation of mark-recapture and
telemetry data. Therefore, I organized a Preble's Meadow Jumping Mouse
Research Working Group with the following objective: To explore the idea
of coordination of research efforts across multiple principal
investigators to enhance comparability and quality of data across the
range of z. h. preblei for use in developing sound management strategies
for conservation of the mouse. Such an effort would maximize data
qu~ntity, quality, and comparability over varying conditions throughout
the range of z. h. preblei in the most effective and efficient way
possible.
To make this work, all principle investigators must agree to
follow data collection protocols, establish 'ownership' of data and
future publications, and work cooperatively on the possible sharing of
equipment and technical assistance during peak data collection periods.
This working group needs to involve all interested principle
investigators involved in field studies of z. h. preblei as well as
cooperative investigators, and specialized data analysts with expertise
in the study design, analysis, and interpretation of mark-recapture and
telemetry data.
The first meeting of the working group (November 12, 1997) was a
success with all principle investigators supportive of the idea of a
coordinated, cooperative research program. The second meeting of the
Research Working Group is scheduled for February 4, 1998 where we will
outline what research questions will be addressed at which sites and
draft standardized protocols for data collection. A proposed agenda for
the Research Working Group includes the following tasks, task leaders,
and a timetable to initiate a cooperative research effort:
Task

Task Leader,
Affiliation

Date

Identify all potential
participants: project leaders,
cooperating investigators, data
analysts.
Prioritize research questions.

T. Shenk, Colorado
Division of Wildlife

January
1998

All project leaders*

Identify sites to best address
prioritized research needs.
Design studies specific to
research question to be addressed
at each site.

All project leaders

January
1998
January
1998
JanuaryFebruary
1998

All project leaders,

cooperating
investigators, data
analysts
All project leaders

March 1998
Evaluate needs at each site to
conduct specified research.
March 1998
Identify discrepancies between
All project leaders
needs and available funds,
equipment, and personnel currently
allocated for each site.
Attempt to balance discrepancies.
March 1998
All project leaders, cooperating
investigators
* To date: M. Bakeman, c. Meaney, T. Ryon, R. Schorr, T. Shenk

�5

3.

Evaluate known information on Preble's meadow jumping mouse in the
context of providing information necessary to develop sound strategies
for conservation of Preble's meadow jumping mouse.
Known information on the ecology of Preble's meadow jumping mouse
was summarized and presented in the Conservation Plan (see Appendix A).

4.

Define and prioritize needed research components to develop sound
strategies for conservation of Preble's meadow jumping mouse.
The following outline is a complete list of research needs to
provide information to develop sound management strategies for
conservation of z. h. preblei. Research needs are not listed in order
of priority, but listed in a logical manner to provide completion of
needs.
Demographic studies: Information on the population dynamics of Preble's
meadow jumping mouse is necessary to determine which areas support
populations where the rate of population growth is~ 1. Key parameters
to estimate include:
Survival:

•

estimates of survival, including
►
annual
►
over-summer
►
over-hibernation
• investigate possible factors affecting survival, including
►
weight
sex
age
abundance (i.e., density dependent response)
habitat features: stream reach, vegetation composition
weather
►
predation
►
disease
Approach: mark-recapture techniques
►
►

►
►

►

Recruitment:

•

estimate recruitment (as an alternative to reproductive
parameters listed below)
• investigate possible factors affecting recruitment, including
►
weather
►
habitat features
Approach: mark-recapture techniques
Population structure:

• estimate sex ratios
• estimate age ratios
Approach: mark-recapture techniques
Abundance:

•

estimate abundance
investigate factors affecting abundance, including
►
habitat features (see under habitat use)
Approach: mark-recapture techniques for closed populations

•

Immigration, emigration:

•

estimate rates of immigration and emigration

�6

•

investigate possible factors affecting immigration, emigration
habitat features (see under habitat use)
►
abundance (i.e., density-dependent response)
Approach: estimate rates from mark-recapture data, identify
existence with radio telemetry
►

Reproduction:

•
•
•
•
•

estimate number of litters per year
estimate number of young per litter
estimate age at first reproduction
estimate juvenile survival
investigate possible factors affecting reproduction, including
►
habitat features: food availability, nest site
availability, cover availability
►
abundance (i.e., density-dependent response)
►
weather
Approach: from telemetry work
Dispersal is a key process in metapopulation theory
and to maintain genetic diversity between isolated populations. Key
parameters to evaluate include:

Dispersal Studies:

Population parameters

• who disperses
• time of dispersal
• estimate rate
Approach: estimate rate with mark-recapture, document who and when
from both telemetry and mark-recapture data
Habitat parameters

•
•
•

through what habitat
end point descriptions (disperses from what to what)
landscape features (connectivity with other riparian strips,
corridor use, overland use)
Approach: document where from both telemetry and mark-recapture
data
Conservation of z. h. preblei should maintain
populations throughout the range of its natural variation and to try to
identify ecological limits for the subspecies. Key concerns include:

Distribution Studies:

Range-wide distribution:

•

conduct trapping surveys to better define the eastern boundary
of the range of z. h. preblei
• conduct trapping surveys in areas of potential sympatry of z.
h. preblei with z. princeps
Approach: determine from trapping surveys
Habitat Studies: To identify and define habitat requirements of z. h.
preblei studies should be conducted to address the following:
Habitat use:

•
•
•

estimate distances traveled: daily, seasonally
describe landscape features (connectivity with other potential
sites, geology)
determine seasonal use

�7

•
•
•
•
•

describe hibernacula
describe nest sites
estimate distance to nearest open water from other habitats used
describe hydrology (water quality, flow) in areas of use
evaluate effects of abundance on habitat used (i.e., density
dependent responses)
Approach: estimate from telemetry work
Physiological Studies: Physiological studies will provide information
on the mechanisms driving habitat selection.
Physiological requirements:
• estimate dependency of z. h. preblei on open water
• determine energetic requirements to survive hibernation
Approach: estimate from laboratory studies
Systematic Studies: To better define the relationship of z. h. preblei
to other subspecies of z. hudsonius and other species of Zapus the
following studies should continue.
Molecular systematic relationships:
• further explore genetic relationships among different z. h.
preblei populations
• further explore genetic relationships among different
subspecies of z. hudsonius
• further explore genetic relationships among different species
of Zapus.
Approach: explore through laboratory studies
Systematic relationships:
• link genetic relationships to systematic studies of z.
hudsonius.

Approach: explore through museum studies
Community Studies: Composition of the community where z. h. preblei
occur could help explain ecological tolerances of the subspecies,
providing insight to the mechanisms determining its distribution.
Small mammal assemblages:
• comparison of small mammal assemblages in areas where
populations of z. h. preblei occur and areas where they do not
►
species composition
►
relative abundance
Approach: estimate from trapping surveys
There are currently five research projects on z. h. preblei
planned to begin spring of 1998. Each of these projects is designed to
provide further information on the ecology or demography of Preble's
meadow jumping mouse. However, if research methodologies were
standardized and coordinated across all the projects, comparability and
quality of the data would be greatly enhanced. Such a coordinated effort
would maximize data quantity, quality, and comparability over varying
conditions throughout the range of z. h. preblei in the most effective
and efficient way possible. Comparable information gained across the
ecological range of z. h. preblei would then provide more useful
information for use in developing sound management strategies for

�8

conservation of the mouse. Therefore, a research group was formed
including all principal investigators of the five studies as well as
other interested personnel. This research group has developed
standardized protocols to be followed in all studies. These include
protocols on techniques, data collection, and data analyses for (1)
mark-recapture, (2) radio-telemetry, (3) habitat use, and (4) genetic
sampling.
5.

Begin study design for research co address a high priority need co
develop sound strategies for conservation of Preble's meadow jumping
mouse.
There are four components of z. h. preblei ecology that are
currently unknown and yet key to any sound conservation strategy for the
subspecies. These are (1) detailed demographic studies estimating
survival and reproduction and determining the factors influencing each
of the parameters, (2) detailed studies evaluating movements and
dispersal habitat of individuals within and among populations, (3)
detailed studies to define hibernation needs, primarily descriptions of
suitable hibernacula criteria and food requirements for sufficient fat
storage prior to immergence, and (4) better defined distributions of the
mouse.
The following describes the research I will be conducting
beginning Spring 1998 to address these needs.
Demography Study: Information on the population dynamics of Preble's
meadow jumping mouse is necessary to determine which areas support
populations where the rate of population growth is stable or suggests an
increasing population. Key parameters to estimate include survival
(annual, over-summer, and over-hibernation), reproduction, dispersal
rates, and density. A combination of mark-recapture techniques and
radio-telemetry studies will be used to estimate these parameters and
evaluate possible factors affecting such parameters.
Intensive trapping efforts will be conducted in June and August of
1998 and in May of 1999 within a given population. All animals captured
will be permanently marked with PIT (passive integrated transponders)
tags. Select mice will also be fitted with radio transmitters.
Survival estimates and evaluation of possible factors affecting
survival, including weight, sex, age, abundance (i.e., density dependent
response), habitat features (stream reach, vegetational composition),
and weather will be obtained from data collected from mark-recapture
efforts.
Dispersal is a key process in meta-population theory and to
maintain genetic diversity between isolated populations. The key
objectives are to estimate rate of dispersal and to determine who
disperses, time of dispersal, and describe suitable dispersal habitat.
These estimates will be obtained from analyses of both the markrecapture data and from following radio-collared individuals. Estimates
of immigration and emigration rates will be obtained from data collected
during the mark-recapture efforts as well as an evaluation of possible
factors affecting these rates including habitat features and abundance
(i.e., density-dependent response). Data on who disperses, when
dispersal occurs, and dispersal habitat will be obtained by following
radio-collared animals.
From the mark-recapture data collected during the trapping
sessions, abundance and density estimates can also be made. Other
ancillary information which can be obtained from data collected during

�9

the tapping sessions include estimates of sex and age ratios within the
populations sampled.
Reproduction parameters such as number of litters per year, number
of young per litter, and age at first reproduction will be estimated
from radio-collared females. An analysis of variance will be conducted
to evaluate possible factors affecting reproduction, including habitat
features such as food availability, nest site availability, and cover
availability as well as the possible effects of abundance (i.e.,
density-dependent response) and weather.
A complete study plan entitled "Temporal and spatial variation in
the demography of Preble's meadow jumping mouse (Zapus hudsonius
preblei) is included in Appendix B.
Distribution, Habitat Use, and Monitoring Study: Conservation of z. h.
preblei should maintain populations throughout the range of its natural
variation and to try to identify ecological limits for the subspecies.
Key concerns include range-wide distribution, habitat use, and
population persistence at a given site. To address these concerns a
study will be designed where a sampling frame of suitable habitat will
be constructed. The starting point for developing the sampling frame
will be to determine the feasible distributional range of z. h. preblei.
A conservative approach will be used for elevational and directional
limitations. Once the potential distribution map is developed, all but
potentially suitable habitat within the feasible range of the subspecies
will be eliminated. From this sampling frame, random sites will be
selected to conduct trapping surveys. Therefore, all successful
trapping sites will provide further information on the distribution of
the mouse.
Information on habitat will be collected at all sites surveyed,
regardless of trapping success for Preble's meadow jumping mouse.
Comparisons of habitat variables from both successful and unsuccessful
sites will be used to better define suitable habitat for the subspecies.
Habitat variables recorded will include both site level characteristics
such as vegetational composition, cover, and composition of ·other small
mammal species·as well as landscape level characteristics including
connectivity with other potential sites, geology, hydrology, and
distance to development. Data collected on movements of radiotelemetered mice will also provide information on seasonal use of
different habitats, dispersal corridor and end point habitat
characteristics, and descriptions of nest sites and hibernacula.
Repeated annual visits to the randomly selected sites will provide
information on population persistence at a given site. Such a
monitoring scheme will be necessary for evaluating the continued status
of the mouse as well potentially evaluating the efficacy of any
conservation planning efforts.
Genetic tissue samples will also be collected from mice captured
at these new locations. Future genetic analyses should help to better
define the relationship among (1) different populations of z. h.
preblei, (2) other subspecies of z. hudsonius and (3) other species of
Zapus.
A complete study plan entitled "Habitat use and distribution of
Preble"s meadow jumping mouse (Zapus hudsonius preblei) in Larimer and
Weld Counties, Colorado" is included in Appendix C.

6.

Complete a draft conservation plan for Preble's meadow jumping mouse.
The draft conservation plan, entitled 'Conservation Assessment

�10

and Preliminary Conservation Strategy for Preble's Meadow Jumping Mouse
(Zapus hudsonius preblei)' was completed and is attached as Appendix A.
The document was submitted to the USFWS during the Open Comment Period
for the Proposed Listing of Preble's meadow jumping mouse as endangered.

Prepared by

~---_5/J_
~ a Shenk

�Table 1.

Current and proposed research projects for Preble's meadow jumping mouse.
Marking method

Study
location

Principle
Investigate
r

Pit
tags

Parameters to estimate

Telemetr Surviva Reproducti Recruitme Abundanc Diapers Habita Populatio Stomach
t Uset
on
nt
y
1
e
al
n
content
structure analyses

Rocky Flats

Tom Ryon

X

X

X

X

X

AOA*

Air Force
Academy

Rob Schorr

X

X

X

X

X

AOA

X

X

AOA

X

X

AOA

Boulder Open Carron
Meaney
Space
Lyons

X

Mark

Bakeman
Cherokee
Park?

Tanya Shenk

X

X

X

X

X

X

X

X

AOA

Douglas Cty
(Plum
Creek)?

Tanya Shenk

X

X

X

X

X

X

X

X

AOA

* AOA As opportunity arises

I-'
I-'

��13

APPENDIX A

CONSERVATION ASSESS:MENT AND
PRELIMINARY CONSERVATION STRATEGY FOR
PREBLE'S MEADOW JUMPING MOUSE (Zapus hudsonius preblei)

prepared by
Tanya Shenk
Colorado Division of Wildlife
317 West Prospect
Fort Collins, Colorado 80526

January 1998

�14

EXECUTIVE SUMMARY
In 1994 a petition was submitted to the U. S. Fish and Wildlife Service from the Biodiversity Legal
Foundation (USFWS 1997a) to list Preble's meadow jumping mouse (Zapus hudsonius preblei) under the
Endangered Species Act (ESA). A Proposed Rule to list Preble's meadow jumping mouse as endangered
under the ESA was submitted by the U. S. Fish and Wildlife Service on March 25, 1997 (USFWS 1997a).
Following the Proposed Rule to list the species as endangered, the Colorado Division of Wildlife agreed to
develop a species conservation assessment and preliminary conservation strategy which would provide a
framework for conservation efforts. This document is the result of that agreement between the Colorado
Division of Wildlife and The U.S. Fish and Wildlife Service. Therefore, the purpose of this document is to
summarize the current known ecology and status of Z. h. preblei, to outline goals for conservation of the
subspecies, to prioritize what information is most needed to develop sound conservation strategies to meet
those goals, and to suggest future research required to provide such information. This document will provide
the Colorado Division of Wildlife with a prioritized list of research needs to direct ecologists and managers
toward obtaining the necessary information for developing, implementing, and evaluating strategies for
conserving the Preble's meadow jumping mouse. Should the Final Decision list the species as either
threatened or endangered, this document could also provide scientific information for any Habitat
Conservation Plan(s) to be developed under the ESA.
Any conservation plan for Z. h. preblei should address what is needed for recovery of the subspecies,
including how much habitat is needed and where, what information and conservation actions are needed,
whether restorations are needed, and what biological information is needed to manage or conserve the mouse.
Some of the basic information required to define these needs includes the distribution of the mouse and its
habitat, population dynamics (survival, reproduction, and dispersal), minimal habitat requirements, genetic
variation between and among populations, physiology, hibernation requirements, and resilience of
populations to human alteration of their habitat. This document attempts to summarize what is currently
known on each of these topics, prioritizes what information is still most needed to develop conservation
strategies based on the conservation goals, and suggests future research required to provide missing
information.
A review of the studies conducted on Preble's meadow jumping mouse shows that there is
insufficient information to fully address defining range-wide ecological requirements, limiting factors, limits
of species tolerance, or population status. Most work to date has focused on geographic distribution
(presence or absence of Z. h. preb/ei), taxonomy, and habitat descriptions of sites where mice have and have
not been captured. Although available information is limited, it is clear that measures must be taken to begin
developing a conservation strategy for Z. h. preblei. The primary objectives necessary to develop a
successful conservation strategy for Preble's meadow jumping mouse are:
1.
2.
3.
4.
5.
6.
7.

8.
9.
10.

Document the present distribution of Z. h. preblei.
Identify populations of Z. h. preblei where the rate of population growth ~ 1.
Protect populations of Z. h. preblei where the rate of population growth~ 1.
Maintain current range of natural variability of Z. h. preblei.
Identify ecological requirements for sustaining viable populations of Z. h. preblei
throughout its range of natural variability.
Protect habitats to sustain existing populations of Z. h. preblei where the rate of population
growth~. 1.
Promote protection and management of habitat for conservation of Z. h. preblei in all
currently or recently occupied habitat, and in habitat suitable for restoration of mouse
populations.
Monitor the status of populations of Z. h. preblei throughout its known range to detect
changes in local distribution.
Identify threats to the conservation of Z. h. preblei.
Eliminate or minimize threats to conservation of Z. h. preblei.

�15

11.
12.
13.

Integrate Preble's meadow jumping mouse conservation strategy objectives with
management and habitat objectives of other Front Range riparian species.
Promote scientific management of Preble's meadow jumping mouse.
Promote public support for conservation efforts and scientific management of Preble's
meadow jumping mouse through public education.

In order to achieve the stated objectives outlined above, the following actions must occur:
1.
2.
3.
4.
5.
6.
7.
8.
9.

Conduct population studies to estimate and determine what factors influence demographic
parameters and rate of population change.
Conduct studies to better define the ecological requirements of Z. h. preblei (food, cover,
water, hibernation requirements, etc.).
Conduct research to evaluate the effects of potential threats on survival, reproduction,
dispersal, and abundance of Preble's meadow jumping mouse.
Implement habitat and population management practices that emphasize the conservation of
Preble's meadow jumping mouse throughout the natural variability of its range.
Develop survey protocols to monitor trends in the distribution of Z. h. preblei and protocols
to store and analyze survey data.
Conduct trapping surveys to better define the boundaries of the range of Z h. preblei.
Implement research on Preble's meadow jumping mouse biology to better understand the
mechanisms driving the ecological requirements.
Further explore genetic relationships among different Z. h. preblei populations, among
different subspecies of Z. hudsonius, and among different species of Zapus.
Develop educational programs to promote positive public support for Preble's meadow
jumping mouse conservation.

The criterion to be used to evaluate the success of this program will be the maintenance of local selfsustaining populations of Preble's meadow jumping mouse which are geographically distributed throughout
the range of the subspecies and throughout the natural variation of its ecological requirements.
The document is divided into two parts. The first part, a conservation assessment will ( 1)
summarize available information on the taxonomy, distribution, and ecology of Z. h. preblei; and (2) identify
potential threats to the conservation of the mouse. The second part, a preliminmy conservation strategy, will
(1) outline the goals and objectives of a conservation strategy for Z. h. preblei; and (2) summarize prioritized
research needs to provide necessmy information to develop sound conservation strategies.

ACKNOWLEDGMENTS
This document could not have been prepared without generous help from all members of the 'Z. h.
preblei Conservation Document Working Group' (Mark E. Bakeman, Carron A. Meaney, Chris Pague, and
Peter Plage). Members gave freely of their time and expertise and readily shared their data, anecdotal
observations, impressions, and scientific interpretations. This working group truly exemplified how scientists
should interact when working toward a common goal.
Additional scientific contributions came from David M. Armstrong, Alan B. Franklin, Lawrence A.
Riggs, Thomas R Ryon, Robert Schorr, Rick Schroeder, and Bruce Wunder. Technical support during this
effort was provided by Alan B. Franklin, David Lovell, Francie Pusatari, and Michael Wunder. Logistical
support was provided by Steven Nesta, Douglas Robotham, Judy Sheppard, and John Stover.

�16

CONSERVATION ASSESSMENT
INTRODUCTION

The following is a summary of information collected primarily from the five studies conducted
on Z. h. preb/ei. The longest and most varied studies have been conducted on the Rocky Flats
Environmental Technology Site (I 990 through the present) including distribution studies, habitat
surveys, location ofhibernacula, fat requirements for hibernation, and genetic studies conducted by M.
Bakeman, A. Deans, F. Harrington, T. Ryon, R Stoecker, and B. Wunder. Range-wide distributional
and vegetation surveys have been conducted on sites other than Rocky Flats Environmental Technology
Site by (1) Meaney et al. (1995, 1996, 1997), funded by the Colorado Division of Wildlife, (2) City of
Boulder Open Space and Boulder County Open Space, (3) Ensight Technical Services of Boulder,
Colorado funded by the Colorado Department of Transportation, (4) the Colorado Natural Heritage
Program, (5) U. S. Forest Service, Medicine Bow National Forest, Wyoming, and (6) numerous other
environmental consulting firms. An evaluation of historical Z. h. preblei sites was conducted by Ryon
(1996). Genetics studies were conducted in 1995 by B. Wunder and in 1996 and 1997 by Biosphere
Genetics, Inc.
Where data were not available for Z. h. preblei, information from studies of other subspecies of
Z. hudsonius was provided. In particular, studies conducted by Quimby (1951) and Whitaker (1963)
provided substantial information on the species. Caution must be used in extrapolating information
reported for other subspecies of Z. hudsonius to Z. h. preblei, although, such information is useful as a
general framework from which to work until such information becomes available for Z. h. preblei
itself
Possible threats to the conservation of Preble's meadow jumping mouse were derived from
both general principles of conservation biology and information specific to Zapus hudsonius in general,
or the subspecies itself
TAXONOMY

Description
Quimby (1951) described Z. hudsonius as follows: 'A mouse-like rodent with greatly enlarged
hind feet and an exceptionally long tail. The forelegs are relatively short. The ears are somewhat
conspicuous. The body is clothed in moderately long, somewhat dense hair of a rather coarse texture
and several colors. The dorsal portions are marked by a broad stripe of brownish hairs many of which
are tipped with black giving the region a grayish-black appearance. The sides are bright yellowishorange, whereas the underparts and feet are white. The tail is bicolor, dark above and light below, and
sparsely covered with hair which is longer on the terminal part. The mammae are eight, and quite
prominent in lactating females. The male genitalia are inconspicuous except during the breeding
season when the scrotal sac becomes enlarged. The testes enlarge and may be either abdominal,
inguinal, or scrotal during this period.' The skull of Z. hudsonius is small and light with a narrower
braincase and smaller molars than in Z. princeps (from Fitzgerald et al. 1994 p. 18). However,
Fitzgerald et al. (1994) urge caution in distinguishing the two species ·or Zapus in Colorado. Such
caution is further warranted by the recent conflicting identifications of mice based on genetic
characteristics (see Genetics section below).
E. A. Preble (1899) first collected the specimen that is, now, the holotype for Z. h. preblei at
Loveland, Colorado in 1895 and assigned it taxonomically to Z. h. campestris. Krutzsch (1954)
revised the taxonomy of Z. hudsonius and assigned the meadow jumping mice from Colorado and
southeastern Wyoming to their own distinct subspecies. Krutzch (1954) described this subspecies as
having fewer black-tipped dorsal hairs and a less distinct dorsal band; smaller cranial measurements; a
narrower interorbital constriction; smaller, less inflated auditory bullae; narrower incisive foramina; and
a more inflated frontal region (Fig. 1) than Z. h. campestris. Krutzch named this subspecies Z. h.
preblei in honor of the collector of the holotype (and previous reviewer of genus).

�17

Figure 1. Preble's meadow jumping mouse (Z. h. preblei). Note the long tail curves
around handlers index finger and the dark dorsal stripe. Also note the large hind foot and
small first digits on front and rear feet (insert). Photographs by Norm Clippinger.

Measurements for meadow jumping mice in Colorado are: total length 187-255 mm; length of
tail 108-155 mm; length ofhindfoot 28-35 mm (Fitzgerald et al. 1994). Body weights of meadow
jumping mice are variable, not only for different animals, but for the same individual depending on
activity or season (Quimby 1951). Such variability arises from sex, age, reproductive status,
preparation for entering hibernation, and condition on emergence from hibernation. Mean body
weights reported for adult Preble's meadow jumping mice are 19g (n = 37; Meaney et al. 1996), 23.5g
(n = 5, se = 1.2g; Colorado Natural Heritage Program, unpublished data);22.7g (n = 30, se = 0.1g; M.
Bakeman unpublished data 1997), 20.3 g (n = 26, se = 0.5g; Meaney et al. 1997).
Two species of ectoparasites have been identified on Preble's meadow jumping mice (R
Schorr, personal communication). These includes fleas (Megabothris abantis, (identified by K. Gage
of the Center for Disease Control) and a larval form of a tick, either Ixodes sculptus or L kingi.

Genetics
The family Zapodidae (jumping mice) consists of small to medium-sized mice with enlarged
hind feet and exceptionally long tails. Four living genera are recognized in this family, two of which,
Zapus and Napaeozapus, are found in North America (Hall 1981). There are three living species of the
genus Zapus: Z. trinotatus (Pacific jumping mouse), Z. princeps (western jumping mouse), and Z.
hudsonius (meadow jumping mouse). Z. h. preblei is one of twelve living subspecies of the species Z.
hudsonius (Fig. 2a, Krutzsch 1954, Hafner et al. 1981). Z. h. preblei was first described by Krutzsch
(1954) from a specimen collected by E. A. Preble in 1895 near Loveland, Colorado.
Genetics work using DNA sequencing of the mitochondrial DNA non-coding or re D-loop .tE
region was conducted by Biosphere Genetics, Inc., to help determine whether populations of Z. h.
preblei constitute one or more distinct evolutionary units. Genetic samples were collected from livetrapped mice, following a protocol specified by Biosphere Genetics, Inc., adapted and updated from the
U.S. Fish and Wildlife Service standardized protocol. Sampling in 1996 and 1997 by all field crews
(project leaders M. Bakeman, C. Meaney, T. Ryon, B. Stoecker, Colorado Natural Heritage Program)

�18

was performed on meadow jumping mice presumed to be Z. h. preblei, yielding samples from 72
individual mice. Twenty genetic samples were also prepared from specimens provided either directly
or indirectly by five different museums and university cooperators. Samples analyzed from livetrapped mice came from 23 locations in Colorado and two locations in Wyoming (Table 1). Samples
analyzed from specimens provided by museums and cooperators represented reference material for
species and subspecies from Colorado, Indiana, Minnesota, Nebraska, New Mexico, and Wyoming
(Table 1; Fig. 2a and b).
Preliminary DNA sequencing work in 1996 using a 550 basepair fragment of the mitochondrial
DNA non-coding region examined 16 individuals from seven locations in Colorado and found two
populations from Las Animas County (Lake Dorothey area) to be distinct from five other populations
which ranged from Boulder County south to El Paso County. As more samples from additional
trapping locations and museum specimens were brought in to the analysis in 1997, a smaller segment of
the non-coding region included within the original 550 base-pair fragment was used to avoid problems
with non-specificity of one of the primers. DNA sequences were obtained for 433 basepair-long
fragments in all samples analyzed in both years. Phylogenetic relationships among the samples were
inferred from maximum parsimony analysis. Strength of these phylogentic relationships were evaluated
using bootstrap analysis (see Riggs et al. 1997, Appendix A for detailed methodology).
Analysis of the mitochondrial DNA sequence data indicates that mice sampled from
southeastern Albany County, Wyoming, south along the Front Range of the Rocky Mountains to
western Las Animas County, Colorado (Purgatoire Campground, San Isabel National Forest), form a
coherent genetic group (Fig. 3, L. Riggs et al. 1997). This group of samples are distinct from samples
obtained from mice from three other populations. Genetic samples from mice captured in the Dorothey
Lakes area of southern Colorado (Las Animas County) group together and are most closely allied with
· Z. h. luteus, a subspecies described from New Mexico (Riggs et al. 1997). The single genetic sample
collected from Weld County, Colorado (Lone Tree Creek) and six samples obtained from Warren Air
Force Base in Laramie County, Wyoming are most similar to reference samples of Z. princeps from
Colorado (Larimer County) and New Mexico (Taos County) (Riggs et al. 1997). The sequence data
indicate that the samples from specimens identified as Z. h. luteus and samples from specimens of Z.
princeps are more closely allied with each other than either is with the samples defining the Z. h.
preblei gro.up. This closer alliance of the samples of Z. h. luteus with Z. princeps rather than Z. h.
preblei conflicts with results ofHafher et al. (1981), based on a combination of pelage, morphologic,
and genetic data, which support a closer alliance with Z. hudsonius.
Phylogenetic analysis indicates that the group of samples referred to as Z. h. preblei cannot at
this point be distinguished clearly from four reference samples of Z. h. campestris from Weston
County, Wyoming (two samples), Custer County, South Dakota (two samples), one sample of Z. h.
pallidus from Garden County, Nebraska, or from two samples of Z. h. intermedius from an unspecified
county in Minnesota (Fig. 3, L. Riggs et al. 1997). A suggestion from the analyses is that Z. hudsonius
from Indiana (presumed to be Z. h. americanus) may have shared a common ancestor with the
progenitors of samples from Z. h. luteus and Z. princeps more recently than with the Z. h. preblei
group and perhaps other subspecies described for the north central states (Riggs et al. 1997).
A more complete biosystematic evaluation of jumping mice is needed to clarify and further
refine relationships among populations of the group referred to as Z. h. preblei as well as to other
subspecies and species of the genus 7Apus. Such·an evaluation requires detailed analyses of pelage,
morphometric, and genetic data from sufficient numbers of individuals to adequately represent the
populations of interest. However, the mitochondrial DNA non-coding (D-loop) sequence data
available at this time are consistent with the view that a geographically contiguous set of populations
previously recognized as Preble's meadow jumping mouse form a homogenous group recognizably
distinct from other nearby populations and from another geographically-adjacent species of the genus
(Riggs et al. 1997). Therefore, given the genetic data available, Riggs et al. (I 997) conclude Preble's
meadow jumping mouse is a distinct population of Z. hudsonius.

�a.

l.

2.
3.
4.
S.
6.
7.
8.
9.
10.
II.
12.

Z h. acadicvs
Z h. a/cccnsls
Z h. amerlcanus
Z h. campestrls
Z h. canadensts
Z h. hudsonlus
Z h. lntennedius
Z h. la,Jas
Z h. pallidus
Z h. pnblei
Z h. tenellus
Z h. luteus

b.

...

Figure 2. Range of Z. hudsonius and its 12 subspecies (a) and Z. princeps (b) (modified from Hall 1981). Stars
.indicate locations where reference samples were collected from specimens at either museums or from university
cooperators for genetic analysis. Reference samples for Z. h. luteus include two from Otero County, New Mexico,
and two samples from Sandoval County, New Mexico. Reference samples for Z. h. campestris include two from
Weston County, Wyoming, and two samples from Custer County, South Dakota. Two reference samples of Z. h.
intermedius came from Minnesota. Two samples of either Z. h. americanus or Z. h. intermedius came from
Indiana. One sample of Z. h. pallidus came from Garden County, Nebraska. Reference samples for Z. prlnceps
princeps include one sample from Taos County, New Mexico, and four samples from Larimer County, Colorado.

�20

Table 1. List of specimens from which samples were taken for genetic analyses. Each specimen is identified
by a genetic code name, general location, and origin of the specimen.
Code

Location

BAD
BOS
BVC
CCF
CCR
CGA
CZP
DC
DMNH

Origin of Specimen

Badwater Creek, Natrona County, WY
hudsonius
South Boulder Creek, Boulder County, CO
Beaver Creek, El Paso County, CO
Warren Air Force Base, Laramie County, WY
Chicorica Creek, Lake Dorothey State Park, Las Animas Co., CO
Medicine Bow NF, Albany County, WY
Neota Creek, Larimer County, CO
U. S. Air Force Academy, El Paso County, CO
San Isabel National Forest, Las Animas County, CO

ZAHU

East Plum Creek, Douglas County, CO
Hay Gulch, Elbert County, CO
Coal Creek, Jefferson County, CO
Lake De Smet near Buffalo, Johnson County, WY
hudsonius
Lone Pine Creek, Larimer County, CO
Lone Tree Creek, Weld County, CO
Marshall Road, Dry Creek Ditch #2, Boulder County, CO
Rabbit Creek, Larimer County, CO
Rocky Flats Environmental Technology Site, Jefferson County, CO
Roxborough State Park, Douglas County, CO
Smith Creek, U. S. Air Force Academy, El Paso County, CO
St. Vrain, Boulder County Open Space, Boulder County, CO
West Fork Schwacheim Creek, Lake Dorothey, Las Animas Co., CO
Woodhouse Ranch, Douglas County, CO
West Plum Creek, Douglas County, CO
Monument Creek, El Paso County, CO
Ralston Creek, Jefferson County, CO
Indiana

ZHCSDC

Custer County, SD

EPC
HAY
JCC
LDS
LPC
LTC
~

RBC
RF
ROX
SCR
STV
WFS
WHR
WPC
WRN

WRP

ZHCWYW Weston County, WY
ZHLNMO Otero County, NM
ZHLNMS Sandoval County, NM
ZHPNEC Cherry County, NE
ZHPNEG

Garden County, NE

ZPPCOG

Grand County, CO

ZPPNMf

Taos County, NM

Museum specimen identified as Z.

Z. h. preblei survey
Z. h. preblei survey
Z. h. preblei survey
Museum specimen identified as Zapus
Z. h. preblei survey
From B. Wunder identified as Z. princeps
Z. h. preblei survey
Museum specimen identified as
Z. princeps princeps
Z. h. preblei survey
Z. h. preblei survey
Z. h. preblei survey
Museum specimen identified as Z.
Z. h. preblei survey
Z. h. preblei survey
Z. h. preblei survey
Z. h. preblei survey
Z. h. preblei survey
Z. h. preblei survey
Z. h. preblei survey
Z. h. preblei survey
Museum specimen identified as Zapus
Z. h. preblei survey
Z. h. preblei survey
Z. h. preblei survey
Z. h. preblei survey
Museum specimen, may be either
Z. h. intermedius or Z. h. americanus
Museum specimen identified as Z. h.
campestris
Museum specimen identified as Z. h.
campestris
Museum specimen identified as Z. h. luteus
Museum specimen identified as Z. h. luteus
Museum specimen identified as Z. h.
pallidus
Museum specimen identified as Z. h.
pallidus
Museum specimen identified as Z. p.
princeps
Museum specimen identified as Z. p.
princeps

�21

MRD97&amp;lMNH9716
ROX9701

80S9706

EPC9701
ZHCSOC2---

70

LOS1 - - RSS1076

OZP1
OCR
ZH.N

Figure 3. Graphical representation of the genetic relationships among the single most-representative individuals
from eachpopulation or reference group ofjumping mice sampled as determined by Riggs ct al. (1997). The more
branching that occurs between the center circle and the edge of the circle, the more dissimilar that sample, or
group of samples is from the rest of the samples. The numbers on the lines emanating from the center circle are
bootstrap values. Bootstrap values greater than 90 indicate those relationships which are strongly supported. Each
specimen location can be derived by matching the sample code with those in Table 1. Numbers following the
alphabetical code in this figure denote the sample number used in the analyses from that location.

�22
DISTRIBUTION

The meadow jumping mouse (Z. hudsonius) is broadly distributed across North America from
the Atlantic to Pacific coasts, extending south into the United States to Alabama and Georgia and west
across the Great Plains to the base of the Rocky Mountains (Fig. 2a). In general, it is a common
inhabitant of moist, grassy and herbaceous fields. Eleven living subspecies have been described
(Whitaker 1972). Hafner et al. {1981) describe a twelfth subspecies, Z. h. luteus.
Z. h. preblei occurs only in eastern Colorado and southeastern Wyoming (Krutzsch 1954, Long
1965, Armstrong 1972). From its limited ecological and geographic distribution, Fitzgerald et al.
(1994) suggest it is an Ice Age relict, once widespread in tallgrass prairie across the eastern plains of
Colorado but now restricted to scattered localities on the Colorado Piedmont. Similar relict
populations of meadow jumping mice in the White Mountains of Arizona and the Sacramento
Mountains and Rio Grande Valley of New Mexico are described as the subspecies Z. h. luteus (Hafner
et al. 1981).
Numerous surveys have been conducted since 1990 to establish the current distribution of
Preble's meadow jumping mouse {Fig. 4). Surveys have been funded by the U. S. Fish and Wildlife
Service, Rocky Flats Environmental Technology Site, Colorado Division of Wildlife, U. S. Air Force
Academy, Warren Air Force Base, Colorado Department of Transportation, City of Boulder Open
Space and Real Estate Department, and Boulder County Parks and Open Space Department
(Armstrong et al. 1997, P. Plage, personal communication). From 1990 to 1997 such surveys have
yielded captures of Preble's meadow jumping mouse, based on field identification and supported by
the genetic analyses, at the following sites:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.

12.

Lone Pine Creek, Larimer County, Colorado
Rabbit Creek, Larimer County, Colorado
St. Vrain Creek and associated tributaries in Boulder County, Colorado
City of Boulder Open Space, along South Boulder Creek and its tributaries, Boulder
County, Colorado
Coal Creek, Jefferson County, Colorado
Rocky Flats Environmental Technology Site, Jefferson County, Colorado
White Ranch P,ark, Ralston Creek, Jefferson County, Colorado
Plum Creek drainages including Indian Creek, West Plum Creek, and East Plum Creek,
Douglas County, Colorado
Roxborough State Park, Douglas County, Colorado
Hay Creek, Elbert County, Colorado
Monument Creek on the U. S. Air Force Academy {AFAC) and tributaries of Monument
Creek off the AFAC including Smith Creek, Pine Creek, and Jackson Creek, El Paso
County, Colorado
Medicine Bow National Forest, Albany County, Wyoming

Two more sites yielded mice that were identified as Z. h. preblei in the field but were genetically found
to be more closely allied with Z. princeps (see Genetics section). These sites include:

I.
2.

Warren Air Force Base, Laramie County, Wyoming
Lone Tree Creek, Weld County, Colorado

Similarity of the habitat at these sites compared to those where Z. h. preblei (as determined genetically)
were found suggests the possibility of areas of sympatry or parapatry between the two species of Zapus.
According to Fitzgerald et al. (1994) the distributions of Z. princeps (Fig. 2b) and Z. hudsonius (Fig.
2a) do overlap. The area of overlap occurs in eastern Wyoming. The distribution of Z. hudsonius in
Colorado is now known to be larger than shown in Fitzgerald et al. (I 994). The boundaries are
currently as far south as Las Animas County (based on genetically identified specimens of Z. h.

�23

Platte

Goshen
□

Albany

□

□

□

□

•

Wyoming

Laramie

Weld

Colorado

Boulder
0

Adams

Denver

Arap~hoe
•

Elbert

□

El Paso

r:fl
□

Pueblo

Las Animas

a

New Mexico

Figure 4. Distn"bution of historical occurrence (o) of Z. h. preb/ei, sites trapped since 1990 where Z. h. preblei
were found(•). sites trapped since 1990 whereZ. h. preb/ei were not found(□). sites where mice were found and
identified as Z. h. preb/ei in the field but were genetically identified as Z. princeps {[!I), and sites where mice were
found and identified as Z. princeps but were genetically found to be Z. h. preblei (D).

�24

preblei). Captures of Z. princeps and Z. hudsonius (as identified in the museum) have occurred as
close as 8 miles within the same drainage (Armstrong 1972). Z. princeps were reported captured in
1981 (Olson and Knopf 1988) at the Lone Pine site in Larimer County, Colorado, where Z. h. preblei
were captured this year. Because neither specimens or genetic samples were taken in the 1981 study,
identification of those mice will remain in question. The discrepancy may be explained by field
misidentification or Meaney et al. (I 997) also suggest this discrepancy might be explained by
displacement of Z. princeps with Z. h. preblei sometime in the 16 intervening years between trapping
efforts. Although assumed to have different ecological requirements, genetic evidence presented here
suggests further investigation of possible distributional overlap between Z. h. preblei and Z. princeps.
Several notable results from the genetic analysis of specimens acquired from the Denver
Museum of Natural History may affect the location of the southern distribution of Z. h. preblei. One
site yielded mice identified as Z. p. princeps in the field but were found to be genetically more closely
allied with Z. h. preblei. This site is the most southern location to date of Z. h. preblei and is located at:

I.

Purgatoire Campground, San Isabel National Forest, Las Animas County, Colorado

Also from Las Animas County were mice collected and identified as Z. h. luteus (Jones 1996), an
identification also supported by the genetic analysis. These mice were from:
1.
2.

Lake Dorothey State Wildlife Area, Chicorica Creek, Las Animas County, Colorado
Lake Dorothey State Wildlife Area, West Fork Schwacheim Creek, Las Animas County,
Colorado

These sites suggest a more northerly distribution of Z. h. luteus, currently known only from limited
areas in New Mexico and Arizona (Hafner et al. 1981). Identifying the southern boundary of Z. h.
preblei clearly needs further study.
Trapping surveys have also provided evidence that a number of historically occupied sites are
no longer inhabited by the mouse. Ryon (I 996) trapped eight sites of historically occupied sites with
no captures of Z. h. preblei. The eight historic sites had suffered either direct disturbances or
increasing isolation as a result of past land use, affecting vegetation structure and composition (Ryon
1997). Thus, although the perimeter of the range of Z. h. preblei may or may not have remained the
same, specific locations within the range have definitely changed and may have decreased. The pattern
of successful and unsuccessful capture sites (Fig. 4) also suggests that development of the Denver
metropolitan area may have created a north-south severing of the range of Z. h. preblei.
ECOLOGY

The ecology of Preble's meadow jumping mouse has not been studied in detail. However, from
the limited information available there appear to be a number of similarities in its natural history and
ecological requirements to populations of Z. hudsonius studied in more detail in the eastern and midwestern United States. Therefore, select information available on eastern subspecies of Z. hudsonius is
presented below to provide some framework for and possible limitations in ecological tolerances for Z.
h. preblei. However, it is critical to acknowledge the limitation and possible misleading effects of
extrapolating biological information, natural history, and ecological requirements from one subspecies
to another, across the geographic range of a species.

Demography
Reproduction: Meadow jumping mice have been observed to produce up to three litters per
season (Whitaker 1963). Breeding peaks appear to occur in early to mid-June and August with a
possible third litter in September (Whitaker 1963). Juvenile Z. h. preblei have been observed in June,
August, and September (Meaney et al. 1996, 1997, PTI 1996a, M. Bakeman unpublished data, T. Ryon
unpublished data), suggesting two litters per year. Z. hudsonius typically have litters of 5-6 young per

�25

litter (Quimby 1951 ). Age of first reproduction is unknown for Z. h. preblei, however, females of Z.
hudsonius have been observed to give birth at 3 months (i.e., females born in June have been observed
to give birth in August of the same year). Gestation period is approximately 18 days (Quimby 1951).
Young remain dependent on the female for approximately 18 days (Quimby 1951). No evidence of
male parental care exists for Z. hudsonius (Whitaker 1963).

Survival: No information exists on survival rates for populations of Z. h. preblei. Whitaker
(1963) observed an over-winter loss of 67% in a New York population of meadow jumping mice.
Most of this loss was.assumed to be from insufficient fat stores to survive hibernation. Besides
insufficient fat storage prior to hibernation, other observed mortality factors in Z. hudsonius include
predation (Whitaker 1963, Poly and Boucher 1997} and cannibalism (Sheldon 1934). Other assumed
mortality factors for Z. h. preblei include starvation, exposure, and disease.
Population Structure: Armstrong et al. (1997) reported an overall sex ratio for all captured
Preble's meadow jumping mice of 51. 6 males: 48.4 females; approximately 86. 0% of captures were
identified as adults. However, Armstrong et al. (1997) suggested that these data be interpreted with
caution because of possible differences in field techniques.

Longevity: Very few individuals of Z. h. preblei have been permanently marked. Therefore,
recapture information, necessary to determine longevity, is minimal. Several recaptures have yielded
adults surviving through two years, indicating a longevity of at least three years (T. Ryon, unpublished
data). One recapture history from Rocky Flats Environmental Technology Site recorded an adult male
in 1996, two years after it was first captured as an adult in 1994, indicating survival of at least four
years (PTI 1996b). Quimby (1951) found that only a low percentage of Z. hudsonius lived two years
or more, but gave two records of mice that lived for at least two years under natural conditions.
Whitaker (1963) reported a female living at least two years.
Dispersal.: Dispersal information will be key to any conservation strategy designed for Preble's
meadow jumping mouse. Key factors include (1) which segment of the population disperses, (2) when
do they disperse, (3) through what habitat do they disperse, (4) how far will individuals disperse (i.e.,
what is the maximum distance that separates adjacent populations) and (5) how critical is dispersal
(both into and out of a population) to the persistence of a given population. The only data available on
dispersal and/or movement for Z. h. preblei are from marked mice at Rocky Flats Environmental
Technology Site (T. Ryon unpublished data). Two mice, an adult female and an adult male, were
observed approximately 1.6 kilometers from previous locations (incidences occurred separately). Each
of the locations were in the same drainage (Woman Creek).

Population Persistence: For purposes here, population persistence is defined as the presence
of Z. h. preblei at the same site for multiple years. The majority of recent locations of meadow
jumping mice have been the result of survey efforts that focused only on determining presence of Z. h.
preblei. Once survey protocols (USFWS 1997b) are met [i.e., a minimum of 400 trapnights (one trap
set for one night = 1 trapnight) conducted] sites are typically not revisited eliminating the possibility of
determining population persistence at these sites. Thus, these and other sites not yet surveyed may or
may not have persistent populations. Areas where trapping was conducted over multiple years as part
of further research, yielded three sites in Colorado that support persistent populations: Rocky Flats
Environmental Technology Site, the U. S. Air Force Academy near Colorado Springs, and Boulder
Open Space on South Boulder Creek.
Besides establishing the presence of Z. h. preblei over multiple years, other considerations of
persistence include (1) presence in consecutive years versus a 'blinking' in and out of a population as
would be expected in a metapopulation [a set of local populations which interact via dispersal of
individuals moving among populations and where local extinctions and recolonizations occur (Levins

�26

1970)], (2) how populations are sustained in a given area (e.g., source or sink populations), (3)
maximum abundance supportable by a given area, and (4) fluctuations in abundance of a population
over years. If Z. h. preblei exist in areas as part of a metapopulation or as a series of source-sink
populations it would be critical to conserve and protect all key sub-population areas as well as critical
habitat for dispersal. Detailed population studies, including estimating and determining factors
affecting survival, reproduction, and dispersal rates, must be conducted to determine if Z. h. preblei
occurs as either metapopulations or in source-sink populations. There have been no such studies
conducted on Z. h. preblei or Z. hudsonius elsewhere to provide any supporting or refuting evidence of
this hypothesis.
Consistently low abundance in a given area due to limiting ecological requirements (e.g., size
of area of suitable habitat) or fluctuations in population abundance, including years of low abundance,
must be considered in any conservation strategies for Z. h. preblei because of the threat of complete
loss of the population due to catastrophic or extreme environmental conditions. Some evidence exists
for such fluctuations in population abundance at Rocky Flats Environmental Technology Site.
Trapping surveys on the Woman Creek drainage yielded the following captures of Z. h. preblei: seven
in 1993 (EG&amp;G 1993), zero in 1994 (T. Ryon, unpublished data), one in 1995 (T. Ryon, unpublished
data), two in 1996 (PTI 1996a), and 33 in 1997 (T. Ryon, unpublished data). Trapping effort was
consistent from 1995-1997. Repeated trapping surveys conducted over different years intermittently
yielded successful captures of Z. h. preblei along the St. Vrain Creek and lower Coal Creek (three in
1989, zero in 1992, zero in 1994, zero in 1996, one in 1997, M. Bakeman, unpublished data). If
protocols in each year were the same, these data also suggest populations may undergo fluctuations in
abundance.

Hibernation
Jumping mice of the genus Zapus are true hibernators, spending much of their lives in
hibernation. Meadow jumping mice spend approximately 7 months (~210 days) per year in hibernation
(Quimby 1951) whereas estimates for Z. princeps indicate that some populations (e.g., in the western
mountains of Utah) spend up to 300 days per year in hibernation (Cranford 1983). Males emerge prior
to females (Bailey 1923, Bailey 1929, Hamilton 1935, Quimby 1951, Whitaker 1963) with the earliest
annual recorded dates for Z. hudsonius males being April 25-May 16 and females May 4-26.
Trapping surveys for Z. h. preblei were not designed to provide estimates for dates of
immergence or emergence. However, such dates might be approximated by earliest spring and latest
fall capture dates. The earliest spring capture date recorded for an adult male was May 5 in 1993 at
Rocky Flats Environmental Technology Site (M. Bakeman unpublished data) and for an adult female,
May 21 in 1996 also at Rocky Flats Environmental Technology Site (PTI 1996b). Latest fall capture
date for an adult male was October 10 in 1994 at South Boulder Creek (ERO Resources 1995) and
September 28 in 1995 at the Van Fleet Parcel on South Boulder Creek (Armstrong et al. 1997). A
juvenile male was captured as late as October 26 and a female juvenile on October 27 both in 1995 at
Rocky Flats Environmental Technology Site (M. Bakeman, unpublished data).
Whitaker (1963) reported a 67% loss of individuals over hibernation and that average body
mass of individuals emerging from hibernation was greater than the average for mice entering
hibernation. Because no mice are known to store food in their hibemacula, this indicates that the
lighter individuals died during hibernation and only those entering with higher masses survived. All the
energy they use during hibernation and the periodic arousals (the energetically most expensive part of
hibernation) must be the fat they carry into hibernation (B. Wunder, personal communication). Thus,
the ability to put on sufficient fat for overwinter survival during hibernation is a critical factor in the life
history of these mice.
Jumping mice hibernate in underground burrows (Quimby 1951, Whitaker 1963). They are
excellent burrowers and create their own hibemacula Meadow jumping mice are generally solitary
hibernators, however, there have been occurrences of more than one mouse found in a single
hibemaculum. One hibemaculum, located on Rocky Flats Environmental Technology Site, used by Z.

�27

h. preblei has been located (Armstrong et al. 1997). This site was 9m above a creek bed (Walnut
Creek); it had a thick cover of chokecherry (Prunus virginiana) and snowberry (Symphoricarpos spp.),
the mouse was found in a leaf litter nest 30cm beneath the ground in coarse textured soil (Armstrong et
al. 1997). Four possible hibemacula were located by tracking radio-telemetered mice at the U. S. Air
Force Academy in fall 1997. These sites are located 7, 12, 29, and 31 m from a creek bed (R Schorr,
personal communication). There was no consistency among sites in aspect (N/NW, SISE, E, and none
[level ground]). Three sites were in vegetation dominated by coyote willow (Salix exigua), one site
was in vegetation dominated by snowberry and mullein (Verbascum thapsus). However, all four
hibemacula appear to be below coyote willows. These four U. S. Air Force Academy sites have not
been disturbed to protect any hibernating mice and therefore are only possible hibemacula because
there is no confirmation a mouse is actually hibernating there. Confirmation of a true hibemaculum
cannot be made until a chamber, or nest is located. These sites may also possibly be locations of radios
discarded by the mice or dead mice.
Behavior
Jumping mice, including Preble's meadow jumping mouse, are primarily nocturnal or
crepuscular but can be observed during the day. Unlike most other nocturnal small mammals Preble's
meadow jumping mice do not spend the day underground. The mice can be observed during the day,
often under shrubs attempting to remain still (M. Bakeman, T. Ryon, R Schorr personal
communication). The shrubs may provide either cover from predators or thermo~regulation.
As their common name suggests, the saltatorial ability ofjumping mice is well developed.
Although longer jumps have been observed the typical behavior is an initial jump of 60 - 90cm
followed by rapid jumps of approximately 30cm (Quimby 1951). The more common mode of
locomotion, however, is to crawl through or under grass and other vegetation flattening their bodies
close to the ground and proceeding quadrupedally (Quimby 1951). Similar jumping and crawling
behavior has been observed in Preble's meadow jumping mice as well as running, jumping, and
climbing through shrub canopies (M. Bakeman, C. Meaney, T. Ryon, R Schorr personal
communication). Given their preponderance for riparian habitats, it is not surprising to find that the
mice are also strong swimmers (M. Bakeman, C. Meaney, R Schorr, personal communication). Both
swimming and jumping abilities apparently serve more commonly as mechanisms for retreat from
either predation or perceived threats rather than as typical mechanisms for locomotion. The mouse is
also adapted for digging and creates nests of grass, leaves, and woody material (Harrington et al. 1996).
All nests found at the Rocky Flats Technology Site, with the exception of the hibemaculum, were
above-ground, generally at the base of willow (Salix spp.) clumps (M. Bakeman, personal
communication).
There does not appear to be any social structure among individuals within a population of
jumping mice. No evidence exists for parental care by the male or any interaction between males and
females after breeding occurs. Adults of the species Z. hudsonius are essentially solitary individuals.
Except when young, jumping mice are usually silent. On occasion adults have been heard to
emit chirps and other sounds (Quimby 1951, Whitaker 1963). No observations have been made of
vocalizations by Preble's meadow jumping mice. Drumming noises can be produced by vibrating the
tail rapidly against a surface (Svihla and Svihla 1933, Sheldon 1938, Whitaker 1963). Tail rattling,
appearing to be a nervous reaction when placed in a capture bag, has been observed in Preble's
meadow jumping mouse (M. Bakeman, personal communication).
Quimby (1951) and Whitaker (1963) reported that mice in the genus Zapus often washed their
feet, faces, and especially their tails. The tail was grasped in the forepaws, and passed completely
through the mouth, whereas the hands and feet were washed by means of the forepaws.
Bailey (1926) found that jumping mice would reach as high as it could on grass stems, bite
them off and pull them to the ground, repeating the procedure until the head was reached and eaten.
This process would result in a pile of pieces of grass stem, often with the rachis and glumes on top.
Whitaker (1963) found similar behavior in his study of meadow jumping mice in New York. M.

�28

Bakeman (personal communication) found piles of pieces of grass stem in areas where Preble's
meadow jumping mice were known to occur, however these piles may also have been created by
individuals of the species Microtus.

Food Preferences
Specific food habits are unknown for Preble's meadow jumping mouse. Armstrong et al.
(I 997) summarized what is currently known about food habits of meadow jumping mice in general as
follows:
Studies of food habits in central and eastern United States indicate they are governed by
• availability more than preference (Whitaker 1963). Grass seeds of several species are probably
the most important component of the diet, and mice will shift to those species that have
available seed. Invertebrates and fungi are also readily eaten. Mice feed on both adult and
larval invertebrates, especially Coleoptera (beetles). Invertebrate feeding is very important in
the spring as mice emerge from hibernation, and may consist of half of the diet at that time.
Mice also feed on various species of fungi, which are often encountered during burrowing
activity. As the growing season progresses, graminoid seeds dominate the diet.
There is no reason to believe food habitats of one subspecies should differ greatly from those of other
subspecies. This belief is further supported by the indirect evidence available that food habits of Z. h.
preblei are similar to that described above (i.e., the observation of the piles of grass stems observed in
areas where the subspecies is known to occur [see Behavior section]). •
As true hibernators, meadow jumping mice do not cache food in their hibernacula Therefore,
it is assumed they require high quality food for high fat accumulation prior to immergence. Preble's
meadow jumping mice have been observed to increase body weight by 10% in the 2-3 weeks prior to
immergence. Laboratory studies show the mouse can gain mass at rates up to 1.0 grams per day (B.
Wunder, personal communication). This ability to increase fat reserves at such a rate is used by the
mice for preparation to enter hibernation. However, for the mice to successfully gain enough fat prior
to hibernation to ensure a high probability of survival throughout hibernation, food of sufficient quality
must be available. No specific information is available on what foods Preble's meadow jumping mice
eat to meet these ecological requirements. However, from late August through early September, when
adults begin to gain weight, there are many species of graminoids that have available seed. In most
years, grasshoppers are also readily available and probably dominate invertebrate biomass in most
habitats.
Preble's meadow jumping mice are most often found near open water. Dependency on open
water has not been established, however work is currently in progress to establish if such a need exists
(B. Wunder, personal communication). Based on trapping records at Rocky Flats Environmental
Technology Site, trapping success at some sites declines dramatically after creekflow ceases, and it is
suspected there may be a shift in site use because of the absence of open water (M. Bakeman personal
communication).

Habitat Use
Landscape scale: The habitat matrix within the range of Z. h. preblei is mixed grasslands
adjacent to the Colorado Front Range along the Piedmont and along the base of the Laramie Mountains
in Wyoming and extends to the Colorado plains. Within this matrix, Preble's ~eadow jumping mice
occur along stream drainages that contain patches of suitable vegetation. Suitable habitat appears to
have at least two major components. The first component is a supply of open water, at least in part of
the active season (M. Bakeman, C. Meaney, personal communication). Secondly, areas where Preble's
meadow jumping mouse has been found have dense cover (M. Bakeman, C. Meaney, personal
communication).

�29

If Preble's meadow jumping mouse behaves as a metapopulation in the classical sense of a set
of local populations linked by infrequent dispersal then habitat includes not just one area of suitable
habitation but also areas suitable for nearby mouse populations. These suitable areas must also be
linked by dispersal habitat. If the mice are dependent on dense riparian habitat for dispersal as well as
for areas to reproduce, persistence of discrete populations would require a mosaic of suitable discrete
riparian patches interconnected with dispersal corridors of similarly dense riparian vegetation. If mouse
populations function in a source (populations where growth rate~ 1) and sink (those populations where
growth rate&lt; 1, maintained through immigration) system, it will be critical to identify and protect those
populations serving as sources. Thus, for a source-sink population critical habitat will include those
areas that support source population, dispersal habitat to sink areas will be less critical. If local mouse
populations are functionally discrete, such a mosaic of interconnected areas of suitable habitat would
provide a buffer for local, and source, populations against deleterious stochastic events by providing
the opportunity for local population failures to be 'rescued' by immigration from other populations.
Areas of suitable habitat must also provide requirements to survive throughout the life cycle.
These requirements must provide necessities for both the active period and hibernation periods.
During the active p·eriod suitable habitat must provide requirements for daily survival, reproductive
activities (breeding, nesting, and rearing of young to independence), and dispersal. The hibernation
period requires sufficient food supplies to assure fat storage prior to hibernation and suitable
hibemacula (see Hibernation above). Habitat providing all seasonal and life cycle requirements may
or may not occur in a single contiguous area If not in a contiguous area, habitat patches must occur in
a mosaic of usable areas where suitable corridors exist for seasonal movement among sites.
Site sca/,e: Based on studies of Z. h. preblei and Z. hudsonius elsewhere, Z. h. preblei

apparently occurs mostly in undergrowth consisting of grasses, forbs, or both in open wet meadows and
riparian corridors, or where tall shrubs and low trees form an overstory and provide adequate cover
(Armstrong et al. 1997). Meadow jumping mice are widespread in abandoned grassy fields, but is
often more abundant in thick vegetation along ponds, streams, and marshes or in rank herbaceous
vegetation of wooded areas (Whitaker 1963). Preble's meadow jumping mice have been trapped in
natural riparian areas as well as areas altered by anthropogenic influence including ditches and wetlands
adjacent to interstate highways, cement-lined ditches with tall cover, ditches along driveways and
moderate road use, and moderate cattle grazing (M. Bakeman, personal communication).
The majority of sites where Z. h. preblei have been found consist of multistoried cover but the
species composing the cover vary greatly (Armstrong et al. 1997, Meaney et al. 1997) . Vegetation
composition of the dense cover varies considerably and includes both native and non-native species
(Meaney et al. 1996, 1997, Armstrong et al. 1997, M. Bakeman, personal communication). The
herbaceous understory can be primarily grasses or forbs or a mixture of the two. Few of the sites,
however, are dominated by fewer than two understory species. The tall shrub canopy at most sites is
willow (several species), although scrub oak, birch, and alder occur in sites south of the Palmer Divide
(Armstrong et al. 1997). Ponderosa pine is the most common tree at higher elevations. The mouse
appears to tolerate weedy or exotic species in areas that are structurally diverse and species rich; nearly
every successful site contained Canada thistle (Armstrong et al. 1997). Thus, the mouse does not
appear to have an affinity toward any single plant species but instead favors sites that are structurally
diverse and provide adequate cover and food throughout its life cycle.
Preble's meadow jumping mouse mice are typically not found in upland areas away from
riparian habitats but are most often captured where either ground water daylights to seep springs or on
main water channels (M. Bakeman, T. Ryon, personal communication) suggesting a dependence on
open water, at least during their active periods.
Movement of Z. h. preblei on Woman Creek at Rocky Flats Technology Site suggests mice
move along corridors of shrub cover, generally Salix exigua (PTI 1996a, T. Ryon, unpublished data),
suggesting dispersal habitat is similar to habitats used for other activities.

�30

SMALL MAMMAL ASSEMBLAGE

Preble's meadow jumping mice are only one component of the small mammal community
inhabiting areas where they were captured. These mice were more often found at sites with high
species richness and abundance of small mammals (Armstrong et al. 1997, Meaney et al. 1997). The
variety and relative abundance of other small mammalian species trapped during surveys for Preble's
meadow jumping mouse provide some framework for comparison of small mammal assemblages at
sites where Z. h. preblei occurred and sites where no Preble's meadow jumping mice were captured
(Table 2). All trapped sites were either historical sites of known occurrence or apparently suitable
habitat for Z. h. preblei, providing a common basis for comparison. Three small mammal species
(Spermophilus variegatus, Peromyscus nasutus, and Rattus norvegicus) were not captured where Z. h.
preblei occurred but were captured in unsuccessful sites. However, total capture occurrences of these
three species were only one or two sites and the species comprised an extremely small percentage of
the species caught in those areas (Table 2) providing too little information for speculating on possible
interactions between these species and Z. h. preblei.

Table 2. Small mammal community analysis from sites where Preble's meadow jumping mice (Zapus hudsonius
preblei) were captured (n = 28) and not-captured (n = 35). Reported here are number of occUITences a given species
was found in areas with and without Preble's meadow jumping mice captures (n and mean percentage and standard
error (se) of capture that given species contributed to total small mammal captures at a given site. Data are summarized
from Armstrong et al. (1997) and Meaney et al. (1997). All sites were either areas of historical occUITence of Preble's
meadow jumeing mice {n = 82 or OCCUITed in areas of aeearently suitable habitat.
0)

Z. h. preblei Not Captured

Z. h. preblei Captured
Species

% Capture
mean (se)

no

% Capture
mean (se)

no

Zapus hudsonius prehlei

28

6.65 (1.38)

35

Spennophilus variegatus

0

0

2.0

Peromyscus nasutus

0

0

3.0

Rattus norvegicus

0

0

2

9.5 (8.2)

l.0(-)

0

0

Mustela sp.
Chaeotodipus hispidus

2

1.4 (0.2)

5

3.0 (0.8)

Mus musculus

3

5.8 (4.6)

17

18.4 (6.0)

Sorex cinereus

4

1.1 (0.7)

5

2.0 (0.5)

Microtus longicaudus

5

15.8 (6.3)

3

9.6 (4.3)

Neotoma mexicana

5

6.1(1.7)

8

12.5 (3.6)

Reithrodontomys megalotis

5

3.6(1.4)

II

3.7 (0.6)

Microtus spp.

8

18.3 (6.4)

4

5.7 (4.3)

Microtus ochrogaster

18

16.0 (3.7)

25

13.0(3.5)

Microtus pennsylvanicus

21

26.2 (4.4)

32

25.8 (4.4)

Peromyscus maniculatus

27

50.4 (3.4)

32

54.8 (5.2)

�31

The higher occurrence and percent composition of capture of Mus musculus, the house mouse,
in areas where Z. h. preblei was not caught might suggest degradation of habitat for Z. h. preblei in
those areas or possibly competition between the two species (Ryon 1996). The house mouse, thrives
in areas of human habitation and croplands, but also occurs in abandoned fields and ditch banks where
they may displace native rodents (Fitzgerald et al. 1994). Ryon (1996) also reported the presence of
domestic cats (Fe/is catus) at sites where Z. h. preblei historically occurred but were not found during
his study. Contrarily, C. Miller (personal communication) reported house cats along South Boulder
Creek where Preble's meadow jumping mice are known to occur.
Caution must be used when percentage of capture is used as an index.to the composition and
relative abundance of small mammals within a given area Captures may be influenced by trap
placement, bait, season, or trapping protocol. Percentage of capture for a given species may also be
biased because of either trap-shy or trap-happy individuals within a species or because some species, in
general, tend to be easier or harder to trap. Preble's meadow jumping mice appear to favor 'clean'
traps. Once traps have been used and soiled by individuals of other species, the probability of
capturing a meadow jumping mouse in that trap appears to decrease (M. Bakeman, A. Deans, F.
Harrington, T. Ryon, personal communication). For example, of the 60 captures of Z. h. preblei by M.
Bakeman (unpublished data) in 1997 all were captured in traps that had only previously been occupied
by Preble's meadow jumping mice. Evidence to the contrary, however, also exists. On at least one
occasion, R Schorr (personal communication) caught a Preble's meadow jumping mouse in a trap
previously occupied by Sorex sp.
If one does assume no trapping biases occurred, where captured, Z. hudsonius was one of the
less common species in the areas trapped (Table 2). If such rarity in areas of occurrence is genuine
then this combined with both its limited distribution and absence from historically occupied areas
supports the need for immediate protection of the subspecies and its habitat.
POSSIBLE THREATS TO CONSERVATION

•The range of Z. h. preblei corresponds largely to the rapidly developing ~ront Range Urban
Corridor that runs from Colorado Springs, Colorado to Laramie, Wyoming. Therefore, possible threats
to Z. h. preblei survival may include the widespread destruction and modification of riparian corridors
and wet meadow habitats by human land uses (USFWS 1997 a). Agricultural, residential, commercial,
industrial, and recreational development are likely the cause of such impacts. Specific activities such as
water diversion, stream channelization, and sand, gravel and aggregate mining have impacted habitats
required by the mouse Other activities such as overgrazing and development of recreational trails may
also impact Preble's meadow jumping mouse habitat.
Armstrong et al. (1997) summarized results of habitat studies conducted on Z. h. preblei,
including the following summary of disturbance elements.
Over the past 100 years the [riparian habitat used by Z. h. preblei] has become increasingly
urbanized as influenced by grazing, water diversions, wetland conversion, and real estate
development. Compton and Hugie (1993) identified agricultural, residential, and commercial
development as habitat impacts and suspected grazing as having a negative influence on
meadow jumping mouse habitat. Ryon ( 1996) identified alterations to habitat at eight historic
meadow jumping mouse sites. These alterations include water diversion, highway construction,
gravel mining, grazing, and real estate development. Although suitable habitat exists within this
landscape unit, the anthropogenic influence is changing the unit as a whole and fragmenting and
degrading riparian areas in general.
The effect of these land use practices on mouse distribution is poorly understood. Several
investigators have been puzzled at the lack of jumping mice at sites with seemingly well
structured habitat, and the presence of mice at a few sites with less than optimal conditions.
Land use histoiy of an area may provide clues as to whether mice are at a site or if they can be

�32

restored. The reviewers of the [Report on Habitat Findings of the Preble's Meadow Jwnping
Mouse, edited by M. Bakeman] list six potential impacts that were thought to play a role in
distribution of Z. h. preblei including trails, grazing, mining, development, haying, and riparian
hydrology.
In order to threaten conservation of Z. h. preblei a feature or features of their ecological
requirements must be altered in such a way as to make the area unusable to the mouse or limit its
usefulness to such an extent as to deplete the areas' potential for supporting a viable population of Z. h.
preblei. Therefore, a threat is defined as any activity that_has the potential to negatively alter any
ecological requirements of Z. h. preblei. Effects of the potential threats, listed below, may be
permanent or temporary. Management strategies may be developed to offset or eliminate effects from
various activities. However, such management strategies are only as good as our knowledge of the full
complement of ecological requirements necessary to maintain a viable population of Z. h. preblei. The
following defines such ecological requirements, provides specific examples of activities that could
negatively alter these requirements, and suggests how these negative impacts would affect the mouse.

Vegetation composition and structure
Vegetation composition and structure affects many of the ecological requirements of meadow
jumping mice including food, cover, nest sites, and suitable dispersal corridors. Vegetation
composition in areas inhabited by Preble's meadow jumping mouse must include species that would
provide not only daily nutritional requirements but also high quality foods necessary for the quick, high
fat storage that occurs prior to hibernation. Cover may provide concealment from predators, areas for
thermoregulation, and raw material for above-ground nests. Above ground nests appear to be
associated with woody (tree and shrub) structures (M. Bakeman, personal communication). Dispersal
habitat must provide sufficient cover and food to assure successful dispersal from one area to another.
Activities which could threaten vegetation structure include: grazing, development (including
residential, commercial, industrial, and recreational), fire, sand, gravel and aggregate mining. Grazing
may alter vegetation structure by either decreasing or eliminating sufficient tree, shrub, and/or tall grass
cover. Heavy grazing is especially hard on woody plants. Species composition may also be altered by
grazing, eliminating critical food resources. Development of an area may impact species composition,
abundance, and density. Developments such as cutbanks would eliminate all vegetation. Short-term
effects of fire may be deleterious if above-ground nests (especially with young) are destroyed. Longterm effects may be minimal, if the population can withstand minor losses. Mining operations for
aggregate material generally eliminates most vegetation, affecting both structure and composition.
Possible deleterious effects on populations of Z. h. preblei include decreased survival,
reproduction, or ability to disperse.
Riparian Hydrology
Hydrology includes physical presence of open water, water quality, seasonality of available
open water and amount of water flow.
Activities which could threaten suitable hydrologic regimes for populations of Z. h. preblei
include water diversion projects, water management projects including irrigation regimes and ditch
maintenance, and pollution. These activities could result in loss or increase of surface water supplies,
alter flooding events which may be necessary to maintain vegetation composition and structure, and
produce siltation in catchment areas. Such activities do not actually have to occur on areas of suitable
Z. h. preblei habitat but could occur upstream or downstream of the site. Mining operations can
indirectly affect habitat by altering downstream hydrological flows of both surface water and
groundwater. Urbanization may affect water quality and stream flows through siltation of catchment
areas, presence of pesticides in water, increased nutrient load, and vegetation composition. At Rocky
Flats Technology Site, Preble's meadow jumping mice are most often captured where either ground

�33

water daylights to seep springs or on main channels fed by seep springs (T. Ryon, personal
communication) suggesting a dependence on open water, at least during their active periods.
Possible deleterious effects on populations of Z. h. preblei if riparian hydrology is altered
include decreased survival or reproduction.
H abitaJ structure
Habitat structure includes size of suitable area, connectivity of suitable sites to other suitable
sites through corridors, and inclusion of all ecological requirements within a given area Thus, altering
habitat structure could result in fragmentation of a suitable site, isolation. of a site to other suitable
sites, degradation of a suitable site, or total loss of useable habitat
Activities which could threaten habitat structure include: aggregate mining, grazing, real estate
development, pollution, and fire. Movement of Preble's meadow jumping mice on Woman Creek at
Rocky Flats Technology Site suggests mice move along corridors to patches of the most suitable
habitat. Most captures occur in areas of shrub cover, generally Salix exigua (PTI 1996a, T. Ryon,
personal communication).
Possible deleterious effects on populations of Z. h. preblei include decreased abundance due to
a decrease in suitable habitat, loss of inter-connectivity of sites that may be necessary to maintain viable
populations either in a source-sink or metapopulation situation, and may also result in decreased gene
flow through isolation.
Distribution
Distribution can be defined on several scales: range perimeter, distribution within the range,
and distribution within connected suitable habitat. As discussed above (see Distribution section),
based on a comparison of currently known sites and historical sites of occurrence of Z h. preblei it is
clear distribution (within the historical range) has already been altered.
Activities which could alter distribution of Z. h. preblei include real estate development and
sand, gravel and aggregate mining by severely degrading or completely eliminating required habitat.
Possible deleterious effects on Z. h. preblei include loss of populations throughout the
complete ecological range of suitable habitat and further fragmentation within the range of Z h.
preblei. These effects could (I) eliminate critical populations of Z. h. preblei to maintain possible
metapopulations or source populations or (2) restrict gene flow among populations.
Geomorphology
Geomorphology is defined as the description of features of the earth's surface as explained by
the underlying dynamic and structural geology. Important geomorphological features that may help
delineate habitat for Z. h. preblei include stream and floodplain geometry. Steepness of stream banks
may affect vegetation composition ans structure. Underground structure along stream banks may
provide critical hibemacula sites.
Activities that would affect geomorphology include development and mining of sand, gravel,
and aggregate material. Preble's meadow jumping mice have rarely been captured in steep-sided
drainages (M. Bakeman, personal communication).
Possible deleterious affects of altering the geomorphology in areas used by Preble's meadow
jumping mouse include decreased survival due, possibly, to insufficient availability of suitable
hibemacula
Animal Community Composition
Animal community composition includes the ocuurance and abundance of all other species in
Preble's meadow jumping mouse habitat.
The primary activity that may affect populations of Z. h. preblei is development. In particular,
the introduction of the house mouse and the house cat may alter the suitability of a site for Preble's
meadow jumping mouse; the house cat as a new and effective predator, the house mouse as a possible

�34

competitor for resources. Other possible effects of altering the animal community is the introduction of
new diseases and parasites to Preble's meadow jumping mouse.
The possible deleterious effects of altering the animal community within areas of habitat for
Preble's meadow jumping mouse include decreased survival through increased predation, disease,
parasites, or competition for resources.

CONSERVATION STRATEGY
INTRODUCTION

This preliminary conservation strategy describes the current status and the goal, objectives,
strategies, and research that should be implemented to maintain and restore viable populations of Z.
hudsonius throughout its range and to conserve and manage Preble's meadow jumping mouse habitat.
This is intended to be a preliminary planning effort based on the best scientific data available to date.
This strategy may also serve as a starting point for more comprehensive conservation planning efforts
regarding Z. h. preblei.
•
This strategy is designed to be implemented through the cooperation of state, federal, and
municipal government agencies, and involve partnerships with private conservation organizations,
individuals, and landowners. The outlined conservation strategy objectives are not necessarily listed in
order of priority, but in a logical manner that provides for completion of information needs prior to
addressing specific actions.
CURRENT STATUS

On March 25, 1997 the U. S. Fish and Wildlife Service (USFWS) published a proposed rule in
the Federal Register (62 FR 14093) to list Preble's meadow jumping mouse (Z. h. preblei) as
'endangered' under the Federal Endangered Species Act (ESA). Final ruling on the proposed listing is
scheduled by March 25, 1998. There are three possible outcomes depending on progress of
conservation efforts and knowledge gained prior to the decision date: list as endangered, list as
threatened, or withdraw the proposal. The primary reason for the proposed listing of Preble's meadow
jumping mouse under Section 4 of the ESA is 'present or threatened destruction, or modification ofits
habitat or range' as well as lack of meaningful protection. The listing decision will be made by the U. S.
Fish and Wildlife Service solely on the basis of the best scientific data available.
As stated in USWFS 1997b: "All Federal agencies have responsibility under section 7(a)(4) of
the ESA to protect proposed endangered and threatened species and habitats on which they depend.
For projects where a Federal nexus exists (Federal permit, Federal funding, projects on Federal land)
and there is potential affect on Z. h. preblei or its habitat, the Federal action agency should contact the
USFWS. In addition, the USFWS encourages all Federal agencies to review their properties and
projects and make funds available to conduct Z. h. preblei surveys in all potential habitat. It is also
imperative to make project proponents aware of the presence of Z. h. preblei should it be listed prior to
the time all actions related to any project are completed. Section 9(a)(l) of the ESA prohibits the take
(i.e., harass, harm, pursue, hunt, shoot, kill, wound, trap, capture, or collect, or to attempt to engage in
any such conduct) of federally endangered or threatened species, except as provided in sections 6(g)(2)
and 10 of the ESA. If Z. h. preb/ei is listed while a project is impacting it or its habitats, the ESA
would enter into effect to protect Z. h. preblei. A project occurring in poor or marginal habitat but
having potential to disrupt a travel corridor (such as a road crossing a creek) is also of concern as well
as the question of secondary impacts from proposed projects. Projects removed from potential Z. h.
preblei habitat that have the potential to adversely impact the habitat may also require a survey. For
example, a residential or commercial development upslope from a creek supporting potential Z. h.
preblei habitat may significantly increase runoff or otherwise impact the hydrology, and thereby the
habitat present on the creek." Therefore, even prior to a decision on the proposed listing, there is a

�35

great need to provide information on the ecology and ecological requirements necessary for
conservation of Z. h. preblei.
The species Z. hudsonius was designated as Colorado nongame wildlife (Colorado Division of
Wildlife Regulations, Chapter 10, Article N, #1004 A 6), which provides a legal protection against
taking. It is also a Colorado Division of Wildlife Species of Special Concern, which is an
administrative classification rather than a legal one. However, there are current efforts within the
Colorado Division of Wildlife to list the subspecies as State Endangered (J. Sheppard, personal
communication), defined as any species or subspecies of native wildlife whose prospects for survival or
recruitment within the state are in immediate jeopardy. The Colorado Natural Heritage Program
(1997) lists the mouse as an S2 species: imperiled in the state because of rarity (6 to 20 occurrences)
or because of other factors demonstrably making it very vulnerable to extirpation from the state.
Conservation of Preble's meadow jumping mouse was also listed as a specific task to be addressed by
both the State of Colorado and the Department of the Interior in the Memorandum of Agreement (94SMU-058), signed by Governor Roy Romer and Interior Secretary Bruce Babbitt on November 29,
1995, between the State of Colorado and the Department of the Interior concerning 'Programs to
Manage Colorado's Declining Native Species.' The Wyoming Natural Diversity Database (Fertig 1997)
ranks Z. h. preblei as S 1: critically imperiled in the state because of extreme rarity (five or fewer extant
occurrences or very few remaining individuals) or because of some factor of the subspecies life history
that makes it vulnerable to extinction. The Wyoming Department of Game and Fish (1998) ranks the
subspecies as nongame through their Nongame and Wildlife Habitat Protection Programs.
GOAL

The goal of this conservation strategy for Preble's meadow jumping mouse should work
towards the sustainability, protection, and restoration of Z. h. preblei populations and habitats on both
private and public lands to provide the spatial, genetic, and demographic structure needed to promote
long-term species viability and provide species management flexibility. Specific objectives include the
following.
OBJECTIVES

I.

2.

Document the present distribution of Z. h. preblei. This will require the following:
•
Conduct trapping surveys to better define the boundaries of the range of Z. h.
preblei.; conduct trapping surveys in areas of potential sympatry of Z. h. •
preblei with Z. princeps; evaluate effect of small mammal species richness and
composition on the distribution and/or abundance of Z. h. preblei.
•
Further explore genetic relationships among different Z. h. preblei populations,
among different subspecies of Z. hudsonius, and among different species of
Z:O.pus.
Identify populations of Z. h. preblei where the rate of population growth &lt;!: 1. This will
require population studies to estimate the following parameters:
•
Survival (annual, over-summer, over-hibernation), and identity of factors
affecting survival [e.g., weight, sex, age, abundance (i.e., density dependent Z.
h. preblei response), habitat features (e.g., stream reach, vegetation
composition), weather, predation, disease].
•
Reproductive and developmental parameters (i.e., number oflitters per year,
number of young per litter, age at first reproduction, juvenile survival), and
identity of factors affecting reproduction [e.g., habitat features (i.e., food
quality, nest site availability, cover availability), abundance (i.e., density
dependent response), weather].
•
Recruitment, and identity of factors affecting recruitment (e.g., weather, habitat
features).
•
Immigration and emigration rates, and identity of factors affecting immigration,
emigration (e.g., age, habitat features, abundance).

�36

3.
4.
5.

•
Population structure (sex and age ratios)
•
Dispersal parameters (rate, who disperses, time of dispersal)
•
Abundance, and identity of factors affecting abundance (e.g., habitat features).
•
Rate of population change.
Protect populations of Z. h. preblei where the rate of population growth is ::1: I.
Maintain current range of natural variability of Z. h. preblei.
Identify ecological requirements for sustaining viable populations of Z. h. preblei
throughout its range of natural variability. This will require research to address the
following:
•
Estimate habitat use [distances traveled (daily, seasonally), landscape features
(connectivity with other potential sites, geology), seasonal use, hibemacula,
nest sites, distance to nearest open water, hydrology (water quality, flow),
abundance (i.e., density dependent responses), and cover].
•
Dispersal habitat [end point descriptions (disperses from what to what),
landscape features (connectivity with other riparian strips, corridor use,
overland use].
•
Physiology (e.g., estimate dependency of Z. h. preblei on open water, food
habits, effects of varying water quality on Z. h. preb/ei physiology) .

•
6.
7.
8.
9.
10.
11.
12.
13.

Protect habitats to sustain or restore populations of Z. h. preblei with high where the
rate of population growth ::1: 1.
Promote protection, management, and possible restoration of habitat for conservation
of Z. h. preblei in all currently or recently occupied and suitable habitat.
Monitor the status of Z. h. preblei populations throughout its range to detect changes in
local distribution.
Identify threats to the conservation of Z. h. preblei.
Eliminate or minimize threats to Z. h. preblei conservation.
Integrate Preble's meadow jumping mouse conservation strategy objectives with
management and habitat objectives of other Front Range riparian species.
Promote scientific management of Preble's meadow jumping mouse.
Promote public support for Z. h. preblei conservation efforts and scientific
management of Preble's meadow jumping mouse through public education.

RESEARCH NEEDS

There are currently four research projects being conducted on Z. h. preblei, with a fifth planned
to begin spring of 1998. Each of these projects is designed to provide further information on the
ecology or demography of Preble's meadow jumping mouse. However, if research methodologies were
standardized and coordinated across all the projects, comparability and quality of the data would be
greatly enhanced. Such a coordinated effort would maximize data quantity, quality, and comparability
over varying conditions throughout the range of Z. h. preblei in the most effective and efficient way
possible. Comparable information gained across the ecological range of Z. h. preblei would then
provide more useful information for use in developing sound management strategies for conservation
of the mouse.
To achieve such a coordinated research effort all project leaders must agree to follow data
collection protocols, establish 'ownership' of data and future publications, and work cooperatively on
the possible sharing of equipment and technical assistance during peak data collection periods. To
facilitate such a mutual effort will require the participation of all project leaders conducting field studies
of Z. h. preblei as well as cooperative investigators, and specialized data analysts with expertise in the
study design, analysis, and interpretation of mark-recapture and telemetry data A proposed agenda
including tasks, task leaders, and a timetable to initiate a cooperative research effort include:

�37

Task

Task Leader, Affiliation

Date

Identify all potential participants: project leaders,
cooperating investigators, data analysts.

T. Shenk, Colorado Division of
Wildlife

January 1998

Prioritize research questions.

All project leaders*

January 1998

Identify sites to best address prioritized research needs.

All project leaders

January 1998

Design studies specific to research question to be
addressed at each site.

All project leaders, cooperating
investigators, data analysts

January-February
1998

Evaluate needs at each site to conduct specified
research.

All project leaders

March 1998

Identify discrepancies between needs and available
funds, equipment, and personnel currently allocated for
each site.

All project leaders

March 1998

Attempt to balance discrepancies.

All project leaders, cooperating
investigators

March 1998

* To date: M. Bakeman, C. Meaney, T. Ryon, R. Schorr, T. Shenk

The following outline lists research needs to provide information to develop sound
management strategies for conservation of Z. h. preblei. Research needs are not listed in order of
priority, but listed in a logical manner to provide completion of needs.
There are three components of Z. h. preblei ecology that are currently unknown and yet key to
any sound conservation strategy for the subspecies. These are (I) detailed demographic studies
estimating survival and reproduction and determining the factors influencing each of the parameters,
(2) detailed studies evaluating movements and dispersal habitat of individuals within and among
populations, and (3) detailed studies to define hibernation needs, primarily descriptions of suitable
hibernacula criteria and food requirements for sufficient fat storage prior to immergence.

Demographic studies: Information on the population dynamics of Preble's meadow jumping mouse is
necessary to determine which areas support populations where the rate of population growth is &lt;!: 1.
Key parameters to estimate include:
Survival:
• estimates of survival, including
►
annual
►
over-summer
►
over-hibernation
• investigate possible factors affecting survival, including
►
weight
►
sex
►
age
►
abundance (i.e., density dependent response)
►
habitat features: stream reach, vegetation composition
►
weather
►
predation
►
disease
Approach: mark-recapture techniques

�38

Recruitment:
• estimate recruitment (as an alternative to reproductive parameters listed below)
• investigate possible factors affecting recruitment, including
►
weather
►
habitat features
Approach: mark-recapture techniques
Population structure:
• estimate sex ratios
• estimate age ratios
Approach: mark-recapture techniques
Abundance:
• estimate abundance
• investigate factors affecting abundance, including
►
habitat features (see under habitat use)
Approach: mark-recapture techniques for closed populations
Immigration, emigration:
• estimate rates of immigration and emigration
• investigate possible factors affecting immigration, emigration
►
habitat features (see under habitat use)
►
abundance (i.e., density-dependent response)
Approach: estimate rates from mark-recapture data, identify existence with radio telemetry
Reproduction:
• estimate number of litters per year
• estimate number of young per litter
• estimate age at first reproduction
• estimate juvenile survival
• investigate possible factors affecting reproduction, including
►
habitat features: food availability, nest site availability, cover availability
►
abundance (i.e., density-dependent response)
►
weather
Approach: from telemetry work
Dispersal Studies: Dispersal is a key process in metapopulation theory and to maintain genetic
diversity between isolated populations. Key parameters to evaluate include:
Population parameters
• who disperses
• time of dispersal
• estimate rate
Approach: estimate rate with mark-recapture, document who and when from both telemetry
and mark-recapture data
Habitat parameters
• through what habitat
• end point descriptions (disperses from what to what)
• landscape features (connectivity with other riparian strips, corridor use, overland use)
Approach: document where from both telemetry and mark-recapture data

�39

Distribution Studies: Conservation of Z. h. preblei should maintain populations throughout the range
of its natural variation and to try to identify ecological limits for the subspecies. Key concerns include:
Range-wide distribution:
• conduct trapping surveys to better define the eastern boundary of the range of Z. h. preblei
• conduct trapping surveys in areas of potential sympatry of Z. h. preblei with Z. princeps
Approach: determine from trapping surveys
Habitat Studies: To identify and define habitat requirements of Z. h. preblei studies should be
conducted to address the following:
Habitat use:
• estimate distances traveled: daily, seasonally
• describe landscape features (connectivity with other potential sites, geology)
• determine seasonal use
• describe hibernacula
• describe nest sites
• estimate distance to nearest open water from other habitats used
• describe hydrology (water quality, flow) in areas of use
• evaluate effects of abundance on habitat used (i.e., density dependent responses)
Approach: estimate from telemetry work
Physiological Studies: Physiological studies will provide information on the mechanisms driving
habitat selection.
Physiological, requirements:
• estimate dependency of Z. h. preblei on open water
• determine energetic requirements to survive hibernation
Approach: estimate from laboratoiy studies
Systematic Studies: To better define the relationship of Z. h. preblei to other subspecies of Z.
hudsonius and other species of Zapus the following studies should continue.
Molecular systematic relationships:
• further explore genetic relationships among different Z. h. preblei populations
• further explore genetic relationships among different subspecies of Z. hudsonius
• further explore genetic relationships among different species of Zapus.
Approach: explore through laboratoiy studies
Systematic relationships:
• link genetic relationships to systematic studies of Z. hudsonius.
Approach: explore through museum studies
Community Studies: Composition of the community where Z. h. preblei occur could help explain
ecological tolerances of the subspecies, providing insight to the mechanisms determining its
distribution.
Small mammal assemblages:
• comparison of small mammal assemblages in areas where populations of Z. h. preblei
occur and areas where they do not
►
species composition
►
relative abundance
Approach: estimate from trapping surveys

�40
LITERATURE CITED

Armstrong, D. M. 1972. Distribution of mammals in Colorado. University of Kansas, Museum of
Natural History Monograph 3:1-415.
Armstrong, D. M., M. E. Bakeman, A Deans, C. A Meaney, and T. R Ryon. 1997. Conclusions and
recommendations in: Report on habitat findings on the Preble's meadow jumping mouse.
Edited by M. E. Bakeman. Report to USFWS and Colorado Division of Wildlife.
Bailey, B. 1929. Mammals of Sherburne County, Minnesota. Journal ofMammalogy 10:153-164.
Bailey, V. 1923. Mammals of the District of Columbia Proceedings of the Biological Society.
Washington 36:103-138.
Bailey, V. 1926. A biological survey ofNorth Dakota. U.S. Department of Agriculture North
American Fauna No. 49:117-119.
Colorado Division of Wildlife. 1997. Colorado's endangered, threatened, special concern,
undetermined status and candidate species -Terrestrial species. Draft Report for the Colorado
Division of Wildlife.
Colorado Natural Heritage Program. 1997. Colorado's Natural Heritage: Rare and imperiled animals,
plants, and plant communities. Volume III, No. 1. Unpublished Report for the Colorado
Natural Heritage Program.
Compton, S. A, and RD. Hugie. 1993. Status report on z.apus hudsonius preblei, a candidate
endangered species. Pioneer Environmental Services, Inc. Report for the USFWS. Logan,
Utah Logan, Utah.
Cranford, J. A 1983. Ecological strategies of a small hibernator, the western jumping mouse Zapus
princeps. Canadian Journal of Zoology 61:232-240.
EG&amp;G. 1993. Report of Findings: 2nd Year Survey for the Preble's meadow jumping mouse.
Prepared by Stoecker Environmental Consultants for ESCO Associates, Inc., Rocky Flats
Environmental Technology Site, Jefferson County, Colorado
ERO Resources. 1995. Environmental review of South Boulder Creek Management Area Prepared
for City of Boulder Real Estate/Open Space Department. Prepared by ERO Resources Crp.,
Denver, Colorado in association with Stoecker Ecological Consultants, Boulder, Colorado.
Fertig, W. 1997. Wyoming plant and animal species of special concern. Wyoming Natural Diversity
Database. Laramie, Wyoming.
Fitzgerald, J.P., C. A Meaney, and D. M. Armstrong. 1994. Mammals of Colorado. Denver
Museum of Natural History, University Press of Colorado. Niwot, Colorado.
Hafuer, D. J., K. E. Petersen, and T. L. Yates. 1981. Evolutionary relationships of jumping mice
(genus Zapus) of the southwestern United States. Journal ofMammalogy 62:501-512.
Hall, E. R 1981. The mammals of North America John Wiley and Sons, Inc., New York, New York,
2 volumes.
Hamilton, W. J., Jr. 1935. Habits of jumping mice. American Midland Naturalist 16:187-200.
Harrington, F. A., A Deans, M. E. Bakeman, and B. J. Bevirt. 1996. Recent studies of Preble's
meadow jumping mouse at the Rocky Flats Site, Colorado. Journal of the Colorado-Wyoming
Academy of Science 28(1 ): Abstract 18.
Krutzsch, P.H. 1954. North American jumping mice (genus Zapus). University of Kansas
Publications, Museum of Natural History 7:349-472.
Levins, R 1970. Extinction. Lectures in Mathematical Life Sciences 2:75-107.
Long, C. A 1965. The mammals ofWyoming. University of Kansas Publications, Museum of
Natural History, 14:493-758.
Meaney, C. A and N. W. Clippinger. 1995. A survey ofpreble's meadow jumping mouse (Zapus
hudsonius preblei) in Colorado. Report prepared for the Colorado division of Wildlife.
Meaney, C. A, N. W. Clippinger, A Deans, and M. OShea-Stone. 1996. Second year survey for
Preble's meadow jumping mouse (Zapus hudsonius preblei) in Colorado. Report prepared for
the Colorado Division of Wildlife.

�41

Meaney, C. A., A. Deans, N. W. Clippinger, M. Rider, N. Daly, and M. O'Shea-Stone. 1997. Third
year survey for Preble's meadow jumping mouse (Zapus hudsonius preb/ei) in Colorado.
Report prepared for the Colorado Division of Wildlife.
Olson, T. E., and F. L. Knopf 1988. Patterns of relative diversity within riparian small mammal
communities, Platte River watershed, Colorado. Pg. 379-386 in: Proceedings of the
symposium: Management of amphibians, reptiles and small mammals in North America
Flagstaff, Arizona U.S. Forest Service, General Technical Report RM-166.
Poly, W. J., and C. E. Boucher. 1997. Record of a creek chub preying on a jumping mouse in Bruffey
Creek, West Virginia Brimleyana 24: 29-32.
PTI Environmental Services. 1996a Preble's Meadow Jumping Mouse Study at Rocky Flats
Environmental Technology Site, Annual Report 1996. Final. Rocky Flats Environmental
Technology Site, Golden, Colorado.
PTI Environmental Services. 1996b. Preble's Meadow Jumping Mouse Study at Rocky Flats
Environmental Technology Site, Spring 1996. Final. Rocky Flats Environmental Technology
Site, Golden, Colorado.
Quimby, D. C. 1951. The life history and ecology of the jumping mouse, Zapus hudsonius.
Ecological Monographs 21:61-95.
Riggs, L.A., J.M. Dempey, and C. Orrego. 1997. Evaluating distinctness and evolutionary
significance of Preble's meadow jumping mouse: Phylogeography of mitochondrial DNA noncoding region variation. Final Report for the Colorado Division of Wildlife. Denver,
Colorado.
Ryon, T. R 1996. Evaluation of historical capture sites of the Preble's meadow jumping mouse in
Colorado, final report. MS Thesis. University of Denver, Denver, Colorado.
Ryon, T. R 1997. The evaluation of historic capture sites of the Preble's meadow jumping mouse in
Colorado. in Report on habitat findings of the Preble's meadow jumping mouse. Edited by M.
E. Bakeman. Report to USFWS and Colorado Division of Wildlife.
Sheldon, C. 1934. Studies on the life histories of Zapus and Napaeozapus in Nova Scotia Journal of
Mammalogy 15:290-300.
Sheldon, C. 1938. Vermont jumping mice of the genus Zapus. Journal ofMammalogy 19:324-332.
Svihla, A. and R D. Svihla 1933. Notes on the jumping mouse, Zapus trinotatus trinotatus Rhoads.
Journal ofMammalogy 14:131-134.
USFWS. 1997a Proposal to list the Preble's meadow jumping mouse as an endangered species.
USFWS 50 CFR part 17.
USFWS. 1997b. Interim survey guidelines for Preble's meadow jumping mouse. USFWS. Denver,
Colorado.
Whitaker, J. 0., Jr. 1963. A study of the meadow jumping mouse, Zapus hudsonius (Zimmerman), in
cental New York. Ecological Monographs 33:3.
Whitaker, J. 0., Jr. 1972. Zapus hudsonius. Mammalian Species 11:1-7.
Wyoming Game and Fish Department. 1998. Native species status classification system. Cheyenne,
Wyoming.

��43

APPENDIX A

Evaluating distinctness and evolutionary significance of Preble's meadow jumping

Biosphere mouse: Phylogeography of mitochondrial DNA non-coding region variation. Final
genetics Report to the Colorado Division of Wildlife
inc
Reply to: Box 9528, Berkeley, CA 94709
Tel: 510/531-4848
Fax: 510/530-0580
Email: bgioigc.org

EVALUATING DISTINCTNESS &amp; EVOLtrrIONARY SIGNIFICANCE
OF PREBLE'S MEADOW JUMPING MOUSE:
PIIYLOGEOGRAPHY OF MITOCHONDRIAL DNA NON-CODING REGION VARIATION

FINAL REPORT
DECEMBER 8, 1997

Submitted by

Lawrence A. Riggs, Ph.D.
John M. Dempcy, M.A.
Cristian Orrego, Ph.D.
Biosphere Genetics, Inc.
Berkeley, CA

Submitted to

Judy Sheppard
-Terrestrial Section

Colorado Division ofWddlife
Denver,CO

�I •
44

Evaluating Distinctness &amp; Evolutionary Significance
of Preble's Meadow Jumping Mouse:
Phylogeography of Mitochondrial DNA Non-Coding Region Variation

Lawrence A. Riggs, John M. Dempcy, and Cristian Orrego
SUMMARY

We have generated molecular genetic data fotJ1:!~tal_Qf92.jup1ping mice including
71 sampled from 20 populations in Colorado and four populations in Wyoming, and 21
specimens representing three reference groups of closely related tua. DNA sequences
obtained for a.433 basepair (bp)-long portion of the mitochondrial DNA non-coding
region (sometimes referred to as the D-loop) in all samples indiQate that a group of
populations ranging from southeastern Albany County, Wyoming, south along the Front
Range of the Rocky Mountains to western Las Animas County, Colorado, fonn a
coherent group, both genetically and geographically. This group, which we refer to as the
"Preble's group" is distinct from four of five other populations sampled by live trapping
or from museum specimens and may be somewhat differentiated from the fifth of these.
The Preble's group is also clearly distinct from two of the three reference groups and less
markedly differentiated from the third.
Phylogenetic analyses based on these data are still at a preliminary stage and
indicate that the Preble's group of populations is most closely allied with, and not strongly
differentiated from, samples of Z. h. intennedius from Minnesota. Of the four populations
that appear to be distinct from the Preble's group, two sampled near the Colorado-New
Mexico border are closely allied with museum specimens identified as Z. h. luteus from
New Mexico. Two others from the vicinity of Cheyenne, Wyoming, are most similar to
representative samples of Z. princeps from western Larimer Co., Colorado and are next
most closely allied with a Z. princeps specimen from northern New Mexico. A suggestion
from our analysis is that Z. hudsonius from Indiana (possibly either Z. h. americanus or Z.
h. intennedius based on distribution) may be the most ancestral of the populations and
taxa sampled and may have shared a common ancestor with progenitors of fonns presently
known as .Z: princeps princeps and Z. h. luteus.
BACKGROUND

•

Recent applications of molecular genetic methods in systematics, population
genetics, and conservation biology have demonstrated that variation in DNA markers can
• be highly infonnative in the evaluation of genetic distinctness and evolutionary
significance, two important determinants in decisions regarding application of the Federal
Endangered Species Act of 1973 as amended and interpreted by the U. S. Congress. The
study descnoed here sought to discoyer whether and how molecular data might support
and help objectify the view, based on other more traditional criteria, of the Preble's mouse
as an evolutionary unit distinct from other species and subspecies in the genus 7,apus.

I,

�45

Preblc's DNA study

Final Report/12-8-97

Work funded by the Colorado Division of Wtldlife (hereafter CDW) and
performed by Biosphere Genetics, Inc. has evaluated the ability of three different
approaches to quantifying variation in the DNA molecule to provide reliable and
infonnative data addressing issues of key importance in the decision of whether or not to
list the Preble,s mouse. Previous reports to CDW have summarized our finding that
RAPD (randomly amplified polymorphic DNA) markers are not sufficiently repeatable for
use in the context of this study. Methods to assay variation in ~other class of genetic
markers found in nuclear DNA called microsatellites or simple sequence repeats, although
•potentially promising, are not yet sufficiently well developed and validated for zapodids to
apply at this time. A third approach, DNA sequencing of the mitochondrial DNA noncoding region which includes the D-loop, emerged from preliminary work as the method
most appropriate and informative, in combination with other more traditional criteria, for
the determination ofwhether populations of the Preble's meadow jumping mouse (Zapus
hudsonius preblei) constitute one or more distinct evolutionary units with significance
warranting protection under the Federal Endangered Species Act. Results based on
sequence variation in the mitochondrial DNA non-coding region assayed in a subsample of
the 54 mice presumed to be Preble's obtained during the summer of 1996 indicated: (1)
that 7 populations sampled at sites ranging from Longmont to Colorado Springs in
Colorado varied relativ~ly little from one another,, (2) that two other populations sampled
in Las Animas County near Lake Dorothey were similar to one another but differed quite
markedly from the first group, and (3) that none of the individuals sampled in Laramie
'l ~
County in Wyoming could be assayed using the techniques successfully applied to the
other samples, suggesting that this population may also differ to some degree from those
in Colorado.
Field surveys of the occurrence of the Preble"s meadow jumping mouse conducted
by several individuals and organizations during the summer of 1996 were extended to
additional sites in the summer of 1997. CDW spo0$0red some of these efforts and
coordinated the collection, recording and· delivery of tissue samples for DNA analyses
performed by Biosphere Genetics, Inc., also under contract with the Division. In addition,
the U. S. Air Force supported DNA analysis of samples _obtained from trapping efforts
during the· summer of 1996 on the Warren Air Force Base and the inclusion of reference
material representing two additional subspecies of Zapus hudsonius,, Z. k palustris, and Z.
k campestris.
•
METHODS

Tissue Sampling and Storage
A sampling protocol and data forms for using in obtaining samples for.DNA
analysis were developed for CDW and distnouted to all parties participating in the
coordinated trapping effort. The disseminated protocol, adapted and updated from the
•U.S. Fish and Wtldlife Service standardized protocol, descnoed handling and instrument
cleansing procedures to minimize contamination of the sample with human or other
mammalian.DNA Very small samples of tissue were obtained from live-trapped

�I.

46

Prcble's DNA study

Final Rci,ort/12-8-97 •

specimens of mpz(s by using a tagging punch (National Band and Tag Co., Newport, KY)
to remove one or more plugs of tissue from the outer portion of each mouse,s ear. In
some cases, ear tissue was obtained by clipping or notching the ear with scissors. Tissue
plugs or pieces from a given animal were placed in a cryogenic screw-cap vial filled 1/31/2 full with 95% ethanol and labeled with an alpha-numeric code intended to uniquely
specify trapping location and the individual animal caught. Hair samples were collected by
some participants and placed either in a separate labeled vial or ~ the same vial containine
the ear tissue. Samples were conveyed to CDW and accumulatec;{ into lots for deliveiy to
BGL When ·samples were transported from the field or shipped by common canier, they
were at ambient temperature. Upon receipt at BGI, samples were kept refiigerated at 4°C
until tlie time of DNA extraction. Specimens obtained from field surveys and
miscellaneous museum specimens used to expand coverage of the potential range of the
taxa examined in this study are listed in Table 1 of the Appendix to this report.
Reference specimen tissues used for comparison with field-sampledjumping mice
were provided from four separate museum collections (see Appendix I, Table 2) as toes
clipped from museum specimens or as small pieces of internal organs maintained iri the
museum,s frozen collection, usually at-70°C. Toe clips were shipped at ambient
temperature and refiigerated at 4°C upon receipt. Frozen specimens were shipped on dry
ice and extracted upon receipt with any remaining tissue being transferred to ethanol for
further storage. Reference specimens are listed in Table 2 of the Appendix to this report.
DNA Extraction &amp; Purification
We extracted DNA from plugs or pieces of ear tissue using the Hair Lysis Buffer
(HLB) method similar to that of Greer et al. (1995). The tissue was rinsed, either with a
jet of triple-distilled water or by agitation in a drop of distilled water on Parafilm®, then
placed in a volume ofHLB and incub~ted at S6° C with periodic agitation for 10-12
hours. In most cases, this process completely digested the sample leaving only a trace of
particulate matter suspended or settled in the bottom of the tube. With the particulates
centrifuged to the bottom, aliquots of the extract were withdrawn for fractionation and for
purification prior to use in DNA amplifications. Raw DNA extracts were run out on 1.5%
agarose gels and stained with ethidium bromide to quantify the DNA by comparison with
staining intensity of Lambda Hind m fragments run on the same gel. We used Prep-AGenen.1 (Bio-Rad, Hercules, CA) to purify the DNA preparations before sequencing.
Amplification of Mitochondrial DNA Non-coding Region Sequences
We began our examination of the mitochondrial non-coding region using the
primers designated as ECO-THR (L15996) and BAM-TDKD (Hl6401) to amplify an
approximately SSO bp-long segment between the threonine tRNA gene near the
•cytochrome b end of the non-coding region and the TDKD site approximately half way·
through the non-coding region. 1 This primer combination, first used to study human
1

The ECO- and BAM- portions of these primer designations refer to.the addition of restriction enzyme
sequences at the 5' end of the primer sequence. These "tails" are not essential for the present application
and we will use primer designations with and without this notation interchangeably in this report.
Biosphere Genetics,. Inc.

l&gt;age 3

�47

Final Report/12-8-97

Preblc's DNA study

populations (Vigilant et al. 1989) had worked well in studies of other mammals and
typically revealed amounts of sequence variation appropriate to differentiating subspecies
and geographically isolated populations. Because the non-coding region includes a
structure descnoed as a displacement or "D" loop known from work on human and cattle
DNA, we will occasionally refer to the region of DNA studied here as the D-loop.
Amplifications with the above primers were performed in 12.5 µI reaction volumes
using 1 µI oftemplate DNA, 1 unit of the DNA polymerase, Klentaq-1 (Ab Peptides, St.
Lo~ MO), and other reaction components in standard proportions. A Teg~e PH~2 .
thetmocylcer was used to implement a program using an initial denaturation at 94°C for 3
minutes followed by 42 cycies with denaturing at 94° for 45 seconds., annealing at 55° for
1 minutes, and extension at 72° for 1 minutes followed by a final extension at 72° for 5
minutes. Pro4ucts were fractionated on 1.5% agarose gels. ~plification ofthe 550 bp
D-loop fragment was successful, but primer dimer and secondary products also appeared,
sometimes in considerable amounts. We experimented with a variety of modifications to
obtain cleaner product (prim~ reduction, additions ofMgCh at various levels, alternative
forms ofDNA polymerase, etc) and were ultimately able to obtain product with a •
minimum"ofthese additional elements ii1 many, but not all, samples of mice presumed to
be Z h. preblei.
Following the optimization effort, revised reaction conditions were used to assess
D-loop fragment amplification success with all new DNA extracts in 12.S µI reactions,
then applied with slight modifications to the thermocyler program to amplify targeted
products in SO µI reaction volumes to obtain sufficient quantities for automated
sequencing. Two or three SO µI reactions were run for each sample, depending on prior
estimates of the amount of template available in individual DNA extractions~ The quantity
and quality of product generated by each reaction was assessed by agarose gel
fractionation. Reaction volumes were combined when necessary, then cleaned with the
solid-phase reversiole immobilization method (DeAngelis et a 1995) using carboxyl
coated magnetic particles (PerSeptive BioSystems Inc, Cam6ridge, MA). Oeaned,
resuspended DNA products were then dried down to a pellet mthe bottom of a 1.5 ml
eppie tube for shipping by overnight service at ambient temperature to automated
sequencing s~ce.

an

Resolution of Amplification Problems

Some DNA extra~ most notably those of Z. princeps and of putative Z k

,
preblei populations sampled at the Warren Air Force Base in Wyoming, did not amplify
well or at all with the ECO-THR/BAM-TDKD primer combination. We first suspected
that this OCCWTecl because the TDKD primer designed from sequence information on the
human D-loop was not finding sufficient complementarity on the heterologous primer site
in at least some 7.ap,IS populations or taxa. Conventional wisdom suggested that the
ECO-nm. primer site should be-highly conserved in vertebrates. Based on this reasolling,
we designed two ~ew primers for the middle of the D-loop. We examined D-loop
sequences available from Genbank for rat (Rattus norwegicus), mouse (Mus musculus),
vole (Clethrionomysglareolus), gopher (Thomomys bottae), and kangaroo rat
(Dipodomys ordii) as well as our own sequence data for ?.opus. Sequences for the

Paee4

�48

Final Report/12-8-97 ·

relevant portion of the D-loop for Mus, Clethrio11omys and Zapus were used to identify a
primer site most likely to be reasonably conserved in muroid and dipodoid rodents. The
primers designed for this new site are designated PRDL L-15738 (forward primer) and
PRDL H-15720 (reverse primer). We had these primers synthesized (Operon
Technologies, Alameda, CA) for testing and possible use in resolving the difficulties
mentioned above. The relative positions and priming directions of all primers are shown
in Figure 1.
We used PRD¼.!!_-1S~~0 iq coµibination with ECO-THR. in an attempt to amplify
those samples that had not.amplified with the ECO-THR/BAM-TDKD primer
combination. We also attempted to _amplify the entire D-loop by using ECO-THR. in
combination with PHE-rev H29, a primer previously designed for general use in
amplifying portions of the D-loop in mammals (A. Gavazzi, unpublished). Fmally we
..test~ PRDL L-1S738 in combination with PHE-rev H29 for the pwpose of generating D. loop fragments spanning the TDKD site for automated sequencing of this site in 'Zapus.
:resting of these primers on 7.apus DNA extracts revealed that: 1) the ECO-THR/PRDL
H-1S720 primer combination amplified in only two ~f20 samples and did nothing to solve
the previous difficulties encountered with the ECO-THR/BAM-TDKD combination; 2)
the ECO-THR/PHE-rev H29 combination produced a fragment ca. 1500 bp long,
apparently spanning the D-loop successfully in some cases, but not with the DNA extracts
that had been previously problematic, and 3) the PRDL L-15738/PHE-rev H29
combination produced multiple bands in some cases and no amplification in others. We
inferred from these results that our original problem in amplifying some Zapus samples,
most notably those assigned to. Z. princeps and the samples from the Warren Air Force
Base, was not with the lDKD site, but rather with annealing of the ECO-THR primer
designed for a conserved section of the human threonine tRNA gene to the het~rologous
sequence in 7Apus.
Reexamination of the sequences successfully obtained in preliminaly work on
'Zapus suggested that a primer site that would be more highly-conserved between 7.apus
and other mammals might be present internal to the one primed by ECO-THR. Further
testing showed that an available primer designated PROC, for priming of a sequence on
the praline tRNA gene, when used in combination with the BAM-TDKD primer, was
uniformly very successful in amplifying a 433 bp fragment (excluding primer
sequences) of the D-loop. While we have been reluctant to give up on efforts to access
-information about variation existing in and around the THR site, the PROC/BAM-TDKD
primer combination was clearly the tool of choice for compiling the dataset required for
this study within the time frame required. The results presented in this report are for the
433· bp segment of the D-loop falling between the proximal ends of these primer ~ites.

ca.

Automated Sequencing
DNA sequencing of both the S50 bp and 433 bp fragments of the D-loop
generated as descnoed above was perfonned by The University of Maine DNA
Sequencing Core Facility using an ABI model 373A Stretch DNA sequencer. Results of .
one.sequencing pass in each direction were received by e-mail as attached files in ABI
•format. Pherograms in these files were viewed with the program Chromas (v. 1.4, Co1:1or

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Preblc's DNA study

1HR

PROC

Final Rcport/12-8-97

PRDLL15738

ldtNAua! lcRNAno! _I_______N_•_oo_&amp;a_sepaa_·_ _ _ _ _ _ _! ,cRNA,_!
~

PRD H-1S720

~

IDKD

PHEA.

Fig. 1. Relative positions of the primers used in this study for amplification of the mitochondrial
DNA non-coding region. which includes the D-loop. Primers nm. and IDKD were from Vigilant
ct al. (1995), PHE-rev 1129 was from Anita Oavazti and primers prdl L-15738 and prdl H-1S720
arc two new primers designed for this study to work with .2apus and other rodents. Primers arc used
in pair-wise combinations to amplify segments of DNA lying between their positions on this
simplified map. The relative positions of coding and non-coding regions arc indicated by labeled

areas.

McCarthey, Griffith University, Brisbane, Queensland, Australia) and machine-assigned
sequences were exported as text files for use in subsequent analysis.
Data Analysis
Text files containing the two sequencing reads generated from opposite ends of the
amplified fragment were entered into the program MacDNASIS (v. 1, Hitachi Sofl:ware
Engineering Co., Ltd., San Bruno, CA) and combined to obuun a consensus sequence for
the amplified region of each individual mouse sampled. Sequ~®S obtained from both
THR-IDKD and PROC-Ti&gt;KD amplifications were used as available. However, since the
more inclusive THR-TDKD sequences were not available for individuals assigned to ·z
princeps and samples ultimately found to be more closely related to Z princeps than to
the Preble's samples, and since the longer sequences were of variable quality at the
beginning of the 5' to 3' read in a number of the Preble's samples, we~ only the 433
bp sequence available in all samples in all subsequent data analysis.
Consensus sequences were aligned manually using the multiple sequence option of
MacDNASIS. The program MacClade (v. 3, Maddison, 1992) was used to create· a data
matrix of character states for 58 variable sites in the aligned sequences for phylogenetic
analyses. Phylogenetic trees were generated using the parsimony algorithm in PAUP (v.
3.1.1, Swofford, 1993). To expedite review of various options for the rooting of trees;
one individual was selected as most representative of each population (fewest changes
frQm the most commonly shared state at the SS variable sites treated as cbaracters in the
.DNA sequence) and used in the depiction of,nost-parsimonious trees and in bootstrap
analyses. Bootstrap analyses used the 50% majority rule with 100 replications.

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Strict

£8§1i8~

iii
~
lffii

Iii
I

•

·---.

~

mi

™

00
~OSN

I
II
m§

I

I
I

I
I

~

-r.=
========= ~--~~

. __ _ _ _ _ _ _ _ _ _r--_- _
-_
-_-_
-_
-_
-_
--t
I
I

Figure ·2. Strict consensµs tree, identical to_ the single most parsimonious tree generated
using the "branch and bound" option of PAUP v. 3.1.1 (Swofford 1993) on.sequences for
all samples analyzed. Length of this shortest tree is 61 evolutioruuy steps; consistency
index (Cl)= 0.869. Although not supported by bootstrap analysis in the conte.u of
phylogenetic analysis, sub-groupings of populations considered here to be part of the
Preble's group suggest that population subdivision may be discemable by more
appropriate population-analytic methods.
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�51

Final Report/12.S-97

Preble's DNA study

RESULTS

Figure 2 illustrates phylogenetic relationships among all samples included in the
study to date, inferred from maximum parsimony analysis (length = 61 steps, consistency
index [CI] =0.869). Bootstrap analysis for the entire dataset was not practical for this
report. However, bootstrap analyses were performed for various outgroup scenarios
using one individual from each population as described above. No outgroup was
designated for the analysis shown in Figure 2.

·-·The important relationships in Figure 2 are perhaps more easily seen in the
unrooted, circular fonnat tree generated using one representative individual from each
population (Figure 3). •No meaning is attached to the length ofbranches hi this tree. The
19 branches that join the baseline in the center directly (11 o'clock to S o'clock on the
diagram) and four more samples that ·are shown grouped together and joining the baseline
with• a bootstrap value of 53 (indicating little support for treating this group of samples as
distinct from the other 19) form a relatively homogenous group. Also not strongly
diff'erenti~ed is the group of three r~p~enting reference samples of Z. h. intennedius
from Minnesota and Z. k campestris from South Dakota as well as an individual museum .
specimen designated as only Z. hudsonius from Johnson County, Wyoming. Bootstrap
values indicate strong support for reco~g samples of Z. princeps, Z. k luteus, and
populations affiliated with them in the diagram as distinct from the Preble's group.
Further observations following from the analysis are discussed in the following section.

DISCUSSION

Preliminary data analyses conducted before all new populations sampled during the
summer of 1997 and reference material had been analyzed ex_a.mined three options for the
rooting of the phylogenetic tree. When the Indiana population of Z. hudsonius was
assigned as the outgroup (one most parsimonious tree, length·= 63, CI= 0.921), the
strong relationships in the tree were the same ones seen in the tree generated when no
outgroup was assigned (Figures 2 and 3). Essentially, populations ofjumping mice
ranging from southeastern Albany County in Wyoming south along the Front Range of the
Rocky Mountains to western Las Animas County in Colorado were seen to fonn a
coherent group within which separate populations or groups of populations were not
strongly differentiated. Designating Z. princeps as the outgroup resulted in Indiana Z. .
hudsonius appearing as the sister group to the assemblage of presumed Preble's
populations with the populations from the Colorado-New Mexico border· and the Warren
Air Force Base joining the tree at an intennediate level. Bootstrap values for the resulting
tree were uniformly high, but we have not yet resolved doubts about whether Z. prlnceps
can properly be treated as ancestral to Z. hudsonius. Finally, designating Z. hudsonius
intennedius from Minnesota as the outgroup in earlier analyses resulted in a tree in which
all the branches to the Preble's popuiations samples joined the baseline as undifferentiated
from the outgrqup.

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Final Report/12-8-97

MRD97&lt;flMNH9716
ROX9701

CGA1

80S9706

·---

EPC9701

LOSt - -

RF96100

RSS1076 --------------

Figure 3. Bootstrap consensus tree (50% majority rule, 100 replications), based on
analysis of single most-representative individual from each population or reference group,
obtained with no outgroup designated. ijootstrap values are shown next to relevant
branches in the tree. Bootstrap values greater than 90% indicate those relationships which
are strongly supported.
•
•

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�Preble's DNA study

Final Report/12-8-97

There are several notable observations for individual population samples among
our findings based-on analyses completed in late November, 1997. We summarize these
here in list form with population/sample codes in parentheses referring to designations in
the tables of the Appendix:
1. The six jumping mice caught at the Warren Air Force Base (CCF) in the summer of
1996 (identified by field workers as Preble's) and an individual jumping mouse caught
in Weld County, Colorado just south of Cheyenne, Wyoming (LTC), are
indistinguishable from reference samples ofZ. princeps (CZP) provided by Dr. B~ce
Wunder from Larimer County, Colorado. Bootstrap values indicate that this group is,
in tum, most closely affiliated with, but distinct from, a sample of Z. princeps from
Taos·county, New Mexico.
•
2. The eastem-m~st sample identified in the field as Z. h. preb/ei, a single individual from
Elbert County, Colorado (HAY), is confirmed to belong in the Preble's group by DNA
sequence obtained from a sample of three hairs.
3. Jumping mice caught at two sites in the Lake Dorothey area on the Colorado-New
Mexi~ border (CCR and WFS), suspected on the basis of morphological traits to be
similar to Z. h. luteus (Cheryl A Jones, personal communication), are confirmed to be
so on the basis of the non-coding region sequence data. There is also a reasonably
strong indication (bootstrap value·= 88) that these two populations and the Z. h. luteus
samples are, together, likely to have shared a common ancestor with progenitors of Z.
princeps reference samples and the populations sampled north (CCF) and south (LTC)
of Cheyenne, Wyoming. This finding is in contrast to the conclusions ofHafher et al.
(1981) (but see next comment).
4. A suggestion from our analysis (not strongly supported by bootstrap analysis) is that
Z. hudsonius from Indiana (possibly either Z. h. americanus or Z. h. intennedius based
on distnl&gt;ution) may be the most ancestral of the populations and taxa sampled and
may have shared a common ancestor with progenitors of i'ornis presently known as Z.
princeps princeps and Z. h. luteus. We speculate that the forms recognized as
subspecies of Z. princeps and Z. hudsonius present today in the Rocky Mountain and
Northern Great Plains region may be the derivatives of two separate range expansions
occurring at different times during the Pleistocene.
5. Two ·rererence samples obtained from the Denver Museum of Natural Histoiy,
originally identified as Z. princeps from the San Isabel National Forest-in. western Las
Animas County, appear on the basi$ of non-coding region sequence data to belong to
the Preble's group.
6. A single jumping mouse specimen obtained by Chris Garber from the Medicine Bow
National Forest in Wyoming, identified as a Preble's mouse by Dr. David Annstrong
on the basis of his analysis of poorly preserved skeletal material, is confirmed to be a
Preble's by DNA sequencing from a piece of preserved skin.
7. One reference collection sample identified as Z. h. pallidus from Garden County,
Nebraska (ZHPNEG), and two samples identified as .Z: h. campestris from ~eston

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Preble's DNA study

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County, Wyoming (ZHPWYW), are indistinguishable from other samples in the
Preble's group in the present analysis.
8. Two reference collection samples identified as Z. h. campestris from Custer County,
South Dakota, are found to be most similar to a museum specimen identified only to
species level as Z. hudsonius from the vicinity of Buffalo in Johnson County,
Wyoming.
•
Further Researc~ Needs
·--Additional sample.materials and analyses may be required to achieve a rigorous
view of the relationships of the group referred to here as Preble's to other subspecies and
species of the genus Zapus in North America.- The choice ofan appropriate outgroup
remains unresolved, and could benefit from further input from those knowledgeable about
evolution and morphology of the Zapodids in North America and elsewhere. Based on
extensive work on limb myology of the Dipodoidea (Stein, 1990), the superfamily to •
which the genus and the rest of the family Zapodidae belong, the genus Sicista (the birch
mice), represented by species in Europe and Asia, would appear to be an appropriate
outgrouj&gt;. However, divergence between 7.apus and Sicista may be too great to be
effectively measured by variation in the D-loop. Another North American genus,
Napeozapus, has been suggested as a possible outgroup for this analysis. However,
slightly greater adaptation for saltatorial ability and a higher tooth count in Napeozapus
than in Zapus would suggest that the former is derived rather than ancestral to the latter.
Sequence information for the cytochrome b gene potentially forthcoming from other
researchers (T. Yates, personal communication) may be helpful in sorting out relationships
at the species and higher taxonomic levels and may be a useful complement to the noncoding region sequence data in elucidating relationships potentially traceable to
• Pleistocene glaciation events. We have begun to examine a portion of the cytochrome b
gene and the neighboring threonine gene in a separate study.

.

The DNA sequence results reported here indicate the ~eed for a reexamination of
external and skeletal morphology in Zapus. .In at least a few cases (DMNH, LDS), the
sequence data suggest that .even species level identifications cannot always be made
unambiguously in the field. Patterns of morphological variation across the range of the
species and subspecies of interest may be such that more careful examination of museum
accessions is to be recommended as well. One promising dental character that may
distinguish Z. hudsonius·from Z. princeps is the presence of a deep anteromedian fold 'in
the anteroconid of the molar ml in the former as descnoed by Klingener (1963) and
applied in an analysis of cave floor faunal remains by Hafner (1993). It will be interesting
to learn what this character may say about the taxonomic identity of the. samples
referenced above and about specimens available in museum collections for the areas near
the northeQt and sotithem boundaries of the Preble's mouse range.
•
Further analysis of molecular markers at the species, subspecies, and population
levels is needed to confirm the findings suggested by this study and to further delineate
patterns of variation bearing on conservation and management ofZ. h. preblei. We have
material in hand to continue to expand sample sizes for a number of the populations
already swveyed and our initial contacts with several museums in the context of the
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Final Rcport/12-8-97 55

present study indicate that sample sizes of comparative taxa can also be increased for at
least some parts of the relevant subspecis ranges. Because there has been relatively little
recent suivey activity in Wyoming and only a few reference specimens from museum
collections were included in this study, the northern extent of populations assignable to the
Preble's group is poorly defined. New trapping suivey initiatives and DNA analysis of
more material available from museums would address this situation. We also recommend
that a nuclear DNA dataset be generated to complement the mitochondrial DNA dataset.
A portion of our work not reported here has evaluated two classes ofDN~ markers
potentially appropriate to tills task and b ~ applications of ipicrosatellite methods to
development of markers likelyto be applicable both to phylogenetic analysis of
relationships at the species and subspecies level and to population genetic analyses
supporting assessment and monitoring of population differentiation and gene flow, genetic
·parameters of population viability, and mating system analysis. •
We expect that further examination of the results obtained in this study, both by
ourselves and others, will lead to a more comprehensive definition of research needs and
priorities along two possibly divergent paths, one inclined to address fundamental issues of
systematics and biology, and the other focused more sharply on the near-term
requirements that may be imposed by the outcome of the pending decision on the status of
the Preble's mouse by the U.S. Fish and Wddlife-Service. We urge that planning attention
be devoted to providing for both ongoing research and for integration of assessment and
monitoring activities into any prospective recovery effort.. Molecular ecology has much to
offer in both areas of endeavor. .
Conclusion
Based on resuits.to date, we conclude that mitochondrial DNA non-coding region
(D-loop) sequence data appear consistent with the view that a geographically contiguous
set of populations previously recognized as the Preble's mea&lt;Jow jumping mouse (Z. h. •
preblei) form a homogenous group recogniz.ably distinct from other nearby populations
and from another geographically-adjacent species of the genus.

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Final Report/12-8-97

REFERENCES CITED

DeAngelis, M.M., D. G. Wang, and T. L. Hawkins. 1995. Solid-phase reversible
immobilization for the isolation of PCR products. Nucleic Acids Research
23{22):4742-4743.
Greer, C.E., C.M Wheeler, and M.M. Manos. 1995. PCR ampijfication from Paraffinembedded tissues: Sample preparation ~d the effects of fixation. pp .99-112, in:
PCR Primer, A Laboratory Manual, C.W. Dieffenbach and G.S. D.veksler (eds.. )
CHSL Press, New York, 1995.
Hafner, D.J. 1993. Reinterpretation of the Wiconsinan mammalian fauna and
paleoenvironment ofthe Edwards Plateau, Texas. J. Mamm. 74(1):162-167.
Hafner, D.J., K.E. Petersen, and T.L. Yates. 1981. Evolutionary relationships ofjumping
mice (genus Zap11s) of the Southwestern United States. J. Mamm. 62(3):501-512.
Klingener. D. 1963. Dental evolution of Za.pus. I. Mamm. 44:248-260.
Maddison, W.P. and D.R. Maddison. 1992. MacClade v. 3: analysis of phylogeny and
character evolution. Sinauer Associates, Inc. Sunderland, Massachusetts.
Stein, B. R. 1990. Limb myology and phylogenetic relationships in the superfamily
Dipodoidea (birch mice, jumping mice, arid jerboas). Z. zool. Syst. Evolut.-forsch.
28:299-314.
Swofford, D.L. 1993. PAUP - Phylogenetic Analysis Using Parsimony- version 3.1.1.
Computer program distributed by the Illinois Natural His~ory Survey. Campaign,

Illinois.
Vigilant, L., R. Pennington, H. Harpending, T.D. Kocher, and AC. Wilson. 1989.
Mitochondrial DNA sequences in single hairs from a southern African population.
Proc. Natl. Acad. Sci. USA, 86:9350-9354.
Walsh, P.S., D.A. Metzger, and R. Higushi. 1991. Chelex® 100 as a·medium for simple
extraction of DNA for PCR-based typing from forensic material. Biotechniques.
10(4):506-513.

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�57

Appendix

Tables in this appendix contain information on the populations and species samples included in
• this study. All samples received ·for which DNA was extracted are listed.· Those for which DNA. sequence data was successfully obtained for the analyses reported in. the main document are
indicated as explained in each table.
Additions and corrections were still being received as the final draft of this report was going to
press. Questions about incomplete or inaccurate data should be referred to the Colorado Division
ofWddlife, Terrestrial Section, Attn: Judy Sheppard.

A "°"'"nrliv A

�Table 1. Sampling locations for jumping mice analyzed as put~tive Preble's mice as {Zapus hudsonius prcblei). This table includes both samples obtained by
live-trapping during the summers of 1996 and 1997, and samples from museum specimens not identified to subspecies or otherwise designated as reference
material (included in Table 2). Numbers of samples for which DNA sequence data were successfully obtained in time for the analyses presented in the main
body of the report arc shown in parentheses under the number of samples processed. The individuals included in the analyses arc indicated·by an.asterix in the
column headed "Original sample #s."
S1D1plo

Codo
BAD
BOS

Locality/site name &amp; desaiption or other soorce
informltkin
B■dwttcrCredc, Natrona Co., Wyoming
. 'oNIAl
rein.and
SoUlh BoalderCredc. near intcnedion with
Eat Boulder Dltdi, on City ofBoulder Open
Sptee. Boulder Co;. CO. 5300 ft. Lousivi'Uo
Quadrangle, T J S, R 70 W

No.

Original •
-1011.

1

m

CU13469•

13 B0S9702
(1) • BOS9703

BOS9704
B0S9105
BOS9706•
8089707
BO89708
BOS9709
BO89710
BOS9711
BO89712
BO89715
BO89716

4
(2)

BVC

Bemr Credc, 2 1/2 milea SW of Monument, El
Pllo Co., CO. 7000 ft. Palmer Lake
quadrangle. T 11 S, R 68 W

CCF

Crow Credc, Wamn Air Form Bue, Laramie

6

Co., WY. [elmitionanclquadrangloNIA)
T14N,R67W

(6)

CCR

Crlo:,rica Credc, Lako Dorothay Stlto W"ddlifo
Area, LIi Anhnn Co., co

DC

CCF9604•

6
(4)

N Brandl, Middle Fode. Lodgq,olo Credc. Polo
Mt. Umt, Modi.cine Bow National Foreat, ce. 2
ml. S, 15 ml. B.Laramie, Aibeny Co., WY,
7600ft. -•o•NIA1
Deaclman Credc, U.S. Air Foroo Mademy, El

1
(1)

PuoCo..CO,

(2)

{elevation and qu■dnmglo NIA)

CCF9602•
CC~3•

[Elev.-?)

CGA

BVC9701 •
BVC9702
BVC9703•
BVC9704•
CCF960l•

5

CCF9605*
·CCF9606•
432•
433•
503
504 ..
505•
506•
[Specimen
tag]
97DC02N
97DC03N
.97DCQ2s•
97DCOSS•

97DC07S

1/4-1/4
Section
NIA

Lat-Loog
coordinirtcs
NIA

3, W 1/2
3, Wl/2
3, Wl/2
3, Wl/2
3, W 1/2
3, Wl/2
3, Wl/2
3, Wl/2
3, Wl/2
3, Wl/2
3, Wl/2
3, W lf.2
3, W 1/2

39"59' 30" N .
105°12'55" w

29.NE 1/4
29,NEl/4
29,NE 1/4
29.NE 1/4
27
27
27
27
27
27
NIA

39"03'27.2"
104°53'49.8"
NIA

39"00'02"
104°21'39"

UTM

Coords.
NIA
4818450.00, 4427090.00
4811450.00, 4427090,00
4818450.00, 4427090.00
4818450.00, 4427090.00
4818450.00, 4427090.00
4818450.00, 4427090.00
4818450.00. 4427090.00
4818450.00, 4427090.00
4818450.00, 4427090.00
4818450.00, 4427090.00
4818450.00, 4427090.00
4818450.00, 4427090.00
4818450.00, 4427090.00

Collettor(1)

Spoosorin&amp;'Participating
0rl!llnizlrtion(1)

P.Robfntcn&amp;E.

·Andenon
C. Meaney &amp; N.
Clippinger

Univ. of Colorado
Museum. Boulder. CO
Colorado Division of
Wildlife
Carron Mean.:y,
Consultant

i

i

5088970.00, 4323168.00
5088970.00, 4323168.00
5088970.00, 4323168.00
5088970.00, 4323168.00
NIA

N. Clippinger

NIA

C.AJones

C. Flemming
C.Paguo •

Colorado Division of
Wildlife
Carron Meanc:y.
Consultant
Colorado Natural
Heritage Program
U. S. Air Force

Denver Mll!eum of
Natural History

'
TlSN
R71 W
sec 11

NIA

NIA

NIA

NIA

C.O■rber

(collector)
D. Aimstra:tg
4318360.00. 513700.00
4318360.00. 513700.00
4318360.00, 513700.00
4318380.00, 513650.00
4318300.00, 513650.00

P.Sd!uennan,

s. Aslc,

University Museum, Univ.
ofColorado
Colorado Naturill
Heritage Program

J. Hobert

Paee A-2

U1
(X)

�i

Table 1 continued (2nd page).
EPC

Eat PJmn Creek. 6500 ft. Doagtu Co., CO.
DawlanButtoquadranglo, T9S,R67W

BAY
JCC

IDS
I.PC

Hay Ouldl, tn'butaryto Running Crock near

Mer, Elbat Co., CO. 6,225ft. Cabin Ouldl
'e, T7S.R64W.
Coll Creek. R.lnlom'Edwmk Homeateld
Ranch, Jeffinon Co., co.
(Bin.•?)
IEdondo-~- 00) T 2 S. R 70 W
Lib De Snxtnear Baflitlo. Johnson Co., WY.
[elmdlon and quadranglo NIA]

I
3
(1)

BPC9701•
BPC9702
EPCf703

9,E 1/2
9,E 1/2
9,E 1/2

I
(I)

HAY-1•

E 1/2

NIA

4
(3)

9601*
9602•
9603
9604•
CU15132•

7,8,17,18

[Information
neededftom
collecton]

[Information needod)

C.Flcmming
C.Plgue

NIA

NIA

NIA

LPC970l•
LPC9702•
LPC9703•
LPC9704*
LPC970.5
LPC9706
LPC9707
LPC9708
LPC9709
LPC9710
LTC-1*

4,SW 114
9NW,NW
4,SW 1/4
9NW,NW
4;SW1/4
9NW,NW
4,SW 114
9NW,NW
4,SWl/4
9NWNW
NENE,SE
SE

40046'11.0"
10.5°21'36.7"

4696010.00, 45132560.00
4696010.00, 45132560.00
4696010.00, 45132560.00
4696010.00, 45132560.00
4696010.00, 45132560.00
4696010.00, 4.5132.560.00
4696010.00, 45132560.00
4696010.00, 4.5132560.00
4696010.00, 45132560.00
4696010.00. 45132560.00
5063300.00, 45333900.00

A.Crockett
J.MMerritt
D. Armstronst
A. Deans

MRD970l•

16,NW
1/4

39"58'1.6"
105°13'.59.7''

4798400.00, 44242200.00

A. Deans

21,NW
1/4
18, SE 114
1.5,NW
1/4
10,SW 1/4
10,SWt/4
10, SW 1/4
10,SW 1/4
10.SWl/4

40049'2.5.6"
105°21"8.6"

471.5010.00, 4.5212170.00
471.5010.00, 4.5212170.00
471.5010.00, 4.5212170.00
4702850.00, 4.5194120.00
471.5010.00, 4.5212170.00
4715010.00, 4.5212170.00
4702850.00, 4.5212170.00
47028.50.00, 4.5212170.00

A. Dean's

Colorado Division of
Wildlife
Carron t..-1.:an,:y. Consuhant

T.Ryon

PTI Environmental Services

I
(I)

Lem PinoCreek. Lowerai«okeo State
WildHfl, Area. Llrlmer Co., 00. 6200 ft.
Livamoro Mountain quadrangle, T 10 N. R 71

10
(4)

Lem Tree Creek. at 1-25, llOl1han podim Weld
Co., CO. 5,900 ft. Carr Soulhwest quadrangle,
T. ll-12N.R.67W.
ManhaD Road, Dry Crock Ditdl #2, bctwem
Mmball road and South BoulderCredc.
Boulder Co., CO. 5700 ft. Louimllo
• TlS.R70W
Rabbit Creek. Lower C!erokeo SWA CL 9 mi.
NW Uwnnoro, La1'.im«Co. 00. 6300 ft.
Livamoro Mountain quadranglo ,T 10 N, R 71

1
(1)

8
(4)

RBC9701°
RBC9702•
RBC9703•
RBC9704•
RBC970.5
RBC9706
RBC9707
RBC9708

Rocky Flm &amp;tvha11nmtal Tedmology Sito,
1cfflnon Co. 00.
5780ft.
Loufmllo, CO, T2 S, R 70 W

10
(6)

ZAHl196-62•
ZAHU96-63•

w

LTC
MRD

.

RBC

t
(l)

Atmendbc A

40057' 5.8" N
104"55'29.3" W

5090040.00, 4347802?
5090040.00, 4347802?
5090040.00, 4347802?
509.0040.00. 4347802?
540660.00, 4368470.00
(?)

ADeana

A.Dims

A.Deana

.

w

RF

39"16'46.3" N
104°53'44.2" w

NIA

~·
ZAHU96-6.5•
HU96-100•
HU96-10l•
RF-97-102
RF-97-103
RF-97-104
RF-97-10.5

11,.5W
11,.5W
11,.5W
11.,w

Colorado Division of
Wildlife
Canon Meaney.
Consuhant
Colorado Division of
Wildlife
Carron Meanev. Consuhant
Colorado Natural Heritage
Program
Univ. of Colorado Museum.
Boulder.CO
Colorado Division of
Wildlifo
Carron M~ey. Consuhant

Colorado Division of
Wildlifo
Carron Meanev. Consuhant
Colorado Division of
Wildlife
Carron M.:aney. Consuhant

l11

4832800.00, 44148500.00
4832800.00, 44148.500.00
4832800.00, 44148.500.00
4832800.00, 44148.500.00

ID

Pa!.'c A-J

�°'0

Table I, continued (3rd page).
Roxborough Statol'mknearjundim of Willow
Creek and UttJo wmow Croelc, Dougln Co.,
CO. 7300 ft. Xnsl« quadrangle, T 7 S, R 69

2
(2)

SCR

Smllh Croelc, U.S. Air For00 Acadmly, El Paso
Co., CO. 6,860 ft. Monummt quadrangle,
T12S,R67W

6
(6)

STV

&amp;. Vraln R., Boulder County Open Spaco,
Hygiene, BoutderCo., CO. ,,060 ft. Hygiene
quadrangle, T 3 N. R 70 W

6
(5)

WFS

Wat.POik Sdiachheim Croelc, Lak, Dorothcy
State Wildlife Area. Las Anlmu Co., CO
[Elev.•?)
JOuadnmltlo • ?t ITwmrn&gt;,/RnVSeo • ?l
Woodhomc Randt, Douglu Co., CO. 5,760 ft.
Kass1« quandrang1e. T 7 S, R68 W

4
(4)

ROX

w

WHR

7
(5)

ROX970l•

24,E 1/2

ROX9702•

24, E 1/2

SCRI•
SCR2•
SCRJ•
SCRS*
SCR6*
SCR7STVl
STV2•
STV3•
STV4•
STV5•
STV6•
530•
531*
532*
533•
WHRl•

wmu•-

39° 25'44.s''
105°03'48.9"
39° 26'10.l"
105°04'24.0"

4945290.00, 43643880.00

6NE,SE
114

NIA

36, SE 1/4

AI&gt;eam

Colorado Division of Wildlife
Carron Meaney. Consuhant

NIA

C. Meaney

Colorado Division ofWidlifc

NIA

NIA

C. Meaney

Colorado Division of Wildlife

NIA

37"00'25"
104"22'32"

NIA

C.A.Jonea

Dcnva- Museum of Natural
History

36, NE 114,
SWl/4

NIA

NIA

C.Meancyand
N. Clippinger

Colorado Division of Wildlife

36, SW 1/4,
Elt'2

[Need info.
from collector]

[Infonnstion needed)

?

?

NIA

NIA

4309600.00, 5139400.00
4309580.00. 5139400.00
4309550.00, 5139400.00
4309SS0.OO, S139400.00

P.Sdtuerman
S.Ask
J. Hobert

04774210.00.
44084950.00
04774210.0Q.
440845&gt;50.00
04774210.00.
44084950.00

JanPdcrsoo

4936880.00, 43651170.00

WHR3
WHR4*

WHR5•
WPC

Well l'1um Croelc, Dougln Co., CO
{Detailed dc,c:ription needed from collector]
[Elav.•?)
[Quadnmglo • ?). T 7 S, R 68 W

WRN

Monummt Creek near cx1ofluaicnrith Pinc
Croelc, N. tide of Woodman ROid, Et Paso Co.,

co.
WRP

WhiteRmdll'm. Ralltm Croelc,oJfHwy.U
norlh o!Ooldm. Jeft'encn Co., Colorado, 5740
ft. Ratstm Butt.es quadnmgtc, T 2 S. R._70 W

Appendix A

8
(8)

s
(1)

3
(2)

WHR6*
WHR7
WPCl•
WPC2•
WPCJ*
.WPC4•
WPC5*
WPC6*
WPC7•
WPC8•
97WRN130
97WRN138•
97WRN142
97WRN143
9'7WRN75
WRffl25
WRm41•
WRm49•

31

Colorado Natural Heritage
Program

Page A-4

�Table 2. Reference specimens ofjumping mice provided by museums and other investigators, used as representatives of recognized species and subspecies of
the genus Zapus for comparison with specimens listed in Table 1.
Original 11mplo

Specimen information provided by IOUr00
Individual or imtftuden
~Creek.FR 1'6 off'Col(? Hwy 14,
LarfmerCo.CO. 10,000ft.
Aalgnedto Zap,11 prtncq,,

No.
(4)

CZPB•
CZP9'

DMNH

Pmptoiro Campground, 262.S m. San babel
National Porat, Lu Anlmn Co.. Colorado.
Aalffll'!dto 7..tmtt, Drlnt:.DI at DMNH

2
(1)

CZP12'
CZP13'
7916'
7917

RSS

Zaprt, httd,omr11 amplca provided by Bnaco

2
(2)

Sample Code
CZP

ZHLNMO

Wunder, Anoka County. Minnelcta. maine,
NB 1/4 ofNB, Sec. l, T31N, R23W
Presumed to bo Z. h. lntmrtdtit1
Zaprt, httd,omr11 mq,lca provided by Bruce
Wunder, origin in Indiana; may be Z. h.
tnrmn.dml or Z. h. ammcamu
Zapr,1 hffdl0fffl11 can,patrll ftom Culta' Co.,
81), provided by tho Mulcmn ofNatural
m.iirv. Unfv. ofKanm
Zaprt, httdltmltt1 can,patrt1 ftom Weston
Co.. WY,providedbytho MulCUID ofNatural
m..trv. Unfv. of'Kanm
Zaprt, httd,omr11 (lttter11) ftom Otero Co., NM

ZHLNMS

Zaprt, httd,omr11 (lt1ter11) from Sandoval Co.,

ZAHU
ZHCSDC
ZHCWYW

Fmton Lake, NM
ZHPNBC

Zaprt, httdionhll pc,llldt11 from Cieny Co.,

NB
ZHPNEO

Zap,11 ln1dionh11 pc,11ldt11 from Oanlm Co.,

NB
ZPPCOG
ZPPNMT

Zaprt, prtncq,1 prtnc,p1 ftom Ptannigan
C-. Onmd "-" CO
Zaprt, prtncq,1 prtnc,p1 ftom Taos Co., NM

nos.

1/4-1/4
Section
NIA

Lit-Long

UTM

Collecton'Sourco

Coopenting Institution

Coordinatea

NIA

NIA

B. Wunda-

Colorado State University

NIA

37°15'00" N
105°6'30"W

NIA

C.AJones

Daiver Museum of Natural
History

RSS 1076'
RSS1077'

NIA

NIA

NIA

B. WundaRobatSikes
ElmerBumey

Colorado Stat.: University
University of Minnesota

2
(2)

ZAHU-253'
ZAHU-300•

NIA

NIA

NIA

Colorado Stat.: University

2
(2)

109994'
109995•

NIA

NIA

NIA

B. Wunder
collected by John
WhiUalcec
R. Timm
T.Holmes

2

42469'
42470•

NIA

NIA

NIA

(2)

R. Timm
T.Holmes

Natural History Museum,
Univ. of Kansas, La\vrmcc

2
(2)

NK87&amp;•
NK879•

NIA

NIA

NIA

T.Yates
B.Gannon.

2
(2)

NK3835'
NK3837'

NIA

NIA

NIA

T.Y~
B.qannon

2. . -87043
87044
115762'
2
m 115763
CU14912
2
(0)
CU14913
NK811
2
(1)
NK814'

NIA

NIA

NIA

NIA

NIA

NIA

NIA

NIA

NIA

R. Timm
T.Holmea
R. Timm
T.Holmes
AdeQueiroz

NIA

NIA

NIA

Museum of Southwestern
Biology, Univ. ofNew
Mexico, Albuouemue. NM
Museum of Southwestern
Biology, Univ. ofNew
Mexico. Albuouemue, NM
Natural History Museum.
Univ. ofKansas. Lawrmcc
Natural History Museum,
Univ. of Kansas, Lawrmcc
Univ. of Colorado
Museum. Boulder, CO
Museum of Southwestern
Biology, Univ. ofNew
Mexico, AJbum,,.,.,,.,,. NM

4

(O}

D. Annstrcn2

T. Yates
B.Gannon
.

Natural History Musc:um.
Univ. ofKansas, Lawrence

NIA• not available for this report. In some cases the indicated information may be obtained from the person or institution supplying the material analyzed or
can be inferred from other available information.

.....
°'

Am,cndixA

��63

I
State of ___C
....o"""l,...o=ra...,d...,o.___ __
Project No.
W-153-R-l l
Work Plan No. _ _..,._0=66=2=---Task No. _ _ _ _--=-3_ _ __

APPENDIXB
11

STUDY PLAN
Cost Center 3430
Mammals Research
Conservation ofPreble's meadowjumpin2 mouse
Temporal and spatial variation in the demography of
Preble's meadow jumping mouse (Zapus hudsonius

preblei)
TEMPORAL AND SPATIAL VARIATION IN THE DEMOGRAPHY OF
PREBLE'S MEADOW JUMPING MOUSE (Zapus hudsonius preblei)

A. NEED
On May 12, 1998 the U.S. Fish and Wildlife Service (USFWS) published a final rule in the
Federal Register ( 63 FR 26517) to list Preble's meadow jumping mouse (Zapus hudsonius preblei) as
'threatened' under the Federal Endangered Species Act (ESA) of 1973, as amended. Recovery goals
for Preble's meadow jumping mouse should work towards the sustainability, protection, and restoration
of Z. h. preblei populations and habitats on both private and public lands to provide the spatial, genetic,
and demographic structure needed to promote long-term species viability and provide species
management flexibility. Recovery efforts for the subspecies will be most effective ifreliable
information is available on the basic ecology of the subspecies and this information used to design
recovery efforts such as Habitat Conservation Plans. A review of studies conducted on Preble's
meadow jumping mouse shows that there is insufficient information to fully address defining rangewide ecological requirements, limiting factors, limits of species tolerance, or population status (Shenk
1998). Most work to date has focused on geographic distribution (presence or absence of Z. h.
preb/ei), taxonomy, and habitat descriptions of sites where mice have and have not been captured. For
Preble's meadow jumping mouse in particular, information on dispersal, habitat use, and population
dynamics is most needed to identify minimal ecological requirements of the subspecies.
Monitoring, by way of estimating demographic parameters (such as survival, abundance, and
reproduction), of a single population over time provides an opportunity to document demography of a
species, estimate temporal fluctuations in demography, and gain insights into the temporal variation
inherent in demographic parameters. Monitoring of multiple populations over time and over multiple
geographic locations provides the opportunity to gain further understanding of population processes
and detaches time effects from spatial effects. Population monitoring activities do not constitute
scientific experiments, in the spirit of manipulation of salient ecological variables, however, replication
of monitoring activities for natural populations over long periods of time and in diverse geographic
locations can lead to insights into population processes (Cook and Campbell 1979). These insights can
then be translated into hypotheses useful for predicting changes in population demography resulting
from either natural perturbations (e.g., flooding events) or anthropogenic modifications (e.g., gravel
mining). Experimentation would then be required to test these hypotheses and establish cause and
effect.
There are three components of Z. h. preblei ecology that are currently unknown and yet key to
any sound conservation strategy for the subspecies. These are (I) detailed demographic studies
estimating survival, reproduction, immigration, emigration, and abundance and determining the factors
influencing each of the parameters, (2) detailed studies evaluating movements and dispersal habitat of
individuals within and among populations, and (3) detailed studies to define hibernation needs,
primarily descriptions of suitable hibemacula criteria and food requirements for sufficient fat storage
prior to immergence. The overall objective of this study is to provide estimates for all three of these

�64

needs from three different populations of Preble's meadow jumping mouse. Thus, providing the
opportunity to estimate spatial variation in the demography of the species.
The three study populations occur in areas of different habitat matrices. The first study area
limits animals within the population to a single drainage. The second population occurs in an area that
combines a tributary and main drainage. The third population occurs in an area with both a tributary
and main drainage as well as a series of ponds and irrigation ditches available to the animals.
Continuing the study for multiple years will provide the opportunity to estimate temporal variation in
the demography of the subspecies.

B.

OBJECTIVES

Specific objectives for this study on Preble's meadow jumping mouse include:
I.
2.
3.
4.
5.
6.
7.

Evaluate temporal and spatial variation in daily and seasonal movements of Preble's
meadow jumping mouse.
Estimate and evaluate temporal and spatial variation of over-summer, over-winter,
and annual survival rates for Preble's meadow jumping mouse.
Estimate and evaluate temporal and spatial variation of reproduction, immigration,
and emigration for Preble's meadow jumping mouse..
Estimate and evaluate spatial variation in abundance and density for Preble's
meadow jumping mice.
Evaluate temporal and spatial variation of habitat use in Preble's meadow jumping
mouse.
Document temporal and spatial differences in composition of foods consumed by
Preble's meadow jumping mice.
Collect genetic tissue samples for future analyses to document and compare
variation within and among populations of Preble's meadow jumping mouse.

C. EXPECTED RESULTS
There are three components of Z. h. preblei ecology that are currently unknown and yet key to
any sound conservation strategy for the subspecies. These are (I) detailed demographic studies
estimating survival, reproduction, immigration, emigration, and abundance and determining the factors
influencing each of the parameters, (2) detailed studies evaluating movements and dispersal habitat of
individuals within and among populations, and (3) detailed studies to define hibernation needs,
primarily descriptions of suitable hibemacula criteria and food requirements for sufficient fat storage
prior to immergence. The overall objective of this study is to provide estimates for all three of these
needs from three different populations of Preble's meadow jumping mouse providing the opportunity to
estimation spatial variation in the demography of the species. Continuing the study for multiple years
will provide the opportunity to estimate temporal variation in the demography of the subspecies
Performance Indicators
I.
Provide descriptions of movements of mice for three Preble's meadow jumping mouse
populations.
2.
Provide estimates of survival and reproduction for three Preble's meadow jumping
mouse populations.
3.
Provide estimates of immigration, emigration, and abundance for three Preble's
meadow jumping mouse populations.
4.
Describe over-summer foods consumed by three Preble's meadow jumping mouse
populations.
5.
Quantify habitat characteristics of three sites where Preble's meadow jumping mouse
are known to occur.
6.
Analyze and publish results of research

�65

D. APPROACH
Study Site Selection
All three study sites selected are areas where Preble's meadow jumping mouse (PMJM) has
been found in the last two years. To evaluate spatial differences in movement of PMJM, sites were
selected that provided a variety of habitat matrices available to the mouse. The first site selected,
CDOW Maytag property, has one primary water source available to the mouse. This water source is
East Plum Creek. Therefore we predict mice will restrict their movements to up and down this single
drainage. The second site, Colorado Open Lands Pine Cliff Ranch, provides both a tributary (Garber
Creek) and a main stem drainage (West Plum Creek). This provides the opportunity to investigate
whether PMJM will move overland to move from one drainage to another or if they are restricted to
moving only along riparian corridors. The third study site, CDOW Woodhouse Property and Dupont
Property, provides an area containing a tributary (Indian Creek),a main stem drainage (West Plum
Creek), and a series of ponds and irrigation ditches scattered throughout the property. This provides an
even greater opportunity to investigate how much the mice will use upland areas or if they restrict their
movements strictly to riparian corridors. Each of these unique habitat matrices provides the
opportunity to estimate spatial variation in nightly and seasonal movements of PMJM.
Movement Study
Background
Movement and dispersal pattern information will be key to any conservation strategy designed
for Preble's meadow jumping mouse. Key factors include (1) which segment of the population
disperses, (2) when do they disperse, (3) through what habitat do they disperse, (4) how far will
individuals disperse (i.e., what is the maximum distance that separates adjacent populations) and (5)
how critical is dispersal (both into and out of a population) to the persistence of a given population.
The only currently available data on dispersal and/or movement for Z. h. preblei are from marked mice
at Rocky Flats Environmental Technology Site (T. Ryon unpublished data). Two mice, an adult female
and an adult male, were observed approximately 1.6 kilometers from previous locations (incidences
occurred separately). Each of the locations were in the same drainage (Woman Creek).

Objectives
The PMJM movement study is designed to describe nightly and seasonal movement patterns of
PMJM and to describe habitats used by PMJM. Specific objectives include:
1.
2.

3.
4.

5.

Describe nightly movements of PMJM. Evaluate difference in nightly movements as
they relate to sex, age, and habitat available to the animals.
Describe 30-day (or life of the radio transmitter) interval movements of PMJM.
Evaluate difference in 30-day (or life of the radio transmitter) interval movements as
they relate to sex, age, and habitat available to the animals.
Describe seasonal movements of PMJM. Evaluate difference in seasonal movements
as they relate to sex, age, and habitat available to the animals.
Describe habitats where mice occur: movement corridors, end point descriptions
(disperses from what to what), and landscape features (connectivity with other riparian
strips).
Estimate the mean amount of time PMJM spend in each available habitat.

Approach
Movement data will be documented primarily from locations of radio-tagged mice from each
of the three study populations. To place radio transmitters on the animals, mice will be captured in
Sherman live traps. Mice weighing&gt; 18 grams will be fitted with MD-2C, I-gram radio transmitters
supplied by Holohill Systems Ltd. (used successfully on PMJM by R Schorr, personal

�66

communication). A maximum of 30 mice at each study site will be radio-tagged. The following
procedures will be used to capture and attach the transmitters to the mice.
Trapping session details
Timing of surveys
1.
Four 7-day trapping sessions will be conducted during the following weeks: June 2-9,
1998; July 21-28, 1998; September 8-15, 1998; and June 2-9, 1999.
2.
Due to the nocturnal nature of PMJM, traps will be set between 19:00hrs and 21 :OOhrs
and checked as early as possible in the morning beginning at 5:00hrs (to reduce stress
and the potential for predation on trapped animals). Time required to complete the
traplines will vary depending on how many animals are caught.

Trapping protocols
1.
Trappers will be advised to follow the Center for Disease Control's Hantavirus
instructions and recommendations when dealing with rodents which include:
a Baseline blood serum samples will be collected and stored at Poudre Valley
Hospital for all surveyors.
b. Respirators are available for use by surveyors if they request their use.
c. Surgical gloves will be used at all times when handling rodents.
d. All equipment will be rinsed first with a I 0% bleach solution, then water after use.
e. Traps and any equipment that may have rodent feces or urine on it will not be
transported in the interior of a vehicle.
f Traps will be cleaned after each use by a mouse.
g. If a surveyor becomes ill with hantavirus symptoms they will report immediately to
a medical facility.
2.
Trappers must be in possession of both a federal and state collecting permit.
Trapping methodology
1.
Small mammal Sherman live traps {folding and non-folding) will be used to conduct
the trapping sessions.
2.
Traps will be set in two parallel lines of trap stations (1 trap per station) on either side
of the drainage. Trap stations will be 5 meters apart for a total of 250 meters; the
parallel transects will be IO meters apart unless extent of habitat, terrain topography, or
stream hydrology do not allow.
3.
Location of transects will be recorded on field data sheets and identified on 7½ minute
topographic maps. Locations will also be recorded to the nearest 5 meters in UTM
coordinates using a Trimble Geo-Explorer GPS.
4.
In case of windy conditions or large number of trap-tampering predators (i.e., raccoons,
foxes, coyotes, etc.), traps will be secured to the ground with hoops of heavy-gauge
malleable wire, stakes, or with other materials that can effectively secure/immobilize
the traps.
5.
A small (~I inch) ball of polyester quilt or wool (fleece) will be placed in each trap as
nesting/bedding material.
6.
Baiting materials will be Manna Pro Sweet 3-way Livestock feed which contains no
animal matter. Ingredients include flaked barley, flaked corn, flaked oats, and cane
molasses. Peanut butter will be used to stick the bait to the trap.
7.
Checking of the traps will be conducted by two surveyors; one person will handle the
traps and animals captured, the other person will record the data
Handling of captured animals
1.
All animal captures will be recorded.

�67

2.

3.

4.

5.

If an animal has been captured in a trap, a ziplock plastic bag will be placed over the
end of the trap. The trap will be opened allowing the animal to fall into the plastic bag.
The animal will be identified to species while in the plastic bag.
If the animal is not a PMJM, identification of the animal will be recorded and the
animal set free.
Each captured PMJM will be scanned to detect the presence/absence of a PIT tag
and/or radio-collar. If a PIT tag or radio-collar is detected and the mouse has been
captured at that same site within the 7-day trapping effort, identification of the mouse
will be recorded and the mouse will be released.
If the animal is a PMJM and no PIT tag or radio collar is detected the PMJM will be
anesthetized for further processing, as follows. All PMJM will be PIT-tagged. If the
PMJM weighs &gt; 18 g a radio-collar will also be put on the animal

Anesthesia
The following protocol has been used successfully on PMJM by R Schorr (personal
communication).
I.
Measure I ml ofMetofane (methoxyflurane) onto one cotton ball.
2.
Place ball into ziplock bag and seal (to keep Metofane fumes in bag).
3.
Lay bag still and move away. This should minimize stress for the mouse and the time
the mouse struggles in the bag, decreasing the amount of time required for the
metofane to work.
4.
After the animal stops movement, wait I minute before removing it from the baggie.
The animal should remain anesthetized for 2-3 minutes.
5.
Time animal is exposed to Metofane and reaction to the anesthesia will be recorded.
PIT tagging the animal
The following protocol has been used successfully on PMJM (C. Meaney, personal
communication).
I.
Each PMJM will have a PIT tag inserted above the shoulder blades by lifting the skin
on its back and inserting the needle with. the PIT tag under their skin and injecting the
tag. Verification of the PIT tag identification number will be made before insertion into
the mouse by running the PIT tag scanner across it.
2.
Skin behind the opening will then be pinched to prevent emergence of the tag.
3.
Surgical glue will then be applied to the opening to prevent the PIT tag from exiting the
body and prevent infection of the mouse.
4.
A PIT tag scanner will be held over the mouse to again verify PIT tag identification
number and that it still works after the insertion procedure (note: PIT tag will be
scanned twice during application to mouse, or once if mouse was previously PIT
tagged).
5.
PIT tag identification number will be recorded on the field data form and the mouse
released.
6.
If, at any time during the handling of the PMJM the animal appears to be severely
stressed (dramatic changes in heartbeat, respiration and responsiveness or gums turning
blue) the animal will be released immediately.
Collaring the animal
The following protocol has been used successfully on PMJM (R Schorr, personal
communication).
I.
Make sure transmitter is functioning before collaring the animal with the transmitter by
tuning the receiver to the transmitter frequency to make sure there is a signal.
2.
Slide crimp and then tubing onto the antenna

�68

3.
4.
5.
6.

7.
8.

Guide antenna through the channel of the transmitter.
As antenna exits the transmitter, guide it through the crimp.
Keep loop made by antenna large enough to fit over the mouse's head.
Once over the neck of the animal, pull antenna to reduce collar size, making sure
rubber tubing is on the dorsal side of the neck. The purpose of the rubber tubing is to
prevent damage to the collar and prevent the person attaching the collar from cinching
the collar too tight. Make sure collar can rotate freely around the animals neck, but not
loose enough to be removed.
Pinch metal crimp to hold the antenna in the desired collar position.
Approximately 2 inches of antenna will be pointing out behind the animal.

Measurements
1.
Each PMJM will be weighed while in the bag, recording the weight in grams using a
Pesola spring balance.
2.
Sex, age Guvenile, adult), and reproductive condition (pregnant, lactating or nonbreeding if it is female; for males the position of the testes will indicate if in breeding
status or non-breeding status) will be noted.
3.
Each PMJM will be measured (total length, length of body, length of hind foot - heel to
distal end of claws) in millimeters. Measurements of total body and tail length will be
taken with the mouse on a firm surface to minimize error.
4.
Capture of every PMJM will be documented by taking a photograph of the mouse on
first capture. If the mouse has been captured previously as noted by the detection of a
PIT tag, no photograph needs to be taken.
5.
If there are feces in the trap where a PMJM was captured, the feces will be collected in
a plastic bag labeled with date and location of the site. Fecal samples will be kept cool
until returned to the CDOW office where they will be frozen. Fecal samples will be
analyzed by the Composition Analysis Laboratory, Inc, 622 ½ Whedbee, Fort Collins,
CO for content.
Handling of trap mortalities and injuries
I.
All trap mortalities will be recorded on a 'Trap Mortality' data form which includes
information on species, potential duration of time spent in the trap, any information
available on cause of death, etc.
2.
All animals found dead in a trap will be double-bagged in a plastic bags and placed in a
cooler with ice. Specimens should be frozen as soon as possible and deposited the
CDOW freezer at the office in Fort Collins. All specimens will be sent to the Colorado
State University Diagnostic Laboratory for detection of any disease and/or other
conditions that may have contributed to cause of death. All PMJM specimens will be
returned to the CDOW.
3.
A museum card will be completed and attached to each PMJM specimen and given to
Cheri Jones, Curator ofMammalogy at the Denver Museum of Natural History, for
study skins and tissue storage once the Diagnostic Laboratory has completed their
evaluation.
4.
If an animal is severely injured (e.g., severed limb, large lacerations) it will be
euthanized by soaking a cotton ball in Metofane (methoxyflurane) and placing the
cotton ball and the mouse in a ziplock baggie until the animal stops breathing. All
specimens will then go through steps 1-3 above.
5.
If an animal appears to be only slightly injured (e.g., broken tail, small laceration) the
animal will be released to the wild. If an animal appears to be cold stressed attempts
will be made to warm it by holding it in the surveyors hands and/or against their body.
If the animal appears to be heat stressed, isopropyl alcohol will be applied with a cotton
swab to the ears, arm pits, and feet to cool it down.

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Training of field crews
1.
All field technicians will be required to spend a full day at the Denver Museum of
Natural History Zoology Department viewing and handling specimens of all small
mammal species likely to be captured in Douglas County.
2.
All field technicians will be provided with a small mammal field guide and a key
specifically designed to list the species most likely to be captured on the trapping sites.
3.
All field technicians will participate in 4 days of practice trapping at the Frank State
Wildlife Area from May 26-29. During these trapping sessions all technicians will
learn how to place, bait and set traps. Field identification will be practiced on all
animals caught each day and verified by crew leaders. All field technicians will also
practice handling, measuring, implanting PIT tags, and taking genetic tissue samples
from deer mice (Peromyscus manicu/atus) until they are competent in this procedure.
Data collection
Once transmitters are in place, locations of individual mice will be made nightly. Because very little is
known about the movements of PMJM the pilot protocols will be established. As we learn more about
PMJM movements, protocols will be adjusted to maximize efficiency and data collection.

To describe nightly movements the following parameters will be estimated:
1. Minimum and maximum distances moved each night animal is followed.
2. Mean minimum and maximum distances moved each night for all mice.
3.
Minimum and maximum distances moved away from the stream center each night by
individual mice.
4.
Mean minimum and maximum distances moved away from the stream center each
night for all mice.
To describe 30-day (or life of the radio transmitter) movements the following parameters will be
estimated:
Minimum and maximum distances moved each 30-day (or life of the radio transmitter)
1.
interval animal is followed.
2.
Mean minimum and maximum distances moved each 30-day (or life of the radio
transmitter) for all mice.
Minimum and maximum distances moved away from the stream center each 30-day (or
3.
life of the radio transmitter) interval by individual mice.
Mean minimum and maximum distances moved away from the stream center each 304.
day (or life of the radio transmitter) interval for all mice.
Locations:
1.
A minimum of 6 locations per individual mouse per night will be made. As many mice
as possible will be tracked on a given night as is feasible to assure the minimum 6
locations per individual. Each individual mouse should be tracked a minimum of 3
nights per week.
2.
The 6 locations per night per individual will be scattered throughout the night to
maximize information learned about nightly movements (i.e., 8 locations taken within a
single hour contains less information than 8 locations taken one each hour).
3.
Three bearings will be taken for each location from pre-determined way stations to
estimate location of the mouse.
4.
Daytime locations will be taken as time permits.

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Demography Study
Background
Information on the population dynamics of Preble's meadow jumping mouse is necessary to
determine which areas support viable populations. To begin to evaluate the viability of a population
information on key demographic parameters must be obtained. Below is a summary of what is know to
date on the demography of Preble's meadow jumping mouse.
Abundance: There is no information on range-wide abundance of Preble's meadow jumping
mouse. However, from trapping surveys it appears that where the subspecies does occur it exists in
low densities and thus one of the rarer components of the small mammal assemblage present.
Reproduction: Meadow jumping mice have been observed to produce up to three litters per
season (Whitaker 1963). Breeding peaks appear to occur in early to mid-June and August with a
possible third litter in September (Whitaker 1963). Juvenile Z. h. preb/ei have been observed in June,
August, and September (Meaney et al. 1996, 1997, PTI 1996a, M. Bakeman unpublished data, T. Ryon
unpublished data), suggesting two litters per year. Z. hudsonius typically have litters of 5-6 young per
litter (Quimby 1951 ). Age of first reproduction is unknown for Z. h. preblei, however, females of Z.
hudsonius have been observed to give birth at 3 months (i.e., females born in June have been observed
to give birth in August of the same year). Gestation period is approximately 18 days (Quimby 1951 ).
Young remain dependent on the female for approximately 18 days (Quimby 1951). No evidence of
male parental care exists for Z. hudsonius (Whitaker 1963).
Survival: No information exists on survival rates for populations of Z. h. preblei. Whitaker
(1963) reported a 67% loss of individuals over hibernation and that average body mass of individuals
emerging from hibernation was greater than the average for mice entering hibernation. Because no
mice are known to store food in their hibernacula, this indicates that the lighter individuals died during
hibernation and only those entering with higher masses survived. All the energy they use during
hibernation and the periodic arousals (the energetically most expensive part of hibernation) must be the
fat they carry into hibernation (B. Wunder, personal communication). Thus, the ability to put on
sufficient fat for overwinter survival during hibernation is a critical factor in the life history of these
mice. Besides insufficient fat storage prior to hibernation, other observed mortality factors in Z.
hudsonius include predation (Whitaker 1963, Poly and Boucher 1997) and cannibalism (Sheldon
1934). Other assumed mortality factors for Z. h. preblei include starvation, exposure, and disease.
Population Structure: Armstrong et al. (1997) reported an overall sex ratio for all captured
Preble's meadow jumping mice of 51. 6 males: 48. 4 females; approximately 86. 0% of captures were
identified as adults. However, Armstrong et al. (1997) suggested that these data be interpreted with
caution because of possible differences in field techniques.
Longevity: Very few individuals of Z. h. preb/ei have been permanently marked. Therefore,
recapture information, necessary to determine longevity, is minimal. Several recaptures have yielded
adults surviving through two years, indicating a longevity of at least three years (T. Ryon, unpublished
data). One recapture history from Rocky Flats Environmental Technology Site recorded an adult male
in 1996, two years after it was first captured as an adult in 1994, indicating survival of at least four
years {PTI 1996b). Quimby (1951) found that only a low percentage of Z. hudsonius lived two years
or more, but gave two records of mice that lived for at least two years under natural conditions.
Whitaker (1963) reported a female living at least two years.
Objectives
Objectives of the demography study are to:
1.
Estimate abundance of PMJM at each of three study populations.
2.
Estimate over-summer, over-winter, and annual survival of PMJM at each of three
study populations.
3.
Estimate temporary emigration of PMJM at each of three study populations.
4.
Estimate immigration of marked PMJM back into each of three study populations.
5.
Evaluate the affect of weight, sex, age, abundance (i.e., density dependent response),

�71

6.

and habitat features such as stream reach, vegetation composition and density on
survival, reproduction, abundance, temporary emigration, and immigration of marked
animals back into three study populations of PMJM.
Estimate age and sex ratios of PMJM at each of three study populations.

Approach
Mark-recapture estimation techniques will be used to estimate abundance, over-summer
survival, over-winter survival, temporary emigration and immigration of marked animals back in to the
three study populations of PMJM.
Abundance: Abundance will be estimated using Pollock's Robust Design (see Kendall et al. 1997,
1995 and Kendall and Nichols 1995 for detail). The robust design is a combination of the CormackJolly-Seber (CJS)(Cormack 1964, Jolly 1965, Seber 1965) live recapture model and the closed capture
models. The key difference from the CJS model is that instead of just one capture occasion between
survival intervals multiple capture occasions are used. These occasions are close together in time
allowing the assumption that no mortality or emigration occurs during theses short time intervals. The
closely spaced encounter occasions are termed "trapping sessions" and each trapping session can be
viewed as a closed capture survey. Four 7-day trapping sessions will be conducted during the
following weeks: June 2-9, 1998; July 21-28, 1998; September 8-15, 1998; and June 2-9, 1999.
Survival: By using the estimate of the probability that an animal is captured at least once from the
trapping sessions designed to estimate abundance, survival between the longer intervals can be
estimated. Four 7-day trapping sessions will be conducted during the following weeks: June 2-9, 1998;
July 21-28, 1998; September 8-15, 1998; and June 2-9, 1999. Thus, estimates of over-summer
survival, over-hibernation survival, annual survival and survival from June-July, July-August, and
August-September can be made.
Temporary emigration and immigration: The longer intervals between trapping sessions also allows
estimation of temporary emigration from the trapping area, and immigration of marked animals back
to the trapping area
Reproduction: Reproductive parameters will be estimated by following radio-tagged females to nest
sites. At each nest found the following will be recorded: date, number of young in each nest and
number oflitters observed for individual females throughout the year

Habitat Use Study
Background
The habitat matrix within the range of Z. h. preblei is mixed grasslands adjacent to the
Colorado Front Range along the Piedmont and along the base of the Laramie Mountains in Wyoming
and extends to the Colorado plains. Within this matrix, Preble's meadow jumping mice occur along
stream drainages that contain patches of suitable vegetation. Suitable habitat appears to have at least
two major components. The first component is a supply of open water, at least in part of the active
season (M. Bakeman, C. Meaney, personal communication). Secondly, areas where Preble's meadow
jumping mouse has been found have dense cover (M. Bakeman, C. Meaney, personal communication).
If Preble's meadow jumping mouse behaves as a metapopulation in the classical sense of a set
of local populations linked by infrequent dispersal then habitat includes not just one area of suitable
habitation but also areas suitable for nearby mouse populations. These suitable areas must also be
linked by dispersal habitat. If the mice are dependent on dense riparian habitat for dispersal as well as
for areas to reproduce, persistence of discrete populations would require a mosaic of suitable discrete
riparian patches interconnected with dispersal corridors of similarly dense riparian vegetation. If mouse
populations function in a source (populations where growth rate~ 1) and sink (those populations where

�72

growth rate &lt; 1, maintained through immigration) system, it will be critical to identify and protect those
populations serving as sources. Thus, for a source-sink population critical habitat will include those
areas that support source population, dispersal habitat to sink areas will be less critical. If local mouse
populations are functionally discrete, such a mosaic of interconnected areas of suitable habitat would
provide a buffer for local, and source, populations against deleterious stochastic events by providing
the opportunity for local population failures to be 'rescued' by immigration from other populations.
Areas of suitable habitat must also provide requirements to survive throughout the life cycle.
These requirements must provide necessities for both the active period and hibernation periods.
During the active period suitable habitat must provide requirements for daily survival, reproductive
activities (breeding, nesting, and rearing of young to independence), and dispersal. The hibernation
period requires sufficient food supplies to assure fat storage prior to hibernation and suitable
hibernacula Habitat providing all seasonal and life cycle requirements may or may not occur in a
single contiguous area If not in a contiguous area, habitat patches must occur in a mosaic of usable
areas where suitable corridors exist for seasonal movement among sites.
Based on studies of Z. h. preblei and Z hudsonius elsewhere, Z. h. preblei apparently occurs
mostly in undergrowth consisting of grasses, forbs, or both in open wet meadows and riparian
corridors, or where tall shrubs and low trees form an overstory and provide adequate cover (Armstrong
et al. 1997). Meadow jumping mice are widespread in abandoned grassy fields, but is often more
abundant in thick vegetation along ponds, streams, and marshes or in rank herbaceous vegetation of
wooded areas (Whitaker 1963). Preble's meadow jumping mice have been trapped in natural riparian
areas as well as areas altered by anthropogenic influence including ditches and wetlands adjacent to
interstate highways, cement-lined ditches with tall cover, ditches along driveways and moderate road
use, and moderate cattle grazing (M. Bakeman, personal communication).
The majority of sites where Z. h. preblei have been found consist of multistoried cover but the
species composing the cover vary greatly (Armstrong et al. 1997, Meaner et al .. 1997). Vegetation
composition of the dense cover varies considerably and includes both native and non-native species
(Meaner et al. 1996, 1997, Armstrong et al. 1997, M. Bakeman, personal communication). The
herbaceous understory can be primarily grasses or forbs or a mixture of the two. Few of the sites,
however, are dominated by fewer than two understory species. The tall shrub canopy at most sites is
willow (several species), although scrub oak, birch, and alder occur in sites south of the Palmer Divide
(Armstrong et al. 1997). Ponderosa pine is the most common tree at higher elevations. The mouse
appears to tolerate weedy or exotic species in areas that are structurally diverse and species rich; nearly
every successful site contained Canada thistle (Armstrong et al. 1997). Thus, the mouse does not
appear to have an affinity toward any single plant species but instead favors sites that are structurally
diverse and provide adequate cover and food throughout its life cycle.
Preble's meadow jumping mouse mice are typically not found in upland areas away from
riparian habitats but are most often captured where either ground water daylights to seep springs or on
main water channels (M. Bakeman, T. Ryon, personal communication) suggesting a dependence on
open water, at least during their active periods.
Movement of Z. h. preblei on Woman Creek at Rocky Flats Technology Site suggests mice
move along corridors of shrub cover, generally Salix exigua (PTI 1996a, T. Ryon, unpublished data),
suggesting dispersal habitat is similar to habitats used for other activities.
Jumping mice of the genus Zapus are true hibernators, spending much of their lives in
hibernation. Meadow jumping mice spend approximately 7 months (~210 days) per year in hibernation
(Quimby 1951) whereas estimates for Z. princeps indicate that some populations (e.g., in the western
mountains of Utah) spend up to 300 days per year in hibernation (Cranford 1983). Males emerge prior
to females (Bailey 1923, Bailey 1929, Hamilton 1935, Quimby 1951, Whitaker 1963) with the earliest
annual recorded dates for Z. hudsonius males being April 25-May 16 and females May 4-26.
Latest fall capture date for an adult male was October 10 in 1994 at South Boulder Creek
(ERO Resources 1995) and September 28 in 1995 at the Van Fleet Parcel on South Boulder Creek
(Armstrong et al. 1997). A juvenile male was captured as late as October 26 and a female juvenile on

�73

October 27 both in 1995 at Rocky Flats Environmental Technology Site (M. Bakeman, unpublished
data).
Jumping mice hibernate in underground burrows (Quimby 1951, Whitaker 1963). They are
excellent burrowers and create their own hibernacula Meadow jumping mice are generally solitary
hibernators, however, there have been occurrences of more than one mouse found in a single
hibernaculum. One hibernaculum, located on Rocky Flats Environmental Technology Site, used by Z.
h. preblei has been located (Armstrong et al. 1997). This site was 9m above a creek bed (Walnut
Creek); it had a thick cover of chokecherry (Prunus virginiana) and snowberry (Symphoricarpos spp.),
the mouse was found in a leaf litter nest 30cm beneath the ground in coarse textured soil (Armstrong et
al. 1997). Four possible hibernacula were located by tracking radio-telemetered mice at the U. S. Air
Force Academy in fall 1997. These sites are located 7, 12, 29, and 31m from a creek bed (R Schorr,
personal communication). There was no consistency among sites in aspect (N/NW, SISE, E, and none
[level ground]). Three sites were in vegetation dominated by coyote willow (Salix exigua), one site
was in vegetation dominated by snowberry and mullein (Verbascum thapsus). However, all four
hibernacula appear to be below coyote willows. These four U. S. Air Force Academy sites have not
been disturbed to protect any hibernating mice and therefore are only possible hibernacula because
there is no confirmation a mouse is actually hibernating there. Confirmation of a true hibernaculum
cannot be made until a chamber, or nest is located. These sites may also possibly be locations ofradios
discarded by the mice or dead mice.
Objective
The objective of the habitat study is to identify and refine habitat requirements of Z. h. preblei,
including hibernation sites, and to determine if they influenced any of the demographic parameters that
will be estimated in this study.
Approach
The general approach is to measure both site specific and landscape features at each of the
three population study sites to document the extent of spatial variation. These quantitative measures of
spatial variation will be used in the analyses to determine if they influenced any of the demographic
parameters that will be estimated in this study. The following habitat characteristics will be measured
and recorded for each site.

Micro-site habitat characteristics
1.
Cover will be measured at 20 random locations along the 250 meter sampled stream stretch.
Mean cover and standard error of the mean will be estimated. Cover will be estimated using a
vegetation profile board (Nudds 1977) that allows for an assessment of visual obstruction in
0.5 meter vertical intervals above ground. The board will be 1.5 meters high and 30.48 cm
wide. The board is marked in alternate black and white colors at 0.5 meter intervals.
Horizontal cover is assessed in each interval by viewing the board from 15 meters away in a
randomly chosen direction. The percentage of each interval concealed by vegetation is
recorded as 0-20, 21-40, 41-60, 61-80, and 81-100% estimated concealment.
2.
Vegetation species composition and richness will be estimated using the Modified-Whittaker
nested vegetation sampling method (Stohlgren et al. 1995). A modified Whittaker plot is 20meters x 50-meters with 10 lm2 and 2 10m2 subplots arranged systematically around the
perimeter and 1 100m2 subplot centered in the inside of the 20 meter by 50 meter plot. Species
composition and percent cover of each species is recorded for each subplot.
3.
Soil samples will be taken at each site for a hydrometer textural analysis (percent sand, silt and
clay). Samples will be collected using a soil probe. Samples will be taken from 0-12 inches,
and 12+ to 24 inches. The 0-12 inch sample will be taken first, removing the probe and soil.
Sample will be placed in a labeled ziplock bag. The probe will then be placed in the same hole
for the 12+ - 24 inch probe. With that soil sample being placed in a separately labeled ziplock
bag. The hydrometer textural analysis will be conducted at the CSU Soils Laboratory.

�74

4.

5.
6.
7.

Mean stream width will be estimated by measuring stream width at 30 locations along the
entire site sampled. The 30 locations will be stratified equidistant from each other to cover the
entire stream stretch in increments of site stream length/20.
Describe potential hibernacula: upland vegetation, take soil sample at site.
Describe nest sites (what they are made of, placement).
Compare parameter estimates from 1-6 for the three population study sites.

Landscape habitat characteristics
The following landscape habitat characteristics will be measured using either GIS, topographic maps,
or aerial infrared photography.
1.
Estimate distance to nearest human habitation and human disturbance.
2.
Estimate connectivity of sites to other streams.
3.
Estimate total length of stream stretch at each site and total length of stream stretch with
suitable habitat at each site.
4.
Compare parameter estimates from 1-3 for the three population study sites.
Hibernation site measurements
Hibernation sites will be identified by following radio-collared mice in late September and early
October. Once a radio-signal remains stationary for 7-10 nights we will assume we have located a
hibernaculum. The following measurements will be taken at each hibernation site:
1.
2.
3.
4.

Distance ofhibernaculum to stream.
Vertical elevation from hibernaculum to stream.
Soil sample (as described above for the Habitat Use Study).
Vegetation species richness within a 5-m radius. Density of vegetation (measured as described
above for the Habitat Use Study).

Composition of Seasonal Food Consumption Study
Background
Specific food habits are unknown for Preble's meadow jumping mouse. Armstrong et al.
(I 997) summarized what is currently known about food habits of meadow jumping mice in general as
follows:
Studies of food habits in central and eastern United States indicate they are governed by
availability more than preference (Whitaker 1963). Grass seeds of several species are probably
the most important component of the diet, and mice will shift to those species that have
available seed. Invertebrates and fungi are also readily eaten. Mice feed on both adult and
larval invertebrates, especially Coleoptera (beetles). Invertebrate feeding is very important in
the spring as mice emerge from hibernation, and may consist of half of the diet at that time.
Mice also feed on various species of fungi, which are often encountered during burrowing
activity. As the growing season progresses, graminoid seeds dominate the diet.
There is no reason to believe food habitats of one subspecies should differ greatly from those of other
subspecies. This belief is further supported by the indirect evidence available that food habits of Z. h.
preblei are similar to that described above (i.e., the observation of the piles of grass stems observed in
areas where the subspecies is known to occur).
As true hibernators, meadow jumping mice do not cache food in their hibernacula Therefore,
it is assumed they require high quality food for high fat accumulation prior to immergence. Preble's
meadow jumping mice have been observed to increase body weight by 10% in the 2-3 weeks prior to
immergence. Laboratory studies show the mouse can gain mass at rates up to 1.0 grams per day (B.
Wunder, personal communication). This ability to increase fat reserves at such a rate is used by the

�75

mice for preparation to enter hibernation. However, for the mice to successfully gain enough fat prior
to hibernation to ensure a high probability of survival throughout hibernation, food of sufficient quality
must be available. No specific information is available on what foods Preble's meadow jumping mice
eat to meet these ecological requirements. However, from late August through early September, when
adults begin to gain weight, there are many species of graminoids that have available seed. In most
years, grasshoppers are also readily available and probably dominate invertebrate biomass in most
habitats.

Objective
The objective of this study is to document seasonal changes in foods consumed by Preble's
meadow jumping mice.
Approach
Fecal samples from traps where PMJM are captured during the four trapping sessions will be
collected and analyzed for composition and percentage of each discrete food type identified in the total
sample. Changes in foods composition by either food type and or percent occurrence will be analyzed
for spatial and temporal differences. Spatial differences will be defined as differences among the three
populations studied. Temporal differences will be defined as differences among the three trapping
sessions (June, July, September).
Molecular Systematic Study
Background
The family Zapodidae Gumping mice) consists of small to medium-sized mice with enlarged
hind feet and exceptionally long tails. Four living genera are recognized in this family, two of which,
Zapus and Napaeozapus, are found in North America (Hall 1981). There are three living species of the
genus Zapus: Z. trinotatus (Pacific jumping mouse), Z. princeps (western jumping mouse), and Z.
hudsonius (meadow jumping mouse). Z. h. preblei is one of twelve living subspecies of the species Z.
hudsonius (Krutzsch 1954, Hafner et al. 1981). Z. h. preblei was first described by Krutzsch (1954)
from a specimen collected by E. A. Preble in 1895 near Loveland, Colorado.
Quimby (1951) described the species Z. hudsonius as follows: 'A mouse-like rodent with
greatly enlarged hind feet and an exceptionally long tail. The forelegs are relatively short. The ears are
somewhat conspicuous. The body is clothed in moderately long, somewhat dense hair of a rather
coarse texture and several colors. The dorsal portions are marked by a broad stripe of brownish hairs
many of which are tipped with black giving the region a grayish-black appearance. The sides are bright
yellowish-orange, whereas the underparts and feet are white. The tail is bicolor, dark above and light
below, and sparsely covered with hair which is longer on the terminal part. The mammae are eight, and
quite prominent in lactating females. The male genitalia are inconspicuous except during the breeding
season when the scrotal sac becomes enlarged. The testes enlarge and may be either abdominal,
inguinal, or scrotal during this period.' The skull of Z. hudsonius is small and light with a narrower
braincase and smaller molars than in Z. princeps (from Fitzgerald et al. 1994 p. 18). However,
Fitzgerald et al. (1994) urge caution in distinguishing the two species of Zapus in Colorado. Such
caution is further warranted by the recent conflicting identifications of mice based on genetic
characteristics.
Analysis of mitochondrial DNA sequence data from 92 individual mice indicates that mice
sampled from southeastern Albany County, Wyoming, south along the Front Range of the Rocky
Mountains to western Las Animas County, Colorado (Purgatoire Campground, San Isabel National
Forest}, form a coherent genetic group (Riggs et al. 1997). This group of samples are distinct from
samples obtained from mice from three other populations. Genetic samples from mice captured in the
Dorothey Lakes area of southern Colorado (Las Animas County) group together and are most closely
allied with Z. h. luteus, a subspecies described from New Mexico (Riggs et al. 1997). The single
genetic sample collected from Weld County, Colorado (Lone Tree Creek) and six samples obtained

�76

from Warren Air Force Base in Laramie County, Wyoming are most similar to reference samples of Z.
princeps from Colorado (Larimer County) and New Mexico (Taos County) (Riggs et al. 1997). The
sequence data indicate that the samples from specimens identified as Z. h. luteus and samples from
specimens of Z. princeps are more closely allied with each other than either is with the samples defining
the Z. h. preblei group. This closer alliance of the samples of Z. h. luteus with Z. princeps rather than
Z. h. preblei conflicts with results ofHafuer et al. (1981), based on a combination of pelage,
morphologic, and genetic data, which support a closer alliance with Z. hudsonius.
A more complete biosystematic evaluation of jumping mice is needed to clarify and further
refine relationships among populations of the group referred to as Z. h. preblei as well as to other
subspecies and species of the genus 'Zapus. Such an evaluation requires detailed analyses of pelage,
morphometric, and genetic data from sufficient numbers of individuals to adequately represent the
populations of interest. However, the mitochondrial DNA non-coding (D-loop) sequence data
available at this time are consistent with the view that a geographically contiguous set of populations
previously recognized as Preble's meadow jumping mouse form a homogenous group recognizably
distinct from other nearby populations and from another geographically-adjacent species of the genus
(Riggs et al. 1997). Therefore, given the genetic data available, Riggs et al. (1997) conclude Preble's
meadow jumping mouse is a distinct population of Z. hudsonius.

Objective
The objective of the genetic component of this study is to document genetic variation within
and among the three study site populations. Efforts are underway to secure funding for this study.
Approach
Genetic tissue samples will be collected from at least 10 and not more than 30 PMJM captured
at each study site. A sample of at least 10 individuals from a population will provide enough
information to document the genetic variation within the population, samples sizes in excess of 30
contribute little to documenting the genetic variation within the population (T. Quinn, personal
communication).
Genetic tissue sampling: collection ofear tissue samples using ear punch tool
The following protocol for collection of genetic tissue samples has been used successfully on
PMJM (M. Bakeman, C. Meaney, T. Ryon, R Schorr, personal communication).
Before checking traps, ear punch tools will be cleaned by immersing them in a 10% bleach
solution for a few minutes, then rinsing thoroughly with clean water. Tools will be dried thoroughly. A
small screw-cap container will be useful to contain the bleach solution and to receive used ear punch
tools. A sports bottle or other container with a squirt or pop-up top may be used for rinsing. Any
previously used containers will be washed thoroughly by hand or in the dishwasher and not used for
other purposes (e.g., drinking) while in the field.
1.
A fresh pair of clean latex gloves will be used when handling each mouse.
2.
With a clean ear punch tool, 2 tissue plugs will be obtained from the mouse's ear. If there is
excessive bleeding, gentle pressure will be applied to the site with a small , dry piece of cotton
for 1 minute. Punch may be applied to deliver the plug as a small circlet of tissue (about the
size of the head of a pin) onto a finger of your gloved hand. Placement of the punch may be
done in any way that is convenient.
3.
Place the finger tip tightly over the end of an opened sample vial and shake to wash the tissue
plug into the ethanol.
4.
Repeat until all three tissue plugs have been collected into the same sample vial. Inspect the
tube to see that all plugs have made it into the ethanol.
5.
Close the sample vial--screw the cap on firmly and check that there is no leakage of ethanol
when the tube is inverted. Label both the vial and the corresponding record on the data sheet
(see item 6 below) with a. unique identifier as follows. Use a seven-place alpha-numeric code
composed of the following:

�77

-

A three-letter designator for the survey location (e.g., WPC = West Plum Creek,
GCR = Garber Creek).
A number beginning with two digits indicating the year (e.g., 98) followed by 2 digits
specifying the individual trapped, numbered sequentially.

Example: WPC9801 = first animal sampled at West Plum Creek in 1998.

6.

Note: The combined seven-place alpha-numeric code needs to be a unique identifier for an
individual mouse across all locations and sites being trapped in studies coordinated by the
Colorado Division of Wildlife.
Record information for the individual sampled on the data sheet provided. Repetitive entries
may be completed before or after the field session but do not allow much time to elapse before
doing this--what is obvious to you at the time may not be so obvious later on. Information for
each sample needs to be complete and unambiguous if the sample itself is to be useful.

After returning from the field, samples will be kept in a cool place or refrigerated until delivery
to the CDOW office at 317 West Prospect, Fort Collins, CO where they will be kept in the freezer for
analyses.

E.

LOCATION

CDOW Maytag Property is located seven miles south of Castle Rock, Colorado along East
Plum Creek. CDOW Woodhouse Property is located on Indian Creek, a tributary of Plum Creek near
Louviers, Colorado. The Dupont Property is located west and south of the town of Louviers and
contains the eastern stretch of Indian Creek and its confluence with Plum Creek. Pine Cliff Ranch,
owned by Colorado Open Lands, is located on Garber Creek and extends eastward to its confluence
with West Plum Creek, 5 miles west of Sedalia
Training sessions for all field technicians and crew leaders will take place at the Frank State
Wildlife Area and Kodak State Wildlife Area located in Weld County, Colorado.
Data analyses and office work will be conducted at the CDOW Research Center, 317 West
Prospect, Fort Collins, Colorado.

F.

SCHEDULE

April-May
April
April-May
May
June 2-9
June-July
July
July 21-28
July-Aug
Sep 8 -15
Sept-Oct,
Sept-Oct.
December
April 1999

Complete Study Plan for a demography study of Preble's
meadow jumping mouse
Select study sites
Purchase equipment for summer 1998 field season
Advertize for, hire, and train 4 technicians
Conduct first trapping session
Collect movement data
Collect site and landscape scale habitat data
Conduct second trapping session
Collect movement data
Conduct third trapping survey
Collect movement data
Collect data on possible hibernation sites
Complete preliminary report for Preble's meadow jumping
mouse technical working group
Complete Final report for 1998 summer field season

�78

F.

PERSONNEL

Tanya Shenk
Gary C. White
2 Crew Leaders
2 Field Technicians
G.

Principal Investigator
Statistical Consultant
CDOW temporary technicians
CNHP temporary technicians

BUDGET

Operating Expenses
radio transmitters (150 @$150)
radio receiver (3 @ $2565 )
pit tag scanner (6@$600)
pit tags (200 @$10.00)
3 portable communication radios
&amp; battery recharger
maps
computer software, upgrades
office supplies
photographic equipment, expenses
field equipment
misc. hardware
Personnel
2 field technician for 4 months each
2 crew leader for 6 months

$22,500
. $ 7,695
$ 3,600
$ 2,000
$ 2,100
$
500
$ 1,500
$
300
$
500
$
800
$
500

$12,000
$30,000

Travel
30,000 miles @0.12 per mile
vehicle rental: 3 vehicles,
4 mo. @$120 per month
overnight travel 30 days@$75 per day
TOTAL

$ 3,600
$ 1,440
$ 2,250

$75,365

�79

I.

LITERATURE CITED

Armstrong, D. M., M. E. Bakeman, A. Deans, C. A. Meaney, and T. R Ryon. 1997. Conclusions and
recommendations in: Report on habitat findings on the Preble's meadow jumping mouse.
Edited by M. E. Bakeman. Report to USFWS and Colorado Division of Wildlife.
Bailey, B. 1929. Mammals of Sherburne County, Minnesota. Journal ofMammalogy 10:153-164.
Bailey, V. 1923. Mammals of the District of Columbia Proceedings of the Biological Society.
Washington 36:103-138.
Cook, T. D. and D. C. Campbell. 1979. Quasi-experimentation: design and analysis issues for field
settings. Houghton-Mifflin, Boston.
Cormack, RM. 1964. Estimates of survival from the sightings of marked animals. Biometrika
51 :429-438.
ERO Resources. 1995. Environmental review of South Boulder Creek Management Area Prepared
for City of Boulder Real Estate/Open Space Department. Prepared by ERO Resources Crp.,
Denver, Colorado in association with Stoecker Ecological Consultants, Boulder, Colorado.
Fitzgerald, J.P., C. A. Meaney, and D. M. Armstrong. 1994. Mammals of Colorado. Denver
Museum of Natural History, University Press of Colorado. Niwot, Colorado.
Hafner, D. J., K. E. Petersen, and T. L. Yates. 1981. Evolutionary relationships of jumping mice
(genus Zapus) of the southwestern United States. Journal ofMammalogy 62:501-512.
Hall, E. R 1981. The mammals of North America John Wiley and Sons, Inc., New York, New York,
2 volumes.
Hamilton, W. J., Jr. 1935. Habits of jumping mice. American Midland Naturalist 16:187-200.
Jolly, G. M. 1965. Explicit estimates from capture-recapture data with both death and immigration
stochastic model. Biometrika 52:225-247.
Jones, C. A. 1996. Mammals of the James John and Lake Dorothey State Wildlife Areas. Final
Report, submitted to the Colorado Division of Wildlife and Colorado Natural Areas Program.
Kendall, W. L., and J. D. Nichols. 1995. On the use of secondary capture-recapture samples to
estimate temporary emigration and breeding proportions. Journal of Applied Statistics.22:751762.
Kendall, W. L., K. H. Pollock, and C. Brownie. 1995. A likelihood-based approach to capturerecapture estimation of demographic parameters under the robust design. Biometrics 51 :293308.
Kendall, W. L., J. D. Nichols, and J.E. Hines. 1997. Estimating temporary emigration using capturerecapture data with Pollock's robust design. Ecology 78:563-578.
Krutzsch, P.H. 1954. North American jumping mice (genus Zapus). University of Kansas
Publications, Museum of Natural History 7:349-472.
Meaney, C. A., N. W. Clippinger, A. Deans, and M. OShea-Stone. 1996. Second year survey for
Preble's meadow jumping mouse (Zapus hudsonius preblei) in Colorado. Report prepared for
the Colorado Division of Wildlife.
Meaney, C. A., A. Deans, N. W. Clippinger, M. Rider, N. Daly, and M. O'Shea-Stone. 1997. Third
year survey for Preble's meadow jumping mouse (Zapus hudsonius preblei) in Colorado.
Report prepared for the Colorado Division of Wildlife.
Nudds, T. D. 1977. Quantifying the vegetative structure of wildlife cover. Wildlife Society Bulletin
5:113-117.
Poly, W. J., and C. E. Boucher. 1997. Record of a creek chub preying on a jumping mouse in Bruffey
Creek, West Virginia Brimleyana 24: 29-32.
PTI Environmental Services. 1996a Preble's Meadow Jumping Mouse Study at Rocky Flats
Environmental Technology Site, Annual Report 1996. Final. Rocky Flats Environmental
Technology Site, Golden, Colorado.

�80

PTI Environmental Services. 1996b. Preble's Meadow Jumping Mouse Study at Rocky Flats
Environmental Technology Site, Spring 1996. Final. Rocky Flats Environmental Technology
Site, Golden, Colorado.
Quimby, D. C. 1951. The life history and ecology of the jumping mouse, 7.apus hudsonius.
Ecological Monographs 21:61-95.
Riggs, L.A., J.M. Dempey, and C. Orrego. 1997. Evaluating distinctness and evolutionary
significance of Preble's meadow jumping mouse: Phylogeography of mitochondrial DNA noncoding region variation. Final Report for the Colorado Division of Wildlife. Denver,
Colorado.
Seber, G. A. F. 1965. A note on the multiple recapture census. Biometrika 52:249-259.
Sheldon, C. 1934. Studies on the life histories of 7.apus and Napaeozapus in Nova Scotia Journal of
Mammalogy 15:290-300.
Shenk, T. M. 1998. Conservation assessment and preliminary conservation strategy for Preble's
meadow jumping mouse (7.apus hudsonius preblei). Special Report. Colorado Division of
Wildlife (in review).
Stohlgren,T. J., M. B. Falkner, and L. D. Schell. 1995. A Modified-Whittaker nested vegetation
sampling method. Vegetatio 117: 113-121.
USFWS. 1997. Interim survey guidelines for Preble's meadow jumping mouse. USFWS. Denver,
Colorado.
Whitaker, J. 0., Jr. 1963. A study of the meadow jumping mouse, 7.apus hudsonius (Zimmerman), in
cental New York. Ecological Monographs 33:3.

�81

APPENDIXC
STUDY PLAN
State of
Colorado
ProjectNo. W-153-R-ll
Work Plan No._....,0=6=6=2_ _ __
Task No. ______2_ _ _ __

Cost Center 3430

Mammals Research
Conservation of Preble's meadow jumping
mouse (.Zaous hudsonius oreblei)
Habitat use and distribution of Preble's meadow
jumping mouse (Zapus hudsonius preblei) in
Larimer and Weld Counties, Colorado

HABITAT USE AND DISTRIBUTION OF PREBLE'S MEADOW JUMPING MOUSE (Zapus hudsonius
preblei) IN LARIMER AND WELD COUNTIES, COLORADO
A. NEED

On May 12, 1998 the U. S. Fish and Wildlife Service (USFWS) published a final rule in the
Federal Register (63 FR 26517) to list Preble's meadow jumping mouse (Zapus hudsonius preblei) as
'threatened' under the Federal Endangered Species Act (ESA) of 1973, as amended. Scarcity of
suitable habitat presumably limits current distribution of Preble's meadow jumping mouse and thus,
maintenance of quality habitat has been identified by the USFWS (63 FR 26517) as the principal
conservation goal. Although Meaney et al. (1997) reported an improved ability to recognize suitable
habitat for Preble's meadow jumping mouse, a more refined and complete definition of potentially
suitable habitat for the mouse does not exist. Because the protection of potentially suitable habitat for
Preble's meadow jumping mouse may occur under the ESA, as well as protection of known locations
where the subspecies occurs, the definition of potentially suitable habitat, as determined by the
USFWS, will directly influence site specific regulatory procedures.
Ideally, a definition of potentially suitable habitat for the subspecies would identify areas where
the Preble's meadow jumping mouse could survive and reproduce in sufficient numbers to sustain
populations throughout its range of natural variability over an extended length of time. During the
active period of the life cycle of the mouse, suitable habitat must provide requirements for daily
survival, reproductive activities (breeding, nesting, and rearing of young to independence}, and
dispersal. The hibernation period requires habitat with sufficient food supplies to assure fat storage
prior to hibernation and hibernacula sites. Habitat providing all seasonal and life cycle requirements
may or may not occur in a single contiguous area If not in a contiguous area, habitat patches must
occur in a mosaic of usable areas where suitable corridors exist for seasonal movement among sites.
Because very little is known about the ecological requirements of the subspecies, potentially suitable
habitat is currently defined only as areas of well-developed, dense herbaceous vegetation consisting of a
variety of grasses, forbs and thick shrubs in close proximity to open water. This definition is vague and
possibly incomplete.
Very few surveys for determining the presence or absence of Preble's meadow jumping mouse
have been conducted in Larimer or Weld Counties, Colorado. Of the surveys nine conducted since
1990, only three sites yielded captures of Preble's meadow jumping mouse. Therefore, very little
information is known about habitat use or current distribution of the subspecies in these two counties.
Quantifying and comparing both landscape and site specific characteristics of habitats where mice are
found and not found in these two counties would further our understanding of habitat use by the
subspecies, particularly in the northern half of its probable range. Any new locations where Preble's

�82

meadow jumping mouse are found during this study would contribute to the range-wide distribution
map currently available for the subspecies. Repeated annual visits to these same randomly selected
sites would also provide information on population persistence at a given site. Such a monitoring
scheme would be necessary for evaluating the continued status of the mouse at each site, providing
further information as to the suitability of the habitat for long-term persistence of the population.
Both Larimer and Weld Counties include habitat that is currently perceived to be outside the
ecological limitations of Preble's meadow jumping mouse. Larimer County provides the opportunity to
explore elevational limitations, currently thought to be 7400 feet (2260m) (USFWS 1997); Weld
County extends beyond the currently believed eastern boundary of the subspecies. Both of these
boundaries will be challenged by selecting survey sites within the two counties beyond the perceived
ecological limits of the subspecies. Genetic tissue samples will be collected on all Preble's meadow
jumping mice captured to assist identification through DNA analysis, particularly for those animals
captured outside the currently perceived ecological limits, and to provide information for future studies
to better define the relationships among different populations of Z. h. preblei, other subspecies of Z.
hudsonius and other species of Zapus.
Thus, the primary objective of this study is to quantify and define habitats used and identify
ecological limitations of the subspecies in Larimer and Weld Counties, Colorado. Such information
could be used by the USFWS to further refine the current definition of potentially suitable habitat for
Preble's meadow jumping mouse.

B. OBJECTIVES
Specific objectives for this study on Preble's meadow jumping mouse (PMJM) include:
1.

Define and quantify habitat characteristics at sites where PMJM was found and sites
where PMJM was not found.

2.

Identify elevational and eastern boundary limitations for PMJM in Larimer and Weld
Counties, Colorado.

3.

Describe the distribution of the PMJM in Larimer and Weld Counties, Colorado.

4.

Select sites and establish monitoring protocols for determining long-term trends in
populations of PMJM.

5.

Collect genetic tissue samples to assure identification of PMJM captured during this
study and for future genetic analyses to better define the relationship of populations of
Z. h. preblei to each other, other subspecies of Z. hudsonius and other species of
Zapus.

C. EXPECTED RESULTS
Conservation of Z. h. preblei should include maintaining populations of the subspecies
throughout the range of its natural variation and to try to identify ecological limits for the subspecies.
Key concerns include range-wide distribution, habitat use, and population persistence at a given site.
This study will address these concerns. Comparisons of habitat variables from both successful and
unsuccessful sites will be used to better define suitable habitat for the subspecies. Habitat variables
recorded will include both site level characteristics such as vegetational composition, cover, and
composition of other small mammal species as well as landscape level characteristics including
connectivity with other potential sites, geology, hydrology, and distance to development. Repeated
annual visits to the randomly selected sites will provide information on population persistence and site
fidelity of individuals at the given sites. Such a monitoring scheme will be necessary for evaluating the
continued status of the mouse at given sites and provide further information on the suitability of the

�83

habitat to sustain populations of PMJM over the long term. Genetic tissue samples collected from
PMJM captured will be used to confirm identification of the mice and for future analyses to better
define the relationship among (1) different populations of Z. h. preblei, (2) other subspecies of Z.
hudsonius and (3) other species of Zapus.
Performa.nce Indicators
1.
Provide a definition of and quantify habitat characteristics at sites where PMJM was
found and sites where PMJM was not found in Larimer and Weld Counties, Colorado.

2.

Update the known distribution of PMJM in Larimer and Weld Counties, Colorado.

3.

Provide monitoring sites and protocols for determining persistence trends of PMJM at
a given site.

4.

Genetically identify all PMJM captured.

5.

Complete a genetic tissue sample collection for future genetic analyses to better define
the relationship of populations of Z. h. preblei to each other, other subspecies of Z.
hudsonius and other species of Zapus.

6.

Analyze and publish results of research.

7.

Update and modify the CDOW conservation plan for PMJM.

D. APPROACH
Distribution Study
Background
The meadow jumping mouse (Z. hudsonius) is broadly distributed across North America from
the Atlantic to Pacific coasts, extending south into the United States to Alabama and Georgia and west
across the Great Plains to the base of the Rocky Mountains. In general, it is a common inhabitant of
moist, grassy and herbaceous fields. Eleven living subspecies have been described (Whitaker 1972).
Hafner et al. (1981) describe a twelfth subspecies, Z. h. luteus.
Z. h. preblei occurs only in eastern Colorado and southeastern Wyoming (Krutzsch 1954, Long
1965, Armstrong 1972). From its limited ecological and geographic distribution, Fitzgerald et al.
(1994) suggest it is an Ice Age relict, once widespread in tallgrass prairie across the eastern plains of
Colorado but now restricted to scattered localities on the Colorado Piedmont. Similar relict
populations of meadow jumping mice in the White Mountains of Arizona and the Sacramento
Mountains and Rio Grande Valley of New Mexico are described as the subspecies Z. h. luteus (Hafner
et al. 1981).
Numerous surveys have been conducted since 1990 to establish the current distribution of
Preble's meadow jumping mouse. Surveys have been funded by the U. S. Fish and Wildlife Service,
Rocky Flats Environmental Technology Site, Colorado Division of Wildlife, U.S. Air Force Academy,
Warren Air Force Base, Colorado Department of Transportation, City of Boulder Open Space, and City
of Boulder Greenways Program (Armstrong et al. 1997, P. Plage, personal communication). From
1990 to 1997 such surveys have yielded captures of Preble's meadow jumping mouse, based on field
identification and supported by the genetic analyses, at the following sites:
1.
2.
3.
4.

Lone Pine Creek, Larimer County, Colorado
Rabbit Creek, Larimer County, Colorado
St. Vrain Creek and associated tributaries in Boulder County, Colorado
City of Boulder Open Space, along South Boulder Creek and its tributaries,
Boulder County, Colorado

�84

5.
6.
7.
8.
9.
10.
11.

12.

Coal Creek, Jefferson County, Colorado
Rocky Flats Environmental Technology Site, Jefferson County, Colorado
White Ranch Park, Ralston Creek, Jefferson County, Colorado
Plum Creek drainages including Indian Creek, West Plum Creek, and East Plum
Creek, Douglas County, Colorado
Roxborough State Park, Douglas County, Colorado
Hay Creek, Elbert County, Colorado
Monument Creek on the U. S. Air Force Academy (AF AC) and tributaries of
Monument Creek off the AFAC including Smith Creek, Pine Creek, and Jackson
Creek, El Paso County, Colorado
Medicine Bow National Forest, Albany County, Wyoming

Two more sites yielded mice that were identified as Z. h. preblei in the field but were genetically found
to be more closely allied with the western jumping mouse, Z. princeps. These sites include:
1.
2.

Warren Air Force Base, Laramie County, Wyoming
Lone Tree Creek, Weld County, Colorado

Similarity of the habitat at these two sites compared to those where Z. h. preblei (as determined
genetically) were found suggests the possibility of areas of sympatry or parapatry between the two
species of Za.pus. According to Fitzgerald et al. (1994) the distributions of Z. princeps and Z.
hudsonius do overlap. The area of overlap occurs in eastern Wyoming. The distribution of Z.
hudsonius in Colorado is now known to be larger than shown in Fitzgerald et al. (1994). The
boundaries are currently as far south as Las Animas County (based on genetically identified specimens
of Z. h. preblei). Captures of Z. princeps and Z. hudsonius (as identified in the museum) have
occurred as close as eight miles of one another within the same drainage (Armstrong 1972). Z.
princeps were reported captured in 1981 (Olson and Knopf 1988) at the Lone Pine site in Larimer
County, Colorado, where Z. h. preblei were captured this year. Because neither specimens or genetic
samples were taken in the 1981 study, identification of those mice will remain in question. The
discrepancy may be explained by field misidentification or Meaney et al. (1997) also suggest this
discrepancy might be explained by displacement of Z. princeps with Z. h. preblei sometime in the
sixteen intervening years between trapping efforts. Although assumed to have different ecological
requirements, genetic evidence presented here suggests further investigation of possible distributional
overlap between Z. h. preblei and Z. princeps.
Several notable results from the genetic analysis of specimens acquired from the Denver
Museum of Natural History may affect the location of the southern distribution of Z. h. preblei. One
site yielded mice identified as Z. p. princeps in the field but were found to be genetically more closely
allied with Z. h. preblei. This site is the most southern location to date of Z. h. preblei and is located at:
1.

Purgatoire Campground, San Isabel National Forest, Las Animas County, Colorado

Also from Las Animas County were mice collected and identified as Z. h. luteus (Jones 1996), an
identification also supported by the genetic analysis. These mice were from:
1.
2.

Lake Dorothey State Wildlife Area, Chicorica Creek, Las Animas County,
Colorado
Lake Dorothey State Wildlife Area, West Fork Schwacheim Creek, Las Animas
County, Colorado

These sites suggest a more northerly distribution of Z. h. luteus, currently known only from limited
areas in New Mexico and Arizona (Hafner et al. 1981 ). Identifying the southern boundary of Z. h.
preblei clearly needs further study.

�85

Objective
Conservation of Z. h. preblei should require maintaining populations of the subspecies
throughout the range of its natural variation and to try to identify ecological limits for the subspecies.
Specific objectives for the distributional component of this study are to (1) clarify the distribution of the
subspecies in Larimer and Weld Counties, Colorado, and (2) define and quantify the amount of suitable
habitat within Larimer and Weld Counties.
Approach
To meet these objectives, this study will include (I) constructing a sampling frame of
potentially suitable habitat within the area of interest (Larimer and Weld Counties, Colorado) and (2)
conducting trapping surveys to determine presence or absence at 30 sites randomly selected from the
sampling frame. Specific approaches to each of these tasks follow.

Sampling.frame
A sampling frame will be developed to delineate potentially suitable habitat for PMJM from
unsuitable habitat. To produce a preliminary map displaying existing potential habitat for Preble's
meadow jumping mouse would require at least three primary layers of ecological information. Two
initial layers, hydrology and vegetative cover would provide a map displaying all areas where these two
ecological requirements of Preble's meadow jumping mouse co-occur. The hydrology layer must be in
enough detail to provide locations of intermittent and small order streams as well as identify water
source (e.g., irrigation ditches, stream, seep). Degree of density of vegetative cover is sufficient for
initial mapping efforts. Demarcation of shrub, trees and grasses will suffice in these initial efforts rather
than species identification.
However, not all combinations of vegetative cover and water provide sufficient habitat to
support Preble's meadow jumping mouse. Thus, mapping potential habitat in such a way would
produce a map displaying far more potential habitat than exists. For example, an extremely critical
ecological requirement for the survival of the mouse, that to date we have very little information for, is
potential hibemacula sites. As a possible index to hibemacula habitat, a third GIS layer, indicating the
presence of alluvial deposits may provide some insight in to hibernation requirements. Areas where
alluvial deposits co-occur with the presence of water and vegetative cover may provide a more realistic
map of potentially suitable habitat for the mouse.
Our ability to survey a site selected at random will be restricted to those areas where we are
able to obtain permission to access the land. We should be able to survey any randomly selected site on
public lands and thus our inference should be unrestricted. Such readily available access will probably
not occur on privately owned or leased lands, thus, restricting inferences made on private lands. By
stratifying the sampling frame, this lack of access on private lands will not restrict inferences that can be
made on public lands. Inference on private lands will depend on the percent of access we get from
private landowners.
The sampling frame will be developed from the 1:24,000 scale Hydrographic GIS layer
developed by the CDOW (Reese Tietje, unpublished data). From this sampling frame a three-stage
sampling design will be used to select the 30 random sites for doing PMJM surveys. Primary sampling
units will be 3rd order streams. Of the 150 3rd order streams that exist within the sampling frame, 30
will be selected on public lands, 30 on private lands. The secondary sampling unit will be the stream
stretch selected within the primary (3rd order stream) unit. The tertiary sampling unit will be the actual
sites along the stream stretch selected at the secondary sampling stage that will be sampled. Each of the
primary, secondary, and tertiary sampling units will be selected using simple random sampling. If the
secondary sampling unit does not yield potentially suitable habitat (i.e., no dense vegetation) secondary
sampling units will continue to be selected at random until one yields potentially suitable habitat.
Determination of suitable habitat will be made by field site visits.
Total stream length of all the secondary sampling units will be recorded as well as total stream
length containing potentially suitable habitat. From these measurements an estimate of the probability

�86

of potentially suitable habitat occurring within the primary sampling unit will be made for each area
surveyed. A mean estimate, over all sites surveyed, of the probability of a primary sampling unit
having potentially suitable habitat will then be made. Because of the random selection of primary
sampling units, inference can be made as to the probability of potentially suitable habitat existing on all
3rd order streams within the sampling frame.
By recording presence or absence of PMJM within the tertiary sampling units we can estimate
the probability of PMJM occurring within potentially suitable habitat. Because of the random selection
of sampling units in each of the two strata {public and private lands) we can then estimate the
probability of PMJM occurring in potentially suitable habitat within both public and private lands.
Trapping surveys
Trapping surveys to determine presence/absence of PMJM will primarily be conducted
following protocols defined by the USFWS (1997). Additional guidelines have also been developed to
accommodate the needs of this project. A brief summary of these guidelines follow.
Landowner contact
1.
To request permission to conduct surveys on private property, landowners will first be
notified by letter. The letter will briefly describe the project and outline specifically
how they might be affected if PMJM were found on their property. The letter will be
followed by a phone call to determine if permission will be granted by the landowner
for access to the property or not.
2.
No private property will be surveyed without prior consent of the landowner.
3.
To request permission to conduct surveys on public land, the agency (e.g., USFS, State
Forest, etc.) responsible will be contacted.
Timing ofsurveys
I.
Trapping surveys will be conducted within the period from June 1 to September 15,
1998. These dates correspond to dates when the mouse is known to be out of
hibernation.
2.
Due to the nocturnal nature of PMJM, traps will be set between l 900hrs and 21 00hrs
and checked as early as possible in the morning beginning at 500hrs (to reduce stress
and the potential for predation on trapped animals). Time required to complete the
traplines will vary depending on how many animals are caught.
3.
Absence of PMJM at a site will be defined as no captures of PMJM from a minimum
of three consecutive nights and 750 trapnights (a trap night is defined as the sum total
number of traps available each night).
4.
Presence of PMJM at a site will be defined as at least one capture of PMJM at the site.
However, to accommodate sample size requirements for the monitoring and genetics
study (see below) trapping efforts will continue until at least 10 individuals are tagged
with Passive Integrated Transponders (PIT) tags.
Survey protocols
1.
Surveyors will be advised to follow the Center for Disease Control's Hantavirus
instructions and recommendations when dealing with rodents which include:
a Baseline blood serum samples will be collected and stored at Poudre Valley
Hospital for all surveyors.
b. Respirators are available for use by surveyors if they request their use.
c. Surgical gloves will be used at all times when handling rodents.
d. All equipment will be rinsed first with a 10% bleach solution, then water after use.
e. Traps and any equipment that may have rodent feces or urine on it will not be
transported in the interior of a vehicle.

�87

2.
3.

f. Traps will be cleaned after each use by a mouse.
g. If a surveyor becomes ill with hantavirus symptoms they will report immediately to
a medical facility.
Surveyors must be in possession of both a federal and state collecting permit.
If PMJM is found at previously undocumented sites these locations must be reported
within one day to the USFWS.

Survey methodology
I.
Small mammal Sherman live traps (folding and non-folding) will be used to conduct
the surveys.
2.
Traps will be set in two parallel lines of trap stations (I trap per station) on either side
of the drainage. Trap stations will be 5 meters apart for a total of 250 meters; the
parallel transects will be 10 meters apart unless extent of habitat, terrain topography, or
stream hydrology do not allow.
3.
Location of transects will be recorded on field data sheets (see Appendix B) and
identified on 7½ minute topographic maps. Locations will also be recorded to the
nearest 5 meters in UTM coordinates using a Trimble Geo-Explorer GPS.
4.
In case of windy conditions or large number of trap-tampering predators (i.e.,
raccoons, foxes, coyotes, etc.), traps will be secured to the ground with hoops of
heavy-gauge malleable wire, stakes, or with other materials that can effectively
secure/immobilize the traps.
5.
A small (~I inch) ball of polyester quilt or wool (fleece) will be placed in each trap as
nesting/bedding material.
6.
Baiting materials will be Manna Pro Sweet 3-way Livestock feed which contains no
animal matter. Ingredients include flaked barley, flaked com, flaked oats, and cane
molasses. Peanut butter will be used to stick the bait to the trap.
7.
Checking of the traps will be conducted by two surveyors; one person will handle the
traps and animals captured, the other person will record the data
Handling ofcaptured animals
I.
All animal captures will be recorded (see Appendix A, Data Forms).
I.
If an animal has been captured in a trap, a ziplock plastic bag will be placed over the
end of the trap. The trap will be opened allowing the animal to fall into the plastic bag.
The animal will be identified to species while in the plastic bag.
2.
If the animal is not a PMJM, identification of the animal will be recorded and the
animal set free.
3.
Each captured PMJM will be scanned to detect the presence/absence of a PIT tag. If a
PIT tag is detected and the mouse has been captured at that same site within the 4-day
trapping effort, identification of the mouse will be recorded and the mouse will be
released.
4.
If the animal is a PMJM and no PIT tag is detected.the PMJM will be weighed while in
the bag, recording the weight in grams using a Pesola spring balance.
5.
Sex, age (juvenile, adult), and reproductive condition (pregnant, lactating or nonlactating, inactive if it is female; for males the position of the testes - scrotal, inguinal,
or abdominal) will be noted.
6.
Each PMJM will be measured (total length, length of body, length ofhind foot-heel to
distal end of claws) in millimeters. Measurements of total body and tail length will be
taken with the mouse on a firm surface to minimize error.
7.
Capture of every PMJM will be documented by taking two photographs of the mouse
on first capture. If the mouse has been captured previously as noted by the detection of
a PIT tag, no photograph needs to be taken.

�88

8.

9.
10.
11.

12.
13.

14.

Each PMJM will have a PIT tag inserted above the shoulder blades by lifting the skin
on its back and inserting the needle with the PIT tag under their skin and injecting the
tag. Verification of the PIT tag identification number will be made before insertion into
the mouse by running the PIT tag scanner across it.
Skin behind the opening will then be pinched to prevent emergence of the tag.
Surgical glue will then be applied to the opening to prevent the PIT tag from exiting the
body and prevent infection of the mouse.
A PIT tag scanner will be held over the mouse to again verify PIT tag identification
number and that it still works after the insertion procedure (note: PIT tag will be
scanned twice during application to mouse, or once if mouse was previously PIT
tagged) .•
PIT tag identification number will be recorded on the field data form and the mouse
released.
If there are feces in the trap where a PMJM was captured, the feces will be collected in
a plastic bag labeled with date and location of the site. Fecal samples will be kept cool
until returned to the CDOW office where they will be frozen. Fecal samples will be
analyzed by the Composition Analysis Laboratory, Inc, 622 ½ Whedbee, Fort Collins,
CO for content.
If, at any time during the handling of the PMJM the animal appears to be severely
stressed (dramatic changes in respiration, heartbeat or responsiveness or gums turning
blue) the animal will be released immediately.

Handling of trap mortalities and injuries
1.
All trap mortalities will be recorded on a 'Trap Mortality' data form which includes
information on species, potential duration of time spent in the trap, any information
available on cause of death, etc. (see Appendix A, Data Formsf
2.
All animals found dead in a trap will be double-bagged in a plastic bags and placed in a
cooler with ice. Specimens should be frozen as soon as possible and deposited the
CDOW freezer at the office in Fort Collins. All specimens will be sent to the Colorado
State University Diagnostic Laboratory for detection of any disease and/or other
conditions that may have contributed to cause of death. All PMJM specimens will be
returned to the CDOW.
3.
A museum card will be completed and attached to each PMJM specimen and given to
Cheri Jones, Curator of Mammalogy at the Denver Museum of Natural History, for
study skins and tissue storage once the Diagnostic Laboratory has completed their
evaluation.
4.
If an animal is severely injured it will be euthanized by soaking a cotton ball in
Metofane (methoxyflurane) and placing the cotton ball and the mouse in a ziplock bag
until the animal stops breathing. All specimens will then go through steps 1-3 above.
5.
If an animal appears to be only slightly injured (e.g., broken tail, small laceration) the
animal will be released to the wild. If an animal appears to be cold stressed attempts
will be made to warm it by holding it in the surveyors hands and/or against their body.
If the animal appears to be heat stressed, isopropyl alcohol will be applied with a cotton
swab to the ears, arm pits, and feet to cool it down.
Training offield crews

1.

2.

All field technicians will be required to spend a full day at the Denver Museum of
Natural History Zoology Department viewing and handling specimens of all small
mammal species likely to be captured in Larimer and Weld Counties.
All field technicians will be provided with a small mammal field guide and a key
specifically designed to list the species most likely to be captured on the trapping sites.

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3.

All field technicians will participate in 4 days of practice trapping at the Frank State
Wildlife Area and/or the Air Force Academy from May 26-29. During these trapping
sessions all technicians will learn how to place, bait and set traps. Field identification
will be practiced on all animals caught each day and verified by crew leaders. All field
technicians will also practice handling, measuring, implanting PIT tags, and taking
genetic tissue samples from deer mice (Peromyscus maniculatus) until they are
competent in this procedure.

Habitat Use Study
Background
Site scale: Based on studies of Z. h. preblei and Z. hudsonius elsewhere, Z. h. preblei
apparently occurs mostly in undergrowth consisting of grasses, forbs, or both in open wet meadows and
riparian corridors, or where tall shrubs and low trees form an overstory and provide adequate cover
(Armstrong et al. 1997). Meadow jumping mice are widespread in abandoned grassy fields, but is
often more abundant in thick vegetation along ponds, streams, and marshes or in rank herbaceous
vegetation of wooded areas (Whitaker 1963). Preble's meadow jumping mice have been trapped in
natural riparian areas as well as areas altered by anthropogenic influence including ditches and wetlands
adjacent to interstate highways, cement-lined ditches with tall cover, ditches along driveways and
moderate road use, and moderate cattle grazing (M. Bakeman, personal communication).
The majority of sites where Z. h. preblei have been found consist of multistoried cover but the
species composing the cover vary greatly (Armstrong et al. 1997, Meaney et al. 1997). Vegetation
composition of the dense cover varies considerably and includes both native and non-native species
(Meaney et al. 1996, 1997, Armstrong et al. 1997, M. Bakeman, personal communication). The
herbaceous understory can be primarily grasses or forbs or a mixture of the two. Few of the sites,
however, are dominated by fewer than two understory species. The tall shrub canopy at most sites is
willow (Salix spp.), although scrub oak (Quercus gambelli), birch (Betula spp.), and alder (A/nus spp.)
occur in sites south of the Palmer Divide (Armstrong et al. 1997). Ponderosa pine (Pinus ponderosa)
is the most common tree at higher elevations. The mouse appears to tolerate weedy or exotic species in
areas that are structurally diverse and species rich; nearly every successful site contained Canada thistle
(Cirsium arvense) (Armstrong et al. 1997). Thus, the mouse does not appear to have an affinity
toward any single plant species but instead favors sites that are structurally diverse and provide
adequate cover and food throughout its life cycle.
Preble's meadow jumping mouse mice are typically not found in upland areas away from
riparian habitats but are most often captured where either ground water surfaces to seep springs or on
main water channels (M. Bakeman, T. Ryon, personal communication) suggesting a dependence on
open water, at least during their active periods.
Movement of Z. h. preblei on Woman Creek at Rocky Flats Technology Site suggests mice
move along corridors of shrub cover, generally Salix exigua (PTI 1996a, T. Ryon, unpublished data),
suggesting dispersal habitat is similar to habitats used for other activities.

Small mammal assemblage: Preble's meadow jumping mice are only one component of the
small mammal community inhabiting areas where they were captured. These mice were more often
found at sites with high species richness and small mammal abundance (Armstrong et al. 1997, Meaney
et al. 1997). The variety and relative abundance of other small mammalian species trapped during
surveys for Preble's meadow jumping mouse provide some framework for comparison of small
mammal assemblages at sites where Z. h. preblei occurred and sites where none were captured. All
trapped sites were either historical sites of known occurrence or apparently suitable habitat for Z. h.
preblei, providing a common basis for comparison. Three small mammal species (Spermophilus
variegatus, Peromyscus nasutus, and Rattus norvegicus) were not captured where Z. h. preblei
occurred but were captured in unsuccessful sites. However, captures of these three species only
occurred at one or two sites and the species comprised an extremely small percentage of the species

�90

caught in those areas providing too little information for speculating on possible interactions between
these species and Z. h. preblei.
The higher occurrence and percent composition of capture of Mus musculus, the house mouse,
in areas where Z. h. preb/ei was not caught might suggest degradation of habitat for Z. h. preblei in
those areas or possibly competition between the two species (Ryon 1996). The house mouse, thrives
in areas of human habitation and croplands, but also occurs in abandoned fields and ditch banks where
they may displace native rodents (Fitzgerald et al. 1994). Ryon (1996) also reported the presence of
domestic cats (Fe/is catus) at sites where Z. h. preblei historically occurred but were not found during
his study. Contrarily, C. Miller (personal communication)
reported house cats along South Boulder Creek where Preble's meadow jumping mice are known to
occur.

Landscape scale: Areas of suitable habitat must provide requirements for PMJM to survive
throughout its life cycle. These requirements must provide necessities for both the active period and
hibernation periods. During the active period suitable habitat must provide requirements for daily
survival, reproductive activities (breeding, nesting, and rearing of young to independence), and
dispersal. The hibernation period requires sufficient food supplies to assure fat storage prior to
hibernation and suitable hibernacula Habitat providing all seasonal and life cycle requirements may or
may not occur in a single contiguous area If not in a contiguous area, habitat patches must occur in a
mosaic of usable areas where suitable corridors exist for seasonal movement among sites.
The habitat matrix within the range of Z. h. preblei is mixed grasslands adjacent to the
Colorado Front Range along the Piedmont and along the base of the Laramie Mountains in Wyoming
and extends to the Colorado plains. Within this matrix, Preble's meadow jumping mice occur along
stream drainages that contain patches of suitable vegetation. Suitable habitat appears to have at least
two major components. The first component is a supply of open water, at least in part of the active
season (M. Bakeman, C. Meaney, personal communication). Secondly, areas where Preble's meadow
jumping mouse has been found have dense cover (M. Bakeman, C. Meaney, personal communication).
If Preble's meadow jumping mouse behaves as a metapopulation in the classical sense [a set of
local populations which interact via dispersal of individuals moving among populations and where local
extinctions and recolonizations occur (Levins 1970)] then habitat includes not just one area of suitable
habitation but also areas suitable for nearby mouse populations. These suitable areas must also be
linked by dispersal habitat. If the mice are dependent on dense riparian habitat for dispersal, as well as
for areas to reproduce, persistence of discrete populations would require a mosaic of suitable discrete
riparian patches interconnected with dispersal corridors of similarly dense riparian vegetation. If mouse
populations function in a source (populations where growth rate~ 1) and sink (those populations where
growth rate &lt; 1, maintained through immigration) system, it will be critical to identify and protect those
populations serving as sources. Thus, for a source-sink population critical habitat will include those
areas that support source population, dispersal habitat to sink areas will be less critical. If local mouse
populations are functionally discrete, such a mosaic of interconnected areas of suitable habitat would
provide a buffer for local, and source, populations against deleterious stochastic events by providing
the opportunity for local population failures to be 'rescued' by immigration from other populations.
Objective
The objective of the habitat study is to identify and refine ecological requirements of Z. h.
preblei in Larimer and Weld Counties, Colorado.
Approach
The general approach is to measure both site specific and landscape features of 30 sites
selected at random to be surveyed for the presence of PMJM. A comparison of sites where PMJM are
found and are not found will then be made in an attempt to refine our current understanding of the
ecological requirements of the subspecies. The following habitat characteristics will be measured and
recorded for each site.

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Micro-site habitat characteristics
1.
Cover will be measured at 20 random locations along the 250 meter sampled stream stretch.
Mean cover and standard error of the mean will be estimated. Cover will be estimated using a
vegetation profile board (Nudds 1977) that allows for an assessment of visual obstruction in
0.5 meter vertical intervals above ground. The board will be 1.5 meters high and 30.48 cm
wide. The board is marked in alternate black and white colors at 0.5 meter intervals.
Horizontal cover is assessed in each interval by viewing the board from 15 meters away in a
randomly chosen direction. The percentage of each interval concealed by vegetation is
recorded as 0-20, 21-40, 41-60, 61-80, and 81-100% estimated concealment.
2.
Vegetation species composition and richness will be estimated using the Modified-Whittaker
nested vegetation sampling method (Stohlgren et al. 1995). A modified Whittaker plot is 20meters x 50-meters with 10 lm2 and 2 10m2 subplots arranged systematically around the
perimeter and 1 100m2 subplot centered in the inside of the 20 meter by 50 meter plot. Species
composition and percent cover (optical estimate) of each species is recorded for each subplot.
3.
Soil samples will be taken at each site for a hydrometer textural analysis (percent sand, silt and
clay). Samples will be collected using a soil probe. Samples will be taken from 0-12 inches,
and 12+ to 24 inches. The 0-12 inch sample will be taken first, removing the probe and soil.
Sample will be placed in a labeled ziplock bag. The probe will then be placed in the same hole
for the 12+ - 24 inch probe, with that soil sample being placed in a separately labeled ziplock
bag. The hydrometer textural analysis will be conducted at the CSU Soils Laboratory.
4.
Mean stream width will be estimated by measuring stream width at 30 locations along the
entire site sampled. The 30 locations will be stratified equidistant from each other to cover the
entire stream stretch in increments of site stream length/30.
5.
Compare parameter estimates from 1-4 for sites where PMJM were captured and sites where
PMJM were not captured.
Landscape habitat characteristics
The following landscape habitat characteristics will be measured using either GIS, topographic maps,
or aerial infrared photography.
1.
Estimate distance to nearest human habitation and human disturbance.
2.
Estimate connectivity of sites to other streams from I :24,000 topographic maps.
3.
Estimate total length of stream stretch at each site and total length of stream stretch with
suitable habitat at each site.
4.
Compare parameter estimates from 1-3 for sites where PMJM were captured and sites where
PMJM were not captured.

Monitoring Study
Background
For purposes here, population persistence is defined as the presence of Z. h. preblei at the same
site for multiple years. The majority of recent locations of meadow jumping mice have been the result
of survey efforts that focused only on determining presence of Z. h. preblei. Once survey protocols
(USFWS 1997) are met [i.e., a minimum of 400 trapnights (one trap set for one night= I trapnight)
conducted] sites are typically not revisited eliminating the possibility of determining population
persistence at these sites. Thus, these and other sites not yet surveyed may or may not have persistent
populations. Areas where trapping was conducted over multiple years as part of further research,
yielded three sites in Colorado that support persistent populations: Rocky Flats Environmental
Technology Site, the U. S. Air Force Academy near Colorado Springs, and Boulder Open Space on
South Boulder Creek.
Besides establishing the presence of Z. h. preblei over multiple years, other considerations of
persistence include (I) presence in consecutive years versus a 'blinking' in and out of a population as
would be expected in a metapopulation, (2) how populations are sustained in a given area (e.g., source
or sink populations), (3) maximum abundance supportable by a given area, and (4) fluctuations in

�92

abundance of a population over years. If Z. h. preblei exist in areas as part of a metapopulation or as a
series of source-sink populations it would be critical to conserve and protect all key sub-population
areas as well as critical habitat for dispersal. Detailed population studies, including estimating and
determining factors affecting survival, reproduction, and dispersal rates, must be conducted to
determine if Z. h. preblei occurs as either metapopulations or in source-sink populations. There have
been no such studies conducted on Z. h. preblei or Z. hudsonius elsewhere to provide any supporting
or refuting evidence for either metapopulation or source-sink structure.
Consistently low abundance in a given area due to limiting ecological requirements (e.g., size
of area of suitable habitat) or fluctuations in population abundance, including years of low abundance,
must be considered in any conservation strategies for Z. h. preblei because of the threat of complete
loss of the population due to catastrophic or extreme environmental conditions. Some evidence exists
for such fluctuations in population abundance at Rocky Flats Environmental Technology Site.
Trapping surveys on the Woman Creek drainage yielded the following captures of Z. h. preblei: seven
in 1993 (EG&amp;G 1993), zero in 1994 (T. Ryon, unpublished data), one in 1995 (T. Ryon, unpublished
data), two in 1996 (PTI 1996a), and 33 in 1997 (T. Ryon, unpublished data). Trapping effort was
consistent from 1995-1997. Repeated trapping surveys conducted over different years intermittently
yielded successful captures of Z. h. preblei along the St. Vrain Creek and lower Coal Creek (three in
1989, zero in 1992, zero in 1994, zero in 1996, one in 1997, M. Bakeman, unpublished data). If
protocols in each year were the same, these data also suggest populations may undergo fluctuations in
abundance.
Objective
The objective of the monitoring study is to establish a monitoring protocol to evaluate the status
(i.e., presence or absence) of Z. h. preblei populations at specific sites and to detect changes in local
distribution from year to year. Detection of PIT-tagged individuals from year to year will also provide
evidence for site fidelity and/or movements of individual mice from one area to another.
Approach
Trapping surveys will be repeated each year at 20 randomly selected sites of those surveyed.
Of the sites surveyed, monitoring sites will be established from a random selection often sites where no
PMJM are captured and 10 sites where PMJM are captured in 1998. These 20 sites will be surveyed
every year thereafter.
1.
3.
4.
5.
6.
7.

Trapping surveys will be conducted as described in the Distribution Study.
Habitat will be evaluated at all sites as described in the Habitat Use Study and comparisons
made to results from previous years.
Each PMJM captured will be PIT-tagged as per the protocols outlined in the Distribution
Study.
Population persistence at a given site will be evaluated as the number of years when a given site
hadPMJM.
Recaptures of PIT-tagged individuals will be mapped from year to year to provide evidence for
site fidelity and/or movements of individual mice from one area to another.
Detailed protocols for long-term data analyses will be designed once a state-wide, long-term
monitoring program is fully developed.

Molecular Systematic Study
Background
The family Zapodidae Gumping mice) consists of small to medium-sized mice with enlarged
hind feet and exceptionally long tails. Four living genera are recognized in this family, two of which,
'Zapus and Napaeozapus, are found in North America (Hall 1981). There are three living species of the
genus 'Zapus: Z. trinotatus (Pacific jumping mouse), Z. princeps (western jumping mouse), and Z.
hudsonius (meadow jumping mouse). Z. h. preblei is one of twelve living subspecies of the species Z.

�93

hudsonius (Krutzsch 1954, Hafner et al. 1981). Z. h. preblei was first described by Krutzsch (1954)
from a specimen collected by E. A. Preble in 1895 near Loveland, Colorado.
Quimby (I 951) described the species Z. hudsonius as follows: 'A mouse-like rodent with
greatly enlarged hind feet and an exceptionally long tail. The forelegs are relatively short. The ears are
somewhat conspicuous. The body is clothed in moderately long, somewhat dense hair of a rather
coarse texture and several colors. The dorsal portions are marked by a broad stripe of brownish hairs
many of which are tipped with black giving the region a grayish-black appearance. The sides are bright
yellowish-orange, whereas the underparts and feet are white. The tail is bicolor, dark above and light
below, and sparsely covered with hair which is longer on the terminal part. The mammae are eight, and
quite prominent in lactating females. The male genitalia are inconspicuous except during the breeding
season when the scrotal sac becomes enlarged. The testes enlarge and may be either abdominal,
inguinal, or scrotal during this period.' The skull of Z. hudsonius is small and light with a narrower
braincase and smaller molars than in Z. princeps (from Fitzgerald et al. 1994 p. 18). However,
Fitzgerald et al. (I 994) urge caution in distinguishing the two species of Zapus in Colorado. Such
caution is further warranted by the recent conflicting identifications of mice based on genetic
characteristics.
Analysis of mitochondrial DNA sequence data from 92 individual mice indicates that mice
sampled from southeastern Albany County, Wyoming, south along the Front Range of the Rocky
Mountains to western Las Animas County, Colorado (Purgatoire Campground, San Isabel National
Forest), form a coherent genetic group (Riggs et al. 1997). This group of samples are distinct from
samples obtained from mice from three other populations. Genetic samples from mice captured in the
Dorothey Lakes area of southern Colorado (Las Animas County) group together and are most closely
allied with Z. h. luteus, a subspecies described from New Mexico (Riggs et al. 1997). The single
genetic sample collected from Weld County, Colorado (Lone Tree Creek) and six samples obtained
from Warren Air Force Base in Laramie County, Wyoming are most similar to reference samples of Z.
princeps from Colorado (Larimer County) and New Mexico (Taos County) (Riggs et al. 1997). The
sequence data indicate that the samples from specimens identified as Z. h. luteus and samples from
specimens of Z. princeps are more closely allied with each other than either is with the samples defining
the Z. h. preblei group. This closer alliance of the samples of Z. h. luteus with Z. princeps rather than
Z. h. preblei conflicts with results ofHafuer et al. (1981), based on a combination of pelage,
morphologic, and genetic data, which support a closer alliance with Z. hudsonius.
A more complete biosystematic evaluation of jumping mice is needed to clarify and further
refine relationships among populations of the group referred to as Z. h. preblei as well as to other
subspecies and species of the genus Zapus. Such an evaluation requires detailed analyses of pelage,
morphometric, and genetic data from sufficient numbers of individuals to adequately represent the
populations of interest. However, the mitochondrial DNA non-coding (D-loop) sequence data
available at this time are consistent with the view that a geographically contiguous set of populations
previously recognized as Preble's meadow jumping mouse form a homogenous group recognizably
distinct from other nearby populations and from another geographically-adjacent species of the genus
(Riggs et al. 1997). Therefore, given the genetic data available, Riggs et al. (I 997) conclude Preble's
meadow jumping mouse is a distinct population of Z. hudsonius.

Objective
Because of the uncertainty of the identification of the mice captured in Weld County, Colorado,
and because currently perceived ecological boundaries of PMJM will be challenged in the survey effort,
the objective of the genetic component of this study is to genetically identify the PMJM captured during
this study. Therefore, genetic tissue samples will be collected from each PMJM captured to confirm
identification of the animal. These genetic tissue samples could also provide further data to better
define the relationships of different populations of Z. h. preblei as well as to other subspecies of Z.
hudsonius and other species of Zapus through molecular systematic relationships and to link these
genetic relationships to systematic studies of Z. hudsonius. Efforts are underway to secure funding for
these studies.

�94

Approach
Genetic tissue samples will be collected from every PMJM captured during the study. To date,
positive identification of the individual to subspecies cannot be made using only genetic information.
However, results of the DNA analysis combined with the morphometric data that will also be collected
(e.g., body length, tail length) and the photograph of the individual should provide sufficient
information to support the field identification to subspecies.
As established by the USFWS (1997) Survey Guidelines, presence of PMJM is established
when only one individual is captured. Thus, we could stop our trapping efforts after the first PMJM
capture. However, because we would also like to provide sufficient genetic data to more fully explore
the relationships of different populations of Z h. preblei we will attempt to collect genetic tissue
samples from a minimum of IO individuals per successful survey site. A sample of at least IO
individuals from a population will provide enough information to document the genetic variation within
the population (T. Quinn, personal communication).
Genetic tissue sampling: collection ofear tissue samples using ear punch tool
The following protocol has been used on PMJM (M. Bakeman, C. Meaney, T. Ryon, R
Schorr, personal communication).
Before checking traps, clean the ear punch tools by immersing them in a I 0% bleach solution
for a few minutes, then rinsing thoroughly with clean water. Dry tools thoroughly. A small screw-cap
container will be useful to contain the bleach solution and to receive used ear punch tools. A sports
bottle or other container with a squirt or pop-up top may be used for rinsing. Wash any previously
used containers thoroughly by hand or in the dishwasher and do not use for other purposes (e.g.,
drinking) while in the field.
I.
Use a fresh pair of clean latex gloves when handling each mouse.
2.
With a clean ear punch tool, obtain 2 tissue plugs from the mouse's ear. If there is excessive
bleeding, gentle pressure will be applied to the injured area for approximately I minute. Punch
may be applied to deliver the plug as a small circlet of tissue (about the size of the head of a
pin) onto a finger of your gloved hand. [Placement of the punch may be done in any way that is
convenient or useful as an ear mark in the context of your own work. A consistent location on
one ear can help identify recaptured mice that have already been sampled.]
3.
Place the finger tip tightly over the end of an opened sample vial and shake to wash the tissue
plug into the ethanol.
4.
Repeat until all three tissue plugs have been collected into the same sample vial. Inspect the
tube to see that all plugs have made it into the ethanol.
5.
Close the sample vial--screw the cap on firmly and check that there is no leakage of ethanol
when the tube is inverted. Label both the vial and the corresponding record on the data sheet
(see item 6 below) with a unique identifier as follows. Use a seven-place alpha-numeric code
composed of the following:
-

A three-letter designator for the survey location (e.g., STV = St. Vrain, SCR = Smith
Creek).
A number beginning with two digits indicating the year (e.g., 98) followed by 2 digits
specifying the individual trapped, numbered sequentially.

Example: STV9801 = first animal sampled at St. Vrain in 1998.

6.

Note: The combined seven-place alpha-numeric code needs to be a unique identifier for an
individual mouse across all locations and sites being trapped in studies coordinated by the
Colorado Division of Wildlife.
Record information for the individual sampled on the data sheet provided. Be sure to include
all data requested. Repetitive entries may be completed before or after the field session but we

�95

recommend not allowing much time to elapse before doing this--what is obvious to you at the
time may not be so obvious to us, or to you, later on. Information for each sample needs to be
complete and unambiguous if the sample itself is to be useful.
After returning from the field, samples will be kept in a cool place or refrigerated until delivery
to the CDOW office at 317 West Prospect, Fort Collins, CO where they will be kept in the freezer for
analyses.

E.

LOCATION

Trapping surveys will be conducted at 30 sites selected at random from the sampling frame
developed for Larimer and Weld Counties, Colorado. No survey site will occur at elevations greater
than 7600 feet and not east of the UTM Easting Coordinate of 602000. The molecular systematic
studies will be conducted in genetic laboratories using the genetic tissue samples collected in the field
(ear punches).
Training sessions for all field technicians and crew leaders will take place at the Frank State
Wildlife Area located in Larimer County, Colorado 2.3 miles east ofl-25 on Highway 392 and 0.5
miles south on County Road 13.
Data analyses and office work will be conducted at the CDOW Research Center, 317 West
Prospect, Fort Collins, Colorado.

F.

SCHEDULE

March 1998
April 1998
May 1998
May 1998
May 1998
June-September 1998
October 1998
Oct 1998-March 1999
December 1998
Aprill999
Aprill999

G.

Purchase equipment for summer 1998 field season
Complete sampling frame and select trapping sites
Complete Study Plan for a distribution study of Preble's meadow
jumping mouse
Advertize for, hire, and train technicians
Train field crews
Conduct trapping surveys, collect site habitat data
Conduct GIS analyses of the sites surveyed
Conduct analyses
Provide USFWS with a preliminary report of the results of the study
Complete analyses for 1998 season.
Submit Final Report for the 1998 season to the CDOW and USFWS

PERSONNEL

Tanya Shenk
Gary C. White
I CDOWTFTE
4 CNHP temporary employees

Principal Investigator
Statistical Consultant
Field Crew leader
Field Technicians

�96

H.

BUDGET

The following is a budget to conduct habitat use and distributional information for 30 sites to be
completed in summer 1998.
Operating Expenses
PIT Tags
PIT tag scanners
PIT tag software
genetic sampling kit expenses
traps
topographic maps
photographic equipment, expenses
laboratory analyses (fecal, soil)
camera trap supplies
misc. equipment (gloves, cotton, bait, etc.)

$
$
$
$
$
$
$
$
$
$

Personnel
4 field technician for 3.5 months each
1 crew leader for 5 months
GIS contract work
Statistical consultant

$24,000
$24,000
$ 4,000
$ 3,000

Travel
30,000 miles @0.12 per mile
vehicle rental: 3 vehicles, 4 mo. @$120 per month
overnight travel 30 days @$75 per day

$
$
$

TOTAL

$80,290

I.

3,000
1,800
300
500
2,000
500
3,500
1,200
5,000
200

3,600
1,440
2,250

LITERATURE CITED

Armstrong, D. M. 1972. Distribution of mammals in Colorado. University of Kansas, Museum of
Natural History Monograph 3:1-415.
Armstrong, D. M., M. E. Bakeman, A. Deans, C. A. Meaney, and T. R Ryon. 1997. Conclusions and
recommendations in: Report on habitat findings on the Preble's meadow jumping mouse.
Edited by M. E. Bakeman. Report to USFWS and Colorado Division of Wildlife.
EG&amp;G. 1993. Report of Findings: 2nd Year Survey for the Preble's meadow jumping mouse.
Prepared by Stoecker Environmental Consultants for ESCO Associates, Inc., Rocky Flats
Environmental Technology Site, Jefferson County, Colorado
Fitzgerald, J.P., C. A. Meaney, and D. M. Armstrong. 1994. Mammals of Colorado. Denver
Museum of Natural History, University Press of Colorado. Niwot, Colorado.
Hafner, D. J., K. E. Petersen, and T. L. Yates. 1981. Evolutionary relationships of jumping mice
(genus Zapus) of the southwestern United States. Journal ofMammalogy 62:501-512.

�97

Hall, E. R 1981. The mammals of North America John Wiley and Sons, Inc., New York, New York,
2 volumes.
Jones, C. A. 1996. Mammals of the James John and Lake Dorothey State Wildlife Areas. Final
Report, submitted to the Colorado Division of Wildlife and Colorado Natural Areas Program.
Krutzsch, P.H. 1954. North American jumping mice (genus Zapus). University of Kansas
Publications, Museum of Natural History 7:349-472.
Levins, R 1970. Extinction. Lectures in Mathematical Life Sciences 2:75-107.
Long, C. A. 1965. The mammals of Wyoming. University of Kansas Publications, Museum of
Natural History, 14:493-758.
Meaney, C. A., N. W. Clippinger, A. Deans, and M. OShea-Stone. 1996. Second year survey for
Preble's meadow jumping mouse (Zapus hudsonius preblei) in Colorado. Report prepared for
the Colorado Division of Wildlife.
Meaney, C. A., A. Deans, N. W. Clippinger, M. Rider, N. Daly, and M. O'Shea-Stone. 1997. Third
year survey for Preble's meadow jumping mo.use (:lapus hudsonius preblei) in Colorado.
Report prepared for the Colorado Division of Wildlife.
Nudds, T. D. 1977. Quantifying the vegetative structure of wildlife cover. Wildlife Society Bulletin
5:113-117.
Olson, T. E., and F. L. Knopf. 1988. Patterns of relative diversity within riparian small mammal
communities, Platte River watershed, Colorado. Pg. 379-386 in: Proceedings of the
symposium: Management of amphibians, reptiles and small mammals in North America.
Flagstaff, Arizona U. S. Forest Service, General Technical Report RM-166.
PTI Environmental Services. 1996a Preble's Meadow Jumping Mouse Study at Rocky Flats
Environmental Technology Site, Annual Report 1996. Final. Rocky Flats Environmental
Technology Site, Golden, Colorado.
Quimby, D. C. 1951. The life history and ecology of the jumping mouse, Zapus hudsonius.
Ecological Monographs 21:61-95.
Riggs, L. A., J. M. Dempey, and C. Orrego. 1997. Evaluating distinctness and evolutionary
significance of Preble's meadow jumping mouse: Phylogeography of mitochondrial DNA noncoding region variation Final Report for the Colorado Division of Wildlife. Denver,
Colorado.
Ryon, T. R 1996. Evaluation of historical capture sites of the Preble's meadow jumping mouse in
Colorado, final report. MS Thesis. University of Denver, Denver, Colorado.
Stohlgren,T. J., M. B. Falkner, and L. D. Schell. 1995. A Modified-Whittaker nested vegetation
sampling method. Vegetatio 117: 113-121.
USFWS. 1997a Proposal to list the Preble's meadow jumping mouse as an endangered species.
USFWS 50 CFR part 17.

�98

USFWS. 1997b. Interim survey guidelines for Preble's meadow jumping mouse. USFWS. Denver,
Colorado.
Whitaker, J. 0., Jr. 1963. A study of the meadow jumping mouse, Zapus hudsonius (Zimmerman), in
cental New York. Ecological Monographs 33:3.
Whitaker, J. 0., Jr. 1972. Zapus hudsonius. Mammalian Species 11:1-7.

�0 Entcrcu
0 Checked
SMALL MAMMAL TRAPPING FORM
DATE_ _ _/_· _J___ _
SITEI.D(DRAINAGE). _ _ _ _ _ _ _ _ _ _ _ TOPOQUAD. NAME _ _ _ _ _ _ _ _ _ _UlME _ _ _ _ _ _ _ _ _ _ _UTMN_ _ _ _ _ _ _ _ _ _ _ PAGE

HANDLER_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
TRAP TYPE _ _ _ _ _ _ _ _ _ _ _ __
TEMPERATURE _ _ _ __
OBS
NUM

Tnp

NO. OF TRAPS _ _ _ _ _ _ SAMPLE SITE _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ TIME START _ _ _ _ TIMEFINISH _ _ _ __

CLOUD COVER (0-8) _ __

WIND _ _ _ _ _ _ __

COMMONNAME

OF

RECORDER._ _ _ _ _ _ _ _ _ _ _ _ _ __

[NJ/

TOTAL

BAG

MORT

WT(I)

WT(g).

TAIL
LENGTII

B°"1

Length

HIND
FOOT

(111111)

(mm)

(mm)

PRECIPITATION _ _ _ _ _ _ _ _ _ _ __
EAR
(mm)

SEX

REP.

#Ear

COND

Plugs

PITT1g#

RADIO

PJM

SIie

FREQ

Phoeo

Pbollo

COMMENTS

~~

&amp;~

"r1Z

0

t:,

~ ~

&gt;

'°ID
COMMENTS:_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __

�100

Zapus hudsonius preblei Injury/Mortality Documentation

Found dead
Found severely injured, euthanized
Slightly injured, returned to wild
Died during handling
Date/Time:------------------------------Location: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
Weather Conditions: - - - - - - - - - - - - - - - - - - - - - - - - - - Approximate Time Trap Set:._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
Time Trap Checked:._ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
Field Technician(s) Present:
Information:
Species: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __
PIT TAG Number: - - - - - - - - - - - - - - - - - - - - - - - - - - Weight (g): - - - - - - - - - - - - - - - - - - - - - - - - - Total Body Length (mm): - - - - - - - - - - - - - - - - - - - - - - Tail Length ( m m ) : - - - - - - - - - - - - - - - - - - - - - - - - - Hindfoot Length (mm): - - - - - - - - - - - - - - - - - - - - - - Ear Length ( m m ) : - - - - - - - - - - - - - - - - - - - - - - - - Sex: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __

Reproductive Condition(s): - - - - - - - - - - - - - - - - - - - - - - - - Description of Injury: - - - - - - - - - - - - - - - - - - - - - - - - - - Details of Probable Reasons for Injury or Mortality:

Signature of Technician(s):

�1

Colorado Division of Wildlife
Wildlife Research Report
July 1999

JOB PROGRESS REPORT
State of ----..-=..a---=="'------Colorado
P roj ect No. _ _ _W..:..:--=15:;..;:3;_-R=:.;::...;-1=2'---_ _ __
Work Package No. _0=6=6=2'--------Task No. _ _ _ _-=-1_ _ _ _ _ _ __

Cost Center 3430
Mammals Program
Preble's Meadow Jumping Mouse Conservation
Develop Conservation Plan for Preble's Meadow
Jumping Mouse

Period Covered: July 1, 1998 - June 30, 1999
Author: Tanya M. Shenk
·Personnel: J. Brinker, J. Eussen, M. Miller, M. Sivert, M. Wild, CDOW, K Burnham, G. White,
CSU

ABSTRACT
Preliminary analysis of the movement data collected on radio-collared PMJM indicate (1)
maximum movements of&gt; 1 mile, (2) greater use of upland habitats than previously assumed, (3)
general site fidelity to both daytime nesting sites and nighttime feeding sites, (4) seasonal shifts in
movement patterns, (5) use of both perennial and intermittent tributaries adjacent to the capture
drainage, and (6) long distance movements in September to new locations, presumably in preparation
for hibernation. Mouse locations were categorized by the distance criteria used in the USFWS
Proposed 4-D Rule to provide the greatest amount of information to evaluate if the proposed
regulations would be sufficient to ensure protection of PMJM. Given the high proportion of locations
within both the proposed buffer zone (150-300 feet) and outside any area of protection(&gt; 300 feet),
data from this study do not support the regulations regarding the 300 foot protection zone from the
center of the capture stream. Analyses were not completed using the criteria of protection up to 300
feet from the edge of contiguous wetlands because a delineation of contiguous wetlands for any of the
three study sites is not yet available. Once these contiguous wetlands are mapped, similar analyses will
be conducted using edge of the wetland rather than stream center for perpendicular distance
measurements. Eight possible hibemacula were located during this study. Five of the eight mice using
these possible hibemacula traveled ;;,: 90 meters from the center of their typical September night time
locations. Vegetation characteristics of the eight sites located during this study are similar to other
hibemacula described for PMJM. Natural mortality factors documented during this study included
predation by house cats, garter snakes, rattlesnakes, and fox as well as accidents by drowning and road
kill. High percentages of arthropods and endogenous fungus were found in the 85 PMJM fecal samples
analyzed thus far. The combination of shifts in both general mouse movements, individual mouse
movements, and diet provide strong circumstantial evidence that PMJM may be selecting for or require
specific seasonal diets.
A total of39 sites were surveyed for PMJM in Larimer and Weld Counties, Colorado with a
total of 16,671 trap-nights completed. Of the 39 sites survey, Zapus spp. were captured at 21

�2

locations. A total of 71 unique individuals were captured in the 21 locations, with recaptures of 14 of
those individuals. All sites where Zapus spp. were captured were located in Larimer County. lbree
soil samples from 0-12 inches and 12-24 inches were collected at all sites where possible. Soils at
some sites were too rocky to collect the 12-24 inch soil samples. Nine fecal samples were collected
from traps where Zapus spp. were captured. Initial result indicate that arthropods, fungus, and willows
are important dietary components of the Zapus diet. Measurements of habitat characteristics at both the
site and landscape levels were completed. Genetic tissue samples were collected from 68 of the 71
jumping mice captured. Analyses of these tissue samples is pending.
A total of 186 individual mice were captured and PIT-tagged at three study sites (73 mice at
Maytag Property, 77 mice at PineCliffRanch, and 36 mice at Woodhouse Ranch) during the 1998 field
season. These mice were captured over three different trapping sessions with an effort of 17,330 trapnights. Genetic tissue samples were collect!;ld for at least 30 individual mice at each of the three study
sites. Density estimates were expected to increase as the summer progressed to account for the birth
pulses in late June, and late July-August. This was the trend observed at Maytag. PMJM densities at
Woodhouse Ranch increased from June to July but did not increase further during the September
trapping session. Mean PMJM density over all sites and sessions was 40.5 (range 16.9-79.0) mice per
. kilometer of stream stretch. Defining summer as June 1 - October 5, over-summer survival was
estimated as 0.36 (se = 0.056) over all three study sites. Temporary emigration and immigration rates
were estimated but both had extremely high variances associated with those estimates. Thus, these
estimates cannot be used, with any confidence, to provide information on movements of mice into and
out of these populations. Very little new information was gained during this study on reproductive
parameters of PMJM. Most adult mice captured exhibited evidence of active reproductive behavior,
either pregnancy, lactation, or enlarged genitalia However, we were unable to loca~e any breeding
nests. Juvenile mice were not captured during the June trapping session. Juvenile mice were captured
at all three sites during both the July and September trapping sessions.
Preliminary results from the demography, movement and distribution studies of PMJM have
suggested the need to continue with research currently being addressed in these three studies.
However, the preliminary results also suggest further research be conducted on (1) use of upland
habitat by PMJM, (2) refining water requirements of PMJM (i.e., do they require stream habitat or are
wetland areas sufficient), (3) range-wide distributional boundaries (e.g., elevation restrictions), and (4)
investigating areas of potential sympatry or hibridization with Z. princeps (western jumping mouse).
The demography and movement studies will be modified during the summer 1999 field season to
further investigate upland use and water requirements.
This report includes results from only the first year of a multi-year project to follow individually
marked PMJM through time. Collection of more data, and more years of data, will improve our ability
to evaluate demographic parameters, movement patterns, and habitat use and evaluate how they vary
across space and time.

�3

PREBLES'S MEADOW JUMPING MOUSE CONSERVATION
Tanya M. Shenk

P.N. OBJECTIVE
Develop and implement a conservation plan for Preble's meadow jumping mouse in Colorado.

SEGMENT OBJECTIVES
1.

Evaluate movement data of Preble's meadow jumping mouse as it relates to landscape features
at two study sites.

2.

Conduct presence/absence surveys for Preble's meadow jumping mouse at 30 sites in Larimer
and Weld Counties, Colorado.

3.

Refine and prioritize needed research components to develop sound strategies for conservation
of Preble's meadow jumping mouse.

4.

Analyze data and prepare a Federal Aid Job Progress Report.

Status Report
I,

Evaluate movement data ofPreble's meadow jumping mouse as it relates to landscape
features at two study sites.

Movement data of PMJM were collected on radio-collared mice to evaluate the effects of
landscape features on movement patterns. Preliminary analysis of the movement data is presented as a
draft manuscript, Movement patterns ofPreble's meadow jumping mouse (Zapus hudsonius preblei)
as they vary across time and space, in Appendix A
In summary, movement data collected on radio-collared PMJM indicate (I) maximum
movements of&gt; I mile, (2) greater use of upland habitats than previously assumed, (3) general site
fidelity to both daytime nesting sites and nighttime feeding sites, (4) seasonal shifts in movement
patterns, (5) use of both perennial and intermittent tributaries adjacent to the capture drainage, and (6)
long distance movements in September to new locations, presumably in preparation for hibernation.
2.

Conduct presence/absence surveys for Preble's meadow jumping mouse at 30 sites in
Larimer and Weld Counties, Colorado.
a. Presence/absence surveys

Preliminary analysis of the PMJM survey data is presented as a draft manuscript, Habitat use
and distribution of Preble's meadow jumping mouse (Zapus hudsonius preblei) in Larimer and Weld
Counties, Colorado, in Appendix B.
In summary, a total of39 sites were surveyed for PMJM in Larimer and Weld Counties,
Colorado with a total of 16,671 trap-nights completed. Of the 39 sites survey, Zapus spp. were

�4

captured at 21 locations. A total of 71 unique individuals were captured in the 21 locations, with
recaptures of 14 of those individuals. All sites where Zapus spp. were captured were located in
Larimer County. Three soil samples from 0-12 inches and 12-24 inches were collected at all sites
where possible. Soils at some sites were too rocky to collect the 12-24 inch soil samples. Nine fecal
samples were collected from traps where Zapus spp. were captu{ed. Initial result indicate that
arthropods, fungus, and willows are important dietary components of the Zapus diet. Measurements of
habitat characteristics at both the site and landscape levels were completed. Genetic tissue samples
were collected from 68 of the 71 jumping mice captured.

b.

Abundance, over-summer survival, over-winter, annual survival estimates and
population age and sex structure ofPreble 's meadow jumping mouse populations at
two study sites.

Preliminary analysis of the demography study ofPMJM is presented as a draft manuscript,
Temporal and spatial variation in the demography ofPreble's meadow jumping mouse (Zapus
hudsonius preblei), in Appendix C.
In summary, a total of 186 individual mice were captured and PIT-tagged at three study sites.
Mean PMJM density over all sites and sessions was 40.5 (range 16.9-79.0) mice per kilometer of
stream stretch. Defining summer as June 1 - October 5, over-summer survival was estimated as 0.36
(se = 0.056) over all three study sites. Temporary emigration and immigration rates were estimated
but both had extremely high variances associated with those estimates. Thus, these estimates cannot
be used, with any confidence, to provide information on movements of mice into and out of these
populations. Very little new information was gained during this study on reproductive parameters of
PMJM. Most adult mice captured exhibited evidence of active reproductive behavior, either
pregnancy, lactation, or enlarged genitalia However, we were unable to locate any breeding nests.
Juvenile mice were not captured during the June trapping session. Juvenile mice were captured at all
three sites during both the July and September trapping sessions, indicating two birth pulses.

4.

Refine and prioritize needed research components to develop sound strategies for
conservation ofPreble's meadow jumping mouse.

Preliminary results from the demography, movement and distribution studies of PMJM have
suggested the need to continue with research currently being addressed in these three studies.
However, the preliminary results also suggest further research be conducted on (1) use of upland
habitat by PMJM, (2) refining water requirements of PMJM (i.e., do they require stream habitat or are
wetland areas sufficient), (3) range-wide distributional boundaries (e.g., elevation restrictions), and (4)
investigating areas of potential sympatry or hibridization with Z. princeps (western jumping mouse).
The demography and movement studies will be modified during the summer 1999 field season to
further investigate upland use and water requirements.

5.

Analyze data and prepare a Federal Aid Job Progress Report.

A Federal Aid Job Progress Report was submitted to the CDOW on August 16, 1999.

�5

APPENDIX A
MOVEMENT PATTERNS OF PREBLE'S MEADOW JUMPING MOUSE (Zapus hudsonius preblei)
As THEY VARY ACROSS TIME AND SPACE

Tanya Shenk and Maile M. Sivert

Abstract
Preliminary analysis of the movement data collected on radio-collared Preble's meadow
jumping mice (PMJM) indicate (I) maximum movements of&gt; I mile, (2) greater use of upland
habitats than previously assumed, (3) general site fidelity to both daytime nesting sites and nighttime
feeding sites, (4) seasonal shifts in movement patterns, (5) use of both perennial and intermittent
tributaries adjacent to the capture drainage, and (6) long distance movements in September to new
locations, presumably in preparation for hibernation. Mouse locations were categorized by the distance
criteria used in the USFWS Proposed 4-D Rule to provide the greatest amount of information to
evaluate if the proposed regulations would be sufficient to ensure protection of PMJM. Given the high
proportion oflocations within both the proposed buffer zone (150-300 feet) and outside any area of
protection(&gt; 300 feet), data from this study do not support the regulations regarding the 300 foot
protection zone from the center of the capture stream. Analyses were not completed using the criteria
of protection up to 300 feet from the edge of contiguous wetlands because a delineation of contiguous
wetlands for any of the three study sites is not yet available. Once these contiguous wetlands are
mapped, similar analyses will be conducted using edge of the wetland rather than stream center for
perpendicular distance measurements. Eight possible hibernacula were located during this study. Five
of the eight mice using these possible hibernacula traveled :?: 90 meters from the center of their typical
September night time locations. Vegetation characteristics of the eight sites located during this study
are similar to other hibernacula described for PMJM. Natural mortality factors documented during this
study included predation by house cats, garter snakes, rattlesnakes, and fox as well as accidents by
drowning and road kill. High percentages of arthropods and endogenous fungus were found in the 85
PMJM fecal samples analyzed thus far. The combination of shifts in both general mouse movements,
individual mouse movements, and diet provide strong circumstantial evidence that PMJM may be
selecting for or require specific seasonal diets.
These data are limited to the first year of a multi-year study and thus annual variation in mouse
movement patterns cannot yet be addressed. Continuation of this study, at least through the 1999 field
season will provide information on annual variation in PMJM movement patterns.
This is an interim progress report. Further analyses will be conducted on these data and data collected
during the 1999 field season.

llltroduction
Movement and dispersal pattern information will be key to any conservation strategy designed
for Preble's meadow jumping mouse (PMJM). Documenting daily and seasonal movement patterns of
PMJM will provide information on habitats used by the mice and on the relative configuration and
juxtaposition of these habitats. Configuration of habitats include vegetation and size of the areas used.
Juxtaposition includes relative locations of different habitats used such as nest sites, feeding areas, and
movement corridors connecting those areas. Key dispersal factors to document for PMJM include (I)
which segment of the population disperses, (2) when do they disperse, (3) through what habitat do they
disperse, (4) how far will individuals disperse (i.e., what is the maximum distance that separates
adjacent populations) and (5) how critical is dispersal (both into and out of a population) to the
persistence of a given population.

�6

Areas of suitable habitat must provide requirements to survive throughout the life cycle. These
requirements must provide necessities for both the active period and hibernation periods. During the
active period suitable habitat must provide requirements for daily survival, reproductive activities
(breeding, nesting, and rearing of young to independence), and dispersal. The hibernation period
requires sufficient food supplies to assure fat storage prior to hib~mation and suitable hibernacula
Habitat providing all seasonal and life cycle requirements may or may not occur in a single contiguous
area If not in a contiguous area, habitat patches must occur in a mosaic of usable areas where suitable
-corridors exist for seasonal movement among sites.
The habitat matrix within the range of Z. h. preblei is mixed grasslands adjacent to the
Colorado Front Range along the Piedmont and along the base of the Laramie Mountains in Wyoming
and extends to the Colorado plains. Within this matrix, PMJM occur along stream drainages that
contain patches of suitable vegetation. Suitable habitat appears to have at least two major components.
The first component is a supply of open water, at least in part of the active season (M. Bakeman, C.
Meaney, personal communication). Secondly, areas where PMJM has been found have dense cover
(M. Bakeman, C. Meaney, personal communication).
Based on studies of Z. h. preb/ei and Z. hudsonius elsewhere, Z. h. preblei apparently occurs
mostly in undergrowth consisting of grasses, forbs, or both in open wet meadows and riparian
corridors, or where tall shrubs and low trees form an overstory and provide adequate cover (Armstrong
et al. 1997). Meadow jumping mice are widespread in abandoned grassy fields, but are often more
abundant in thick vegetation along ponds, streams, and marshes or in rank herbaceous vegetation of
wooded areas (Whitaker 1963). The mouse does not appear to have an affinity toward any single plant
species but instead favors sites that are structurally diverse and provide adequate cover and food
throughout its life cycle. PMJM are typically not found in upland areas away from riparian habitats but
are most often captured where either ground water becomes visible as either seep springs or as main
water channels (M. Bakeman,T. Ryon, personal communication) suggesting a dependence on open
water, at least during their active periods. PMJM have been trapped in natural riparian areas as well as
areas altered by anthropogenic influence including ditches and wetlands adjacent to interstate
highways, cement-lined ditches with tall cover, ditches along driveways and moderate road use, and
moderate cattle grazing (M. Bakeman, personal communication).
The only currently available data on dispersal and/or movement for Z. h. preblei are from
marked mice at Rocky Flats Environmental Technology Site (T. Ryon unpublished data). Two mice,
an adult female and an adult male, were observed approximately 1.6 kilometers from previous
locations (incidences occurred separately). Each of the locations were in the same drainage (Woman
Creek). Movement of Z. h. preblei on Woman Creek at Rocky Flats Technology Site suggests mice
move along corridors of shrub cover, generally Salix exigua (PTI 1996a, T. Ryon, unpublished data),
suggesting dispersal habitat is similar to habitats used for other activities.
If PMJM occurs as metapopulations in the classical sense of a set oflocal populations linked by
infrequent dispersal then habitat includes not just one area of suitable habitation but also areas suitable
for nearby mouse populations. These suitable areas must also be linked by dispersal habitat. If the
mice are dependent on dense riparian habitat for dispersal as well as for areas to reproduce, persistence
of discrete populations would require a mosaic of suitable discrete riparian patches interconnected with
dispersal corridors of similarly dense riparian vegetation. If mouse populations function in a source
(populations where growth rate :2: 1) and sink (those populations where growth rate&lt; 1, maintained
through immigration) system, it will be critical to identify and protect those populations serving as
sources. Thus, for a source-sink population critical habitat will include those areas that support source
population, dispersal habitat to sink areas will be less critical. If local mouse populations are
functionally discrete, such a mosaic of interconnected areas of suitable habitat would provide a buffer

�7

for local, and source, populations against deleterious stochastic events by providing the opportunity for
local population failures to be 'rescued' by immigration from other populations.
To begin to understand PMJM movement, dispersal, and habitat use we monitored radiocollared mice at three different study areas. Study areas were selected to cover a variety of habitat
configurations to evaluate spatial variation in movement patterns of PMJM. To address temporal
variation in PMJM movement, dispersal, and habitat use we will' continue this study for at least one
more field season at the same three field sites. This is an interim report, after one field season of data
collection.

Study sites
To evaluate spatial differences in movements of PMJM, the three sites selected provided a
variety of habitat matrices available to the mouse. The first site selected, the Maytag Property, has one
primary water source available to the mouse. This water source is East Plum Creek. Therefore, we
predicted mice would restrict their movements to up and down this single drainage. The second site,
PineCliffRanch, has both a tributary (Garber Creek) and a main stem drainage (West Plum Creek).
This provided the opportunity to investigate whether PMJM will use upland areas to move from one
drainage to another or if they are restricted to only moving along riparian corridors. The third study
site, Woodhouse Ranch, provided an area with a tributary (Indian Creek) and a series of ponds and
irrigation ditches within 0.5 kilometers of the drainage. The configuration at Woodhouse Ranch
provided an even greater opportunity to investigate how much the mice use upland areas or if they
restrict their movements strictly to riparian corridors. By replicating the same methodologies at each of
these three unique habitat matrices we can begin to estimate spatial variation in nightly and seasonal
movements of PMJM.
Objectives
This PMJM movement study is designed to describe nightly and seasonal movement patterns
of PMJM and to describe habitats used by PMJM. These movement patterns will be described for
three different study areas to evaluate spatial variation, and over two different years at the same three
study areas to evaluate temporal variation. Specific objectives include:
1. Describe nightly movements of PMJM. Evaluate difference in nightly movements as they
relate to sex, age, and habitat available to the animals.
I. Describe 30-day (or life of the radio transmitter) interval movements of PMJM. Evaluate
difference in 30-day (or life of the radio transmitter) interval movements as they relate to
sex, age, and habitat available to the animals.
2. Describe seasonal movements of PMJM. Evaluate difference in seasonal movements as
they relate to sex, age, and habitat available to the animals.
3. Describe habitats where mice occur: movement corridors, end point descriptions (i.e.,
movement from what to what), and landscape features (connectivity with other riparian
areas and other habitats used).
4. Estimate the mean amount of time PMJM spend in each available habitat.
5. Evaluate spatial and temporal variation in movement patterns of PMJM.
The objective of the habitat use study is to identify and refine habitat requirements of Z. h.
preblei, including hibernation sites, and to determine if they influenced any of the demographic
parameters that will be estimated in this and complementary studies (see Shenk and Sivert 1999).

�8

Metl,ods
Movement data were documented primarily from locations of radio-collared mice from each of
the three study populations. To place radio transmitters on the animals, mice were captured in
Sherman live traps. Mice weighing&gt; 18 grams were fitted with either :MD-2C, I-gram radio
transmitters supplied by Holohill Systems Ltd. (used successfully on PMJM by R Schorr, personal
communication) or I-gram radio transmitters supplied by Advanced Telemetry Systems (ATS).
Three trapping sessions were conducted during the following weeks: June 2-9, 1998; July 21Aug 6, 1998; and September 8-15, 1998. Trappers were advised to follow the Center for Disease
Control's Hantavirus instructions and recommendations when dealing with rodents. Due to the nocturnal nature of PMJM, traps were set between 19:00hrs and 21:00hrs and checked as early as possible in
the morning beginning at 5:00hrs (to reduce stress and the potential for predation on trapped animals).
Time required to complete the traplines varied depending on how many animals were caught.
Small mammal Sherman live traps (folding and non-folding) were used to conduct the trapping
sessions. Traps were set in two parallel lines of trap stations (1 trap per station) on either side of the
drainage. Trap stations were 5 meters apart for a total of 250 meters; the parallel transects were 10
meters apart unless extent of habitat, terrain topography, or stream hydrology do not allow. Location of
transects were recorded to the nearest 5 meters in UTM coordinates using a Trimble Geo-Explorer
GPS. A small (~l inch) ball of polyester quilt material was placed in each trap as nesting/bedding
material. Baiting material was Manna Pro Sweet 3-way Livestock feed which contains no animal
matter; ingredients include flaked barley, flaked com, flaked oats, and cane molasses. Peanut butter
was used to stick the bait to the trap.
Traps were checked by two surveyors. All animal captures were recorded. If an animal was
captured in a trap, a ziplock plastic bag was placed over the end of the trap. The trap was opened
allowing the animal to fall into the plastic bag. The animal was identified to species while in the plastic
bag. If the animal was not a PMJM, identification of the animal was recorded and the animal set free.
Each captured PMJM was checked to detect the presence/absence of a PIT-tag and/or radio-collar. If a
PIT-tag or radio-collar was detected and the mouse had been captured at that same site within the same
trapping session, identification of the mouse was recorded and the mouse was released. If the animal
was a PMJM and no PIT-tag or radio collar was detected the PMJM was anesthetized for further
processing, as follows. All PMJM were PIT-tagged for a complementary demography study on
PMJM at these same three study sites (see Shenk and Sivert 1999 for details). If the PMJM weighed&gt;
18 g a radio-collar was also put on the animal.
Each PMJM was weighed while in the bag, the weight recorded in grams using a Pesola spring
balance. Sex, age (juvenile, adult), and reproductive condition (pregnant, lactating or non-breeding if it
is female; for males the position of the testes indicated if in breeding status or non-breeding status) was
noted. Each PMJM w~ measured (total length, length of body, length of hind foot-heel to distal end
of claws) in millimeters. Mice were placed in a plexiglass photobox to reduce handling stress while
taking the photograph. If the mouse had been captured previously as noted by the detection of a PITtag, no photograph was taken.
If there were feces in the trap where a PMJM was captured, the fecal material was collected in
a plastic bag labeled with date, location of the site, and animal PIT-tag number. Fecal samples were
kept cool until returned to the CDOW office where they were frozen. Salt was added to each specimen
bag for preservation. Once the field season was over all fecal samples were analyzed by the
Composition Analysis Laboratory, Inc, 622 ½ Whedbee, Fort Collins, CO for content.
All trap mortalities were recorded on a 'Trap Mortality' data form which included information
on species, potential duration of time spent in the trap, and any information available to help determine
cause of death. All animals found dead were double-bagged in a plastic bag and placed in a cooler
with ice. Specimens were frozen as soon as possible and deposited in the CDOW freezer at the office
. ·. . :

�9

in Fort Collins. A museum card was completed and attached to each PMJM specimen and the
specimen and card were given to Cheri Jones, Curator of Mammalogy at the Denver Museum of
Natural History, for study skins and tissue storage.
If an animal was severely injured (e.g., severed limb, large lacerations) it was euthanized by
soaking a cotton ball in Metofane (methoxyflurane) and placing the cotton ball and the mouse in a
ziplock bag until the animal stopped breathing. If an animal appeared to be only slightly injured (e.g.,
broken tail, small laceration) the animal was released to the wild. If an animal appeared to be coldstressed attempts were made to warm it by holding it in the surveyors hands and/or against their body.
If the animal appeared to be heat stressed, isopropyl alcohol was applied with a cotton swab to the ears,
arm pits, and feet to cool it down.
During the last trapping session homeopathic first aid treatments were used in an attempt to
minimize stress and improve recovery of each PMJM. Homeopathic first aid kits and instruction was
provided by WildAgain Wildlife Rehabilitation, Evergreen, Colorado.

PIT-tagging and radio-collaring
Each PMJM was individually marked with a Passive Integrated Transponder (PIT-tag). PITtags are electromagnetic, glass-encased tags that emit a passive signal (125 kHz) that can be decoded
by a portable reader. Destron-Fearing PIT-tags were used on all mice. We used portable readers from
Biomark to read the PIT-tags.
All mice were anesthetized to PIT-tag them. Anesthesia procedures followed protocols
successfully used on PMJM before (R. Schorr personal communication). Mice were anesthetized by
placing them and a cotton ball with 1 ml ofMetofane (methoxyflurane) into a sealed ziplock bag (to
keep Metofane fumes in bag). The bag was then lain aside to minimize stress for the mouse and the
time the mouse struggles in the bag. The less agitated the mouse is in the bag the less time required for
the metofane to take affect. The mouse was observed at all times to make sure the mouse did not
position itself such that the cotton ball was in direct contact with its face, which might cause the mouse
to have a severe reaction to the anesthesia. After the animal stopped moving, the handlers waited one
minute before removing the mouse from the bag. The animal typically remained anesthetized for 2-3
minutes once outside the bag.
Each PMJM was PIT-tagged using a protocol successfully used by C. Meaney (personal
communication). Each PMJM had a PIT-tag inserted above the shoulder blades by lifting the skin on
its back and inserting the individually sterilized needle with the PIT-tag under their skin and injecting
the tag. Verification of the PIT-tag identification number was made before and after insertion into the
mouse by running the PIT-tag scanner across it. The skin behind the opening was then pinched to
prevent emergence of the tag. PIT-tag identification number was recorded on the field data form.
Each radio transmitter was checked to ensure proper functioning before collaring the animal
with the transmitter by tuning the receiver to the transmitter frequency to make sure there was a signal.
The radio antenna was fed through a small piece of plastic tubing and then back through the radio to
make a collar of the plastic coated antenna. The loop made by the antenna was kept large enough to fit
over the mouse's head. Once over the neck of the animal, the antenna was pulled to reduce collar size,
making sure rubber tubing was on the dorsal side of the neck. The purpose of the rubber tubing was to
prevent damage to the collar and prevent the person attaching the collar from cinching the collar too
tight. The collar was tested to be sure it could rotate freely around the animals' neck, but was not loose
enough to be removed. The metal crimp was flattened to hold the antenna in the desired collar position.
Approximately two inches of antenna was left to extend out behind the animal.
If, at any time during the handling of the PMJM the animal appeared to be severely stressed
(dramatic changes in heartbeat, respiration and responsiveness or gums turning blue) first aid was
administered and, once recovered, released without further processing.

�IO

Movement data
Once transmitters were in place, locations of individual mice were made nightly. Because very
little is known about the movements of PMJM pilot protocols were established and then modified.
Final protocols included tracking up to eight individual mice per person per night. A minimum of six
locations per individual mouse per night were made. Each individual mouse was tracked a minimum
of three nights per week. The six locations per night per individual were scattered throughout the night
to maximize information learned about nightly movements (i.e., eight locations taken within a single
hour contains less information than eight locations taken one each hour). Each location was determined
by locating the mouse and recording the position as a file in a Trimble Geo-Explorer GPS. Each GPS
location (file) was differentially corrected for 2-5 meter accuracy. Daytime locations were taken as
time permitted.
To describe nightly movements the following parameters were estimated: (I) minimum and
maximum distances moved each night animal was followed, (2) mean minimum and maximum
distances moved each night for all mice, (3) minimum and maximum distances moved away from the
stream center each night by individual mice, and (4) mean minimum and maximum distances moved
away from the stream center each night for all mice.
To describe 30-day (or life of the radio transmitter) movements the following parameters were
estimated:(!) minimum and maximum distances moved each 30-day (or life of the radio transmitter)
interval animal was followed, (2) mean minimum and maximum distances moved each 30-day (or life
of the radio transmitter) for all mice, (3) minimum and maximum distances moved away from the
stream center each 30-day (or life of the radio transmitter) interval by individual mice, (4) mean
minimum and maximum distances moved away from the stream center each 30-day (or life of the radio
transmitter) interval for all mice. Mortality factors for any mouse found dead was recorded
Both site specific and landscape features were recorded at each of the three population study
sites to document the extent of spatial variation. These quantitative measures of spatial variation were
used in the analyses to determine if they influenced any of the movement parameters estimated in this
study. The following habitat characteristics were measured and recorded for each site.
~

Site characteristics
Cover was measured at 20 random locations along the 250 meter sampled stream stretch.
Mean cover and standard error of the mean was estimated. Cover was estimated using a vegetation
profile board (Nudds 1977) that allowed for an assessment of visual obstruction in 0.5 meter vertical
intervals above ground. The board was 2.0 meters high and 30.48 cm wide. The board was marked in
alternate black and white colors at 0.5 meter intervals. Horizontal cover was assessed in each interval
by viewing the board from 15 meters away in a randomly chosen direction. The percentage of each
interval concealed by vegetation was recorded as 0-20, 21-40, 41-60, 61-80, and 81-100% estimated
concealment.
Vegetation species composition and richness was estimated using the Modified-Whittaker
nested vegetation sampling method (Stohlgren et al. 1995). A modified Whittaker plot is 20-meters x
50-meters with 10 I m2 and 2 10m2 subplots arranged systematically around the perimeter and 1 100m2
subplot centered in the inside of the 20 meter by 50 meter plot. Species composition and percent cover
of each species was recorded for each subplot.
Soil samples were taken at each site for a hydrometer textural analysis (percent sand, silt and
clay). Samples were collected using a soil probe. Samples were taken from 0-12 inches, and 12+ to
24 inches. The 0-12 inch sample was taken first, removing the probe and soil. Samples were placed in
a labeled ziplock bag. The probe was then placed in the same hole for the 12+ - 24 inch probe with
that soil sample being placed in a separately labeled ziplock bag. The hydrometer textural analysis was
conducted at the Colorado State University Soils Laboratory.

�11

Mean stream width was estimated by measuring stream width at 30 locations along the entire
site sampled. The 30 locations were stratified equidistant from each other to cover the entire stream
stretch in increments of site stream length/30.
Each nest site was described including distance from the stream and vegetation.

Landscape characteristics
The following landscape habitat characteristics were measured using either GIS, topographic maps, or
aerial infrared photography.
1. Distance to nearest human habitation and human disturbance.
2. Connectivity of sites to other streams.
3. Total length of stream stretch at each site and total length of stream stretch with suitable
habitat at each site.
Hibernation site measurements
Hibernation sites were identified by following radio-collared mice in late September and early
October. Once a radio-signal remained stationary for 2-10 nights we assumed we located a
hibernaculum. The following measurements were taken at each hibernation site:
1.
2.
3.
4.

Distance ofhibernaculum to stream.
Vertical elevation gain from stream to hibernaculum.
A soil sample was taken as described above.
Vegetation species richness within a 5-m radius. Density of vegetation was measured as
described above.

Results
PIT-tagging and radio-tracking effort
A total of 186 individual mice were captured and PIT-tagged at the three study sites (Table 1:
73 mice at Maytag Property, 77 mice at PineCliffRanch, and 36 mice at Woodhouse Ranch). These
mice were captured over three different trapping session with an effort of 17,330 trap-nights. A total
of 125 radio-collars were put on mice over the three trapping sessions (Table 1: 48 at Maytag property,
4 7 at PineCliff Ranch, and 3 0 at Woodhouse Ranch). A total of 62 females and 63 males were radiocollared over the field season.
Initial protocols called for using triangulation methods (simultaneous compass bearing readings
from three different locations) to determine mouse locations. Triangulation was used during the month
of June. Locations were estimated in late June from these data and found to have large variances
associated with most locations. Field protocols were changed for the latter two tracking sessions to
walk-up locations. A walk-up location required technicians to use the signal strength indicator on the
receiver to determine when they were within 2-7 meters of the mouse. GPS location files were
collected each time a mouse was located. File name was recorded as well as the UTM coordinates
displayed on the GPS. These files were later differentially corrected to provide a positional accuracy of
2-5 meters.
Due to the large variances on the mouse locations collected during June these locations are not
reported here. Further analyses will be conducted on these data to see if any information on PMJM
movements can be gained. The walk-up method was first evaluated to ensure we were not causing the
mice to move in response to us. Given the consistency of individual mouse locations throughout the
night and on a day to day basis we felt the method was being employed in such a way that we were not
affecting mouse movement patterns. However, it should be noted that T. Ryon (personal communication) observed mice moving in response to him when he tried to conduct similar walk-up locations.

�12

Daily movements
Percent of PMJM locations, as determined from radio-tracking, at each of three distance
categories were calculated for each study site and the latter two radio-tracking sessions (Table 2). The
majority of locations at Maytag, PineCliff, and Woodhouse were within 46m of stream center for both
tracking periods (July-August and September-October). For all areas and tracking periods except
Maytag during the last tracking session, 90% of PMJM movements were within 91m of either side of
the center of the capture drainage. Mouse movements at Maytag during September-October resulted
in 32.6% of the locations being&gt; 91m from the stream center.
Analyses were also conducted on mice captured on PineCliff Ranch separating mice by
drainage of initial capture. These analyses were conducted to address questions that might arise when
connecting drainages. occur in areas known to have PMJM, but only one drainage has been surveyed.
Mice initially captured on Garber Creek showed similar movement patterns as far as distance from
center of capture drainage (i.e., Garber Creek) as mice from both Maytag and Woodhouse (Table 2).
Mice initially captured on West Plum Creek showed movements more often&gt; 91m from center of the
capture drainage (Table 2).
Seasonal movement
The distribution of mouse locations at Maytag Property for the July-August tracking session is
different from the distribution of PMJM locations for the September-October tracking session. The
pattern shifts from heavy use along East Plum Creek to the north of the trapline to a more concentrated
distribution either side of the trap line. The more concentrated use of the areas east and west of the
trap line also resulted in locations being further from the center of the creek. The northern end of the
trap line is largely vegetated by willows with the remainder of the trap line more diversely vegetated.
Mouse movements were more concentrated along the drainages at PineCliff Ranch during the
September-October tracking sessions than during the July-August tracking sessions. Vegetation along
both West Plum Creek and Garber Creek along the trapline was primarily willow.
At Woodhouse Ranch, the distribution of mouse locations also shifted between tracking
sessions. Mouse movements were more concentrated along the southern half of the trap line in
September-October as compared to the more even distribution of mouse locations recorded for JulyAugust The northern end of the trap line is dominated by willows, the middle and southern end of the
trapline is in more diverse riparian habitat.
Eight mice were captured, radio-collared, and tracked for two tracking sessions, one mouse
was captured, radio-collared, and tracked for all three tracking sessions (Table 3). Other mice were
captured during more than one trapping session but radio collars were not replaced either because all
the radio collars had been put on other mice or because the physical condition of the animal was such
that we decided not to replace the radio-collar. Such conditions included mice who had significant hair
worn off the neck from the previous radio collar. In no incidence did we find open wounds caused by
radio collars.
Of the nine mice radio-collared for more than one session, four provided information to
evaluate seasonal changes in areas and habitats use between the July-August tracking period and the
September-October tracking period. One mouse, a male from Maytag was observed only once during
the September-October tracking session, providing no information concerning seasonal changes in
movement patterns. Movement data from June have not been fully analyzed and are not included in
this report. Thus, changes in areas used by individual mice between June and either the July-August or
September-October tracking session are not summarized here.
A female at Maytag exhibited a seasonal movement shift, small sample size prohibited any evaluation
of the movement patterns of the Maytag male (n = l in September-October). There does not appear
to be any shift in areas used by the male tracked during both latter sessions at Pine Cliff Ranch,

�13

however, sample sizes were small (n = 17, 14). Two females at Woodhouse Ranch exhibited a shift in
areas used between July-August and September-October. However, caution should be used in
interpreting these results because of low sample sizes in the latter tracking session (n = 14, 6).

Nest sites
,.
Numerous daytime nest sites were located at all thee study sites. Nest sites were made of
tightly woven vegetation, located on the ground. Nest material included leaves, grass, and small sticks.
There was only one small entrance hole on each of the nests found. When observing mice in their nests
the mice would peer out of the hole and remain motionless as long as we were present. No breeding
nests were located, however there were several locations at each of the study sites where adult females
returned to repeatedly. Each of these sites were in patches of extremely dense vegetation or
underneath a large downed log. We did not disturb these areas because we did not want to cause
failure of the nest.
Hibemacula
Eight potential hibernacula were located, at least one at each study site (Table 4).
Mortality factors
Mortalities factors of radio-collared mice included predation by rattlesnake, garter snake, fox,
and house cat (Table 5). Four probable predations were also noted and identified by finding tightly
crimped (i.e., no possibility of the mouse having slipped the collar over its head) radio-collars lying on
the ground. Two accidental deaths were documented, a road kill and drowning. Mortality factors also
included trapping and/or handling mortalities and unknown causes.
Fecal analysis
The amount of bait found in each of the fecal samples was quantified as either 100%, abundant
(&gt; 70%), trace (&lt; 10%) or 0%. The following summaries are made after eliminating all samples of
100% bait, and then only classifying the fecal sample contents other than bait.
Fecal analyses indicate a seasonal shift in diets. The most common item found in the fecal
samples during the June trapping session at all three sites were arthropods. This was true for three of
the five June samples collected at Maytag (Table 6), eight of ten June samples at PineCliff (Table 7),
and four of five June samples collected at Woodhouse (Table 8). Other common items included
endogenous fungus (1) and seed (1) at Maytag; endogenous fungus (2) at PineCliff,; and Poa (1) at
Woodhouse.
During the July 21-August 4 trapping session the most common items in the fecal samples at
Maytag were arthropod (2), endogenous fungus (1), pollen (1), and Carex (1). During the same
trapping period, the most common items in five of eight samples collected at PineCliff were
endogenous fungus, the other three samples having a majority of arthropod (1 ), moss (1 ), and pollen
(1 ). The two samples from Woodhouse during this trapping session were composed primarily of either
mushroom or seed.
On August 13, nine samples were collected during an extra trapping session (on the same
trapline as the other trapping sessions occur) with the most common items in the fecal samples being
moss (4), endogenous fungus (3) or pollen (2). All three samples collected from PMJM captured at a
back drainage on August 23n1 at Woodhouse Ranch were primarily fungus.
The September trapping session at Maytag yielded samples with majority fecal contents of
arthropod (2), moss (2), pollen (2), endogenous fungus (1 ), and seed (1 ). Ten samples from PineCliff
during September had majority fecal contents of arthropod (3), endogenous fungus (3), and seed (3).
Eight of nine samples taken from Woodhouse contained primarily arthropods, with one a trace of seed.

�14

Discussion
Preliminary analysis of the movement data collected on radio-collared Preble's meadow
jumping mice (PMJM) indicate (1) maximum movements of&gt; 1 mile, (2) greater use of upland
habitats than previously assumed, (3) general site fidelity to both daytime nesting sites and nighttime
feeding sites, (4) seasonal shifts in movement patterns, (5) use of both perennial and intermittent
tributaries adjacent to the capture drainage, and (6) long distance'movements in September to new
locations, presumably in preparation for hibernation.
Initial evaluation of PMJM movement data focused on maximum distances mice moved
perpendicular to the capture drainage. This focus resulted from criteria used in the USFWS Draft 4-D
Ruling (1998) to provide special regulations for the mouse. The 4-D Rule defines a Mouse Protection
Area (MPA) as "extending 300 feet on each side of the stream measured from the centerline, or 300
feet from the exterior boundary of any contiguous wetlands, whichever is further." The 4-D Rule also
states "the basis for the 300-foot standard is that mice have been documented to regularly move up to
150 feet from streams and wetlands. The remaining 150-foot zone serves as a buffer zone to avoid
disturbance of PMJM habitat associated with human activities. We believe that this zone will
encompass the normal home range of the Preble's and will provide an adequate buffer from adjoining
development."
Mouse locations were categorized by the distance criteria used in the 4-D Rule to provide the
greatest amount of information to evaluate if the proposed regulations would be sufficient to ensure
protection of PMJM. Given the high proportion oflocations within both the buffer zone (150-300 feet)
and outside any area of protection(&gt; 300 feet), data from this study do not support the regulations
regarding the 300 foot buffer from the center of the capture stream. Analyses were not completed
using the criteria of protection up to 300 feet from the edge of contiguous wetlands because a
delineation of contiguous wetlands for any of the three study sites is not yet available. Once these
contiguous wetlands are mapped, similar analyses will be conducted using edge of the wetland rather
than stream center for perpendicular distance measurements.
To address the issue of whether or not connected but untrapped tributaries should be included
in the designation of MP A's, the more detailed analyses of mouse movements at PineCiiffRanch were
conducted. The issue of whether or not Garber Creek, a tributary of West Plum Creek, would be
included in that particular MP A is not at issue since both the main drainage, West Plum Creek and the
tributary, Garber Creek have been trapped in that area with mice captured on both drainages. Rather,
the analysis was conducted to test how well the proposed regulation to protect only 300 foot from the
center of the capture stream would have 'encompassed the normal home range of the Preble's and will
pro.vide an adequate buffer from adjoining development." It is clear from the results that the regulation
would have failed to accomplish its objective, with up to 47% of the mouse locations falling beyond the
300 foot demarcation when only the capture drainage was considered.
Use of tributaries was also an issue at the Maytag Property. Two mice moved away from East
Plum Creek in September and focused their movements ~300 meters from their previous locations, up
a dry drainage dominated by upland grasses and gambel oak. These two mice continued to use this
new area and were not observed again near East Plum Creek for at least two weeks. Normal radiofailure (i.e., batteries failed after ~4 weeks) after this time did not allow us to determine if the mice
ever returned to East Plum Creek or if they hibernated in their new location. No tributaries were
available to mice at Woodhouse Ranch. In summary, movement patterns of mice at the Maytag
Property suggest use of tributaries, and at PineCliffRanch extensive use of a tributary.
Jumping mice of the genus Zapus are true hibernators, spending much of their lives in
hibernation. Meadow jumping mice spend approximately 7 months (~210 days) per year in
hibernation (Quimby 1951) whereas estimates for Z. princeps indicate that some populations (e.g., in
the western mountains of Utah) spend up to 300 days per year in hibernation (Cranford 1983).

�15

Jumping mice hibernate in underground burrows (Quimby 1951, Whitaker 1963). They are excellent
burrowers and create their own hibernacula Meadow jumping mice are generally solitary hibernators,
however, there have been occurrences of more than one mouse found in a single hibernaculum.
Eight possible hibernacula were located during this study. The greatest perpendicular distance
from the center of the main drainage at the site (East Plum Creek for Maytag Property, West Plum
Creek for PineCliffRanch, and Indian Creek for Woodhouse Rari'ch) was 341 meters. However, if
tributaries were considered, greatest distance from center of the nearest drainage to any of the eight
sites. was 78 meters. Five of the eight mice using these possible hibernacula traveled ~ 90 meters
from the center of their typical September night time locations. One mouse, a female at Maytag moved
750 meters to a possible hibernacula
Vegetation characteristics of the eight sites located during this study (Table 4) are similar to
other hibernacula described for PMJM. One confirmed hibernaculum, located on Rocky Flats
Environmental Technology Site, used by Z. h. preblei has been located {Armstrong et al. 1997). This
site was 9m above a creek bed (Walnut Creek); it had a thick cover of chokecherry (Prunus
virginiana) and snowberry (Symphoricarpos spp.), the mouse was found in a leaf litter nest 30cm
beneath the ground in coarse textured soil {Armstrong et al. 1997). Four possible hibernacula were
located by tracking radio-telemetered mice at the U. S. Air Force Academy in fall 1997. These sites
are located 7, 12, 29, and 3 lm from a creek bed (R Schorr, unpublished data). There was no
consistency among sites in aspect. Three sites were in vegetation dominated by coyote willow (Salix
exigua), one site was in vegetation dominated by snowberry and mullein (Verbascum thapsus).
However, all four hibernacula appeared to be below coyote willows.
The eight sites located during this study and the four U. S. Air Force Academy sites were not
disturbed to protect any hibernating mice and therefore are only possible hibernacula because there is
no confirmation a mouse actually hibernated there. Confirmation of a true hibernaculum cannot be
made until a chamber, or nest is located. The other explanation for these collar locations might be either
locations of radios discarded by the mice or dead mice carried underground by a predator. Location or
more hibernation sites was limited primarily by normal battery failure of the radio transmitters before
mice went into hibernation.
Prior to the 1998 field season, natural mortality factors reported for Z. hudsonius included only
insufficient fat storage prior to hibernation (Whitaker 1963 ), predation (Whitaker 1963, Poly and
Boucher 1997, R. Schorr unpublished data) and cannibalism (Sheldon 1934). Other assumed natural
mortality factors for Z. h. preblei included starvation, exposure, and disease. This study further reports
confirmation of predation by house cats, garter snakes, rattlesnakes, and fox. Other documented
natural mortality factors now include accidents by drowning and road kill.
The high percentage of arthropods and endogenous fungus found in the fecal samples provides
a new aspect to evaluating PMJM habitat requirements. When considering habitats used by PMJM, or
in trying to predict habitats that might be suitable for the subspecies, consideration should be given as
to whether those habitats could support the arthropods and fungus apparently being selected for by the
mouse. Arthropods are a food source high in protein and fat which would benefit mice emerging from
hibernation and mice preparing for hibernation. Whitaker (1963) reported a 67% loss of individuals
over hibernation and that average body mass of individuals emerging from hibernation was greater than
the average for mice entering hibernation. Because no mice are known to store food in their
hibernacula, this indicates that the lighter individuals died during hibernation and only those entering
with higher masses survived. All the energy they use during hibernation and the periodic arousals (the
energetically most expensive part of hibernation) must be the fat they carry into hibernation (B.
Wunder, personal communication). The ability to put on sufficient fat for overwinter survival during
hibernation is a critical factor in the life history of these mice. Thus, appropriate and sufficient food
sources must be available to the mouse to meet these nutritional requirements.

�16

The apparent seasonal shift in mouse movements between the July-August and September
tracking sessions may be a result of diet switching. The broader diets suggested by the fecal analyses
from samples collected during July and August possibly represent both a wider availability of suitable
foods and the ability of PMJM to exploit these resources. It might also suggest a need to exploit these
other resources to provide the mouse with necessary food requirements for breeding. Because mice
tracked during each session were not generally the same mice there is a possibility these apparent
movement shifts might only be different areas used by different mice. The probability of this being the
case is small for two reasons. The first is the low density of mice in the stream (Shenk and Sivert
1999). Given that, the proportion of mice followed during each session is a high proportion of the mice
in the population. Thus, each subset of mice should be representative of the population. Secondly,
evidence from the four mice followed during both the latter tracking sessions also exhibited movement
shifts between sessions.
The combination of shifts in both general mouse movements, individual mouse movements,
and diet provide strong circumstantial evidence that PMJM may be selecting for or require specific
seasonal diets. If this is the case, all these requirements must be considered and provided for to ensure
conservation of the subspecies. A detailed literature search and further studies need to be conducted to
investigate the possible implications of these dietary patterns.
These data are limited to the first year of a multi-year study and thus annual variation in mouse
movement patterns cannot yet be addressed. Continuation of this study, at least through the 1999 field
season will provide information on annual variation in PMJM movement patterns.
This study looked at PMJM movements at only three sites. These sites were selected based on
known presence of PMJM. Other sites, perhaps because of different habitat configurations or sites of
poorer quality may require mice to move further from the creek or may allow mice to remain closer to
the creek in order to obtain all life requirements. However, these study sites were specifically selected
to address spatial variation in movement patterns of PMJM due to different spatial configuration and
juxtaposition of habitats. And although all study sites were different they could all be considered
within the general description of what is consider typical habitat for PMJM.
It should also be noted that we generally trapped along the creek. Thus, mice captured and
subsequently radio-collared and followed were those mice that use the area near the most prominent
drainage. If there are mice that do not regularly use the main channel and thus were not available for
capture there would be a bias in the data towards fewer observations 300 feet away from the creek. To
test for such a bias, further research needs to be conducted trying to capture mice further from the
creek and compare their movements and locations of those movements in relation to distance from the
creek. We plan to test for this bias during the 1999 field season at Maytag Property and Woodhouse
Ranch.
This is an interim progress report of a multi-year study. Further analyses will be conducted on
these data and data collected during the 1999 field season.

Literature Cited
Armstrong, D. M., M. E. Bakeman, A. Deans, C. A. Meaney, and T. R. Ryon. 1997. Conclusions and
recommendations in: Report on habitat findings on the Preble's meadow jumping mouse.
Edited by M. E. Bakeman. Report to USFWS and Colorado Division of Wildlife.
Bailey, B. 1929. Mammals of Sherburne County, Minnesota Journal ofMammalogy 10:153-164.
Bailey, V. 1923. Mammals of the District of Columbia Proceedings of the Biological Society.
Washington 36:103-138.
Cook, T. D. and D. C. Campbell. 1979. Quasi-experimentation: design and analysis issues for field
settings. Houghton-Miffiin, Boston.

�17

Cormack, R. M. 1964. Estimates of survival from the sightings of marked animals. Biometrika
51:429-438.
ERO Resources. 1995. Environmental review of South Boulder Creek Management Area Prepared
for City of Boulder Real Estate/Open Space Department. Prepared by ERO Resources Crp.,
Denver, Colorado in association with Stoecker Ecological Consultants, Boulder, Colorado.
Fitzgerald, J.P., C. A. Meaney, and D. M. Armstrong. 1994. Mammals of Colorado. Denver
Museum of Natural History, University Press of Colorado. Niwot, Colorado.
Hafner, D. J., K. E. Petersen, and T. L. Yates. 1981. Evolutionary relationships of jumping mice
(genus Zapus) of the southwestern United States. Journal ofMammalogy 62:501-512.
Hall, E. R. 1981. The mammals of North America. John Wiley and Sons, Inc., New York, New
York, 2 volumes.
Hamilton, W. J., Jr. 1935. Habits of jumping mice. American Midland Naturalist 16:187-200.
Jolly, G. M. 1965. Explicit estimates from capture-recapture data with both death and immigration
stochastic model. Biometrika 52:225-247.
Jones, C. A. 1996. Mammals of the James John and Lake Dorothey State Wildlife Areas. Final
Report, submitted to the Colorado Division of Wildlife and Colorado Natural Areas Program.
Kendall, W. L., and J. D. Nichols. 1995. On the use of secondary capture-recapture samples to
estimate temporary emigration and breeding proportions. Journal of Applied Statistics.22:751762.
Kendall, W. L., K. H. Pollock, and C. Brownie. 1995. A likelihood-based approach to capturerecapture estimation of demographic parameters under the robust design. Biometrics 51 :293308.
Kendall, W. L., J. D. Nichols, and J.E. Hines. 1997. Estimating temporary emigration using capturerecapture data with Pollock's robust design. Ecology 78:563-578.
Krutzsch, P.H. 1954. North American jumping mice (genus Zapus). University of Kansas
Publications, Museum of Natural History 7:349-472.
Meaney, C. A., N. W. Clippinger, A. Deans, and M. OShea-Stone. 1996. Second year survey for
Preble's meadow jumping mouse (Zapus hudsonius preblei) in Colorado. Report prepared for
the Colorado Division of Wildlife.
Meaney, C. A., A. Deans, N. W. Clippinger, M. Rider, N. Daly, and M. O'Shea-Stone. 1997. Third
year survey for Preble's meadow jumping mouse (Zapus hudsonius preblei) in Colorado.
Report prepared for the Colorado Division of Wildlife.
Nudds, T. D. 1977. Quantifying the vegetative structure of wildlife cover. Wildlife Society Bulletin
5:113-117.
Poly, W. J., and C. E. Boucher. 1997. Record of a creek chub preying on a jumping mouse in Bruffey
Creek, West Vjrginia Brimleyana 24: 29-32.
PTI Environmental Services. 1996a Preble's Meadow Jumping Mouse Study at Rocky Flats
Environmental Technology Site, Annual Report 1996. Final. Rocky Flats Environmental
Technology Site, Golden, Colorado.
PTI Environmental Services. 1996b. Preble's Meadow Jumping Mouse Study at Rocky Flats
Environmental Technology Site, Spring 1996. Final. Rocky Flats Environmental Technology
Site, Golden, Colorado.
Quimby, D. C. 1951. The life history and ecology of the jumping mouse, Zapus hudsonius.
Ecological Monographs 21:61-95.
Riggs, L. A., J. M. Dempey, and C. Orrego. 1997. Evaluating distinctness and evolutionary
significance of Preble's meadow jumping mouse: Phylogeography of mitochondrial DNA noncoding region variation. Final Report for the Colorado Division of Wildlife. Denver, Colorado.

�18

Seber, G. A. F. I 965. A note on the multiple recapture census. Biometrika 52:249-259.
Sheldo~ C. 1934. Studies on the life histories of Zapus and Napaeozapus in Nova Scotia Journal of
Mammalogy 15:290-300.
Shenk, T. M. 1998. Conservation assessment and preliminary conservation strategy for Preble's
meadow jumping mouse (Zapus hudsonius preblei). Colqrado Division of Wildlife FY 199798 Annual Report.
... •
Shenk, T. M. and M. M. Sivert. 1999. Temporal and spatial variation in the demography of Preble's
meadow jumping mouse (Zapus hudsonius preblei). Colorado Division of Wildlife JanuaryMarch 1999 Quarterly Report.
Stohlgren,T. J., M. B. Falkner, and L. D. Schell. 1995. A Modified-Whittaker nested vegetation
sampling method. Vegetatio 117: 113-121.
USFWS. 1997. Interim survey guidelines for Preble's meadow jumping mouse. USFWS. Denver,
Colorado.
Whitaker, J. 0., Jr. 1963. A study of the meadow jumping mouse, Zapus hudsonius (Zimmerman), in
cental New York. Ecological Monographs 33 :3.

Table 1. Number of Preble's meadow jumping mice captured and radio-collared at each study site
durin~ each traeein~ session.
# CaQturedt
Site

Trapping
session

Trap
nights

Maytag

June

Maytag

# Radio-collared

female
(%)

male(%)

total

female

male

total

1949

9(64)

5 (36)

14

9

5

14

July

2370

15 (54)

13 (46)

28

ll

5

16

Maytag

September

3256

18 (43)

24 (57)

42

IO

8

18

PineCliff

June

1095

6 (32)

13 (68)

19

5

13

18

PineCliff

July

1603

8(50)

8(50)

16

6

7

13

PineCliff

September

1544

13 (28)

33(72)

46

4

12

16

Woodhouse

June

1525

4 (57)

3 (43)

7

2

3

5

Woodhouse

July

2420

9 (64)

5(36)

14

8

4

12

Woodhouse

September

1568

8 (44)

IO (56)

18

7

6

13

17330

90

114

204

62

63

125

TOTAlS

t Some captured animals were PIT-tagged during previous trapping sessions

�19
Table 2. Percent locations of Preble's meadow jumping mice at each of three distance categories for
each study site and radio-tracking session. PineCliffRanch locations are also divided into percent
locations for each distance category from center of the stream of initial capture for mice captured on
either West Plum Creek or Garber Creek.
% locations at each distance from center of main
Site

Tracking period

N

Maytag

Jul-Aug 1998

Maytag

&lt;46m
(150 feet)

46 - 91 m
150-300 feet

&gt;91 m
(300 feet)

901

75.6

21.0

3.4

Sep-Oct 1998

900

47.8

19.6

32.6

PineCliff Ranch

Jul-Aug 1998

302

86.1

11.9

2.0

PineCliff Ranch

Sep-Oct 1998

520

81.2

9.2

9.6

Woodhouse Ranch

Jul-Aug 1998

377

91.S

8.5

0.0

Woodhouse Ranch

Sep-Oct 1998

533

67.6

32.1

0.4

Pine Cliff Ranch
Garber Creek

Jul-Aug 1998

210

68.1

10.S

21.4

Pine Cliff Ranch
Garber Creek

Sep-Oct 1998

499

75.6

9.8

14.6

Pine Cliff Ranch
West Plum Creek

Jul-Aug 1998

92

32.6

20.7

46.7

Pine Cliff Ranch
West Plum Creek

Sep-Oct 1998

21

52.4

0.0

47.6

Table 3. Preble's meadow jumping mice radio-collared and tracked (X) for more than one tracking
session. Location of capture, sex, identification, and number of locations (n) for each mouse during
each tracking session is noted.
Tracking Session
Site

Sex

PIT-tag#

Maytag

F

Maytag

Junei

July-Aug

n

Sep-Oct

4140371625

X

X

25

*

F

4141435234

X

Maytag

F

4140753620

X

Maytag

F

41412B4A2D

X

Maytag

M

4141241836

Woodhouse

F

41413£610B

Woodhouse

F

41413E7B07

PineCliff

F

4141125D66

PineCliff

M

41413D4C04

1 Locational data from June is not included in this report.

* Mouse captured but radio-collar not replaced.

X

X

n

X

52

X

82

103

X

105

X

93

X

X

78

X

14

X

66

X

s

X

13

X

18

X

IS

*

�20

Table 4. Possible hibemacula for Preble's meadow jumping mouse at three study areas in Douglas
County, Colorado. Sex, beginning date of stationary signal, duration of stationary signal, distances
from the main drainage (East Plum Creek at Maytag Property, West Plum Creek at PineCliffRanch, or
Indian Creek at Woodhouse), nearest tributary, and center of night time locations are presented.
Primary vegetation at the site is also noted.
Distance (m) from:
Site

Sex

Date

Days

Main
Drainage

Tributary

Center
Night
Location

Vegetation

Woodhouse

M

9/22

12

40

NIA

91

skunkbush, sumac,
hawthome,chokecherry

Woodhouse

M

9/27

9

33

NIA

67

clematis vine, snowberry

Woodhouse

M

9129

5

23

NIA

116

narrowleaf cottonwood,
Bromus spp., chokecherry

PineCliff

M

9117

5

210

JO

29

Salix spp.

PineCliff

M

9/23

11

35

40

90

Salix spp., alysium

PineCliff

M

9/23

11

120

35

70

Salix spp., grass

PineCliff

M

9/25

9

100

78

72

snowberry, Salix spp.,
alysium, thistle

PineCliff

F

9/25

9

70

l05

l05

snowberry, Salix spp.

PineCliff

M

9125

9

341

0

Salix spp., cottonwood,
snowberry

Maytag

F

9/23

14

120

750

gambel oak, chokecherry,
alysium

NIA

�Table 5. Known and probable mortalities of Preble's meadow jumping mice from Maytag Property, PineCliffRanch, and Woodhouse Ranch
collected during the 1998 field season (June I-October 31 ). Probable cause of death, date radio-collars located, description of how what was found,
sex of the animal 2 and dis12osition of s12ecimen noted.
Site where
found

Mortality factor

Date

How obtained

Sex

Current location
of specimen

Maytag

handling stress

June 8

died during processing of the mouse, never came out of anesthesia

female

DMNH

Maytag

handling stress

July 27

died from anesthesia shock

female

DMNH

Maytag

trap mortality

June 10

trap mortality

male

Maytag

trap mortality: heat stress

Sept. 10

trap mortality, probably over-heated

female

DMNH
DMNH

Maytag

predation

July 2

tracked radio-collar, found collar in fox scat

female

no body, scat at CDOW

Maytag

predation

Sept. 21

radio-collar tracked to a rattlesnake, waited and picked up snake scat with the radiocollar in it

female

no body, scat at CDOW

Maytag

road kill

Sept. 15

tracked radio-collar; found highly decomposed, unsalvageable body covered with
ants, side of road-probably road kill

male

no body

Maytag

unknown

Aug. 1

tracked radio-collar; found highly decomposed, unsalvageable body

male

no body

PineCliff

possible predation

Aug. 6

possible predation; crimp still tightly on collar when retrieved

female

no body

PineCliff

possible predation

Aug. 12

tightly crimped collar found on ground, no part of mouse detected; suspect predation
since movement detected earlier

female

no body

PincCliff

possible predation

Sept. 13

possible predation; crimp still tightly on collar when retrieved

male

no body

PineCliff

drowning

Aug. 6

radio-tracked collar; found mouse in water

female

rnv:IN-:::I

Woodhouse

handling stress

June 5

died during handling while trying to readjust radio-collar

male

Woodhouse

radio-collar:
suffocation/starvation

Aug. 6

radio-tracked collar, found dead mouse; collar may have been too tight

female

DMNH
DMNH

Woodhouse

predation

Aug. 11

radio-collar found in snake scat

female

no body, scat at CDOW

Woodhouse

predation

Sept. 23

radio-collar tracked to a garter snake, waited and found collar in snake scat

female

no body, scat at CDOW

Woodhouse

predation

Sept. 29

radio-collar tracked to a house cat, waited and found collar in house cat scat

female

no body, scat at CDOW

Woodhouse

possible predation

Aug. I

tightly crimped radio-collar found in exposed area

female

no body

Woodhouse

unknown

Aug. 7

radio-tracked collar, found dead mouse (skeleton) on shrub

female

DMNH

Woodhouse

unknown

Sept. 15

radio-tracked collar and found dead mouse

male

DMNH

ts)

�N
Table 6. Percent contents of fecal samples collected from traps where Preble's meadow jumping mice were captured. All samples were collected
N
from Maytag Property during the 1998 field season. Several samples are from the same animal captured on different dates. Amount of bait in each
samp 1e was quant1"fid
o o t e samp l:),'T'fi
e
e as l00¾'A'f.
0
or ab un dant (703/cfh
&gt;
or trace amount (103/cfth
&lt;
e samp1:),
e or Oo/cfh
oO
o o t e samp1e was b.
rut.
endogenous
VerAgro- EquiLesunknown mushID
Date Bait arthropod fungus
seed moss IPOilen Poa Helianthus Salix 'querella bascum Carex ovron setum flower forb
room

4l405E402

Jun 3

A

76

414l25476E
4141382614

Jun 3

T

Jun4

T

64
7

·4140271625

Jun 8

T

4

.4l4119674D

Jun 11

A

91

4l407E5E35
4141106852
4141287948

Jul 21
Jul 21

0
100

16

Jul 28

100

41417Al807
• 4141297F0F

Jul 28
Jul 28

100
A

4141407328

Jul 28

T

4141360708
41411E6879
4141283D24
4l4l3A026A

Jul 29
Aug 3
Aug 13

A
T

UNKNOWN
4140371625
4140205478
4141187C76
4141284A2D
. 4141241836
4140173A6D
414125476
• 4140753620

Aug 13
Aug 13
Aug 13
Aug 13
Aug 13
Aug 13
Aug 13
Aug 13
Seo 7
Seo 9
Sep 9

0
A
A
A
T
T
T
T
T
A
A

92

23

13

16

4

l
96
9
4

82

18

2
47

30

4
3
17

96
16
25

7

46

11

29
67
59

12

60

2

46

3

25

20
6
98
4

41412CC443
41417CIE42
41411E6879
4141284A2D

Sep IO
Sep IO

T

Seo 11
Seo 12

A
A

73
20

4140754707

Sen 12

T

24

21

12

3
16
5
·"

2

5
2
43
16
14

90

11

6

100
100
100

T
A

414164363C

24

89
78

11

5

84

30

19
84

4

65
5

5
27
80

7

35

34

�Table 7. Percent contents of fecal samples collected from traps where Preble's meadow jumping mice were captured. All samples were collected
from PineCliffRan~h during the 1998 field season. Several samples are from the same animal captured on different dates. Amount of bait in each
sample was quantified as 100%, 'A' for abundant (&gt; 70% of the sample 'T' for trace amount(&lt; 10% of the sample), or 0% of the sample was bait.

ID
UNKNOWN
4140761237
4141 IA3D4B
4140755157

UNKNOWN
UNKNOWN
4140755157

UNKNOWN
UNKNOWN
41411Alll4
4141714141
41413D4C04
4141505F54
·.414125D66
413F6F7EOA
4140784Bl4
41411AEC12
41412F2433
41412F5E45
41413C604F
.414176064A
4141656001
;414138666D
41415B4748
41412F2F62
4141370528
4141350155
41415E434A
4141491F02
4140502204

Date Bait arthropod seed
100
Jun3
A
Jun4
0
96
4
Jun4
A
,,
97
Jun4
A
T
Jun4
A
Jun4
A
88
Jun4
8
T
Jun 7
T
T
T
Jun 8
A
Jun 8
T
88
6
Jul 11
A
4
Jul 21
0
13
2
Jul 21
0
37
Jul 21 100
Jul 21
T
8
Jul 21
T
8
Jul 22 100
Jul 22
A
Jul 24
A
41
Jul 24
A
T
3
7
Seo9
T
3
8
Seo9
Seo 11 A
100
14
Seo 11
T
6
Sep 14 A
96
4
75
Seo 14 T
22
Sep 15 A
83
Sep 15 A
T
Sep 16 A
Sep 16 T
17

endogenous
Chenopodium
grass
Eleagnus Helianthus lilv oollen Salsola seed comoosite Festuca
funl!US
moss Bromus Poa
seed
4
96
3
T
6

6
4

88

T
0

6
96

85

63

84

92
8

100
100
18
90
86
74

41
3
6
3

5

12

83

�· Ta,ble 8. Percent contents of fecal samples collected from traps where Preble's meadow jumping mice were captured. All samples were collected
from Woodhouse Ranch during the 1998 field season. Several samples are from the same animal captured on different dates. Amount of bait in
• each sample was quantified as 100%, 'A' for abundant(&gt; 70% of the sample), 'T' for trace amount(&lt; 10% of the sample), or 0% of the sample
. was bait
PIT-tag#

Date

Bait

arthropod

41407B2575

Jun 3

A

100

414l3E610B

Jun 3

A

100

41413E610B

Jun4

A

100

41407B2575

Jun4

T

100

414147354F

Jun4

T

24

UNKNOWN

Jul 27

T

41413E610B

Aug4

T

4141076B41

Aug4

100

4141250646

Aug23

0

12

41404A7D58

Aug23

T

4

'414128F2607

Aug23

0

41415D402E

Aug23

100

41406A1049

Sep 9

A

100

4141313E6F

Sep 9

A

74

4141350C2A

Sep 10

JOO

endogenous
fungus

mushroom

Poa

seed

Agropyron

Sporobolus
seed

Chenopodium composite Equisetum

flower

76
50

50

23

77
88
96
89

11

26

T

414133085

Sep 10

A

UNKNOWN

Sep 11

0

100

414173462B

Sep 11

T

70

4143P5772B

Sep 11

0

45

4141611413

Sep 12

0

98

41414A6B6F

Sep 12

0

88

4140241303

Sep 12

0

88

30
33

7

15
2

12
2

10

�25
APPENDIXB

HABITAT USE AND DISTRIBUTION OF PREBLE'S MEADOW JUMPING MOUSE (Zapus hudsonius

preblei) IN LARIMER AND WELD COUNTIES, COLORADO
Tanya M. Shenk and James T. Eussen

Abstract
A total of39 sites were surveyed for Preble's meadow jumping mouse in Larimer and Weld
Counties, Colorado with a total of 16,671 trap-nights completed. Of the 39 sites survey, Zapus spp.
were captured at 21 locations. A total of 71 unique individuals were captured in the 21 locations, with
recaptures of 14 of those individuals. All sites where Zapus spp. were captured were located in
Larimer County. Three soil samples from 0-12 inches and 12-24 inches were collected at all sites
where possible. Soils at some sites were too rocky to collect the 12-24 inch soil samples. Nine fecal
samples were collected from traps where Zapus spp. were captured. Initial result indicate that
arthropods, fungus, and willows are important dietary components of the Zapus diet. Two trap
mortalities of Zapus spp. occurred. Both specimens were saved and delivered to Cheri Jones of the
Denver Museum of Natural History on October 26, 1998. Measurements of habitat characteristics at
both the site and landscape levels were completed. Genetic tissue samples were collected from 68 of
the 71 jumping mice captured. Analyses of these tissue samples is pending.
Introduction
The meadow jumping mouse (Z. hudsonius) is broadly distributed across North America from
the Atlantic to Pacific coasts, extending south into the United States to Alabama and Georgia and west
across the Great Plains to the base of the Rocky Mountains. In general, it is a common inhabitant of
moist, grassy and herbaceous fields. Eleven living subspecies have been described (Whitaker 1972).
Hafner et al. (1981) describe a twelfth subspecies, Z. h. luteus.
Z. h. preblei occurs only in eastern Colorado and southeastern Wyoming (Krutzsch 1954, Long
1965, Armstrong 1972). From its limited ecological and geographic distribution, Fitzgerald et al.
(1994) suggest it is an Ice Age relict, once widespread in tallgrass prairie across the eastern plains of
Colorado but now restricted to scattered localities on the Colorado Piedmont. Similar relict populations
of meadow jumping mice in the White Mountains of Arizona and the Sacramento Mountains and Rio
Grande Valley of New Mexico are described as the subspecies Z. h. luteus (Hafner et al. 1981 ).
On May 12, 1998 the U. S. Fish and Wildlife Service (USFWS) published a final rule in the
Federal Register (63 FR 26517) to list Preble's meadow jumping mouse (Zapus hudsonius preblei) as
'threatened' under the Federal Endangered Species Act (ESA) of 1973, as amended. Scarcity of
suitable habitat presumably limits current distribution of Preble's meadow jumping mouse (PMJM) and
thus, maintenance of quality habitat has been identified by the USFWS (63 FR 26517) as the principal
conservation goal. Although Meaney et al. ( 1997) reported an improved ability to recognize suitable
habitat for PMJM, a more refined and complete definition of potentially suitable habitat for the mouse
does not exist. Because the protection of potentially suitable habitat for PMJM may occur under the
ESA, as well as protection of known locations where the subspecies occurs, the definition of potentially
suitable habitat, as determined by the USFWS, will directly influence site specific regulatory
procedures.
Ideally, a definition of potentially suitable habitat for the subspecies would identify areas where
the PMJM could survive and reproduce in sufficient numbers to sustain populations throughout its
range of natural variability over an extended length of time. During the active period of the life cycle of
the mouse, suitable habitat must provide requirements for daily survival, reproductive activities
(breeding,
nesting,. and rearing
of young to independence), and dispersal.
The hibernation
period
.
..
.
.
~

•

.

•

�26

requires habitat with sufficient food supplies to assure fat storage prior to hibernation and hibernacula
sites. Habitat providing all seasonal and life cycle requirements may or may not occur in a single
contiguous area If not in a contiguous area, habitat patches must occur in a mosaic of usable areas
where suitable corridors exist for seasonal movement among sites. Because very little is known about
the ecological requirements of the subspecies, potentially suitable habitat is currently defined only as
areas of well-developed, dense herbaceous vegetation consisting of a variety of grasses, forbs and thick
shrubs in close proximity to open water. This definition is vague and possibly incomplete.
Numerous surveys have been conducted since 1990 to establish the current distribution of
PMJM. However, very few surveys for determining the presence or absence of PMJM have been
conducted in Larimer or Weld Counties, Colorado. Of the surveys conducted up to 1997, only three
sites yielded captures of PMJM in either Larimer or Weld Counties. In Larimer County, two sites
(Lone Pine and Rabbit Creeks) yielded captures of PMJM, based on field identification and supported
by genetic analyses conducted to date (Riggs 1998). One mouse was captured on Lone Tree Creek in
Weld County that was identified as Z. h. preblei in the field but was genetically found to be more .
closely allied with the western jumping mouse, Z. princeps (Riggs 1998). Therefore, very little
information is known about habitat use or current distribution of the subspecies in these two counties.
Both Larimer and Weld Counties include habitat that is currently perceived to be outside the
ecological limits of PMJM. Larimer County provides the opportunity to explore elevational limitations,
currently thought to be 7400 feet (2260m) (USFWS 1997); Weld County extends beyond the
currently believed eastern boundary of the subspecies. Both of these boundaries will be challenged by
selecting survey sites within the two counties beyond the perceived ecological limits of the subspecies.
Genetic tissue samples will be collected on all PMJM captured to assist identification through DNA
analysis, particularly for those animals captured outside the currently perceived ecological limits, and to
provide information for future studies to better define the relationships among different populations of
Z. h. preblei, other subspecies of Z. hudsonius and other species of Zapus.
Quantifying and comparing both landscape and site specific characteristics of habitats where
PMJM are found and not found in these two counties would further our understanding of habitat use by
the subspecies, particularly in the northern half of its probable range. Any new locations where PMJM
are found during this study would contribute to the range-wide distribution map currently available for
the subspecies. Repeated annual visits to these same randomly selected sites would also provide
information on population persistence at a given site. Such a monitoring scheme would be necessary
for evaluating the continued status of the mouse at each site, providing further information as to the
suitability of the habitat for long-term persistence of the population.
Thus, the primary objective of this study is to quantify and define habitats used and identify
ecological limits of the subspecies in Larimer and Weld Counties, Colorado. Such information could
be used by the USFWS to further refine the current definition of potentially suitable habitat for PMJM.

Objectives
Conservation of Z. h. preblei should require maintaining populations of the subspecies
throughout the range of its natural variation and to try to identify ecological limits for the subspecies.
Specific objectives for the distributional component of this study are to (1) clarify the distribution of the
subspecies in Larimer and Weld Counties, Colorado, and (2) define and quantify the amount of suitable
habitat within Larimer and Weld Counties.
The objective of the habitat study is to identify and refine ecological requirements of Z. h.
preblei in Larimer and Weld Counties, Colorado. Because of the uncertainty of the identification of the
mouse captured in Weld County, Colorado, and because currently perceived ecological boundaries of
PMJM will be challenged in the survey effort, the objective of the genetic component of this study is to
genetically identify all Zapus spp captured during this study. Therefore, genetic tissue samples will be
. collected from each jumping mouse captured to confirm identification of the animal. These genetic

�27

tissue samples could also provide further data to better define the relationships of different populations
of Z. h. preblei as well as to other subspecies of Z. hudsonius and other species of 7.apus through
molecular systematic relationships and to link these genetic relationships to systematic studies of Z.

hudsonius.
Specific objectives for this study on PMJM include:
.
1. Define and quantify habitat characteristics at sites wllere PMJM was found and sites where
PMJM was not found.
2. Identify elevational and eastern boundary limitations for PMJM in Larimer and Weld
Counties, Colorado.
3. Describe the distribution of PMJM in Larimer and Weld Counties, Colorado.
4. Select sites and establish monitoring protocols for determining long-term trends in
populations of PMJM.
5. Collect genetic tissue samples to assure identification of jumping mice captured during this
study and for future genetic analyses to better define the. relationship of populations of Z.
h. preblei to each other, other subspecies of Z. hudsonius and other species of 7.apus.

Study sites
Trapping surveys will be conducted at a minimum of30 sites selected at random from the
sampling frame developed for Larimer and Weld Counties, Colorado. No survey site will occur at
elevations greater than 7600 feet and not east of the UTM Easting Coordinate of 602000. The
molecular systematic studies will be conducted in genetic laboratories using the genetic tissue samples
collected in the field (ear punches).
Methods
For simplicity, the methods described below assume all jumping mice captured are PMJM.
To meet these objectives, this study included (1) constructing a sampling frame of potentially
suitable habitat within the area of interest (Larimer and Weld Counties, Colorado) and (2) conducting
trapping surveys to determine presence or absence at a minimum of 30 sites randomly selected from
the sampling frame. Specific approaches to each of these tasks follow.

Sampling frame
A sampling frame was developed to delineate potentially suitable habitat for PMJM from
unsuitable habitat. To produce a preliminary map displaying existing potential habitat for PMJM would
require at least three primary layers of ecological information. Two initial layers, hydrology and
vegetative cover would provide a map displaying all areas where these two ecological requirements of
PMJM co-occur. The hydrology layer must be in enough detail to provide locations of intermittent and
small order streams as well as identify water source (e.g., irrigation ditches, stream, seep). Degree of
density of vegetative cover is sufficient for initial mapping efforts. Demarcation of shrub, trees and
grasses will suffice in these initial efforts rather than species identification.
However, not all combinations of vegetative cover and water provide sufficient habitat to
support PMJM. Thus, mapping potential habitat as described above would produce a map displaying
far more potential habitat than exists. For example, an extremely critical ecological requirement for the
survival of the mouse, that to date we have very little information for, is potential hibernacula sites. As
a possible index to hibernacula habitat, a third GIS layer, indicating the presence of alluvial deposits
may provide some insight in to hibernation requirements. Areas where alluvial deposits co-occur with
the presence of water and vegetative cover may provide a more realistic map of potentially suitable
habitat for the mouse.
Our ability to survey a site selected at random would be restricted to those areas where we are
_able to bbtain permission to access th_e land. We shou_ld_be able_to survey any randomly se_lected site

�28

on public lands and thus our inference should be unrestricted. Such readily available access would
probably not occur on privately owned or leased lands, thus, restricting inferences made on private
lands. By stratifying the sampling frame, this lack of access on private lands would not restrict
inferences that can be made on public lands. Inference on private lands will depend on the percent of
access we get from private landowners.
The sampling frame was developed from the 1:24,000 sc'ale Hydrographic GIS layer
developed by the CDOW (Reese Tietje, unpublished data). From this sampling frame a three-stage
sampling design was used to select 40 random sites (to ensure meeting our objective of a minimum of
30) for conducting PMJM surveys. Primary sampling units were 3rd order streams. Of the 150 3rd
order streams that exist within the sampling frame, 40 were selected on public lands, 40 on private
lands. The secondary sampling unit was the stream stretch selected within the primary (3rd order
stream) unit. The tertiary sampling unit was the actual sites along the stream stretch selected at the
secondary sampling stage that were sampled. Each of the primary, secondary, and tertiary sampling
units were selected using simple random sampling. If the secondary sampling unit did not yield
potentially suitable habitat (i.e., no dense vegetation) secondary sampling units continued to be selected
at random until one yielded potentially suitable habitat. Determination of suitable habitat was made by
field site visits.
Total stream length of all the secondary sampling units were recorded as well as total stream
length containing potentially suitable habitat. From these measurements an estimate of the probability
of potentially suitable habitat occurring within the primary sampling unit can be made for each area
surveyed. A mean estimate, over all sites surveyed, of the probability of a primary sampling unit
having potentially suitable habitat was made. Because of the random selection of primary sampling
units, inference can be made as to the probability of potentially suitable habitat existing on all 3rd order
streams within the sampling frame.
By recording presence or absence of PMJM within the tertiary sampling units we can estimate
the probability of PMJM occurring within potentially suitable habitat. Because of the random selection
of sampling units in each of the two strata (public and private lands) we can then estimate the
probability of PMJM occurring in potentially suitable habitat within both public and private lands.

Trapping surveys
Trapping surveys to determine presence/absence of PMJM were primarily conducted following
protocols defined by the USFWS (1997). Additional guidelines have also been developed to
accommodate the needs of this project. Trapping surveys were conducted within the period from June
I to September 15, 1998. These dates correspond to dates when PMJM is known to be out of
hibernation.
Trappers were_advised to follow the Center for Disease Control's Hantavirus instructions and
recommendations when dealing with rodents. Due to the nocturnal nature of PMJM, traps were set
between 19:00hrs and 21 :00hrs and checked as early as possible in the morning beginning at 5:00hrs to
reduce stress and the potential for predation on trapped animals. Time required to complete the
traplines varied depending on how many animals were caught.
Small mammal Sherman live traps (folding and non-folding) were used to conduct the trapping
sessions. Traps were set in two parallel lines of trap stations (I trap per station) on either side of the
drainage. Trap stations were 5 meters apart for a total of 250 meters; the parallel transects were 10
meters apart unless extent of habitat, terrain topography, or stream hydrology did not allow. Location
of transects were recorded on field data sheets and 7.5° topographic maps.
A small (~l inch) ball of polyester quilt was placed in each trap as nesting/bedding material.
Baiting material was Manna Pro Sweet 3-way Livestock feed which contains no animal matter;
ingredients include flaked barley, flaked corn, flaked oats, and cane molasses. Peanut butter was used
to stick the bait to the trap.

�29

Traps were checked by two surveyors. All animal captures were recorded. If an animal had
been captured in a trap, a ziplock plastic bag was placed over the end of the trap. The trap was opened
allowing the animal to fall into the plastic bag. The animal was identified to species while in the plastic
bag. If the animal was not a PMJM, identification of the animal was recorded and the animal set free
without further handling. Each captured PMJM was checked to detect the presence/absence of a PITtag (See below). If a PIT-tag was detected and the mouse had been captured at that same site within
the same trapping session, identification of the mouse was recorded and the mouse was released. If the
animal was a PMJM and no PIT-tag was detected the PMJM was anesthetized for further processing,
as follows. All PMJM were PIT-tagged.
Each PMJM was weighed while in the bag, recording the weight in grams using a Pesola
spring balance. Sex, age (juvenile, adult), and reproductive condition (pregnant, lactating or nonbreeding if it was female; for males the position of the testes indicated if in breeding status or nonbreeding status) was noted. Each PMJM was measured (total length, length of body, length of hind
foot - heel to distal end of claws) in millimeters. Capture of every PMJM was documented by taking a
photograph of the mouse on first capture. Mice were placed in a plexiglass photobox to reduce
handling stress while taking the photograph. If the mouse had been captured previously as noted by the
detection of a PIT-tag, no photograph was taken.
If there were feces in the trap where a PMJM was captured, the fecal material was collected in
a plastic bag labeled with date, location of the site, and animal PIT-tag number. Fecal samples were
kept cool until returned to the CDOW office where they were frozen. Salt was added to each specimen
bag for preservation. Once the field season was over all fecal samples were analyzed by the
Composition Analysis Laboratory, Inc, 622 ½ Whedbee, Fort Collins, CO for content.
All trap mortalities were recorded on a 'Trap Mortality' data form which included information
on species, potential duration of time spent in the trap, and any information available to help determine
cause of death. All animals found dead were double-bagged in a plastic bag and placed in a cooler
with ice. Specimens were frozen as soon as possible and deposited in the CDOW freezer at the office
in Fort Collins. A museum card was completed and attached to each PMJM specimen and the
specimen and card were given to Cheri Jones, Curator of Mammalogy at the Denver Museum of
Natural History, for study skins and tissue storage.
If an animal was severely injured (e.g., severed limb, large lacerations) it was euthanized by
soaking a cotton ball in Metofane (methoxyflurane) and placing the cotton ball and the mouse in a
ziplock bag until the animal stopped breathing. If an animal appeared to be only slightly injured (e.g.,
broken tail, small laceration) the animal was released to the wild. If an animal appeared to be coldstressed attempts were made to warm it by holding it in the surveyors hands and/or against their body.
If the animal appeared to be heat stressed, isopropyl alcohol was applied with a cotton swab to the ears,
arm pits, and feet to cool it down.

PIT-tagging
Each PMJM was individually marked with a Passive Integrated Transponder (PIT-tag). PITtags are electromagnetic, glass-encased tags that emit a passive signal (125 kHz) that can be decoded
by a portable reader. Destron-Fearing PIT-tags were used on all mice. We used portable readers from
Biomark to read the PIT-tags.
All mice were anesthetized to PIT-tag them. Anesthesia procedures followed protocols
successfully used on PMJM before (R. Schorr personal communication). Mice were anesthetized by
placing them and a cotton ball with 1 ml ofMetofane (methoxyflurane) into a sealed ziplock bag (to
keep Metofane fumes in bag). The bag was then lain aside to minimize stress for the mouse and the
time the mouse struggles in the bag. The less agitated the mouse is in the bag the less time required for
the metofane to take affect. The mouse was observed at all times to make sure the mouse did not
.. position itself such that the c_otton ball was in direct cont~ct with its face, which might c~use the mouse

�30

to have a severe reaction to the anesthesia After the animal stopped moving, the handlers waited one
minute before removing the mouse from the bag. The animal typically remained anesthetized for 2-3
minutes once outside the bag.
Each PMJM was PIT-tagged using a protocol successfully used by C. Meaney (personal
communication). Each PMJM had a PIT-tag inserted above the s~oulder blades by lifting the skin on
its back and inserting the individually sterilized needle with the PIT-tag under their skin and injecting
the tag. Verification of the PIT-tag identification number was made before and after insertion into the
mouse by running the PIT-tag scanner across it. The skin behind the opening was then pinched to
prevent emergence of the tag. PIT-tag identification number was recorded on the field data form.
If, at any time during the handling of the PMJM the animal appeared to be severely stressed
(dramatic changes in heartbeat, respiration and responsiveness or gums turning blue) first aid was
administered and, once recovered, released without further processing.
Absence of PMJM at a site was defined as no captures of PMJM from a minimum of four
consecutive nights and 400 trap nights ( a trap night is defined as the sum total number of traps
available each night). Presence of PMJM at a site was defined as at least one capture of PMJM at the
site. However, to accommodate sample size requirements for the monitoring and genetics study (see
below) trapping efforts continued until at least 10 individuals were tagged with PIT-tags.

Habitat Use
The general approach was to measure both site specific and landscape features of at least 30
sites selected at random to be surveyed for the presence of PMJM. A comparison of sites where
PMJM were found and were not found was then made in an attempt to refine our current
understanding of the ecological requirements of the subspecies. The following habitat characteristics
were measured and recorded for each site.
Site characteristics
Cover was measured at 20 random locations along the 250 meter sampled stream stretch.
Mean cover and standard error of the mean will be estimated. Cover was estimated using a vegetation
profile board (Nudds 1977) that allows for an assessment of visual obstruction in 0.5 meter vertical
intervals above ground. The board was 2.0 meters high and 30.48 cm wide. The board was marked in
alternate black and white colors at 0.25 (0.50) meter intervals. Horizontal cover was assessed in each
interval by viewing the board from 15 meters away in a randomly chosen direction. The percentage of
each interval concealed by vegetation was recorded as 0-20, 21-40, 41-60, 61-80, and 81-100%
estimated concealment.
Vegetation species composition and richness was estimated using the Modified-Whittaker
nested vegetation sampling method (Stohlgren et al. 1995). A modified Whittaker plot is 20-meters x
50-meters with 10 lm2 and 2 10m2 subplots arranged systematically around the perimeter and 1 100m2
subplot centered in the inside of the 20 meter by 50 meter plot. Species composition and percent cover
(optical estimate) of each species was recorded for each subplot.
Soil samples were taken randomly at each site for a hydrometer textural analysis (percent sand,
silt and clay). Samples were collected using an AMS 24" soil recovery probe. Samples were taken
from 0-12 inches, and 12+ to 24 inches. The 0-12 inch sample was taken first, removing the probe and
soil. Samples were placed in a labeled ziplock bag. The probe was then placed in the same hole for
the 12+ - 24 inch probe, with that soil sample being placed in a separately labeled ziplock bag. The
hydrometer textural analysis will be conducted at the CSU Soils Laboratory.
Mean stream width was estimated by measuring stream width at 30 locations along the entire
site sampled. The 30 locations were stratified equidistant from each other to cover the entire stream
stretch in increments of site stream length/30.

�31

The above listed parameter estimates will be compared for sites where PMJM were. captured
and sites where PMJM were not captured.

Landscape characteristics
The following landscape habitat characteristics will be measured and compared for sites where
PMJM were captured and sites where PMJM were not captured using either GIS, topographic maps,
or aerial infrared photography.
1. Distance to nearest human habitation and human disturbance.
2. Connectivity of sites to other streams from 1:24,000 topographic maps.
3. Total length of stream stretch at each site and total length of stream stretch with suitable habitat
at each site.
Molecular Systematics
Genetic tissue samples were collected from all PMJM captured during the study. To date,
positive identification of the individual to subspecies cannot be made using only genetic information.
However, results of the DNA analysis combined with the morphometric data that will also be collected
(e.g., body length, tail length) and the photograph of the individual should provide sufficient
information to support the field identification to subspecies.
As established by the USFWS (1997) Survey Guidelines, presence of PMJM is established
when only one individual is captured. Thus, we could stop our trapping efforts after the first PMJM
capture. However, because we would also like to provide sufficient genetic data to more fully explore
the relationships of different populations of Z. h. preblei we will attempt to collect genetic tissue
samples from a minimum of 10 individuals per successful survey site. A sample of at least 10
individuals from a population will provide enough information to document the genetic variation within
the population {T. Quinn, personal communication).
Genetic tissue sampling
Genetic tissue samples were collected from every PMJM captured at each survey site. The
following protocol was used based on previous success with PMJM (M. Bakeman, C. Meaney, T.
Ryon, R. Schorr, personal communication).
A fresh pair of clean latex gloves were used to handle each mouse. With a clean ear punch tool,
one tissue plug was obtained from each mouse ear. If there was excessive bleeding, gentle pressure
was applied to the injured area for approximately one minute. Each ear plug was placed in a vial of
95% ethanol. Both the vial and the corresponding record on the data sheet were labeled with a unique
identifier as follows. A seven-place alpha-numeric code was composed as follows: a three-letter
designator for the survey location ( e.g., MYT = Maytag Property); a number beginning with two digits
indicating the year (e.g-., 98); followed by 2 digits specifying the individual trapped, numbered
sequentially. For example: MYT9801 = first animal sampled at Maytag Property in 1998.
After returning from the field, all samples were put in a cool place or refrigerated until delivery
to the CDOW office at 317 West Prospect, Fort Collins, CO where they are being held in the freezer
for future analyses. Ear punch tools were cleaned after each use by immersing them in a 10% bleach
solution for a few minutes, rinsing them thoroughly with clean water, and then dried thoroughly to
prevent rusting. Dull ear punch were discarded and replaced with new sharp punches to ensure the
quickest, cleanest cut possible.
Results
Trapping results
Thirty-nine sites were surveyed for PMJM in Larimer and Weld Counties, Colorado (Fig. 1),
with a total survey effort of 16,671 trap-nights. Of the 39 sites survey, Zapus spp. were captured at 21
survey sites (Table 1). A total of 71 unique. individuals-were captured in the 21 locations, wit}:l_·

�32

recaptures of 14 of those individuals. All sites where jumping mice were captured were located in
Larimer County.
Two trap mortalities of Zapus spp. occurred. Both specimens were saved and delivered to
Cheri Jones of the Denver Museum of Natural History on October 26, 1998.
Numbers of other small mammal species captures was recorded
for each site surveyed (Table
&lt;
2).
Nine fecal samples were collected from traps where Zapus spp. were captured. Results of
eight samples indicate the jumping mice at the capture sites in Larimer County feed on arthropods and
fungus which occurred in 50% (4) of the samples, followed by willows, pollen, and moss occurring in
38% (3), 25% (2) and 25% (2) of samples respectively. Other food items found included, moss,
horsetail, unknown flowers, and unknown seeds (Table 3).

Habitat characteristics
Measurements of habitat characteristics at both the site and landscape levels were completed.
No single habitat feature could be identified as unique to either sites where jumping mice were
captured or sites where jumping mice were not captured. Kentucky blue grass (Poa pratensis),
snowberry (Symphoricarpos spp), several species of willow (Salix spp.), and Mountain Alder were
most abundant in areas occupied by Zapus spp. Horsetail (Equisetum spp), wild rose (R.osa spp), and
cottonwood were also common. Dominant vegetation at survey sites with negative trapping results for
jumping mice included wheat grass {Agropyron spp), Canary reed grass (Phalaris angustifolia),
thistle, and willows (Table 4). Russian olive (E/aeaqnus angustifolia) occurred in 6 (33%) of the areas
where no jumping mice were found, while absent in areas where jumping mice were captured.
Jumping mice were captured in vegetation adjacent to large rivers, small streams, ponds,
ditches, and seeps. Mean stream width varied considerably for both sites where jumping mice were
captured (0.3-24.Sm) and where no jumping mice were captured (0.0-20m)(Table 4).
No jumping mice were found in locations surveyed east of Interstate 25(125) during 4,716
nights of trapping effort. Habitat features along certain stretches of Willow Creek within the Pawnee
National Grasslands and near the town of Briggsdale are similar to areas where jumping mice were
found west ofl25. However, these sites are extremely isolated and the surrounding landscape is in
either rangeland or agriculture production.
From late June through late August, 22 locations in Larimer County were surveyed. Zapus
spp were found in 20 of these 22 sites. The exceptions being the effluent below Seaman Reservoir on
the Poudre River and Soldier Canyon west ofHorsetooth Reservoir. Below Seaman Reservoir just
prior to and during trapping efforts, livestock (primarily cattle) were allowed to graze along this section
of the Poudre River. Habitat composition along Soldier Canyon is similar to that of Arthur's Rock ~3/4
miles to the south (occupied by Zapus spp). However water is permanent along the Arthur's Rock
drainage but flows intermittently through Soldiers Canyon.
Only one jumping mouse was captured west ofl25 after August 24 during 5,382 nights of
trapping effort at nine different sites. All locations trapped after August 24 were within drainages
known to be occupied by Zapus spp., including four sites along the Big Thompson River (this study),
two along the Poudre River (this study), and one each along Rabbit Creek (Meaney et al. 1997), Bull
Creek (this study) and Lone Tree Creek (Meaney et al. 1997). The surrounding areas that were
trapped along Bull Creek and Lone Tree Creek had been extensively grazed, leaving only isolated
patches of vegetation over most of the site, however all other locations were similar in habitat
composition to known PMJM locations.
Three soil samples from 0-12 inches and 12-24 inches were collected at all sites where
possible. Soils at some sites were too rocky to collect the 12-24 inch soil samples. A total of 104 012inch samples and 46 12-24 inch soil samples were delivered on October 21, 1998 to the Colorado
State University-Soil Composition lab for soil-textural analyses. To date-these analyses have not beeri.
compJeted.

�33

Genetic sampling
Genetic tissue samples were collected from 68 of the 71 jumping mice captured. Analyses of
these tissue samples is pending.
Discussion
The habitat matrix within the range of Z. h. preblei is mixed grasslands adjacent to the
Colorado Front Range along the Piedmont and along the base ofti.e Laramie Mountains in Wyoming
and extends to the Colorado plains. Within this matrix, PMJM occur along stream drainages that
contain patches of suitable vegetation. Suitable habitat appears to have at least two major components.
The first component is a supply of open water, at least in part of the active season (M. Bakeman, C.
Meaney, personal communication). Secondly, areas where PMJM has been found have dense cover
(M. Bakeman, C. Meaney, personal communication).
Based on studies of Z. h. preb/ei and Z. hudsonius elsewhere, Z. h. preblei apparently occurs
mostly in undergrowth consisting of grasses, forbs, or both in open wet meadows and riparian
corridors, or where tall shrubs and low trees form an overstory and provide adequate cover (Armstrong
et al. 1997). Meadow jumping mice are widespread in abandoned grassy fields, but are often more
abundant in thick vegetation along ponds, streams, and marshes or in rank herbaceous vegetation of
wooded areas (Whitaker 1963).
Vegetation at sites where Zapus spp were captured in this study were structurally diverse. No
single plant species dominated areas occupied or unoccupied by Zapus spp. Such diversity in a
multistory cover has been reported for the majority of other sites where Z. h. preblei have been found
(Armstrong et al. 1997, Meaney et al. 1997). Vegetation composition of the dense cover varied
considerably and included both native and non-native species as was found by other studies (Meaney et
al. 1996, 1997, Armstrong et al. 1997, M. Bakeman, personal communication). Results from this
study continue to support the habitat descriptions provided by Armstrong et al. (1997) which follows:
The herbaceous understory is primarily grasses or forbs or a mixture of the two. Few of the sites,
however, are dominated by fewer than two understory species. The tall shrub canopy at most sites is
willow (Salix spp.), although scrub oak (Quercus gambelli), birch (Betula spp.), and alder (A/nus spp.)
occur in sites south of the Palmer Divide Ponderosa pine (Pinus ponderosa) is the most common tree
at higher elevations. The mouse appears to tolerate weedy or exotic species in areas that are
structurally diverse and species rich; nearly every successful site contained Canada thistle (Cirsium
arvense ). Thus, the mouse does not appear to have an affinity toward any single plant species but
instead favors sites that are structurally diverse and provide adequate cover and food throughout its life
cycle.
PMJM have been trapped in natural riparian areas as well as areas altered by anthropogenic
influence including ditches and wetlands adjacent to interstate highways, cement-lined ditches with tall
cover, ditches along driveways and moderate road use, and moderate cattle grazing (M. Bakeman,
personal communication). Open water was present at all sites surveyed in this study, with stream width
varying across locations with and without jumping mice.
Jumping mice were captured in 21 new locations in both the Poudre River and the Big
Thompson River drainages in Larimer County. No jumping mice were captured at any survey site
located in Weld County, however there may still be some sites within and adjacent to the Pawnee
National Grasslands that may support PMJM (M. Ball, personal communication).
Fish Creek, north of Bull Creek is the only location trapped after the 24th of August where
jumping mice occurred. Poor trap success in late summer especially in areas along the Big Thompson
and Poudre Rivers, including locations near Cherokee Park SWA, may be influenced in part by
jumping mice entering hibernation. Elevation at these sites ranged from 5800 ft along the Poudre River
to 7600 ft along Bull Creek north of Cherokee Park, much higher then the maximum elevation in
D_ouglas (Shen~.and S.i':ert 1999,a, l 999b.) and Boulder. Countie~_(M.eaney_et al 19_99) \1/,heren_o
r_edu~tion..in trap success
•
•
••
. ... " could be detect_~d.
.

.

.

.

..

•;

�34

Food habit studies using scat analysis indicate jumping mice captured in Larimer County fed
on several different food types. This is similar to Shenk and Sivert (1999b) in Douglas County,
Colorado who also reported several food items in Z. h. preblei scat. It appears jumping mice captured
in Larimer County fed on willows, with willow present in 38% of the scats examined. This is in
contrast to Shenk and Sivert (1999b) who report virtually no willows in the scat examined from 85
fecal samples collected at three sites in Douglas County.
,,
PMJM are only one component of the small mammal community inhabiting areas where they
were captured. These mice were more often found at sites with high species richness and small
mammal abundance (Table 2). The highest occurrences of Mus musculus captures occurred on sites
where jumping mice were not found. This is similar to results summarized in Shenk (1998). The
presence oflarge numbers of house mice might suggest degradation of habitat for Z. h. preblei in those
areas or possibly competition between the two species (Ryon 1996). Jumping mice were also not
found in areas where large numbers of captures of deer mice (&gt; 115) occurred.
These preliminary analyses have treated all the jumping mice captured the same. However, the
truth may be they are all PMJM, all western jumping mice, or a mixture of the two. Once the genetic
study is completed and species identifications confirmed these analyses will need to be reevaluated in
light of that information. If some of the mice captured are identified as western jumping mice it would
be most beneficial to compare areas of occupancy by this species to areas occupied by PMJM and to
areas potentially occupied by both. According to Fitzgerald et al. (1994) the distributions of Z.
princeps and Z. hudsonius do overlap. The area of overlap occurs in eastern Wyoming. The
distribution of Z. hudsonius in Colorado is now known to be larger than shown in Fitzgerald et al.
(1994). The boundaries are currently as far south as Las Animas County, based on genetically
identified specimens of Z. h. preblei (Riggs 1998). Captures of Z. princeps and Z. hudsonius (as
identified in the museum) have occurred as close as eight miles of one another within the same
drainage (Armstrong 1972). Z. princeps were reported captured in 1981 (Olson and Knopf 1988) at
the Lone Pine site in Larimer County, Colorado, where Z. h. preblei were captured by Menaey et al.
(1997). Because neither specimens or genetic samples were taken in the 1981 study, identification of
those mice will remain in question. The discrepancy may be explained by field misidentification or
Meaney et al. (1997) also suggest this discrepancy might be explained by displacement of Z. princeps
with Z. h. preb/ei sometime in the sixteen intervening years between trapping efforts. Although
assumed to have different ecological requirements, genetic evidence presented by Riggs (1998)
suggests further investigation of possible distributional overlap between Z. h. preb/ei and Z. princeps.
These preliminary results from this study suggests further research should be conducted to
continue evaluating range-wide distributional boundaries (e.g., elevation restrictions). Further studies
should also be conducted to investigate areas of potential sympatry or hibridization of PMJM with Z.
princeps (western jumping mouse).

Literature Cited
Armstrong, D. M. 1972. Distribution of mammals in Colorado. University of Kansas, Museum of
Natural History Monograph 3:1-415.
Armstrong, D. M., M. E. Bakeman, A. Deans, C. A. Meaney, and T. R. Ryon. 1997. Conclusions and
recommendations in: Report on habitat findings on the Preble's meadow jumping mouse. Edited
by M. E. Bakeman. Report to USFWS and Colorado Division of Wildlife.
EG&amp;G. 1993. Report of Findings: 2nd Year Survey for the Preble's meadow jumping mouse.
Prepared by Stoecker Environmental Consultants for ESCO Associates, Inc., Rocky Flats
Environmental Technology Site, Jefferson County, Colorado
Fitzgerald, J. P., C. A. Meaney, and D. M. Armstrong. 1994. Mammals of Colorado. Denver
Museum of Natural History, University Press of Colorado. Niwot, Colorado.
H::uner, D. J., K, E. Petersen, .and T. L. Yates. 198 L Evolutionary relationships of jumping mice
.,. . . . .. (genµs µipus) of the s,outhwestern U~ited States. Journ.~ of_M!iJllmalogy 6~:501-51.2 ...

�35

Hall, E. R 1981. The mammals of North America John Wiley and Sons, Inc., New York, New
York, 2 volumes.
Jones, C. A. 1996. Mammals of the James John and Lake Dorothey State Wildlife Areas. Final
Report, submitted to the Colorado Division of Wildlife and Colorado Natural Areas Program.
Krutzsch, P.H. 1954. North American jumping mice (genus Zapus). University of Kansas
Publications, Museum of Natural History 7:349-472.
••
Levins, R 1970. Extinction. Lectures in Mathematical Life Sciences 2:75-107.
Long, C. A. 1965. The mammals of Wyoming. University of Kansas Publications, Museum of
Natural History, 14:493-758.
Meaney, C. A., N. W. Clippinger, A. Deans, and M. OShea-Stone. 1996. Second year survey for
Preble's meadow jumping mouse (Zapus hudsonius preblei) in Colorado. Report prepared for the
Colorado Division of Wildlife.
Meaney, C. A., A. Deans, N. W. Clippinger, M. Rider, N. Daly, and M. O'Shea-Stone. 1997. Third
year survey for Preble's meadow jumping mouse (Zapus hudsonius preblei) in Colorado. Report
prepared for the Colorado Division of Wildlife.
Nudds, T. D. 1977. Quantifying the vegetative structure of wildlife cover. Wildlife Society Bulletin
5:113-117.
Olson, T. E., and F. L. Knopf 1988. Patterns ofrelative diversity within riparian small mammal
communities, Platte River watershed, Colorado. Pg. 379-386 in: Proceedings of the symposium:
Management of amphibians, reptiles and small mammals in North America Flagstaff, Arizona
U.S. Forest Service, General Technical Report RM-166.
PTI Environmental Services. 1996a Preble's Meadow Jumping Mouse Study at Rocky Flats
Environmental Technology Site, Annual Report 1996. Final. Rocky Flats Environmental
Technology Site, Golden, Colorado.
•
Quimby, D. C. 1951. The life history and ecology of the jumping mouse, Zapus hudsonius.
Ecological Monographs 21:61-95.
Riggs, L. A., J. M. Dempey, and C. Orrego. 1997. Evaluating distinctness and evolutionary
significance of Preble's meadow jumping mouse: Phylogeography of mitochondrial DNA noncoding region variation. Final Report for the Colorado Division of Wildlife. Denver, Colorado.
Ryon, T. R 1996. Evaluation of historical capture sites of the Preble's meadow jumping mouse in
Colorado, final report. MS Thesis. University of Denver, Denver, Colorado.
Shenk, T. M. 1998. Conservation assessment and preliminary conservation strategy for Preble's
meadow jumping mouse (Zapus hudsonius preblei). Colorado Division of Wildlife FY 1997-98
Annual Report.
Shenk, T. M. and M. M. Sivert. 1999. Temporal and spatial variation in the demography of Preble's
meadow jumping mouse (Zapus hudsonius preblei). Colorado Division of Wildlife JanuaryMarch 1999 Quarterly Report.
Shenk, T. M. and Sivert M. 1999. Movement patterns of Preble's meadow jumping mouse (Zapus
hudsonius preblei) as they vary across time and space. Colorado Division of Wildlife January March 1999 Quarterly Report.
Stohlgren,T. J., M. B. Falkner, and L. D. Schell. 1995. A Modified-Whittaker nested vegetation
sampling method. Vegetatio 117:113-121.
USFWS. 1997a Proposal to list the Preble's meadow jumping mouse as an endangered species.
USFWS 50 CFR part 17.
USFWS. 1997b. Interim survey guidelines for Preble's meadow jumping mouse. USFWS. Denver,
Colorado.
Whitaker, J. 0., Jr. 1963. A study of the meadow jumping mouse, Zapus hudsonius (Zimmerman), in
cental New York. Ecological Monographs 33:3.
Whitaker, J, 0., Jr. -1972. Zapus-.,hudsonius. M~malian Species.1.1:l-I .. _,.

�36

Table I. Survey site locations and trapping results for presence ofjumping mice (Zapus spp.) in
Larimer and Weld Counties, Colorado. Positive identification to species is pending.
Number

Weights (grams)

General Description
ofLocation

3 total
3 females

21, 23.5

unnamed drainage to
north of Arthur's Rock
drainage

7480 feet

13 total
6 females
7males

20, 21.5, 28, 22,
26.6, 19, 23, 22,
25, 20.5, 23, 22, 23

west of Prairie Divide
Road

E485875
N4498154

5120 feet

2 total
I male
I female

18.5, 19

near Watson Lake,
northwest of Laporte

7nt987/9/98

E467500
N4502140

6320 feet

12 total
8 females
4 males

21.5,25, 19,20,
24, 21, 19, 21,
23.5, 21, 23

drainage runs along
west side of Stove
Prairie Road into the
Poudre River

Meadow
Creek

7/10/987/13/98

E467149
N4524532

6680 feet

3 total
3 females

17,22.5,25.5

along Cherokee Park
Road

Young
Gulch

7/12/987/15/98

E470750
N4502380
E470650
N4503800

6240 feet

I total
I female
2 total
2 female

22

tributary of Poudre
River

Dates
trapped

U1M
coordinates

Elevation

Arthur's
Rock

6/23/986/26/98

E485250
N4490700

5520 feet

Bull Creek

6/28/987/1/98

E458594
N4525510

Poudre
River

7ll/987/10/98

Skin Gulch

Drainage

ofZapus
spp.found

5840 feet

33, 23.5

Sevenmile
Creek

7/12/987/15/98

E450611
N4505834

7000 feet

2 total
I female
1 male

24, 24.8

tributary of Poudre
River

N. Fork
Poudre
River

7/207/22/98

E468100
N 4527485

6440 feet

2 total
I female
I male

20, 22.5

Cherokee Park,
drainage above
Halligan Reservoir

Pendergrass
Creek

7/267/29/98

E461380
N 4501300

7000 feet

I total
I male

28

tributary ofS. Fork of
the Poudre River

Buck Gulch

8/3-4/98

E463575
N4502360

6400 feet

2 total
2 females

10, 23.5

tributary of Poudre
River just east of Big
Narrows

Lakey
Canyon

8/3-4/98

E466550
N 4491360

7120 feet

~ total

28.5, 22, 30, 13

tributary of Buckhorn
Creek

Little Bear
Gulch

8/5-7/98

E 475650
N 4483745

6600 feet

2 total
2 female

29, 16

Buckhorn Mtn. area

Bear Gulch

8/6-7/98

E 472500
N 4483550

7200 feet

1 total
I female

19.5

tributary of Buckhorn
Creek

N. Fork, Big
Thompson

8/9-11/98

E 462950
N 4478090

7080 feet

1 total
1 female

24.5

by Glen Haven

N. Fork
Poudre
River

8/9-11/98

E 478692
N4516030

5900 feet

7 total
3 female
3 male
_l escaped

22, 17.5, 17.5, 18,
17, 28,

Robert's property

3 females
1 male

�37
Drainage

Dates
trapped

U1M

Elevation

Number
ofZapus
spp.found

Weights (grams)

General Description
of Location

coordinates

North
Poudre
Canal

8/17-18/98

E478000
N 4518600

6000 feet

4 total
4 male

23, I 9, 13, 18

irrigation ditch and
pond - Knight's
property

North Fork
ofPoudre

8/18-19/98

E472935
N 4523400

6100 feet

I total
I female

28.5

Phantom Canyon

Little
Thompson
River

8/19-20/98

E468500
N 4459400

6600 feet

I total
I male

17.5

northwest of Pinewood
Sprngs, off Hwy 36

Cedar Creek

8/21-22/98

E 477097
N 4477899

6080 feet

5 total
3 female

20, 28, 18.5, 33, 15

2male
Sheep
Creek

8/21-22/98

E470451
N 4490818

6700 feet

I total
I male

18.5

tributary of Buckhorn
Creek

Fish Creek

9/9-10/98

E462800
N 4537100

7400 feet

I total
I female

18.5

tributary of Fish Creek

6/2-6/5/98

E 547250
N 4522450

5160 feet

0

E 502350
N 4506750

5180 feet

drainage
Geary Creek
Windsor
Ditch

6n-6n0t98

Geary Creek, Pawnee
National Grasslands

0

Windsor ditch, Cobb

LakeSWA

Willow
Creek

· 6/116/14/98

E 537260
N 4521900

5200 feet

Willow
Creek

6/126/15/98

E 545310
N 4516687

5060 feet

0

Willow Creek, Pawnee
National Grasslands

Crow Creek

6/166/19/98

E 555711
N 4499260

4820 feet

0

Crow Creek, Pawnee
National Grasslands

Owl Creek

6/236/26/98

E 522550
N 4523050

5450 feet

0

Owl Creek, Pawnee
National Grasslands

Soldier
Canyon

6/28-7/1/98

E 484350
N 4492950

5520-5600
feet

0

Soldier Canyon
drainage, Lory State

0

Willow Creek, Pawnee
National Grasslands

Park
Seaman
Reservoir

7/237/26/98

E480I00
N 4505680

5400 feet

0

effiuent of Seaman
Reservoir, North Fork
of the Poudre River

South Fork
Rabbit
Creek

8/248/27/98

E 470150
N 4515100

6334 feet

0

South Fork Rabbit
Creek, Cherokee Park

Banner
Lakes

8/248/26/98

E 537850
N4435190

5030 feet

0

Banner Lakes SWA

Big
Thompson
River

8/27-30/98

E497210
N 4470130

4870 feet

0

Big Thompson River at
Simpson Ponds SWA

South Side
Ditch

9/1-4/98

E 484350
N 4473690

5100 feet

0

South Side Ditch, Big
. ThompsoJJ. Canyon

SWA

�38
Dates
trapped

UfM

Big
Thompson
River

9/1-4/98

Long Gulch

Elevation

Number
ofZapus
spp.found

E467150
N4473120

6800 feet

0

Big Thompson River

9/1-9/4/98

E465850
N4473450

7100 feet

0

Long Gulch, Big
Thompson drainage

Lone Tree
Creek

9/9-9/12/98

E506850
N4536000
E 506320
N 4535400

5900 feet

0

Long Tree Creek,
Meadow Springs
Ranch

Bull Creek

9/129/15/98

E462150
N 4534150

7600 feet

0

Bull Creek

South Fork
Poudre
River

9/139/16/98

E462250
N4503650

6400 feet

0

South Fork Poudre
River

Poudre
River

9/139/16/98

E470955
N4504350

5800 feet

0

Poudre River

Drainage

coordinates

Weights (grams)

General Description
ofLocation

�•Table 2. Numbers of other small mammal captures at the 39 sites surveyed for Preble's meadow jumping mouse in Larimer and Weld
Counties2 Colorado. S2ecies codes are listed below the table.
Mumu
Other
Drainage
PMJM Sos2 Sxs2 Tase Tahu Chhi Rese Perna Petr Pese
Neme
Mise
• Arthur's Rock
: Bull Creek
• Poudre River at
Watson Lake
• Skin Gulch
Meadow Creek
Youn Gulch
Seven Mile Creek
North Fork Poudre River
• •Pendergrass Creek
Buck Gulch
Lake Can on
: Little Bear Gulch
•. Bear Gulch
: North Fork Big ThomQson
• North Fork of Poudre
River
North Poudre Canal
North Fork of Poudre
River
• Little ThomQson River
Cedar Creek
She Creek
•• Fish Creek drainage
Ge Creek
Windsor Ditch
• Willow Creek
Willow Creek
Crow Creek
Owl Creek
.•. Soldier Can on
Seamen Reservoir
South Fork Rabbit Creek
. Banner Lakes

2

3

13
2
12
3
3
2
2
1
2
4
2

27
1

34

5

43

25
3

1
22

6

5

3

106
113
114
11

5

14

15
46
15
6
23

2

8

11
5

8

8
3

2

7
4

4

5

1

9

22
2
2

1
5
1

2
0
0

0
0
0
0

43
14
8

0

9

3

65
15

5
2

5
15
3
37
16
1
6
g

0

0

1

79

2
7

2

0

1

2

4
3

,.

1
2

6

2
8
8

2

30
174
12

211
176

93
13

110
32
39
28
166

4
3
1

1

13

w.

6

'°

�~

0

PMJM

Drainage
Big Thompson River
• South Side Ditch
Big Thompson River
Lon Gulch
Lone Tree Creek

0
0
0
0
0

Bull Creek
., South Fork Poudre River

0
0

Poudre River

Sosp Sysp Tasp Tahu

2

Chhi

Resp

Mumu

IO

25
59

8
13

11
104

67

5

22

14

4

0

:' Sosp =Sorex spp.
• Chhi =Clzaetodipus lzispidus
Petr =Peromyscus troei
·: Mumu =Mus musculus

Neme

16
31
1

1

3 ·'

Pesp

28
12
186
83
174

1

4

Perna Petr

6
3

Misp

Other

21
81
9
72

Tasp =Tamiasciurus hudsonicus
Perna =Peromyscus maniculatus
Neme= Neotoma mexicana

Sysp =Sylvilagus spp.
Resp =Reithrodontomys spp.
Pesp =Peromyscus spp.
Misp =Microtis spp.

•. Table 3. Percent contents of fecal samples collected from traps where Preble's meadow jumping mice were captured. All samples were
· collected during the 1998 field season. Amount of bait in each sample was quantified as 100%, 'A' for abundant(&gt; 70% of the sample), T for
trace amount (&lt; 10% of the sample), or 0% of the sample was bait.
endogenous
Date
Salix seed moss pollen Equisetum flower Salsola
Location
bait arthropods
fungus
PIT-tag ID#
41412PH3D
: 4 I405A3326
41405C68l8
41414A5459
Juvenile
Juvenile
41413A7757
4141310654
Juvenile

Seven Mile Creek
Seven Mile Creek
North Fork Poudre
North Fork Poudre
Sheep Creek
Buck Gulch
Buck Gulch
Bear Gulch
Fish Creek

July 14
July 18
July21
Aug 11
Aug22
Aug4
Aug4
Aug7
Sept 10

T
T
A
T

A
A
T
A
0

2

89

11
53

9

89

41

6

78
91

15

100

T
7
9

7

7

100
79

7

�41

Table 4. Mean stream width and dominant understory, shrub, and overstory vegetation at each of the
sites surveyed for Preble's meadow jumping in Larimer and Weld County, Colorado during 1998.
Mean
Stream
wid~(m)
Drainage:!:

PMJM

X

Dominant Overstory
se(X)

Grass/Forb

Shrub

Tree

Bluegrass/Horsetail
Bluegrass
AltaFescue
Bluegrass/Canada
Thistle
Bluegrass/Canada
thistle

Wild Plum
Willow
Willow
Snowbeny/ Chock
Cherry

Elm
Mountain Alder
Cottonwood

Snowbeny
Willow
Wax.current

Mountain alder

Arthur's Rock
Bull Creek
Poudre R. at Watson Lake

y
y
y

0.77
1.75
24.47

1.01
0.2
0.54

Skin Gulch

y

0.28

5.15

Meadow Creek

l.77

0.97

Young Gulch
Seven Mile Creek

y
y
y

1.22
3.38

1.06
1.14

North Fork Poudre River
Pendergrass Creek
Buck Gulch
Lakey Canyon
Little Bear Gulch
Bear Gulch
North Fork Big Thompson

y
y
y
y
y
y
y

8.30
l.72
0.52
0.84
0.46
0.53
6.93

3.03
0.53
0.26
0.18
0.26
1.9
l.73

North Fork of Poudre River

y
y

12.50
11.97

6.97

y
y
y
y
y

8.30
2.93
2.07
2.58
0.49

1.43
1.82
1.1
0.4
2.12

0.00
7.07
9.20

0.91
5.74
2.41

Willow Creek
Crow Creek

N
N
N
N
N

l.78
0.89

Owl Creek

N

8.00
3.37
2.40

Wheatgrass
Wheatgrass
Canada Thistle
Canada Thistle

0.39

Cone Flower

North Poudre Canal
North Fork of Poudre River
Little Thompson River
Cedar Creek
Sheep Creek
Fish Creek drainage
Geary Creek
Windsor Ditch
Willow Creek

Soldier Canyon
Seamen Reservoir
South Fork Rabbit Creek
Banner Lakes
Big Thompson River
South Side Ditch
Big Thompson River
Long Gulch
Lone Tree Creek

N
N
N

1.20
9.87
0.52
5.20
10.27
14.17
15.53
1.18
3.84
0.20
8.53

1.24

0.42
0.79
2.41

Bluegrass
Bluegrass
Bluegrass/
wheatgrass
Columbine
Black-eyed susan
Aster
Bluegrass
Bluegrass/ yarrow
Bluegrass
Bluegrass/Canada
thistle
Bluegrass
Bluegrass/ Canada
thistle
Canada thistle
Bluegrass
Blue grama
Canada thistle
Wheatgrass

Bluegrass/
Dandelion
Cheatgrass
Wheatgrass
Canary Reed Grass
Canary Reed Grass
Canary Reed Grass
Canada Thistle
Horsetail
Yarrow

Cottonwood

Ponderosa pine
Juniper

Willow
Mountain alder
Snowbeny
Aspen/ maple
Wax.current
Juniper
Wild rose/ wild grape
Spruce
Wild raspberry
Aspen
Willow
Mountain alder
Snowberry
Mountain alder
Willow
Willow

Cottonwood
Cottonwood

Snowbeny
Willow
Willow
Wild rose
Willow

Mountain alder
Cottonwood
Ponderosa pine
Mountain alder
Ponderosa pine
Cottonwood

(Absent)
Willow
(Absent)
Wax.Current
Wax.Current
Willow
Willow
Willow
Willow
Willow

(Absent)
(Absent)
(Absent)
Elm
Russian Olive
Cottonwood
Ponderosa pine
Mountain Alder
Russian Olive
Russian Olive
Cottonwood
Mountain Alder
Ponderosa Pine
Willow

N
0.2
N
6.57
Snowbeny
Willow
N
0.38
N
0.25
Willow
N
Willow
l.86
Snowberry
N
0.1
Wild Rose
Bull Creek
N
Juniper
1.18
Goosebcny
South Fork Poudre River
N
ERR
Golden Banner
Snowbeny/ Wild Rose Ponderosa Pine
Poudrc River
N
20.00
Common Lupine
Choke Cherry
Juniwr
i Drainages ar~ list~d in the same order ~s i~ Table 1 so that exa~t locations of each site could be obtained by using both tables.
..
.
._
.
.··..

�•

II

■

l'=,-b'--tf-r----~~~&gt;c-f'-J

art ~ollins~
1---1L

•
■

Zapus spp.
Found
Site Trapped
No Zapus spp.
Found

D County Line
Nstreams

/V Roads
Figure 1. 1998 survey site locations and trapping results for presence of Preble's meadow jumping mouse (PMJM) in Larimer and Weld Counties,
Colorado. Locations where PMJM were found are indicated by a red circle, locations where PMJM were not found are indicated by a green circle.

�43
APPENDIXC
TEMPORAL AND SPATIAL VARIATION IN THE DEMOGRAPHY OF PREBLE'S MEADOW JUMPING
MOUSE (Zapus hudsonius preblei)

Tanya M. Shenk and Maile M. Sivert

Abstract
A total of 186 individual mice were captured and PIT-tagged at three study sites (73 mice at
Maytag Property, 77 mice at PineCliffRanch, and 36 mice at Woodhouse Ranch). These mice were
captured over three different trapping sessions with an effort of 17,330 trap-nights. Genetic tissue
samples were collected for at least 30 individual mice at each of the three study sites. Density
estimates were expected to increase as the summer progressed to account for the birth pulses in late
June, and late July-August. This was the trend observed· at Maytag. PMJM densities at Woodhouse
Ranch increased from June to July but did not increase further during the September trapping session.
Mean PMJM density over all sites and sessions was 40.5 (range 16.9-79.0) mice per kilometer of
stream stretch. Highest densities occurred at PineCliff, where the vegetation is primarily willow and
both a mainstem and tributary were used by mice. Lowest densities occurred at Woodhouse Ranch
where the riparian vegetation has fewer willow but was dense with other riparian vegetation.
Vegetation at Maytag provided some areas of dense willow with the remaining areas being of moderate
density of riparian vegetation. The lower density of PMJM reported for Woodhouse Ranch might be
explained by the composition and densities of other small mammals at that site. Woodhouse Ranch
had the highest captures of both house mice and voles of the three sites studied. Defining summer as
June 1 - October 5, over-summer survival was estimated as 0.36 (se = 0.056) over all three study sites.
Temporary emigration and immigration rates were estimated but both had extremely high variances
associated with those estimates. Thus, these estimates cannot be used, with any confidence, to provide
information on movements of mice into and out of these populations. Very little new information was
gained during this study on reproductive parameters of PMJM. Most adult mice captured exhibited
evidence of active reproductive behavior, either pregnancy, lactation, or enlarged genitalia However,
we were unable to locate any breeding nests. Juvenile mice were not captured during the June trapping
session. Juvenile mice were captured at all three sites during both the July and September trapping
sess10ns.
This report includes results from only the first year of a multi-year project to follow
individually marked PMJM through time. Collection of more data, and more years of data, will
improve our ability to evaluate demographic parameters and estimates of how they vary across space
and time.

Introduction
On May 12, 1998 the U.S. Fish and Wildlife Service (USFWS) published a final rule in the
Federal Register (63 FR 26517) to list Preble's meadow jumping mouse (Zapus hudsonius preblei) as
'threatened' under the Federal Endangered Species Act (ESA) of 1973, as amended. Recovery goals
for Preble's meadow jumping mouse (PMJM) should work towards the sustainability, protection, and
restoration of Z. h. preblei populations and habitats on both private and public lands to provide the
spatial, genetic, and demographic structure needed to promote long-term species viability and provide
species management flexibility. Recovery efforts for the subspecies will be most effective if reliable
information is available on the basic ecology of the subspecies and this information used to design
recovery efforts such as Habitat Conservation Plans. A review of studies conducted on PMJM shows
that there is insufficient information to fully address defining range-wide ecological requirements,
.- . limiti~g _factors, .l.imits. of speci~s toler:µice, _oi:_popula~ion st~Ws (Shenk 199_8) .. Most work to date _has

�44

focused on geographic distribution (presence or absence of Z. h. preblei), taxonomy, and habitat
descriptions of sites where mice have and have not been captured. For PMJM in particular,
information on dispersal, habitat use, and population dynamics is most needed to identify minimal
ecological requirements of the subspecies.
Monitoring, by way of estimating demographic parameters (such as survival, abundance, and
reproduction), of a single population over time provides an opportunity to document demography of a
species, estimate temporal fluctuations in demography, and gain insights into the temporal variation
inherent in demographic parameters. Monitoring of multiple populations over time and over multiple
geographic locations provides the opportunity to gain further understanding of population processes
and detaches time effects from spatial effects. Population monitoring activities do not constitute
scientific experiments, in the spirit of manipulation of salient ecological variables, however, replication
of monitoring activities for natural populations over long periods of time and in diverse geographic
locations can lead to insights into population processes (Cook and Campbell 1979). These insights can
then be translated into hypotheses useful for predicting changes in population demography resulting
from either natural perturbations (e.g., flooding events) or anthropogenic modifications (e.g., gravel
mining). Experimentation would then be required to test these hypotheses and establish cause and
effect.
The primary objective of this study is to investigate spatial and temporal variation in the
demography of PMJM. Demographic parameters to be estimated include survival, reproduction,
temporary emigration, immigration, population structure, and density. These demographic parameters
will be estimated from individually marked animals from geographically distinct populations. To
evaluate spatial differences in the demography of PMJM, populations were selected from three sites
that provided a variety of habitat matrices available to the mouse. Multiple years of conducting the
study at those same sites will provide an estimate of the temporal variation in demography of PMJM.

Study sites
Demography of PMJM was evaluated for three populations. All three populations selected
were located in areas where PMJM had previously been found. To evaluate spatial differences in the
demography of PMJM, populations were selected on sites that provided a variety of habitat matrices
available to the mouse. The first site selected, Colorado Division of Wildlife (CDOW) Maytag
Property, has one primary water source available to the mouse. This water source is East Plum Creek.
The second site, Colorado Open Lands PineCliffRanch, provides both a tributary (Garber Creek) and a
main stem drainage (West Plum Creek). The third study site, CDOW Woodhouse Ranch provides an
area containing a tributary (Indian Creek) and a series of ponds and irrigation ditches scattered
throughout the property.
Objectives
Objectives of the demography study are to:
1. Estimate abundance and density of PMJM for each of three study populations.
2. Estimate over-summer, over-winter, and annual survival of PMJM at each of three study
populations.
3. Estimate temporary emigration of PMJM at each of three study populations.
4. Estimate immigration of marked PMJM back into each of three study populations.
5. Estimate reproduction of PMJM at-each of three study populations.
6. Evaluate the affect of weight, sex, age, abundance (i.e., density dependent response), and
habitat features such as stream reach, vegetation composition and density on survival,
reproduction, abundance, temporary emigration, and immigration of marked animals back
into three study populations of PMJM.
.7, J;stimate _1;1ge ~d.se~ ratios 9f PMJM at e~Gh of three stµdy pop4lati.ons ..
..

. . .- .
~

.

. . ..

�45

Met/,ods
Trapping
Three trapping sessions were conducted during the following weeks: June 2-9, 1998; July 21August 5, 1998; and September 8-15, 1998. Trappers were advised to follow the Center for Disease
Control's Hantavirus instructions and recommendations when dealing with rodents. Due to the
nocturnal nature of PMJM, traps were set between 19:00hrs an&lt;l'21:00hrs and checked as early as
possible in the morning beginning at 5:00hrs to reduce stress and the potential for predation on trapped
animals. Time required to complete the traplines varied depending on how many animals were caught.
Small mammal Sherman live traps (folding and non-folding) were used to conduct the trapping
sessions. Traps were set in two parallel lines of trap stations (1 trap per station) on either side of the
drainage. Trap stations were 5 meters apart for a total of 250 meters; the parallel transects were 10
meters apart unless extent of habitat, terrain topography, or stream hydrology did not allow. Location
of transects were recorded on field data sheets. Each trap location was also recorded to the nearest 5
meters in UTM coordinates using a Trimble Geo-Explorer GPS.
A small (~1 inch) ball of polyester quilt was placed in each trap as nesting/bedding material.
Baiting material was Manna Pro Sweet 3-way Livestock feed which contains no animal matter;
ingredients include flaked barley, flaked com, flaked oats, and cane molasses. Peanut butter was used
to stick the bait to the trap.
Traps were checked by two surveyors. All animal captures were recorded. If an animal had
been captured in a trap, a ziplock plastic bag was placed over the end of the trap .. The trap was opened
allowing the animal to fall into the plastic bag. The animal was identified to species while in the plastic
bag. If the animal was not a PMJM, identification of the animal was recorded and the animal set free
without further handling. Each captured PMJM was checked to detect the presence/absence of a PITtag and/or radio-collar. If a PIT-tag or radio-collar was detected and the mouse had been captured at
that same site within the same trapping session, identification of the mouse was recorded and the
mouse was released. If the animal. was a PMJM and no PIT-tag or radio collar was detected the
PMJM was anesthetized for further processing, as follows. All PMJM were PIT-tagged. If the PMJM
weighed&gt; 18 g a radio-collar was also put on the animal for movement data collection (see Shenk and
Sivert 1999).
Each PMJM was weighed while in the bag, recording the weight in grams using a Pesola
spring balance. Sex, age (juvenile, adult), and reproductive condition (pregnant, lactating or nonbreeding if it was female; for males the position of the testes indicated if in breeding status or nonbreeding status) was noted. Each PMJM was measured (total length, length of body, length of hind
foot - heel to distal end of claws) in millimeters. Capture of every PMJM was documented by taking a
photograph of the mouse on first capture. Mice were placed in a plexiglass photobox to reduce
handling stress to take a photograph. If the mouse had been captured previously as noted by the
detection of a PIT-tag, no photograph was taken.
If there were feces in the trap where a PMJM was captured, the fecal material was collected in
a plastic bag labeled with date, location of the site, and animal PIT-tag number. Fecal samples were
kept cool until returned to the CDOW office where they were frozen. Salt was added to each specimen
bag for preservation. Once the field season was over all fecal samples were analyzed by the
Composition Analysis Laboratory, Inc, 622 ½ Whedbee, Fort Collins, CO for content. These analyses
were for a complementary study on food habits and movements of PMJM at the same three study areas
(see Shenk and Sivert 1999 for details).
All trap mortalities were recorded on a 'Trap Mortality' data form which included information
on species, potential duration of time spent in the trap, and any information available to help determine
cause of death. All animals found dead were double-bagged in a plastic bag and placed in a cooler
with ice. Specimens were frozen as soon as possible and deposited in the CDOW freezer at the office
in.Fort Collins .. A museum card was.. completed and attached-to each PMJMspecimen.and the.

�46

specimen and card were given to Cheri Jones, Curator of Mammalogy at the Denver Museum of
Natural History, for study skins and tissue storage.
If an animal was severely injured (e.g., severed limb, large lacerations) it was euthanized by
soaking a cotton ball in Metofane (methoxyflurane) and placing the cotton ball and the mouse in a
ziplock bag until the animal stopped breathing. If an animal appeared to be only slightly injured (e.g.,
broken tail, small laceration) the animal was released to the wild.' If an animal appeared to be coldstressed attempts were made to warm it by holding it in the surveyors hands and/or against their body.
If the animal appeared to be heat stressed, isopropyl alcohol was applied with a cotton swab to the ears,
arm pits, and feet to cool it down.
During the last trapping session homeopathic first aid treatments were used in an attempt to
minimize stress and improve recovery of each PMJM. Homeopathic first aid kits and instruction was
provided by WildAgain Wildlife Rehabilitation, Evergreen, Colorado.

PIT-tagging
Each PMJM was individually marked with a Passive Integrated Transponder (PIT-tag). PITtags are electromagnetic, glass-encased tags that emit a passive signal (125 kHz) that can be decoded
by a portable reader. Destron-Fearing PIT-tags were used on all mice. We used portable readers from
· Biomark to read the PIT-tags.
All mice were anesthetized to PIT-tag them. Anesthesia procedures followed protocols
successfully used on PMJM before (R. Schorr personal communication). Mice were anesthetized by
placing them and a cotton ball with 1 ml ofMetofane (methoxyflurane) into a sealed ziplock bag (to
keep Metofane fumes in bag). The bag was then lain aside to minimize stress for the mouse and the
time the mouse struggles in the bag. The less agitated the mouse is in the bag the less time required for
the metofane to take affect. The mouse was observed at all times to make sure the mouse did not
position itself such that the cotton ball was in direct contact with its face, which might cause the mouse
to have a severe reaction to the anesthesia After the animal stopped moving, the handlers waited one
minute before removing the mouse from the bag. The animal typically remained anesthetized for 2-3
minutes once outside the bag.
Each PMJM was PIT-tagged using a protocol successfully used by C. Meaney (personal
communication). Each PMJM had a PIT-tag inserted above the shoulder blades by lifting the skin on
its back and inserting the individually sterilized needle with the PIT-tag under their skin and injecting
the tag. Verification of the PIT-tag identification number was made before and after insertion into the
mouse by running the PIT-tag scanner across it. The skin behind the opening was then pinched to
prevent emergence of the tag. PIT-tag identification number was recorded on the field data form.
If, at any time during the handling of the PMJM the animal appeared to be severely stressed
(dramatic changes in heartbeat, respiration and responsiveness or gums turning blue) first aid was
administered and, once recovered, released without further processing.
Genetic tissue sampling
Genetic tissue samples were collected from the first 30 PMJM captured at each study site.
The following protocol was used based on previous success with PMJM (M. Bakeman, C. Meaney, T.
Ryon, R. Schorr, personal communication).
A fresh pair of clean latex gloves were used to handle each mouse. With a clean ear punch tool,
one tissue plug was obtained from each mouse ear. If there was excessive bleeding, gentle pressure
was applied to the injured area for approximately one minute. Each ear plug was placed in a vial of
95% ethanol. Both the vial and the corresponding record on the data sheet were labeled with a unique
identifier as follows. A seven-place alpha-numeric code was composed as follows: a three-letter
designator for the survey location (e.g., MYT = Maytag Property); a number beginning with two digits
•. . .
-indicating the year-.(e.g., 98); followed by 2- digits specifying the individual trapped, numbered
. . . . -~~quentt&lt;J:lly,. fot e.~ample: MYT_980J ;= fir~t ari~al sampled,at Maytag ProP.~rty)~ J9~_8.

�47
After returning from the field, all samples were put in a cool place or refrigerated until delivery
to the CDOW office at 317 West Prospect, Fort Collins, CO where they are being held in the freezer
for future analyses. Ear punch tools were cleaned after each use by immersing them in a 10% bleach
solution for a few minutes, rinsing them thoroughly with clean water, and then dried thoroughly to
prevent rusting. Dull ear punch were discarded and replaced with new sharp punches to ensure the
quickest, cleanest cut possible.
'

Demographic parameter estimation
Mark-recapture estimation techniques were used to estimate abundance, over-summer
survival, over-winter survival, temporary emigration, and immigration of marked animals back in to the
three study populations of PMJM.
Abundance: Abundance was estimated using Pollock's Robust Design (see Kendall et al.
1997, 1995 and Kendall and Nichols 1995 for detail) in Program MARK (White and Burnham 1999).
The robust design is a combination of the Cormack-Jolly-Seber (CJS)(Cormack 1964, Jolly 1965,
Seber 1965) live recapture model and the closed capture models. The key difference from the CJS
model is that instead of just one capture occasion between survival intervals multiple capture occasions
are used. These occasions are close together in time allowing the assumption that no mortality or
emigration occurs during these short time intervals. The closely spaced encounter occasions are
termed "trapping sessions" and each trapping session is viewed as a closed capture survey whereby
abundance can be estimated. Three 7-day trapping sessions were conducted during the following
weeks: June 2-9, 1998; July 21-28, 1998; and September 8-15, 1998. Abundance estimates were
calculated for each trapping session.
Survival: By using the estimate of the probability that an animal is captured at least once from
the trapping sessions designed to estimate abundance, survival between the longer intervals was
estimated. Analyses were conducted to estimate over-summer survival, and survival from June-July
and August-September. A fourth 7-day trapping session to be conducted June 1-8, 1999 will provide
information to estimate over-hibernation and annual survival.
Temporary emigration and immigration: The longer intervals between trapping sessions also
allows estimation of temporary emigration from the trapping area, and immigration of marked animals
back to the trapping area using Pollock's Robust Design.
Reproduction: Reproductive parameters were estimated by evaluating the reproductive status
and age of captured PMJM.
Results
Trapping and PIT-tagging Effort
A total of 186 tndividual PMJM were captured from the three study areas during the three
1998 trapping sessions ·(Table 1: 73 at Maytag Property, 77 at PineCliff Ranch, and 36 at Woodhouse
Ranch). These mice were captured over three different trapping sessions with an effort of 17,330 trapnights. Every PMJM captured was PIT-tagged, providing each mouse with a unique, permanent, lifetime identification marker.
Other small mammals captured during the trapping sessions included Peromyscus spp.,
Mexican wood rat (Neotoma mexicana), house mouse (Mus musculus), vole (Microtis spp.), western
harvest mouse (Reithrodontomys megalotis), hispid pocket mouse (Chaetodipus hispidus), and
shrew (Sorex spp.). House mice were captured at all three study areas during either June or
September (Tables 2, 3). Species and relative numbers of captures within each of those species were
similar for Maytag Property and PineCliffRanch (Tables 2,3). Species richness and relative number of
captures between these sites were also similar in June and September with the exception of an increase
in vole captures at both sites in September. Most of these common species were also captured at
Woocihouse
Rqnch
during both June-::. and
September
2,3).
However, hispid
pocket
mice
an_d..
. . .
. . ..
. ·...
·........ ··. .· . -~ ... •..
. . .
. . ,-, . . (Taples
. ' .. . ...
: . ·. -· . . .- .. - ~- ... .
. . . .
.
.
·• .., .
:

:

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�48

Mexican woodrats were also captured at Woodhouse Ranch and not at either of the other two sites.
Numbers of house mice and vole captures at Woodhouse Ranch were greater than at either Maytag or
PineCliff during June and September, with numbers of captures for both species increasing in the
September trapping session (Tables 2,3).

Age and Sex Ratios
As expected, no juvenile PMJM were captured during the June trapping session as it was too
soon after hibernation for any litters to have been born and/or if born the juveniles would still be
restricted to their nests. Juvenile mice were captured during both the July and September trapping
sessions at all three sites. Juveniles as small as I 0g were captured. Sex ratios may be biased towards
males, however further analyses need to be completed to confirm this hypothesis (Table I).
Genetic tissue sampling
Genetic tissue samples were collected from 40 individual mice at Maytag, 30 mice at PineCliff
Ranch, and 32 mice at Woodhouse Ranch. Additional samples were collected from four mice captured
at a back drainage on the Woodhouse Ranch. Samples are currently being stored in the cooler at the
CDOW Research Center in Fort Collins, Colorado. A Request for Proposals was submitted through
the Colorado Department of Natural Resources. A committee is currently evaluating the three proposal
that were submitted. Samples from these three populations will be used in studies to evaluate genetic
uniqueness of PMJM populations.
Abundance and Density
Mark-recapture analysis methodologies were used to estimate abundance at each of the three
study sites for each of the three trapping sessions (Table 4). Abundance estimates and length of the
trapline were used to estimate an unadjusted density of mice per kilometer of stream stretch. Mice that
typically don't use the area of stream stretch where the traps were placed could be trapped because they
were attracted to the area by the artificial food source. Including these mice in the density estimates for
the stream stretch covered by the trapline would artificially increase density estimates. Therefore, an
adjustment was made to the density estimates.
Locations of each individual mouse were classified as either within the stream stretch that was
trapped or above or below the stream stretch where traps were placed. If greater than 50% oflocations
of an individual mouse were off the trapline the mouse was categorized as an 'off-trapline' mouse; if
less than or 50% of the locations were within the trapline the mouse was categorized as an 'on-trapline'
mouse. The percent of off-line mice for each trapping session and each site was calculated and a mean
adjustment parameter (p) estimated. This adjustment parameter is sensitive to the length of the
trapline. The shorter the trapline the greater the adjustment would have to be. Regression models
were run and AIC used to select the best regression model to estimate p by trapline length. These
adjustment parameters are simply an estimated percent of mice that should be considered resident mice
along the stream stretch where traps were placed. The density estimates were then decreased to
percentage p. Use of the adjustment parameter provided a more realistic estimate of density of mice
per kilometer of stream stretch. Without the adjustment densities would be inflated.

•·.· ·•.··

·:·_.

-·

Survival
Survival rate was estimated using the mark-recapture estimator for Pollock's Robust Design in
Program MARK. The best fitting model combined data from all three study sites over all three
trapping sessions. Survival was estimated as 0.75 (se = 0.033) for a five week period. Extrapolating
this survival rate across the summer results in an over-summer (June 1- October 5, 18 weeks) survival
rate of 0.355 (se = 0.056). No estimates of over-winter survival can be made until trapping sessions
.occur in S.ummer.19.99~-, ...,. .
- . ·.
. ;_-.
&lt;,_ ,.... •
•__ .... , .... , .
. ...•...,_ ... _: .•

�49

Temporary emigration and immigration
Temporary emigration rate and immigration was estimated using the mark-recapture estimator
for Pollock's Robust Design in Program MARK. The best fitting model combined data from all three
study sites over all three trapping sessions for these two parameters. Temporary emigration was
estimated as 0.64 (se = 2.21), immigration was estimated as 0.45,, (se = 89.94).
Reproduction
No estimates of reproduction could be made. We located what we believed to be nest sites at
several locations. We believe these sites to be nest locations with young because we followed radiocollared adult females (see Shenk and Sivert 1999) to these sites on numerous morning during
breeding season. However, all sites were in very thick vegetation and we were not able to visually
observe a nest with young. We felt it to be in the best interest of the mouse to not disturb the areas
which might possibly cause failure of the nest.

Discussion
Information on the population dynamics of PMJM is necessary to determine which areas
support viable populations. To begin to evaluate the viability of a population information on key
demographic parameters must be obtained. Conducting studies on individually marked animals
provides the greatest insight on the demography of a population.
In general, estimated sex ratios from this study are comparable to those found by Armstrong et
al. ( 1997) who reported an overall sex ratio for all captured PMJM of 51. 6 males: 48.4 females;
approximately 86.0% of captures were identified as adults. There is a possible male sex bias at
PineCliffRanch. However, small sample sizes and possible trapping biases by sex may explain the
discrepancy.
Density estimates were expected to increase as the summer progressed to account for the birth
pulses in late June, and late July-August. This was the trend observed at Maytag. PMJM densities at
Woodhouse Ranch increased from June to July but did not increase further during the September
trapping session. Mean PMJM density over all sites and sessions was 40.5 (range 16.9-79.0) mice per
kilometer of stream stretch. Highest densities occurred at PineCliff, where the vegetation is primarily
willow and both a mainstem and tributary were used by mice. Lowest densities occurred at
Woodhouse Ranch where the riparian vegetation has fewer willow but was dense with other riparian
vegetation. Vegetation at Maytag provided some areas of dense willow with the remaining areas being
of moderate density of riparian vegetation. The lower density of PMJM reported for Woodhouse
Ranch might be explained by the composition and densities of other small mammals at that site.
Woodhouse Ranch had the highest captures of both house mice and voles of the three sites studied.
Defining summer as June 1 - October 5, over-summer survival was estimated as 0.36 (se =
0.056) over all three study sites. Meaney et al. (1999) report a one-month summer survival rate of
78%. Extrapolating Meaney et al.'s (1999) estimate over our summer period(~ four months) would
result in a similar over-summer survival rate estimate of 36%. Prior to studies conducted in 1998 no
information existed on survival rates for populations of Z. h. preblei although Whitaker (1963) reported
a 67% loss of Z. hudsonius over hibernation. Temporary emigration and immigration rates were
estimated but both had extremely high variances associated with those estimates. Thus these estimates
cannot be used, with any confidence, to provide information on movements of mice into and out of
these populations.
Very little new information was gained during this study on reproductive parameters of PMJM.
Most adult mice captured exhibited evidence of active reproductive behavior, either pregnancy,
lactation, or enlarged genitalia. However, we were unable to locate any breeding nests. Juvenile mice
were not captured during the June trapping session. Juvenile mice were captured at all three sites
during .both the. Ju_ly .wd .S_eptember trappi1.1g sessions, .. Giv.e_n .t.h~t Jm~e.d.ing pea,k.s appe_~ to, 9.c_&lt;;,UJ: to. ..
. •. ·'···· -· •.

.

. . . . ·•. _.,,

...

�50

early to mid-June and August with a possible third litter in September (Whitaker 1963) this was not
unexpected and agrees with previous observations (Meaney et al. 1996, 1997, PTI 1996a, M.
Bakeman unpublished data, T. Ryon unpublished data).
This report includes results from only the first year of a multi-year project to follow
individually marked PMJM through time. Collection of more data, and more_ years of data, will
improve our ability to evaluate demographic parameters and estimates of how they vary across space
and time.

... ·.· ..•

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Meaney, C. A, A Deans, N. W. Clippinger, M. Rider, N. Daly, and M. O'Shea-Stone. 1997. Third
year survey for Preble's meadow jumping mouse (Zapus hudsonius preblei) in Colorado.
. ._., .-. Report.pre,paredfor.theColorado.piyisiooofW.ildlife.... .. : .
.., ,,.
.- . .
. ...._..
,
..
..
. . .: . . . : · . ... ..•· . ·- .~
•.

~

,•

..

:

�51

Meaney, C. A., A. Ruggles, B. Lubow, N. W. Clippinger, and A. Deans. 1999. Preliminary results:
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.
Nudds, T. D. 1977. Quantifying the vegetative structure ofwildllfe cover. Wildlife Society Bulletin
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Poly, W. J., and C. E. Boucher. 1997. Record of a creek chub preying on a jumping mouse in Bruffey
Creek, West Virginia Brimleyana 24: 29-32.
PTI Environmental Services. 1996a Preble's Meadow Jumping Mouse Study at Rocky Flats
Environmental Technology Site, Annual Report 1996. Final. Rocky Flats Environmental
Technology Site, Golden, Colorado.
PTI Environmental Services. 1996b. Preble's Meadow Jumping Mouse Study at Rocky Flats
Environmental Technology Site, Spring 1996. Final. Rocky Flats Environmental Technology
Site, Golden, Colorado.
Quimby, D. C. 1951. The life history and ecology of the jumping mouse, Zapus hudsonius.
Ecological Monographs 21:61-95.
Riggs, L. A., J. M. Dempey, and C. Orrego. 1997. Evaluating distinctness and evolutionary
significance of Preble's meadow jumping mouse: Phylogeography of mitochondrial DNA noncoding region variation. Final Report for the Colorado Division of Wildlife. Denver, Colorado.
Seber, G. A. F. 1965. A note on the multiple recapture census. Biometrika 52:249-259.
Sheldon, C. 1934. Studies on the life histories of Zapus and Napaeozapus in Nova Scotia Journal of
Mammalogy 15:290-300.
Shenk, T. M. 1998. Conservation assessment and preliminary conservation strategy for Preble's
meadow jumping mouse (Zapus hudsonius preblei). Colorado Division of Wildlife FY199798 Annual Report.
Shenk, T. M. and Sivert M. 1999. Movement patterns of Preble's meadow jumping mouse (Zapus
hudsonius preblei) as they vary across time and space. Colorado Division of Wildlife January
- March 1999 Quarterly Report.
Stohlgren,T. J., M. B. Falkner, and L. D. Schell. 1995. A Modified-Whittaker nested vegetation
sampling method. Vegetatio 117:113-121.
USFWS. 1997. Interim survey guidelines for Preble's meadow jumping mouse. USFWS. Denver,
Colorado.
Whitaker, J. 0., Jr. 1963. A study of the meadow jumping mouse, Zapus hudsonius (Zimmerman), in
cental New York. Ecological Monographs 33:3.

.

.-:- • • •·

!..

• . . ~.

.. . ·.• •

. . -··:

. ....

.. ··. :· .. · .....

·-·

···:·

·._:

.... :-

... -.~ .· -. . .

�52
Table 1. Number of Preble's meadow jumping mice PIT-tagged and captured at each of the three study
sites for each of the three trapping sessions. Trapping effort is recorded as number of trap nights for each
session at each site.

# Capturedt

# PIT-tagged

Site

Trapping
session

Trap
nights

Female

Male

Unknown

Total

Female(%)

Male(%)

Total

Maytag

Jun

1949

9

5

0

14

9 (64)

5 (36)

14

Maytag

Jul

2370

13

13

0

26

15 (54)

13 (46)

28

Maytag

Sep

3256

12

20

1

33

18 (43)

24 (57)

42

PineClitf

Jun

1095

6

13

0

19

6 (32)

13 (68)

19

PineClitf

Jul

1603

7

8

0

15

8 (50)

8 (50)

16

PineClitf

Sep

1544

12

31

0

43

13 (28)

33(72)

46

Woodhouse

Jun

1525

4

3

0

7

4 (57)

3 (43)

7

Woodhouse

Jul

2420

8

5

0

13

9 (64)

5(36)

14

Woodhouse

Sep

1568

6

9

1

16

8 (44)

IO (56)

18

17330

77

107

2

186

90

114

204

TOTALS

t Some captured animals were PIT-tagged during previous trapping sessions

Table 2. Number of other small mammal species captured during the June 1998 trapping session at
Maytag ProEerty, PineCliffRanch, and Woodhouse Ranch.

Peromyscus
Date
Site
seeMaytag
27
Jun2
42
Jun 3
Maytag
Jun4
Maytag
48
Jun 5
Maytag
34
53
Jun 7
Maytag
Jun 8
Maytag
39
Maytag
41
Jun 11
Maytag
45
Jun 12
_ 36
Jun 13
Maytag
Jun2
Pine Cliff
36
Jun 3
Pine Cliff
Jun 4
Pine Cliff
39
Jun 5
Pine Cliff
34
22
Jun 7
Pine Cliff
Jun8
Pine Cliff
35
Woodhouse
13
Jun2
Woodhouse
23
Jun 3
Woodhouse
21
Jun4
Woodhouse
12
Jun 5
Woodhouse
13
Jun 7
Woodhouse
18
Jun 8
Jun 14 Woodhouse
16
• )u;i"15· •• Woodhouse
·s
. ..~. ..... ;- ....
-. •. ·-·
'·.•

Reithrodontomys Chaetodipus
megalotis
hispidus
Microtis
Harvest
mice
4
1
0
2
2
2
0
0
6
3
0
0
0
I
4

o· •

Hispid
pocket mice
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
3
1
0
0
ff
.... : . .

spp.
voles
0
0
0
2
4
0

Sorex
spp.
shrews
0
0

4
3
0
0
0
2
0
7
0
2
5
7
3
9
14
6 _.... ·.
.. ••.. ···

0
0
0
0
I
0
0
0
0
0
0
0
0
0
0
0
0
0
1

Mus
Zapus
Neatoma
muscu/us hudsonius mexicana
House
preblei
Mexican
mice
PMJM
woodrat
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0

IO
3
5
4
3
3
5
5

0
0

0
_.......

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

4
2
I
4
2
6
3
3
0

-.· .•...-

··- • •.

()
.• ::.- . .

.~ '! •

�53
Table 3. Number of other small mammal species captured during the September 1998 trapping session at
Maytag ProEerty, PineCliffRanch, and Woodhouse Ranch.

ReithroPero- dontomys Chaetodipus
Mus
myscus megalotis
hispidus
Microtis Sorex musculus
,·'
Hispid
house
spp.
harvest
spp.
spp.
Date
Site
mice
pocket mice
voles
shrews
mice
Sep9
Maytag
30
0
0
0
5
1
Maytag
39
Sep 10
0
0
4
0
1
Sep 11
Maytag
35
4
0
4
0
0
Sep 12
Maytag
35
6
0
8
0
0
31
Sep 13
Maytag
0
0
10
2
Sep 14
Maytag
30
3
0
9
2
0
Maytag
Sep 15
36
2
0
17
2
2
Sep 16
Maytag
31
3
0
16
1
0
Sep9
Pinecliff
15
0
2
0
0
19
Sep 10 Pinecliff
0
0
4
0
Sep 11
Pinecliff
16
0
0
7
1
0
Sep 12 Pinecliff
21
0
0
7
0
0
Sep 13 Pinecliff
18
0
0
II
0
0
Sep 14
Pinecliff
17
0
0
8
0
0
Sep 15
Pinecliff
16
0
0
12
0
Sep 16 Pinecliff
22
0
0
16
1
0
Sep9 Woodhouse
15
0
1
47
2
7
Woodhouse
15
Sep 10
0
0
60
15
Sep 11 Woodhouse
18
70
0
0
21
Sep 12 Woodhouse
18
0
73
2
18
Sep 13 Woodhouse
13
0
67
0
13
Sep 14 Woodhouse
19
0
2
80
0
15
17
Sep 15 Woodhouse
0
3
73
2
14

Zapus
hudsonius
preb/ei
PMJM
12
19
11
8
8

11
9
8

11
8
13
7
12
8
7
14

7
7
6
6
3

Neatoma
mexicana

Mexican
woodrat
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
0
0
0
0

Table 4. Stream reach abundance (N) and density estimates for Preble's meadow jumping mouse (PMJM)
from three sites in Douglas County, Colorado for three trapping sessions. Both adjusted and unadjusted
density estimates (PMJM per km of stream stretch) are reported. Adjustments were made to the density
estimates to account for the EOSitive bias introduced when animals are attracted to a traEline.
Trapping
session

ii

Maytag

Jun

18

Maytag

Jul

31

Maytag

Sep

44

PineCliff

Jun

PineCliff

Lower

Upper

(m)

2.7

15

21

550

32.7

0.80

26.0

11.4

20

42

608

51.0

0.81

41.4

1.8

42

46

494

89.l

0.78

69.3

30

5.7

24

36

490

61.2

0.78

47.5

Jul

17

0.9

16

18

504

33.7

0.78

26.3

PineCliff

Sep

51

3.3

48

54

504

101.2

0.78

79.0

Woodhouse

Jun

11

3.8

7

15

510

21.6

0.78

16.9

Woodhouse

Jul

20

5.2

15

25

516

38.8

0.79

30.4

Woodhouse

Se_Il

]7

2J

~74

J4.8

Q,8Q

20

. .

se(N)

:-.-··

__3.1

... ·.

Trapline
Length

Adjusted
Density

Unadjusted
Density
(PMJM/km)

Site

.... ; •·.- ... -_ ..

95% Confidence
Interval

p

(PMJM/
km)

28

....... -·- .

�1

Colorado Division of Wildlife
Wildlife Research Annual Report
July 2000

JOB PROGRESS REPORT
State of

Colorado

Cost Center 3430

Project No.

W-153-R-13

Mammals Program

Work Package No. --~0'""""6-"-6=-2_ _ _ _ __

Preble's Meadow Jumping Mouse Conservation -

Task No.

Develop Conservation Plan for Preble's Meadow
Jumping Mouse

1

Period Covered: July 1, 1999 - June 30, 2000
Author: Tanya M. Shenk and Gary C. White

---------------------------

ABSTRACT
The second field season of a three year study on the demography and movement patterns of Prebles
meadow jumping mouse (Zapus hudsonius preblei) was completed. A total of 175 individual mice were
captured on stream-side transects at three study sites (60 mice at Maytag Property, 60 mice at PineCliff
Ranch, and 55 mice at Woodhouse Ranch) during the 1999 field season. These captures included 34 mice
PIT-tagged in 1998 (14 at Maytag Property, 12 at PineCli:ffRanch, and 8 at Woodhouse Ranch). These
mice were captured over three different trapping sessions with an effort of 19,222 trap-nights. Most adult
mice captured exhibited evidence of active reproductive behavior, either pregnancy, lactation, or enlarged
genitalia. We were able to locate one potential maternal nest. Juvenile mice were not captured during the
June trapping session. Juvenile mice were captured at all three sites during both the July and September
trapping sessions. Natural mortality factors documented during both years include predation by house cats,
garter snakes, rattlesnakes, yellow-bellied racers, bullfrogs, weasel, and fox as well as accidents by
drowning and ro.µl kill. In 1999 mice were also found in torpor throughout the summer, often in very
exposed areas frequently resulting in death by either exposure or predation. Preliminary analysis of the
movement data collected on radio-collared PMJM in 1999 support results found in 1998. In particular we
were able to document again in this second field season that PMJM exhibit (1) greater use of upland
habitats than previously assumed, (2) general site :fidelity to both daytin1e nesting sites and nighttime
feeding sites, (3) seasonal shifts in movement patterns, and (4) use of both perennial and intermittent
tributaries adjacent to the capture drainage. Detail~ vegetation maps for all three study sites were created
th:-ough intensive field mapping. These maps will be used in conjunction with the movement data to further
refine habitat use information. Thirteen possible hibernacula were located in 1999. Tirree sites were
located at Woodhouse Ranch and ten possible hibernacula at Pine Cliff Ranch. In contrast to 1998 data,
these potential hibernation sites were located closer to the stream. However, at both Pine Cliff and
Woodhouse Ranches stream banks rise out of the floodplain in closer proximity to the stream than at
Maytag Property where the potential hibernation sites located in 1998 were located long distances from the
stream center. Vegetation characteristics of the 21 sites located during both 1998 and 1999 are similar to

�2
other hibernacula described for PMJM. By cooperating with other researchers PMJM densities (mice/km of
stream) were estimated from nine study areas during June 1998 and June 1999, providing a total of 15
study area x year combinations. With these limited data available, 68% of the variation in PMJM density
was explained by a model that includes riparian shrub and tree cover (ha/km stream). These results
suggest that habitat quality of PMJM can be predicted by the riparian shrub and tree cover available on a
site.
Preliminary results from the demography, movement and distribution studies of PMJM have
suggested the need to continue with research questions currently being addressed. However, the
preliminary results also suggest further research be conducted on (1) use of upland and riparian habitat by
PMJM, (2) refining water requirements of PMJM (i.e., do they require stream habitat or are wetland areas
sufficient?), (3) range-wide distributional boundaries (e.g., elevation restrictions), and (4) investigating
areas of potential syrnpatry or hibridization with the western jumping mouse (Z. princeps). The
demography and movement studies were modified for the summer 2000 field season to further investigate
upland use and water requirements, including a habitat modification experiment. This report includes
results from the first two years of a multi-year project to follow individually marked PMJM through time.
Collection of more data, and more years of data, will improve our ability to evaluate demographic
parameters, movement patterns, and habitat use and evaluate how they vary across space and time.

�3

DEVELOP CONSERVATION PLAN FOR PREBLE'S MEADOW JUMPING MOUSE
Tanya M. Shenk an" Gary C. White

P. N. OBJECTIVE
Conservation of Preble's meadow jumping mouse (Zapus hudsonius preblei) in Colorado.

SEGMENT OBJECTIVES FY99-00
1. Estimate abundance, over-summer survival, annual survival, and population age and sex structure of
Preble's meadow jumping mouse at three study sites.
2.. Evaluate movement data of Preble's meadow jumping mouse as it relates to landscape features at three
study sites.
3. Refine and prioritize needed research components to develop sound strategies for conservation of
Preble's meadow jumping mouse.
4. Develop study plan to evaluate meta-population dynamics in Preble's meadow jumping mouse (to be
funded in FY00-01).
5. Prepare a Federal Aid Job Progress Report.

PERFORMANCE INDICATORS FY99-00
1.
2.
3.
4.

Second year survival rate estimates for three populations of PMJM.
Second year abundance and density estimates for three populations of PMJM.
Second year movement patterns for three populations of PMJM.
Study plan for PMJM meta-population study.

INTRODUCTION
On May 12, 1998 the U.S. Fish and Wildlife Service (USFWS) published a final rule in the Federal
Register (63 FR 26517) to list Preble's meadow jumping mouse (Zapus hudsonius preblei) as 'threatened'
under the Federal Endangered Species Act (ESA) of 1973, as amended. Recovery goals for Preble's
meadow jumping mouse (PMJM) should work towards the sustainability;. protection, and restoration of Z.
h. preblei populations and habitats on both private and public lands to provide the spatial, genetic, and
demographic structure needed to promote long-term species viability and provide species management
flexibility. Recovery efforts for the subspecies will be most effective if reliable information is available on
the basic ecology of the subspecies and this information used tc.&gt; design recovery efforts such as Habitat
Conservation Plans. A review of studies conducted on PMJM shows that there is insufficient information
to fully address defining-range-wide ecological requirements, limiting factors, limits of species tolerance, or
population status (Shenk 1998). Most work to date has focused on geographic distribution (presence or
absence of Z. h. preblei), taxonomy, and habitat descriptions of sites where mice have and have not been
captured. For PMJM in particular, information on dispersal, habitat use, and population dynamics is most
needed to identify minimal ecological requirements of the subspecies.
Monitoring, by way of estimating demographic parameters (such as survival, abundance, and
reproduction), of a single population over time provides an opportunity to document demography of a

�4
species, estimate temporal fluctuations in demography, and gain insights into the temporal variation
inherent in demographic parameters. Monitoring of multiple populations over time and over multiple
geographic locations provides the opportunity to gain further understanding of population processes and
detaches time effects from spatial e:f;fects. Population monitoring activities do not constitute scientific
experiments, in the spirit of manipulation of salient ecological variables, however, replication of monitoring
activities for natural populations over long periods of time and in diverse geographic locations can lead to
insights into population processes (Cook and Campbell 1979). These insights can then be translated into
hypotheses useful for predicting changes in population demography resulting from either natural
perturbations (e.g., flooding events) or anthropogenic modifications (e.g., gravel mining). Experimentation
would then be required to test these hypotheses and establish cause and effect.
Movement and dispersal pattern information will be key to any conservation strategy designed for
PMJM. Documenting daily and seasonal movement patterns of PMJM will provide information on habitats
used by the mice and on the relative configuration and juxtaposition of these habitats. Configuration of
habitats include vegetation and size of the areas used. Juxtaposition includes relative locations of different
habitats used such as nest sites, feeding areas, and movement corridors connecting those areas. Key
dispersal factors to document for PMJM include (1) which segment of the population disperses, (2) when
do they disperse, (3) through what habitat do they disperse, (4) how far will individuals disperse (i.e., what
is the maximum distance that separates adjacent populations) and (5) how critical is dispersal (both into
and out of a population) to the persistence of a given population.
Areas of suitable habitat must provide requirements to survive throughout the life cycle. These
requirements must provide necessities for both the active period and hibernation periods. During the active
period suitable habitat must provide requirements for daily survival, reproductive activities (breeding,
nesting, and rearing of young to independence), and dispersal. The hibernation period requires sufficient
food supplies to assure fat storage prior to hibernation and suitable hibernacula. Habitat providing all
seasonal and life cycle requirements may or may not occur in a single contiguous area. If not in a
contiguous area, habitat patches must occur in a mosaic of usable areas where suitable corridors exist for
seasonal movement among sites.
The habitat matrix within the range of Z. h. preblei is mixed grasslands_adjacent to the Colorado Front
Range along the Piedmont and along the base of the Laramie Mountains in Wyoming and extends to the
Colorado plains. Within this matrix, PMJM occur along stream drainages that contain patches of suitable
vegetation. Suitable habitat appears to have at least two major compop.ents. The first component is a
supply of open water, at least in part of the active season. Secondly, areas where PMJM has been found
have dense cover.
Based on studies of Z. h. preblei and Z. hudsonius elsewhere, Z. h. preblei apparently occurs mostly in
undergrowth consisting of grasses, forbs, or both in open wet meadows and riparian corridors, or where tall
shrubs and low trees form an overstory and provide adequate cover (Armstrong et al. 1997). Meadow
jumping mice are widespread in abandoned grassy fields, but are often more abundant in thick vegetation
along ponds, streams, and marshes or in rank herbaceous vegetation of wooded areas (Whitaker 1963).
The mouse does not appear to have an affinity toward any single plant species but instead favors sites that
are structurally diverse and provide adequate cover and food throughout its life cycle. PMJM are typically
not found in upland areas away from riparian habitats but are most often captured where either ground
water becomes visible as either seep springs or as main water channels (M. Bakeman, T. Ryon, personal
communication) suggesting a dependence on open water, at least during their active periods. PMJM have
been trapped in natural riparian areas as well as areas altered by anthropogenic influence including ditches
and wetlands adjacent to interstate highways, cement-lined ditches with tall cover, ditches along driveways
and moderate road. use, and moderate cattle grazing.
If PMJM occurs as metapopulations in the classical sense of a set of local populations linked by
infrequent dispersal then habitat includes not just one area of suitable habitation but also areas suitable for
nearby mouse populations. These suitable areas must also be linked by dispersal habitat. If the mice are

�5
dependent on dense riparian habitat for dispersal as well as for areas to reproduce, persistence of discrete
populations would require a mosaic of suitable discrete riparian patches interconnected with dispersal
corridors of similarly dense riparian vegetation. If mouse populations function in a source (populations
where growth rate~ 1) and sink (those populations where growth rate&lt; 1, maintained through
immigration) system, it will be critical to identify and protect those populations serving as sources. Thus,
for a source-sink population critical habitat will include those areas that support source population,
dispersal habitat to sink areas will be less critical. If local mouse populations are functionally discrete,
such a mosaic of interconnected areas of suitable habitat would provide a buffer for local, and source,
populations against deleterious stochastic events by providing the opportunity for local population failures
to be 'rescued' by immigration from other populations.
The primary objective of this study is to investigate spatial and temporal variation in the demography
and movement patterns of PMJM. Demographic parameters to be estimated include survival, reproduction,
temporary emigration, immigration, population structure, and density. These demographic parameters will
be estimated from individually marked animals from geographically distinct populations. To evaluate
spatial differences in the demography of PMJM, populations were selected from three sites that provided a
variety of habitat matrices available to the mouse. To begin to understand PMJM movement, dispersal,
and habitat use we monitored radio-collared mice at three different study areas .. Study areas were selected
to cover a variety of habitat configurations to evaluate spatial variation: in movement patterns of PMJM.
Multiple years of conducting the study at those same sites will provide an estimate of the temporal variation
in demography and movement patterns of PMJM.

STUDY SITES
Demography and movement patterns of PMJM are being evaluated for three populations. All three
populations selected were located in areas where PMJM had previously been found. To evaluate spatial
differences in the demography and movement patterns of PMJM, populations were selected on sites that
provided a variety of habitat matrices available to the mouse. The first site selected, Colorado Division of
Wildlife (CDOW) Maytag Property, has one primary water source available to the mouse. This water
source is East Plum Creek. The second site, PineCliff Ranch, provides both a tributary (Garber Creek)
and a main stem drainage (West Plum Creek). This provided the opportunity to investigate whether PMJM
will use upland areas to move from one drainage to another or if they are restricted to only moving along
riparian corridors. The third study site, CDOW Woodhouse Ranch provides an area containing a tributary
(Indian Creek) and a series of ponds and irrigation ditches scattered throughout the property. The
configuration at Woodhouse Ranch provided an even greater opportunity to investigate how much the mice
use upland areas or if they restrict their movements strictly to riparian corridors. By replicating the same
methodologies at each of these three unique habitat matrices we can begin to estimate spatial variation in
nightly and seasonai movements of PMJM.
•
,,

OBJECTIVES
Objectives of the demography study are to:
1. Estimate abundance and density of PMJM for each of three study populations.
2. Estimate over-summer, over-winter, and annual survival of PMJM at each of three study populations.
3. Estimate temporary emigration of PMJM at each of three study populations.
4. Estimate immigration of marked PMJM back into each of three study populations.
5. Estimate reproduction of PMJM at each of three study populations.
6. Evaluate the affect of weight, sex, age, abundance (i.e., density dependent response), and habitat
features such as stream reach, vegetation composition and density on survival, reproduction,
abundance, temporary emigration, and immigration of marked animals back into three study
populations of PMJM.

�6
7. Estimate age and sex ratios of PMJM at each of three study populations.
The PMJM movement study is designed to describe nightly and seasonal movement patterns of PMJM
and to describe habitats used by PMJM. These movement patterns will be described for three different
study areas to evaluate spatial variation, and over three different years at the same three study areas to
evaluate temporal variation. Specific objectives include:
1. Describe nightly movements of PMJM. Evaluate difference in nightly movements as they relate to sex,
age, and habitat available to the animals.
2. Describe 30-day (or life of the radio transmitter) interval movements of PMJM. Evaluate difference in
30-day (or life of the radio transmitter) interval movements as they relate to sex, age, and habitat
available to the animals.
3. Describe seasonal movements of PMJM. Evaluate difference in seasonal movements as they relate to
sex, age, and habitat available to the animals.
4. Describe habitats where mice occur: movement corridors, end point descriptions (i.e., movement from
what to what), and landscape features (connectivity with other riparian areas and other habitats used).
5. Estimate the mean amount of time PMJM spend in each available habitat.
6. Evaluate spatial and temporal variation in movement patterns of PMJM.
The objective of the habitat use study is to identify and refine habitat requirements of Z. h. preblei,
including hibernation sites, and to determine if they influenced any of the demographic parameters that will
be estimated in this and complementary studies (see Shenk and Sivert 1999a, 1999b).

METHODS
See Shenk and Sivert (1999a, 1999b) for field methods.

RESULTS
Demography Study
Trapping and PJT-tagging Effort
A total of 186 individual PMJM were captured from the three study areas during the three 1998
trapping sessions (fable 1: 73 at Maytag Property, 77 at PineCliffRanch, and 36 at Woodhouse Ranch).
These mice were captured over three different trapping sessions with an effort of 17,330 trap-nights. Every
PMJM captured was PIT-tagged, providing each mouse with a unique, permanent, life-time identification
marker.
A total of 175 individual mice were captured on stream-side transects at three study sites during the
1999 field season including 34 mice PIT-tagged in 1998 (fable 1). These mice were captured over three
different trapping sessions with an effort of 19,222 trap-nights.
Other small mammals captured during the trapping sessions included Peromyscus spp., Mexican wood
rat (Neotoma mericana), house mouse (Mus musculus), vole (Microtis spp.), western harvest mouse
(Reithrodontomys megalotis), hispid pocket mouse (Chaetodipus hispidus), and shrew (Sorex spp.). See
Shenk and Sivert (1999a) for details of 1998 field season.
Reproduction
During both 1998 and 1999, most adult mice captured exhibited evidence of active reproductive
behavior, either pregnancy, lactation, or enlarged genitalia. We were able to locate one potential maternal
nest in 1999. Juvenile mice were not captured during either June trapping sessions. Juvenile mice were
captured at all three sites during both the July and September trapping sessions in both years. No estimates
of reproduction could be made.

�7

Survival
Survival rate was estimated using the mark-recapture estimator for Pollock's Robust Design (see
Kendall et al. 1995, 1997 and Kendall and Nichols 1995 for detail) in Program MARK (White and
Burnham 1999). The robust design is a combination of the Cormack-Jolly-Seber (CJS)(Cormack 1964,
Jolly 1965, Seber 1965) live recapture model and the closed capture models. The best fitting model
combined data from all three study sites over all three trapping sessions in 1998. Survival was estimated
as 0. 75 (se = 0.033) for a five week period in 1998. Extrapolating this survival rate across the summer
results in an over-summer (June 1- October 5, 18 weeks) survival rate of 0355 (se = 0.056). No estimates
of over-winter or summer survival in 1999 have been completed.
Temporary emigration and immigration
Temporary emigration rate and immigration was estimated using the mark-recapture estimator for
Pollock's Robust Design in Program MARK. The best fitting model combined data from all three study
sites over all three trapping sessions for these two parameters. Temporary emigration was estimated as
0.64 (se = 2.21), immigration was estimated as 0.45 (se = 89.94).
Age and Sex Ratios
As expected, no juvenile PMJM were captured during either June trapping session as it was too soon
after hibernation for any litters to have been born and/or if born the juveniles would still be restricted to
their nests. Juvenile mice were captured during both the July and September trapping sessions at all three
sites in both years. Juveniles as small as 10g were captured. Sex ratios may be biased towards males,
however further analyses need to be completed to confirm this hypothesis (Table 1).
Density

,.,

Mark-recapture analysis was used to estimate abundance ( N) at each of the three study sites (Maytag
Property, Woodhouse Ranch, and Pine Cliff Ranch) for each of the three trapping sessions in 1998 and for
June 1999 (Table 2) using Program MARK (White and Burnham 1999) and Program CAPTURE (Otis et
al. 1978, White et al. 1981). These abundance estimates and length of the trapline were used to estimate an
unadjusted density of mice per kilometer of stream stretch. However, mice that typically don't use the area
of stream stretch where the traps were placed could be· trapped because they were attracted to the area by
the artificial food source. Including these mice in the density estimates for the stream stretch covered by
the trapline would artificially increase density estimates. Therefore, an adjustment parameter was
estimated to calibrate density estimates for a more realistic estimate of PMJM per kilometer of stream
length. Without the adjustment densities would be inflated.
In collaboration with other PMJM researchers (M. Bakeman, C. Meaney, T. Ryon, and R. Schorr)
population estimates ( N) for a specified length of stream were determined with capture-r~pture
techniques using Program MARK (White and Burnham 1999) and Program CAPTURE (Otis et al. 1978,
White et al. 1981) for nine study areas over two years for early season trapping (June) only. To make
these estimates comparable across study areas with unequal lengths of stream reaches trapped, mouse
density (mice/km of stream) must be computed. However, traps tend to attract mice from some unknown
distance, so that naive density estimate of N divided by stream length is biased high. To remove this bias,
radio-tracking data were used to estimate the proportion of tiine (p) radio-collared mice spent within the
original trapline once the traps were removed. Data from six study areas (Table 3) provided by this study
and the study conducted by T. Ryon at Rocky Flats were used to estimate this correction factor (p) for
population estimates from linear traplines or grids. Only these study areas had radio-collared mice
available from which to estimate the correction factor. Corrections were applied to all study areas with the
function relatingp to trapliri.e length (L) developed from these data.

�8
The Michaelis-Menton model was fit to the observed p value:

L;

P; = - - - L;+2BSW
where L; is the length of the trapline for grid i. Nonlinear least squares were used to minimize the sum of
squared E; values to obtain an estimate of the unknown parameter, BSW (i.e., boundary strip width).
Observations were weighted by the number of radi~llared mice providing the observed value of pi.
Because the variance of a proportion is a function of the value of the proportion, a logistic transformation
was used to stabilize the variances of the E; across the range of the P; values:

Li + 2BSW
Li

1 - ----Li + 2BSW
Predicted values ofp (p) are obtained from either fitted model for a particular trap line length (L) by
substituting the estimate of BSW into the predictive equation:
A

L

p = L + 2BSW.
Estimates of BSW for the two estimation methods are shown in Table 4, predicted values are shown in
Table 3, and the fit of the two fitted equations is shown in Figure 1.
The parameter estimate from the logistic transformation model was used to correct the population
estimates, i.e.,
A

L

p=-----.

L + 2x4I.5446

This model was preferred because of the variance stabilization provided by the logistic transformation.
However, as shown in Figure 1, the difference in the predictions of the two fitted equations is not
biologically important.
To obtain an adjusted number of mice on a trapline or trapping grid, the estimated population on the
grid (N) from mark-recapture estimation is multiplied by the correction (ft) from the above equation to
give the adjusted number:

The variance of Nadj is computed as the variance of a product using the delta method:

�9

where
var(p) = 4L 2 var(BSW) .
(L + 2BSW)4
Similarly, density (mice per unit of length of stream) is computed. as the adjusted. population size divided by
the length of the trapline or the original trapline or grid population estimate over the adjusted. length of the
trapline:

·"

Nadj

N

L

L + 2BSW

D=--=----

The variance of D is computed. using the delta method:

D = var(Naqj) = _ _ _
1 ___-var(N) +
N2
var(BSW) .
2
4
2
L
(L + 2 *BSW)
(L + 2 *BSW)
A

Note that Var(BSW) = SE(BSW)2 with SE(BSW) given in Table 4. •As an example of the variance of
p, a trapline length of 500m results in SE(p) = Jvar(p) = 0.02696. Confidence intervals on the fitted

function of pare shown in Figure 2, computed. as ft±l.96xSE(p).
An alternative approach to computing-confidence intervals on p that we would have thought would
work better than the ±1.96SE(p) intervals shown in Figure 2 is to compute the confidence interval on the
logit(p), and then back.;.transform the interval endpoints:

1

1

1 + exp(-(Iogit(p) - 1.96SE(logit(p))]' 1 + exp(-Vogit(p) + 1.96SEQogit(p))]

where SE(logit(p)) = SE(BSW) = 9.1676/41.5446 = 0.22067 for the data presented. here. After
BSW
• -·
computing confidence intervals by both methods, the results were only negligibly different, with the •·
maximum difference in the interval lengths being only 0.00111 over the range of L from 100 to 2000m.
Riparian Vegetation Cover Data
1'.otal area of riparian shrubs,trees, herbaceous cover, non-vegetated, and open water were computed
for each $tlldy area from riparian vegetation maps (fable 5). These riparian maps were developed from
photo interpretation of infrared aerial photography at a resolution of 1:24,000. Areas of riparian vegetation
were calculated when patches of vegetation were greater than 24 m wide. To estimate area of each
riparian vegetation classification for each study area, stream length for each study area was delineated on
the riparian vegetation map. A 200-m buffer was then generated on either si~ of the study area stream
reach. Within this 200-m buffer total area (ha) of patches with dominant vegetation classified as riparian

�herbaceous, riparian shrub, riparian tree, non-vegetated, and open water were calculated using Arcinfo
(ESRI 1987). No ground truthing of vegetation classification was performed.
Statistical Analysis ofPMJM Density and Riparian Vegetation Cover
The adjusted density and areas of riparian vegetative cover per km of stream (fable 5) were used to
assess the relationship between PMJM density (mice/km of stream) and riparian vegetation cover.
Estimates for multiple years for study areas were treated as separate estimates so that the year-to-year
variation in PMJM density could be evaluated.
An AN OVA of PMJM density for study area and year effects suggested no differences between years
(1998: = 35.08, SE= 8.85; 1999: = 31.04, SE= 6.29; P = 0.511) or across study areas (P = 0.245).
The variation in PMJM density across study areas is what we want to ex.plain with riparian vegetation
cover differences across study areas.
Individually, none of the vegetation cover variables were important predictors of PMJM density (fable
6). When model selection following Burnham and Anderson (1998) was performed across all models
involving the riparian shrub, tree, herbaceous, non-vegetated, and open water cover (ha/km stream )
variables, the best AICc model was shrub and tree cover (fable 7) ex.plaining 68% of the variation in
PMJM density. The next best model included open water as well as shrub and tree cover, explaining 71 %
of the variation of PMJM density. The combination of riparian shrub and tree cover appears to be an
important set of predictors for PMJM density based on the study areas included in this analysis.
The parameter estimates for the best AICc model are shown in Table 8, and a residual plot in Figure 3.
All riparian vegetation cover variables have positive slope parameters, indicating a positive influence on
PMJM density over the range of the vegetation cover variables considered in this analysis.

x

x

Movement Study
Radio-tracking effort
.
A total of 125 radio-collars were put on mice over the three trapping sessions in summer 1998 (fable
9: 48 at Maytag Property, 47 at PineCli:ffRanch, and 30 at Woodhouse Ranch). A total of 62 females and
63 males were radio-collared over the 1998 field season. A total of 138 radio-collars were put on mice
over the three trapping sessions in summer 1999 (fable 9: 51 at Maytag Property, 52 at PineCliffRanch,
and 35 at Woodhouse Ranch). A total of 57 females and 81 males were radio-collared and tracked in
1999.
Daily movements
The general daily movement pattern throughout the active season was for mice to become active at
dusk, remain active through the night, and to return to a day nest location at dawn. Most of our tracking
was confined to night time movements; however we did make a greater effort in 1999 to confirm the mice
were primarily in day nests during daylight hours. This was true for most daytime observations, however
on occasion mice were active in the daytime as well.
Percent of PMJM locations, as determined from radio-tracking, at each of three distance categories
were calculated for each study site and the latter two radio-tracking sessions in 1998 (see Shenk and Sivert
1999b for details). The majority oflocations at Maytag, PineCliff: and Woodhouse were within 46m of
stream center for both tracking periods (July-August and September-October). For all areas and tracking
periods except Maytag during the last tracking session, 90% of PMJM movements were within 9 lm of
either side of the center of the capture drainage. Mouse movements at Maytag during September-October
resulted in 32.6% of the locations being&gt; 91m from the stream center. Similar patterns were observed for
1999.
•
During nigh.time activity periods more than one mouse would often be found foraging in the same area.
These foraging areas were often the same areas used by the same mice on numerous consecutive nights

�11
Seasonal movement
Field methods used in June 1998 did not allow us to document accurate June movement patterns for
that year. The distribution of mouse locations in 1998 at Maytag Property for the July-August tracking
session is different from the distribution of PMJM locations for the September-October tracking session.
In 1998, the pattern shifted from heavy use along East Plum Creek to the north of the trapline to a more
concentrated distribution either side of the trapline. The more concentrated use of the areas east and west
of the trapline also resulted in locations being further from the center of the creek. The northern end of the
trapline is largely vegetated by willows with the remainder of the trapline more diversely vegetated. In
1999 we were able to document movements for all three tracking sessions. Greatest movement away from
the center of the stream occurred in the August session.
In 1998, mouse movements were more concentrated along the drainages at PineCliff Ranch during the
September-October tracking sessions than during the July-August tracking sessions. Vegetation along both
West Plum Creek and Garber Creek along the trapline was primarily willow. In 1999, greatest movements
from either stream center were documented during the August tracking session.
At Woodhouse Ranch, the distribution of mouse locations also shifted between tracking sessions.
Mouse movements during June 1999 were the most diverse of all tracking sessions. Mouse movements
were more concentrated along the southern half of the trapline in September-October as compared to the
more even distribution of mouse locations recorded for July-August in both 1998 and 1999. The northern
end of the trapline is dominated by willows, the middle and southern end of the trapline is in more diverse
riparian habitat.
In September 1999 we had fewer mice radio-collared at each of the three sites because we were not
able to trap mice. We assume the majority of the mice had already hibernated by the time we started our
last trapping effort on September 9, 1999.
Over the two-year study, 27 PMJM were captured, radio-collared, and tracked for more than one
tracking session (fable 10) . Other mice were captured during more than one trapping session but radio
collars were not replaced either because all the radio collars had been put on other mice or because the
physical condition of the animal was such that we decided not to replace the radio-collar. Such conditions
included mice who had significant hair worn off the neck from the previous radio collar. In no incidence
did we find open wounds caused by radio collars.
Of the 27 mice radio-collared for more than one session, we have only analyzed the mice captured in
1998. Of those, four provided information to evaluate seasonal changes in areas and habitats use between
the July-August tracking period and the September-October tracking period: One mouse, a male from
Maytag was observed only once during the September-October tracking session, providing no information
concerning seasonal changes in movement patterns. Thus, changes in areas used by individual mice
between June and either the July-August or September-October tracking session are not summarized here.
A female at Maytag exhibited a seasonal movement shift, small sample size prohibited any evaluation
of the movement patterns of the Maytag male (n = 1 in September-October). There does not appear to be
any shift in areas used by the male tracked during both latter sessions at Pine Cliff Ranch, however, sample
sizes were small (n = 17, 14). Two females at Woodhouse Ranch exhibited a shift in areas used between
July-August and September-October. However, caution should be used in interpreting these results
because of low sample sizes in the latter tracking session (n = 14, 6).
Annual variation in movement patterns
Preliminary comparisons of mouse movements from 1998 to-1999 for tracking sessions August and
September were completed. Mouse movements during August tracking sessions were similar at Maytag
Property. More mice were captured on the southern half of the Maytag Property in 1999 and this is
reflected in the greater nUiilber of locations in the southern half of the property for that year. The same
area located outside a 100m strip from the stream center was used both years during this tracking session
and was comprised primarily of a seep area. August movements at Pine cliff Ranch were further from the

�12

stream in 1999. Mice were also found using an ephemeral stream in August at PineCliff Ranch in 1999.
1bis stream was dry at the time. Similar mouse movements were observed at Woodhouse Ranch over both
August tracking sessions although movements were more concentrated in the north in 1998 and more
concentrated in the south in 1999;
Temporal comparisons of mouse movements in the September tracking sessions are not entirely
comparable because fewer mice were followed in the 1999 September tracking session because we were not
able to capture mice. We assume a large portion of the mice in 1999 were already hibernating when we
started our September trapping and radi~llaring session. We did not observe the greater movements
away from the stream center at Maytag in 1999 that we observed there in 1998, however we probably
missed most of the movements to hibernation sites. Movement patterns at PineClifffRanch and
Woodhouse Ranch were similar for both September tracking sessions with movements being more
concentrated near the stream. The same feeding hotspot at Woodhouse Ranch was used both years in
September.
Habitat Use
Detailed vegetation maps were created using Global Positioning Systems. Combining these vegetation
maps and locations of mice we will be able to describe in further detail habitat use. These analyses are not
yet completed.
Nest sites
Numerous daytime nest sites were located at all three study sites from both years. Most nest sites were
made of tightly woven vegetation, located on the ground. However, we also located underground daytime
nests in summer 1999. Nest material included leaves, grass, and small sticks. There was only one small
entrance hole on each of the nests found. When observing mice in their nests the mice would peer out of
the hole and remain motionless as long as we were present. One possible maternal nest was located in
1999. This possible maternal nest was underground, made of densely packed grasses with the burrow lined
as well. There also were several locations at each of the study sites where adult females returned to
repeatedly. Each of these sites were in patches of extremely dense vegetation or underneath a large downed
log.
Hibernacula
Potential hibernation sites were located by noting stationary radio-telemetry signals over repeated
nights. These signals were coming from underground with no evidence of predation or slipped collars.
Eight potential hibernacula were located, at least one at each study site in 1998. In 1999 a total of 13
potential hibernation sites were located. Three were located at Woodhouse Ranch (I female, 2 males) and
IO sites at PineCliffRanch (2 females, 8 males). In contrast to 1998 data, these potential hibernation sites
were located closer to the stream. However, at both Pine Cliff and Woodhouse Ranches stream banks rise
out of the floodplain in closer proximity to the stream than at Maytag Property where the potential
hibernation sites located in 1998 were located long distances from the stream center.
Vegetation characteristics of the eight sites located during both 1998 and 1999 are similar to other
hibernacula described for PMJM. Hibernation sites are considered potential until the sites can be dug up to
confirm a hibernation chamber. One male mouse was dug up at Pine Cliff Ranch in 1999 to confirm the
site as a true hibernation location and to gain information on the hibernation nest and chamber. The mouse
was in the chamber and was not aroused when the earth was dug out around him. Once we finished our
assessment of the nest the soil was put back in place, leaving the mouse in the chamber. The remaining
hibernation sites will be dug up in June 2000 so as not to disturb other hibernating mice. We hope to
confirm these sites as hibernation sites then and will document features of the hibernation sites at that time.

�13

Mortality factors
Mortalities factors of radicxollared mice in 1998 included predation by rattlesnake, garter snake, fox,
and house cat. Four probable predations were also noted and identified by finding tightly crimped (i.e., no
possibility of the mouse having slipped the collar over its head) radio-collars lying on the ground. Two
accidental deaths were documented, a road kill and drowning. Mortality factors also included trapping
and/or handling mortalities and unknown causes. In 1999 mortality factors also included predation by
bullfrogs, weasel, and yellow-bellied racer (Table 11). Nine mice also died once they entered a state of
torpor above ground. These mice either succumbed to cold or were predated on.
Fecal analysis
The amount of bait found in each of the fecal samples was quantified as either 100%, abundant(&gt;
70%), trace(&lt; 10%) or 0%. The following summaries are made after eliminating all samples of 100%
bait, and then only classifying the fecal sample contents other than bait.
Fecal analyses indicate a seasonal shift in diets. The most common item found in the fecal samples
during the June trapping session at all three sites for 1998 were arthropods. This was true for three of the
five June samples collected at Maytag, eight often June samples at PineCliff, and four of five June samples
collected at Woodhouse. Other common items included endogenous fungus (1) and seed (1) at Maytag;
endogenous fungus (2) at PineCliff,; and Poa (1) at Woodhouse.
During the July 21-August 4, 1998 trapping session the most common items in the fecal samples at
Maytag were arthropod (2), endogenous fungus (1), pollen (1), and Carex (1). During the same trapping
period, the most common items in five of eight samples collected at PineCliff were endogenous fungus, the
other three samples having a majority of arthropod (1), moss (1), and pollen (1). The two samples from
Woodhouse during this trapping session were composed primarily of either mushroom or seed.
On August 13, 1998, nine samples were collected during an extra trapping session (on the same
trapline as the other trapping sessions occur) with the most common items in the fecal samples being moss
(4), endogenous fungus (3) or pollen (2). All three samples collected from PMJM captured at a back
drainage on August 23, 1998 at Woodhouse Ranch were primarily fungus.
The September 1998 trapping session at Maytag yielded samples with majority fecal contents of
arthropod (2), moss (2), pollen (2), endogenous fungus (1), and seed (1). Ten samples from PineCliff
during September 1998 had majority fecal contents of arthropod (3), endogenous fungus (3), and seed (3).
Eight of nine samples taken from Woodhouse contained primarily arthropods, with one a trace of seed.
A total of 329 fecal samples were collected during the 1999 field season. Analyses of these samples
have not been completed. We also collected 16 stomach samples from dead mice. Analyses of these
stomach samples are not yet completed.
DISCUSSION
Information on the population dynamics of PMJM is necessary to determine which areas and habitats
support viable populations. To begin to evaluate the viability of a population information on key
demographic parameters must be obtained. Conducting studies on individually marked animals provides
the greatest insight on the demography of a population.
In general, estimated sex ratios from this study are comparable to those found by Armstrong et al.
(1997) who reported an overall sex ratio for all captured PMJM of51.6 males: 48.4 females;
approximately 86.0% of captures were identified as adults. There is a possible male sex bias at PineCliff
Ranch. However, small sample sizes and possible trapping biases by sex may explain the discrepancy.
Density estimates were expected to increase as the summer progressed to account for the birth pulses in
late June, and late July-August. In 1998, this was the trend observed at Maytag. PMJM densities at
Wcxx:lhouse Ranch increased from June to July but did not increase further during the September trapping
session. Highest densities occurred at PineCliff, where the vegetation is primarily willow and both a

�14
mainstem and tributary were used by mice. Lowest densities occurred at Woodhouse Ranch where the
riparian vegetation has fewer willow but was dense with other riparian vegetation. Vegetation at Maytag
provided some areas of dense willow with the remaining areas being of moderate density of riparian
vegetation. The lower density of PMJM reported for Woodhouse Ranch might be explained by the
composition and densities of other small mammals at that site. Woodhouse Ranch had the highest captures
of both house mice and voles of the three sites studied.
Defining summer as June 1 - October 5, over-summer survival was estimated as 0.36 (se = 0.056) over
all three study sites. Meaney et al. (1999) report a one-month summer survival rate of 78%. Extrapolating
Meaney et al. 's ( 1999) estimate over our summer period (- four months) would result in a similar oversummer survival rate estimate of 36%. Prior to studies conducted in 1998 no information existed on
survival rates for populations of Z. h. preblei although Whitaker (1963) reported a 67% loss of Z.
hudsonius over hibernation. Temporary emigration and immigration rates were estimated but both had
extremely high variances associated with those estimates. Thus these estimates cannot be used, with any
confidence, to provide information on movements of mice into and out of these populations.
Very little new information was gained during this study on reproductive parameters of PMJM. Most
adult mice captured exhibited evidence of active reproductive behavior, either pregnancy, lactation, or
enlarged genitalia. Juvenile mice were not captured during the June trapping session. Juvenile mice were
captured at all three sites during both the July and September trapping sessions. Given that breeding pea.ks
appear to occur in early to mid-June and August with a possible third litter in September (Whitaker 1963)
this was not unexpected and agrees with previous observations (Meaney et al. 1996, 1997, PTI 1996a, M.
Bakeman unpublished data, T. Ryon unpublished data)
Preliminary analysis of the movement data collected on radio-collared PMJM in 1999 supported results
found in 1998. In particular we were able to document again in this second field season that PMJM exhibit
(1) greater use of upland habitats than previously assumed, (2) general site fidelity to both daytime nesting
sites and nighttime feeding sites, (3) seasonal shifts in movement patterns, and (4) use of both perennial and
intermittent tributaries adjacent to the capture drainage.
Jumping mice of the genus Zapus are true hibernators, spending much of their lives in hibernation.
Meadow jumping mice spend approximately 7 months (-210 days) per year in hibernation (Quimby 1951)
whereas estimates for Z. princeps indicate that some populations (e.g., in the western mountains of Utah)
spend up to 300 days per year in hibernation (Cranford 1983). Jumping m.i,ce hibernate in underground
burrows (Quimby 1951, Whitaker 1963). They are excellent burrowers and create their own hibemacula.
Meadow jumping mice are generally solitary hibernators, however, there have been occurrences of more
than one mouse found in a single hibemaculum. Eight possible hibemacula were located during 1998. Five
of the eight mice using these possible hibernacula traveled ~ 90 meters from the center of their typical
September night time locations. Of the 13 possible hibemacula located in 1999, three sites were located at
Woodhouse Ranch and ten possible hibemacula at Pine Cliff Ranch. In contrast to 1998 data, these
potential hibernation sites were located closer to the stream. However, at both Pine Cliff andWoodhouse
Ranches stream banks rise out of the floodplain in closer proximity to the stream than at Maytag Property
where the potential hibernation sites located in 1998 were located long distances from the stream center.
Vegetation characteristics of all the potential hibemacula located over both years are similar to other
hibemacula described for PMJM. One confirmed hibernaculum, located on Rocky Flats Environmental
Technology Site, used by Z. h. preblei has been located (Armstrong et al. 1997). This site was 9m above
a creek bed (Walnut Creek); it had a thick cover of chokecherry (Prunus virginiana) and snowberry
(Symphoricarpos spp.), the mouse was found in a leaf litter nest 30cm beneath the ground in coarse
textured soil (Armstrong et al. 1997). Four possible hibemacula were located by tracking radiotelemetered mice at the U. S. Air Force Academy in fall 1997. These sites are located 7, 12, 29, and 3 lm
from a creek bed (R. Schorr, unpublished data). There was no consistency among sites in aspect. Three
sites were in vegetation dominated by coyote willow (Salix exigua), one site was in vegetation dominated
by snowberry and mullein (Verbascum thapsus). However, all four hibernacula appeared to be below

�15

coyote willows. The eight sites located during this study and the four U. S. Air Force Academy sites were
not disturbed to protect any hibernating mice and therefore are only possible hibernacula because there is
no confirmation a mouse actually hibernated there. Confirmation of a true hibernaculum cannot be made
until a chamber, or nest is located. The other explanation for these collar locations might be either locations
of radios discarded by the mice or dead mice carried underground by a predator. Location or more
hibernation sites was limited primarily by normal battery failure of the radio transmitters before mice went
into hibernation.
Prior to the 1998 field season, natural mortality factors reported for Z. hudsonius included only
insufficient fat storage prior to hibernation (Whitaker 1963), predation (Whitaker 1963, Poly and Boucher
1997, R Schorr unpublished data) and cannibalism (Sheldon 1934). Other assumed natural mortality
factors for Z h. preblei included starvation, exposure, and disease. Natural mortality factors documented
during this study included predation by house cats, garter snakes, rattlesnakes, yellow-bellied racers,
bullfrogs, weasel, and fox as well as accidents by drowning and road kill. In 1999.mice were also found in
torpor throughout the summer, often in very exposed areas frequently resulting in death by either exposure
or predation.
Use of ephemeral drainages was observed at both Maytag Property (in l 998) and Pine Cliff Ranch (in
1999), Two mice moved away from East Plum Creek at Maytag Property in September 1998 and focused
their movements ~300 meters from their previous locations, up a dry drainage dominated by upland grasses
and gambel oak. These two mice continued to use this new area and were not observed again near East
Plum Creek for at least two weeks. Normal radio-failure (i.e., batteries failed after ~4 weeks) after this
time did not allow us to determine if the mice ever returned to East Plum Creek or if they hibernated in their
new location. Use of the ephemeral drainage at Pine Cliff Ranch occurred in the August tracking session.
The high percentage of arthropods and endogenous fungus found in the fecal samples provides a new
aspect to evaluating PMJM habitat requirements. When considering habitats used by PMJM, or in trying
to predict habitats that might be suitable for the subspecies, consideration should be given as to whether
those habitats could support the arthropods and fungus apparently being selected for by the mouse.
Arthropods are a food source high in protein and fat which would benefit mice emerging from hibernation
and mice preparing for hibernation. Whitaker ( 1963) reported a 67% loss of individuals over hibernation
and that average body mass of individuals emerging from hibernation was greater than the average for mice
entering hibernation. Because no mice are known to store food in their hibernacula, this indicates that the
lighter individuals died during hibernation and only those entering with higher masses survived. All the
energy they use during hibernation and the periodic arousals (the energetically most expensive part of
hibernation) must be the fat they carry into hibernation (B. Wunder, personal communication). The ability
to put on sufficient fat for overwinter survival during hibernation is a critical factor in the life history of
these mice. Thus, appropriate and sufficient food sources must be available to the mouse to meet these
nutritional requirements.
The apparent seasonal shift in mouse movements between the July-August and September tracking
sessions may be a result of diet switching. The broader diets suggested by the fecal analyses from samples
collected during July and August possibly represent both a wider availability of suitable foods and the
ability of PMJM to exploit these resources. It might also suggest a need to exploit these other resources to
provide the. mouse with necessary food requirements for breeding. Because mice tracked during each
session were not generally the same mice there is a possibility these apparent movement shifts might only
be different areas used by different mice. The probability of this being the case is small for two reasqns.
The first is the low density of mice in the stream (Shenk and Sivert 1999). Given that, the proportion of
mice followed during each session is a high p:,;-oportion of the mice in the population. Thus, each subset of
mice should be representative of the population. Secondly, evidence from the four mice followed during
both the latter tracking sessions also exhibited movement shifts between sessions.
The combination of shifts in both general mouse movements, individual mouse movements, and diet
provide strong circumstantial evidence that PMJM may be selecting for or require specific seasonal diets. If

�16
this is the case, all these requirements must be considered and provided for to ensure conservation of the
subspecies. A detailed literature search and further studies need to be conducted to investigate the possible
implications of these dietary patterns.
In comparing movement patterns from 1998 to 1999 we were able to evaluate annual variation in daily
and seasonal movement patterns of PMJM. General patterns that emerged from the comparison of the two
years included (1) similar areas being used by the mice over both years, (2) greater use of upland habitats
than previously assumed, (2) general site fidelity to both daytime nesting sites and nighttime feeding sites,
(3) seasonal shifts in movement patterns, and (4) use of both perennial and intermittent tributaries adjacent
to the capture drainage.
This study looked at PMJM movements at only three sites. These sites were selected based on known
presence of PMJM. Other sites, perhaps because of different habitat configurations or sites of poorer
quality may require mice to move further from the creek or may allow mice to remain closer to the creek in
order to obtain all life requirements. However, these study sites were specifically selected to address
spatial variation in movement patterns of PMJM due to different spatial configuration and juxtaposition of
habitats. And although all study sites were different they could all be considered within the general
description of what is consider typical habitat for PMJM.
It should also be noted that we generally trapped along the creek. Thus, mice captured and
subsequently radio-collared and followed were those mice that use the area near the most prominent
drainage. If there are mice that do not regularly use the main channel and thus were not available for
capture there would be a bias in the data towards fewer observations 300 feet away from the creek. To test
for such a bias, traps were placed 300 m from the stream center at Maytag and Woodhouse Properties
during suminer 1999 as part of a Master's Project conducted by a student ay Colorado State University.
Capture of mice in transects placed away from the stream lends further support for use of habitats further
from the creek than initially thought. Mice captured 300 meters from the stream moved near their capture
site and between the capture site and the stream.
The prevailing idea of what constitutes quality PMJM habitat is amount of riparian shrubs. Therefore,
we focused our analysis on describing the relationship between PMJM densities and amount of various
riparian vegetation cover, including riparian shrubs. This analysis is not meant to identify all critical
components of PMJM habitat. For example, if a necessary component of PMJM habitat is open water,
but not necessarily in any large amount, this analysis would not detect this relationship.
The best model describing the relationship between PMJM density and riparian vegetation cover
included shrub and tree cover, the next best model included open water as well as shrub and tree cover.
Tree cover may also reflect shrub and herbaceous cover, because the tree canopy likely may be covering
these other understory vegetation classes . Thus, results from this analysis appear to support the
hypothesis that riparian shrubs are an important component of PMJM habitat. However, because the study
areas included in this analysis were not randomly selected from all possible PMJM habitats, the
conclusions reported here must be treated with some caution. To truly assess the relationship between
PMJM density and riparian vegetation would require estimating densities from a random selection of areas
presumed to have suitable PMJM habitat. Analysis of how the riparian vegetation characteristics at these
study sites relates to their PMJM densities would then provide an unbiased estimate of the relationship.
With.the limited data available, 68% of the variation in PMJM density is explained by a model that
includes riparian shrub and tree cover (ha/km stream), as identified by the vegetation mapping techniques
used in this study. These results suggest that habitat quality of PMJM can be predicted by the shrub and
tree cover available on a site.
This report includes results from only the first two years of a multi-year project to follow individually
marked PMJM through time. Further analyses of these data, collection of more data, and more years of
data, will continue to improve our ability to evaluate demographic parameters estimates and movement
patterns of PMJM and of how they vary across space and time. Preliminary results from the demography,
movement and distribution studies of PMJM have suggested the need to continue with research currently

�17

being addressed in these three studies. However, the preliminary results also suggest further research be
conducted on (1) use of upland habitat by PMJM, (2) refining water requirements of PMJM (i.e., do they
require stream habitat or are wetland areas sufficient), (3) range-wide distributional boundaries (e.g.,
elevation restrictions), and (4) investigating areas of potential sympatry or hibridization with Z. princeps
(western jumping mouse). The demography and movement studies will be modified during the summer
2000 field season to further investigate upland use and water requirements.
Acknowledgments
Additional data on PMJM densities for the vegetation analysis were provided by Mark Bakeman, Rob
Schorr, Carron Meaney, and Tom Ryon. Bruce Lubow provided helpful comments on the first drafts of
the adjusted PMJM density correction method, and computed the estimates ofPMJM population size for
several of the study areas included in this analysis. Seth McClean with CDOW provided the riparian
vegetation data. Mark Bakeman and Tom Ryon provided useful comments on earlier drafts of the
vegetation analysis.
Literature Cited
Armstrong, D. M., M. E. Bakeman, A. Deans, C. A. Meaney, and T. R. Ryon. 1997. Conclusions and
recommendations in: Report on habitat findings on the Preble's meadow jumping mouse. Edited by M.
E. Bakeman. Report to USFWS and Colorado Division of Wildlife.
Burnham, K. P., and D.R. Anderson. 1998. Model selection and inference: a practical informationtheoretic approach. Springer-Verlag, New York, New York, USA. 353pp.
Cook, T. D. and D. C. Campbell. 1979. Quasi-experimentation: design and analysis issues for field
settings. Houghton-Mifllin, Boston.
Cormack, R. M. 1964. Estimates of survival from the sightings of marked animals. Biometrika 51:429438.
Cranford, J. A. 1983. Ecological strategies of a small hibernator, -the western jumping mouse Zapus
princeps. Canadian Journal of Zoology 61:232-240.
ESRI. 1987. ARC/INFO users manual. Environmental Systems Research Institute. Redlands,
California, USA.
Jolly, G. M. 1965. Explicit estimates from capture-recapture data with both death and immigration
stochastic model. Biometrika 52:225-247.
Kendall, W. L., and J. D. Nichols. 1995. On the use of secondary capture-recapture samples to estimate
temporary emigration and breeding proportions. Journal of Applied Statistics.22:751-762.
Kendall, W. L., K. H. Pollock, and C. Brownie. 1995. A likelihood-based approach to capture-recapture
estimation of demographic parameters under the robust design. Biometrics 51:293-308.
Kendall, W. L., J. D. Nichols, and J.E. Hines. 1997. Estimating tempqrary emigration using capturerecapture data with Pollock's robust design. Ecology 78:563-578.
Krutzsch, P.H. 1954. North American jumping mice (genus Zapus). University of Kansas Publications,
Museum ofNatural History 7:349-472.
Meaney, C. A., N. W. Clippinger, A. Deans, and M. OShea-Stone. 1996. Second year survey for Preble's
meadow jumping mouse (Zapus hudsonius preblei) in Colorado. Report prepared for the Colorado
Division of Wildlife.
Meaney, C. A., A. Deans, N. W. Clippinger, M. Rider, N. Daly, and M. O'Shea-Stone. 1997. Third year
survey for Preble's meadow jumping mouse (Zapus hudsonius preblei) in Colorado. Report prepared
for the Colorado Division of Wildlife.
Meaney, C. A., A. Ruggles, B. Lubow, N. W. Clippinger, and A. Deans. 1999. Preliminary results:
Second year study of the impact of trails on small mammals and population estimates for Preble's

meadow jumping mice on City of Boulder Open Space. Report for Greenways Program, City of
Boulder Transportation Department, City of Boulder Open Space, and Environmental Protection
Agency, Region 8.

�18

Otis, D. L., K. P. Burnham, G. C. White, and D. R Anderson. 1978. Statistical inference from capture
data on closed animal populations. Wildlife Monograph 62:1-135.
Poly, W. J., and C. E. Boucher. 1997. Record ofa creek chub preying on a jumping mouse in Bruffey
Creek, West Virginia. Brimleyana 24: 29-32.
PTI Environmental Services. 1996a. Preble's Meadow Jumping Mouse Study at Rocky Flats .
Environmental Technology Site, Annual Report 1996. Final. Rocky Flats Environmental Technology
Site, Golden, Colorado.
PTI Environmental Services. 1996b. Preble's Meadow Jumping Mouse Study at Rocky Flats
Environmental Technology Site, Spring 1996. Final. Rocky Flats Environmental Technology Site,
Golden, Colorado.
Quimby, D. C. 1951. The life history and ecology of the jumping mouse, 7.apus hudsonius. Ecological
Monographs 21 :61-95.
Seber, G. A. F. 1965. A note on the multiple recapture census. Biometrika 52:249-259.
Sheldon, C. 1934. Studies on the life histories of Zapus and Napaeozapus in Nova Scotia. Journal of
Mammalogy 15:290-300.
Shenk, T. M. 1998. Conservation assessment and preliminary conservation strategy for Preble's meadow
jumping mouse (Zapus hudsonius preblei). Colorado Division of Wildlife FY1997-98 Annual Report.
Shenk, T. M. and Sivert M. 1999a. Temporal and spatial variation in the demography of preble's meadow
jumping mouse (Zapus hudsonius preblei). Colorado Division of Wildlife. Annual Report 1999.
Shenk, T. M. and Sivert M. 1999b. Movement patterns of Preble's meadow jumping mouse (Zapus
hudsonius preblei) as they vary across time and space. Colorado Division of Wildlife. Annual
Report.
Whitaker, J. 0., Jr. 1963. A study of the meadow jumping mouse, Zapus hudsonius (Zimmerman), in
cental New York. Ecological Monographs 33:3.
White, G. C., D. R Anderson, K. P. Burnham, and D. L. Otis. 1982. Capture-recapture and removal
methods for sampling closed populations. LA-8787-NERP, Los Alamos National Laboratory, Los
Alamos, New Mexico, USA 235 pp.
White, G. C. and K. P. Burnham.1999. Program MARK: survival estimation from populations of marked
animals. Bird Study 46 Supplement: 120-138.

Table 1. Total number of individual Preble's meadow jumping mice (7.apus-hudsonius preblei) captured in
1998, new individuals captured in 1999, recaptures in 1999 from 1998, and total number of individual mice
caetured in 1999 at three studr sites.
New captures
1999

Total individuals
captured 1998

Site

1999 from 1998

Recaptures in

Total individuals
captured 1999

F

M

u

Total

F

M

Total

F

M

Total

F

M

Total

Maytag Property

34

38

1

73

19

27

46

4

10

14

23

37

60

PineCliff Ranch

25

52

0

77

19

29

48

4

8

12

23

37

60

Woodhouse

17

18

1

36

17

30

47

3

5

8

20

35

55

TOTAL

75

108

2

185

55

86

141

11

23

34

66

109

175

�19
--

Table 2. Stream reach abundance estimates (N) for Preble's meadow jumping mouse (PMJM) from three
sites in Douglas County, Colorado for three traeeing sessions in 1998 and for June 1999.
95% Confidence
Interval

Trapping Session
Site
Maytag
Maytag
Maytag
PineCliff
PineCliff
PineCliff
Woodhouse
Woodhouse
Woodhouse
Maytag
Woodhouse
PineCliff

R se(N)
June98
July98
September98
Junc98
July98
September98
June98
July98
September98
June99
June99
June99

18
31
44
30
17
51
11
20
20
35
32
28

2.7
11.4
1.8
5.7
0.9
3.3
3.8
5.2
3.1
3.8
3.2
2.1

Lower

Upper

15
20
42
24
16
48
7
15
17
24
56
52

21
42
46
36
18
54
15
25
23
39
69
61

Trapline
Length

Adjusted
Density

(m)

(PMJM/km)

550
608
494
490
504
504
510
516
574
1130
504
503

26.2
41.3
69.5
47.7
26.3
78.9
16.8
30.7
27.8
31.2
62.6
56.5

Table 3. Data on the proportion of locations (p) of Preble's meadow jumping mouse locations within the
area defined by parallel lines running through either end of the trap line, sorted into ascending order by
traeline length.
Site
Year
Session
Meanp
SE(p)
Weighted Fit Logistic
Trapline
No.
Length
Weighted Fit
Mice Online
Walnut Creek
1999
May/June
0.946
0.0040
0.761
0.796
325
5
A-upper
Woodhouse
1999
0.629
0.0843
0.800
0.831
June
409
24
Woodhouse
1999
July
0.902
0.0532
0.800
0.831
409
19
Woodhouse
1999
Sept
409
1.000
0.0000
0.800
0.831
6
Walnut Creek
1999
May/June
490
0.308
0.827
0.855
1
Lower
Maytag
1998
Sept
0.954
0.829
494
16
0.0385
0.856
Walnut Creek
1999
May/June
0.828
0.830
500
1
0.858
B-series
PineCliff
1999
0.841
0.0670
0.831
0.858
June
503
12
PineCliff
1999
Sept
503
0.924
0.0464
0.831
0.858
15
PineCliff
1999
July
0.899
0.831
503
22
0.0372
0.858
PineCliff
1998
July
0.805
0.831
504
14
0'.0750
0.858
PineCliff
1998
0.671
0.831
Sept
504
16
0.0964
0.858
Woodhouse
1998
July
12
0.817
0.0712
0.835
0.861
516
Woodhouse
1998
Sept
14
0.883
0.0291
0.849
0.874
574
Maytag
1998
July
0.719
0.0744
0.856
0'.880
608
16
Maytag
1999
Sept
0.969
0.1664
0.917
0.932
1130
11
Maytag
1999
1130
26
0.908
0.0364
0.917
0.932
July
Maytag
1999
7
0.873
0.917
0.932
June
1130
0.1339

�20
Table 4. Estimates of boundary strip width (BSW) for nonlinear weighted least squares fit and nonlinear
weighted least squares fit with the logistic transformation.
Method

Estimate of BSW

SE of estimate

Nonlinear weighted least squares

51.1241

10.1033

Nonlinear weighted least squares with logistic transformation

41.5446

9.1676

Table 5. Data used to evaluate the relationship between Preble's meadow jumping mouse density and riparian
vegetation cover.
Adjusted Area (ha/km)
Adjusted
SE
Stream
InvestiStudy A..rea
Year Density Adjusted
Length
HerbaNonOpen
Tree
gator
(mice/km) Density Shrub
(km)
ceous
Vegetated Water
Shenk

Maytag

1998

32.52

5.84

0.2619

2.4643

2.8571

1.3452

2.0357

0.84

Shenk

Maytag

1999

29.04

3.05

0.1549

1.8239

1.9296

1.0000

1.7817

1.42

Shenk

Pinecli.ff

1998

57.35

18.39

5.4324

3.3649

1.2432

0.0000

1.5946

0.74

Shenk

Pinecli.ff

1999

53.79

5.52

5.4324

3.3649

1.2432

0.0000

1.5946

0.74

Shenk

Woodhouse

1998

15.52

3.14

2.7600

0.0000

1.7200

0.0000

0.0000

0.50

Shenk

Woodhouse

1999

48.52

3.52

2.7600

0.0000

1.7200

0.0000

0.0000

0.50

Bakeman Dirty Woman Cr.

1998

20.46

7.29

2.9190

1.3646

0.2987

0.0861

0.0354

3.95

Bakeman Dirty Woman Cr.

1999

6.89

2.11

1.3769

1.8396

0.4403

0.0000

0.0522

2.68

Bakeman Castle Rock

1999

41.70

26.91

3.8086

0.1584

0.2145

1.0066

1.1683

3.03

Schorr

Monument Cr.

1998

67.08

13.34

5.9363

0.0000

0.4968

0.8535

0.0000

1.57

Schorr

Monument Cr.

1999

28.75

8.52

5.9363

0.0000

0.4968

0.8535

0.0000

1.57

Meany

South Boulder Cr. 1998

48.80

10.60

0.1640

27.4270

3.8629

0.0000

0.1933

4.45

Meany

South Boulder Cr. 1999

34.50

7.75

0.1640

27.4270

3.8629

0.0000

0.1933

4.45

Ryon

Walnut Cr.

1999

5.10

3.34

0.1231

1.0865

0.0416

0.0000

1.0266

6.01

Ryon

Rock Cr.

1998

3.80

0.36

0.3815

0.9505

0.0000

0.0786

0.0219

14.13

Table 6. Results of linear regressions of Preble' s meadow jumping mouse density (mice/km stream )
predicted by riparian vegetation cover (ha/km stream) for 15 study area and year combinations from Table

5.
Variable
Shrub
Herbaceous
Tree
Non-vegetated
Total Cover
Open Water

Intercept
30.22
31.79
30.80
31.51
31.23
35.84

p

R2

0.06
0.67
2.18
0.06

0.638
0.656
0.495 .
0.729
0.596

-2.35

.0.469

0.018
0.016
0.037
0.011
0.022
0.041

Slope
0.63

--·

�21
Table 7. Summary of AICc model selection for the riparian vegetation cover (ha/km stream) variables
Shrub, Tree, Herbaceous, Non-Vegetated, and Open Water predicting Prebles' meadow jumping mouse
density (mice/km stream). AICc, ~-AICc, and Akaike Weights follow definitions in Burnham and
Anderson (1998).
Akaike
R2
AICc
~-AICc
Variables in Model
Wei hts
83.5040
0.6831
0.0000
0.59584
Shrub Tree
86.6162
3.1122
0.7143
0.12570
Shrub Tree Open Water
87.4205
3.9165
0.08408
0.6986
Shrub Tree Non-Vegetated
88.1465
4.6425
0.6836
0.05848
Shrub Tree Herbaceous
89.0245
5.5205
0.5421
0.03770
Shrub Herbaceous
89.3639
5.8599
0.6569
0.03182
Shrub Herbaceous Open Water
90.9029
7.3989
0.6198
0.01474
Shrub Herbaceous Non-Vegetated
91.1034
7.5994
0.3216
0.01333
Shrub
91.8340
8.3300
0.7258
0.00925
Shrub Tree Herbaceous Open Water
92.3015
8.7975
0.7171
0.00732
Shrub Tree Non-Vegetated Open Water
92.8597
9.3557
0.7064
0.00554
Shrub Tree Herbaceous Non-Vegetated
93.5258
10.0218
0.3819
0.00397
Shrub Open Water
94.1043
10.6003
0.6810
0.00297
Shrub Herbaceous Non-Vegetated Open Water
94.5170
0.3396
11.0130
0.00242
Shrub Non-Vegetated
95.4143
11.9103
0.0957
0.00154
Tree
0.0462
96.2135
12.7095
0.00104
Open Water
96.3496
0.0375
12.8456
0.00097 Herbaceous
96.3621
12.8581
0.0367
0.00096 Non-Vegetated
0.3828
98.1688
14.6648
0.00039
Shrub Non-Vegetated Open Water
0.1358
98.5520
15.0480
0.00032
Tree Non-Vegetated
98.7044
15.2004
0.1270
0.00030
Tree Open Water
98.8480
15.3440
0.7345
0.00028
Shrub Tree Herbaceous Non-Vegetated Open Water
0.1059
99.0626
15.5586
0.00025
Herbaceous Non-Vegetated
0.1035
99.1022
15.5982
0.00024
Tree Herbaceous
99.1919
15.6879
0.0982
0.00023
Herbaceous Open Water
99.8370
0.0585
16.3330
0.00017
Non-Vegetated Open Water
0.1459
103.0432
19.5392
0.00003
Tree Non-Vegetated Open Water
0.1358
103.2184
19.7144
0.00003
Tree Herbaceous Non-Vegetated
103.3266
19.8226
0.00003
0.1296
Herbaceous Non-Vegetated Open Water
0.1273
103.3666
19.8626
0.00003
Tree Herbaceous Open Water
108.8576
25.3536
0.1470
0.00000
Tree Herbaceous Non-Vegetated Open Water

Table 8. Parameter estimates for best AI Cc model explaining PMJM density (mice/km stream length) from
vegetative cover variables (ha/km stream length).
Standard
Pr&gt; jtj
Variable
t statistic
Estimate
Error
0.892
Intercept
0.14
0.9853
7.1047
Shrub
Tree

7.2342
10.1308

1.5339
2.7381

4.72
3.70

&lt;0.001
0.()03

�22
Table 9. Number of Preble's meadow jumping mice radi~llared at each study site during each trapping
session for each l'.ear.
1999
1998
Site
Session
Trap nights
Females
Trap Nights Females -Males Tot.al
Males
Tot.al
Maytag
Jun
Maytag
Jul
Maytag
Sep
PineCliff
Jun
PineCliff
Jul
PineCliff
Sep
Woodhouse
Jun
Woodhouse
Jul
Sep
Woodhouse
TOTALS

1949
2370
3256
1095
1603
1544
1525
2420
1568
17330

9
11
10
5

6
4
2
8
7
62

5
5

8
13
7
12
3
4
6
63

14
16
18
18
13
16
5

12
13

125

2604
3191
4341
742
1442
1921
1651
1215
2114
19222

6
10
3
7
6
7
7
8
3
57

12
13
7
.5
10
17
9
5

3
81

18
23
10
12
16
24
16
13
6
138

Table 10. Preble's meadow jumping mice radi~llared. and tracked for more than one tracking session.
Location of capture, sex, identification, and number of locations for each mouse during each tracking
session is noted.
1998
1999
PIT-tag#
Site
Sex
Sep-Oct
Jul-Aug
Jun
Jul-Aug
Sep-Oct
Maytag
414lf87C76
60
24
F
105
Maytag
F
41412B4A2D
103
Maytag
F
413E296246
73
7
Maytag
F
4141276D78
76
3
82
Maytag
F
4140753620
1
93 ·
Maytag
M
4141241836
1
Maytag
4140754707
19
M
70
4135354E37
Maytag
M
37
40
Maytag
41357B5A0E
38
M
49
61
13
Maytag
M
414130663A
144
11
65
Maytag
M
41411E6879
Maytag
4141445465
M
52
74
4141554B28
PineCliff
F
44
21
PineCliff
M
41413D4C04
18
15
4141144535
PineCliff
M
21
38
PineCliff
413E02020F
M
22
9
PineCliff
M
414037184D
45
37
87
6
PineCliff
M
4141714141
12
47
Woodhouse
F
41413E610B
78
14
Woodhouse
F
41413E7B07
5
66
63
16
Woodhouse
F
41414C721F
39
Woodhouse
F
41412A2508
84
93
Woodhouse
4141611413
42
8?
M
46
Woodhouse
M
4141074013
6
Woodhouse
M
4141252D66
63?NC
64
Woodhouse
M
41412D3509
59
?NC
Woodhouse
75
M
41406A1049
9

�23

Table 11. Causes of mortality of Preble's meadow jumping mice from Maytag Property, PineCliff Ranch,
and Woodhouse Ranch collected during; the 1998 and 1999 field season (June I-October 31).
1998
1999
Cause of
Total
Mortality
M.aytag
PineCliff
M.aytag
Woodhouse
PineCliff Woodhouse
Predation
Bullfrog
Garter snake
Rattlesnake

0

0

1

1

l

0
0
0

0

0

0

0
1
0
0
0
0

0
0
0
0
3
0
1
0
0
0

0

Yellowbellied racer
Weasel

Fox
House cat
Raptor
Unknown
Exposure
Drowning
Road.Kill
Handlingffrap

0

Unknown
TOTAL

1
8

1
4

5

0
0
0

2

0

0
0
0

0

1

0

0

l

0
0
1
0

1

0
0
0
1

0
0
0
2
2

1

0
0

19

4

9

0
5

2
0
1
6

3

0
2
3

24

13

17

1
7

2
0
0

0
2

2
8

4

5

3
0
0

2
0

1
,--...

8
ell

5

1

1
1

4

1
9

17
74

■

+---..-------------------------------------------------------1

■

0.9

-----=-----------===== ---

Q.)

&lt; 0.8

--+-----~-----1-

Q.)

i:::::
·.§&lt;
1--&lt;

i:::::
0

0.6

0
·......

0.5

~

,.D

0

1--&lt;

~

■

+------------------------------

b

.......-&lt;

■

0.7

■

-- -

0.4 - + - - - - - - - - I
0.3
200

--------------------------1

■

-

Observed Data
Weighted Least Squares
Weighted Least Squares Logistic

400
600
I

I

I

800

1000

1200

Trapline Length
Figure 1. Observed estimates ofp with the fit of the weighted nonlinear least
squares model, and the logistic transformed nonlinear least squares model.

�24

1
0.9
0.8
~

.-9 0.7
~

0.6

0.5

---·······························

0.4
0

500
1000 1500
Trapline Length (m)

2000

Figure 2. Predicted p with 95% confidence intervals as a function oftrapline length in meters.

20 - . - - - - - - - - - - - - ~
• onument Creek
•C~ouse

10
r✓.l

1

0

·~ -10
r✓.l

-20

• Maytag
•Walnut Creek
• Rock Creek

• South Boulde Creek

• Pinec.
• Maytag

• Pinecliff

• Dirty Woman Creek
. • South Boulder Creek
• Dirty Woman Creek

• Monument Creek

•Woodhouse

-30 - - - . + - - - + - - + - - - + - - - - - - - - + - - - - - + - - I
0 10 20 30 40 50 60 70
PMJM Density (mice/km)
Figure 3. Residuals for the best AICc model explaining PMJM density (mice/km stream length) from the
standardiz.ed vegetation cover variables shrubs and trees (ha/km stream length).

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                  <text>335

JOB PROGRESS REPORT

State of

Colorado

Project No • .....e.W~-~1~5~3~-_R,.,__-~s'---------

Mammals Research

Work Plan No. _ ___,l~0~A,.,__ _ _ _ _ _ __ _

Kit Fox Studies

Job No.

Kit Fox Status in Colorado

1

Period Covered: July 1, 1992 to June 30, 1993
Author: J.P. Fitzgerald and M. .Link, Univ. Northern Colorado, Greeley
Personnel: T. Beck, c. Parmeter, (volunteers M. Reddy, T. Hugo from University
of Northern Colorado).
ABSTRACT

Since 9 March 1992, 9 kit fox have been trapped in 2,725 trap nights of effort
including 1,141 trap nights in the current reporting period. All individuals
(5 males and 4 females) have been captured NE of Montrose in Delta and
Montrose counties in desert-shrub/greasewood habitat. Three males and 4
females have been radio-collared and are periodically being monitored. One
additional kit fox has been observed while spotlighting in Browns Park in
extreme northwestern Moffat county . Den sites used by foxes are in steeper,
rougher terrain than reported in the literature .
Few kit fox have been
reported harvested by trappers responding to the annual survey questionnaire
distributed by the Colorado Division of Wildlife. Contacts with ranchers,
land management agency personnel, CDOW employees, and local trappers have
resulted in only three reports of kit fox in western Colorado. Live trapping
efforts in areas from which kit fox have been historically reported have not
resulted in any captures or visual observations.

�337

KIT FOX (WLPES MACROTIS) DISTRIBUTION AND ABUNDANCE IN WESTERN COLORADO

James P. Fitzgerald and Michelle Link
P.N. Objective

Document the geographic distribution and relative abundance of kit fox in
western Colorado.
Segment Objectives
1.
2.
3.
4.
5.

Identify geographic extent of kit fox distribution in western Colorado.
Determine habitat use by the species and general prey species abundance
in areas used by kit fox.
Compile general harvest information.
Test different survey techniques in areas with kit fox populations.
Identify suitable kit fox populations for more intensive ecological
research.
Methods

Methods are generally the same as previously reported (Link and Beck 1992).
However, captured kit fox are now being collared with transmitters (Model No.
HLPM 2180 LD - Wildlife Materials, Inc.) for monitoring purposes.
Results and Discussion
Determination of Distribution
Since the project began 9 March 1992 a total of 2,794 trap nights of effort
have been expended (Table 1) resulting in capture of 9 kit fox. Seven of the
captured fox, 3 males and 4 females have been radio-collared. Two of the
females have been recaptured and their collars have been replaced. One adult
female captured on 31 May 1992, rehabilitated in captivity with a broken jaw,
and radioed and released to the wild in late summer 1992, was found dead from
injuries (probably inflicted by a coyote) in mid December 1992. All animals
have been captured in a 2590 ha area of Peach Valley in Montrose and Delta
counties.
Live trapping (1,210 trap nights) and spotlighting efforts (54 hours) during
the fiscal year were concentrated in the Big Gypsum, Disappointment, Paradox
and Peach valleys in southwestern Colorado and the Rangely-Dinosaur and
Brown's Park areas of northwestern Colorado. Because of the capture of kit
fox in the Peach Valley area in May and June of 1992 the area continued to
receive periodic, concentrated search effort during the present reporting
period.
One animal identified by Link as a kit fox was observed by spotlight in the
Browns Park area in late June 1993 but no animals were captured during 144
trap nights of effort in that location. Concerted effort will be expended in
that area in 1993-94 to attempt to capture and verify presence of fox in
Moffat County. Of particular interest is whether animals in Moffat County are
"Swift or Kit" foxes as it is possible that "Swift" fox could occupy the "Red
Desert" area of Wyoming and filter south into Moffat County rather than
represent extensions of Kit fox populations from the Colorado River drainage
of Utah.
Sampling has included trapping in a number of different habitat types
including: sagebrush-grasslands; margins of pinyon-juniper woodland, and
desert-shrub/greasewood areas. To date, kit fox have only been captured in
the desert-shrub/greasewood type common to the Peach Valley area. Much of the
area occupied by kit fox in Peach Valley is dominated by mat saltbush
(Atriplex corruaata) on the uplands and ridges with greasewood (Sarcobatus

�338

Table 1. Areas searched, dates of search, and trap nights of effort spent in
trapping, kit fox study, western Colorado, 1992 to June 30, 93.
County and Area
Montezuma Co.
McElmo Canyon
San Miguel Co.
McIntyre Canyon
Disappointment
Valley
Big Gypsum
Valley
Montrose Co.
Paradox Valley

Dates Searched

Total Trap
Nights Effort

Fox Captures
100 Trap Nights

9/9-12/92

60

0

3/5-8/93

77

0

8/3-9/92

141

0

7/5-8/92;
7/29-8/1/92

174

0

8/10-20/92

141

0

168

0

192
836

0
1

Montrose co., Delta &amp;
Mesa co.
Sinbad Valley
3/15-22/92
Delta to Grand
4/28-5/16/92
Junction
Various - May to Present
Peach Valley

V

Mesa co.
Dolores River
Valley-Gateway
to Utah border

3/6-12/92

114

0

Colo. Natl. Mon.

4/20-23/92

78

0

N.W. Grand Junct.
&amp; Rabbit Valley Various - 1992-93

528

0

Rio Blanco Co.
Rangely/Dinosaur

6/16-19/93

72

0

Moffat Co.
Brown's Park

6/22-28/93

144

0

vermiculatus), Nuttall saltbush (A. nuttallii), shadscale (A. confertifolia,
and sagebrush (Artemisia .!ll2.:.) occurring in more localized sites. A
considerable amount of the Peach Valley area occupied by foxes is on lands
used heavily by off road vehicles (ORV's).
Habitat Use and Relationship of Prey Abundance to Kit Fox Abundance
Determining the diets of kit foxes in the Peach Valley area will be part of
the 93-94 work effort. Link has collected numerous kit fox scat samples from
Peach Valley. Remains of white-tailed prairie dogs (Cynomys leucurus),
cottontail (Sylvilagus audubonii), and cricetid mice (Peromyscus) have also
been found at kit fox dens.
No usable relationship appears to exist between numbers of lagomorphs
spotlighted at night and distribution of kit fox. An average of .2 lagomorphs
(mostly cottontails) have been recorded per road km in over 916 km surveyed
(range 1.6 to 0 animals/km). In Peach Valley the average has also been .2/km
in a total of 68 km censused. Lagomorph populations have been very low across

V

�339

western Colorado with highest numbers observed in the Sinbad Valley, Mack and
Brown's Park areas.
Den sites located in the Peach Valley area are not similar to those reported
by other workers (Egoscue 1962, O'Neal et al. 1986, McGrew 1977) who have
found most dens on relatively flat ground with multiple burrow entrances. out
of 13 dens being used in Peach Valley, 4 are located in deep, dry washes, 4
are on the sides of hills with good drainage, two are half way up hills in
washes, two are on top of ridges at 5,600 feet, and one is on the side of a
large u-shaped bowl. Most dens are within 300 m of a well-traveled road, jeep
trail, or pathway (ORV, horse). Use of these "atypical" den sites has led us
to revise search efforts to focus on more broken terrain than suggested by the
literature.
General Harvest Information/ Other Reports of Kit Fox
Table 2 indicates reported harvest data for kit fox from western COlorado.
Take is estimated from trapper survey data and numbers may include other fox
species. The numbers of animals trapped in Montezuma county in 1981, and
reports of kit fox from La Plata county are doubtful.
Table 2. Estimated harvest of kit fox from western Colorado based on trapper
questionnaire returns to the Colorado Division of Wildlife, 1975-1992.
Year

\.__I

County
Delta
Garfield
Gunnison
La Plata
Mesa
Moffat
Montezuma
Montrose
Rio Blanco
Totals

75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92
2

5

2

3

6
2

3

1 13 33
5 2

2

10

7

1
2 33 41

3
192
198

26
4 10
5

5

4 41

13

6
2

Link has made a concerted effort to question ranchers, agency personnel, or
local trappers regarding their knowledge of kit fox. Few reports have been
made. The district wildlife manager (DWM) in the Mack/Grand Junction West
area reported seeing young kit fox in an arroyo north of Mack in 1988.
Extensive trapping has not resulted in any captures in that area. The Fish
and Wildlife Service at Browns Park National Wildlife Refuge had no records of
kit foxes, but one employee (Brad Pech) reported that trappers had taken kit
fox in that area several years ago. Link did spotlight an animal believed to
be a kit fox in that area but none were trapped. The DWM (Divergie) and the
Chevron Oil Company's on-site environmentalist (Sellars) at Rangely have never
observed or heard of kit foxes in that area even after extensive spotlighting
and surveying for Black-footed Ferrets. Ranchers (Tozer Bros.) from McElmo
Canyon, Montezuma County, have not observed any kit fox and trapping efforts
did not produce captures in 1992 in that area, although there are past records
of kit fox in that area (Egoscue 1964). Likewise, trapping efforts in other
areas reported to have kit fox by Miller and McCoy (1965) including the
Colorado National Monument and near the Utah state line in the Grand Valley)
have not resulted in any captures. The BLM ranger (Sering) assigned to the
Delta and Montrose area reported to Link that he observed a kit fox on Flattop Mountain south of the Peach Valley area in June of this year. The Flattop area will be trapped and surveyed in 1993-94.

�340

Test sampling techniques in areas with Kit Fox
The Peach Valley area is the only site with a known population of kit fox.
Those animals have been located by daytime sightings at dens close to roads or
by live-trapping. Trapping success in Peach Valley is low with one capture
per 100 trap nights effort. Two of the radio-collared animals (both females)
have been recaptured 5 months after their first capture allowing for
replacement of their radios. Males appear to be more difficult to recapture
using present techniques.

V

Scent stations baited with standard lure (scented predator survey discs with
FAS, Pocatello Supply Depot) were placed at 10 sites in Peach Valley in June
1992. No kit fox tracks were identified at any stations. The scent station
surveys were abandoned because it was more efficient for one person to work a
trap line than to maintain a station line.
Spotlighting has resulted in observations of 2 kit fox in Peach Valley and 1
in Browns Park.
Identify suitable kit fox populations for more intensive research
The Peach Valley area bas from 4-8 adult fox based on monitoring of radioed
animals. Since these animals represent the only kit fox presently known to
occur in western Colorado the decision was made to radio-collar all animals
captured on the site and to increase efforts to better understand habits of
the animals in that area with the expectation that it may enhance efforts to
locate other kit fox populations. A temporary worker (Parmeter) was hired
from mid-January to mid-April to monitor fox in Peach Valley and to try winter
trapping in the Grand Junction and McIntyre Canyon areas. Attempts to radiotrack animals at night in the Peach Valley area by both Link and Parmeter have
not been effective for determining distances ranged from dens or areas being
hunted. The foxes are aware of the researcher and their behaviors seem to be
more intent in evading the tracker rather than on night hunting. In the 93-94
field season attempts will be made to track some radioed animals using teams
of trackers stationed at high points of ground rather than a single
individual.

~~~ti/res P. Fitzgerald
Contractor, UNC

and

Michelle Link
Graduate Research Assistant

V

�1 93
Colorado Division of Wildlife
Wildlife Research Report
June 30 1994

JOB PROGRESS REPORT
State of -----~C~o~l~o~r~a~d;o=---Project No.

W-153-R-7

Mammals Research

Work Plan No.

10A

Kit Fox Studies

Job No.

1

Kit Fox (Vulpes macrotis)
Status in Colorado

Period Covered:
Author:

July 1, 1993 - June 30, 1994

J.P . Fitzgerald

Personnel: J.P. Fitzgerald, M. Link, T. Verbeck, A. Anderson, L. Dent, J.
Eussen, J. Prather, M. Reddy, D. Watson, T. Beck, B. Gill

Abstract
A total of 1754 trap nights of effort were expended in the project year to
capture 18 kit fox. Trapping efforts included parts of Moffat, Mesa, Garfield,
Delta, and Montrose counties. All captures were made in Montrose and Delta
counties in Peach Valley (8), East of Montrose (9), or North of Delta (1). A
reliable report of a "kit or swift" fox was received from U.S. Fish and Wildlife
Service and BLM personnal in the Vermillion Creek area in northern Moffat County.
Trapping to date in northern Moffat County has not resulted in any fox captures.
Monitoring of radio-collared kit foxes in the Peach Valley study area in Montrose
and Delta county continued. Four (F18, FS, M13, MS) of 6 radio-collared adults
are still alive in that population. On 26 March and 13 April carcasses of two kit
fox, M12 and an untagged animal of unknown sex, were recovered in TS0N, R9W, NE
corner Section 8 within 100 m of each other. The cause of death could not be
determined for either animal. East of Montrose, nine kit fox (4 adult females,
1 adult male, 1 male pup, 3 female pups) were captured and either radio-collared
or ear tagged. Gill and field crew personnel have taken photographs of animals
in that population. In March, the Wildlife Commission closed the season on kit
fox and imposed trapping regulations for the Peach Valley area. The Director of
the Division of Wildlife placed the species on the state special concern list.

�195

KIT FOX (VULPES MACROTIS) STATUS IN COLORADO
James P. Fitzgerald
P. N. Objective
Document the geographic distribution and relative abundance of kit fox in Western
Colorado.
Segment Objectives
1. Continue to monitor radio-collared foxes in the Peach Valley Area.
2. Write up_project results (M.A. thesis - Michelle Link in progress).
3. Begin extensive summer trapping effort.
Methods
Methods continue to be similar to those reported previously (Fitzgerald and Link
1993, Fitzgerald and-Verbeck 1993).·Field Personnel; At the start of the project
year Michelle Link was replaced by Tom Verbeck to take over the kit fox field
research. Verbeck worked from mid-August to January. Allan Anderson monitored fox
populations in Peach Valley from March through late May. Verbeck resigned from
the project in April. Three field crews: Matt Reddy-David Watson; Lonnie Dent-Jim
Bussen; and Jake Prather (alone) began work on the project in late May.
Results and Discussion
Trapping Efforts: Between July 1, 1993 and June 30, 1994 a total of 1754 trap
nights of effort have resulted in a total of 20 captures of 18 individual kit
fox. All captures were made in Montrose or Delta County. Trapping efforts and
locations are summarized in Table 1.
In areas with known kit fox populations (Peach Valley, North of Delta, and
Montrose East) a total of 1012 trap nights of effort-were expended in trapping
the 18 animals captured (56 trap nights/fox). The capture rate of foxes in.traps
placed near(&lt; 200 m) known fox dens is much higher. The 18 individual animals
were captured in a total of 45 trap nights, a capture rate of 2. 5 trap nights per
·fox. It appears that the methods we are employing catch kit foxes efficiently if
foxes are present. It appears kit fox populations across the areas surveyed are
very low resulting in many trap nights of effort with no captures.
In comparing this years trapping effort to efforts by Link, she captured 9 kit
fox during 2,725 trap nights of effort, with all 9 animals captured during 836
trap nights (93 trap nights/fox) of effort in Peach Valley (Fitzgerald and Link
1993).
• The SW Regional Office of CDOW has hired Mr. Doug.McCauley, a taxidermist from
Delta, to work with the project crew to find additional kit fox populations. Mr.
McCauley believes that many more kit foxes exist than our trapping results would
indicate. The understanding with Mr. McCaughley is that he will try to locate kit
fox populations using predator calling and night lighting. He has to show either
the project crew or someone from the SW Regional Office the exact location of
occupied dens and verify the presence of kit fox in order to be paid his fee. To
date he has not taken the crew out but has indicated to Dent and Eussen that he
knows of 2 or 3 active dens on the Colorado-Utah border. We are still trying to
schedule a time when he can go out with us.

�196

Table 1. Areas searched, dates of searches, and trap nights of effort, kit fox
study, western Colorado, July 1, 1993 - June 30, 1994.
Area Searched
and County •

Dates Searched

Number of
Trap Nights

Peach Valley
Montrose Co.

8-29 to 12-6-93
4-5 to 4-24-94

232
139

0

North of Delta
Delta Co.

11-19-93 to 1-6-94
5-27 to 5-30-94

245
39

0

284/1 fox

Montrose East
Montrose Co.

5-27 to 6-18-94

357

9

357/9 foxes

West Gunnison
Gorge. Delta Co.

12-14 to 12-16-93

60

0

60/0

SEW of Wells
Gulch. Delta Co.

6-21 to 6-27-94

230

0

230/0

Brown's Park
Moffat co.

10-5 to 10-12-93

151

0

151/0

Grand Junction
NW, Mesa Co.

10-20 to 10-28-93

129

0

129/0

172

0

172/0

1754

18

1754/18

DeBeque/Parachute 5-30 to 6-7-93
Mesa/Garfield Co's
Totals

Captures

Total Trap Nights
and Success by Area

8

371/8 foxes

l

V

Trapping and Monitoring Effort - Peach Valley Population:
Verbeck from 29 August to 6 December conducted 232 trap nights of effort in Peach
Valley resulting in 8 captures of foxes: M13 (captured twice), Fl4, MlS, M16, MB,
F18, and an animal that escaped before it could be sexed or marked (Table 2).
Animals which were recaptures (F14, MlS, MB, F18) were given new radio-collars
and ear tags. Invariably ear tags were torn out on most of the foxes recaptured.
Anderson conducted 139 trap nights of effort in Peach Valley from 5 April to 24
April with no animals captured and had difficulty picking up radio signals from
collared animals .. Anderson picked up radio-signals from 5 ( Fl8, M12, MS, FS, M13)
of the 6 adults radioed in the area. However, he was unable to locate their
precise den sites because of field conditions and problems with radio-receivers.
on 26 March, Anderson recovered the carcass of Ml2 within a hundred meters of its
den but could not verify cause of death. He recovered the carcass of a kit fox
that had no ear tags or collar about the same distance from that same den on 13
April. Again it was not possible to estimate cause of death. F14 has been missing
since January unless she is represented by the carcass (no radio-collar found)
located near Ml2 - they were both trying to pair in December and January.
Field crews verified presence of M13, Fl8, MS on 19· June in T51N, R9W, S29,30.
This is 4-6 Jan north of locat~ons Verbeck found them ·using in late fall ·and early·
winter (Fitzgerald and Verbeck 1993). They also reported picking up good signals
in TS0N, R9W, S4 from 150.037 radio - a radio frequency that Anderson attributed
to Ml2 found dead on 26 March. This error has to be investigated and resolved,
and attempts made to recapture and recollar an;mals in the valley. Field crews
report that Ml3 is with an apparently unmarked female in a den with 4 pups close
to the water tank in lower (north) Peach Valley. They have also seen several

V

�197

\...-I

foxes crossing the road at night in that same part of Peach Valley. Attempts will
be made later this summer to capture and radio those animals.
Montrose East Population:
Anderson on 23 May received word of a family of foxes along the Landfill Road
(Bostwick Park Road) in T49N, RSW, NE7 and began to observe animals in early
morning and late afternoons. He estimated as many as 12 animals in the area
including pups of the year. He showed the summer field crews the site on 27 May.
Since 28 May a total of 9 kit fox have been trapped and marked in that population
(Table 3). The population includes several adult females which may represent
yearling animals that did not breed. The whelping den included pups from
apparently two different litters based on size differences and estimated numbers
of pups (7-8). The Montrose East population is located southeast of Flattop Mesa.
Habitat is similar to Peach Valley and there is nothing to preclude mixing of the
two populations which are about 12 km apart. However, trapping efforts from
Flattop Mesa north to upper Peach Valley have not resulted in any other fox
captures. The large numbers of females present in the population are encouraging
provided sufficient males are available for mating in 1994-95. Several
enthusiastic local residents are aware of this population and watch it carefully
attempting to protect animals from being shot since they are located close to a
heavily used county road.
Table 2. Kit fox trapped in Peach Valley, Montrose County, Colorado, 1992-July
1, 1994 and dates of last sightings/radio-signals. CR=Collar replaced; ETR =
Ear tags replaced.

~-

\...,,I

Capture or
Date ·Located

Sex

5/14/92 .

M

5/31/92
11/23/92

F

6/25/92

Ear Tag
Number

Weight
Kg

Radio Collar
Frequency

Location

Fate

2.3

not collared

T51N/R9W/S29

Unknown

1

2.0

150.238

T51~/R9W/S29
Tl5S/R94W/S27

Killed by
Coyote

M

4

2.2

not collared

T50N/R9W/Sl6

Unknown

9/28/92

M

2

2.7

150.309

T50N/R9W/S9

Unknown

9/28/92
3/1/93
1/3/94
4/6/94

F

5

2.5

150.338
CR150.956

T50N/R9W/S9
T50N/R9W/Sl7
T50N/R9W/S17
T50N/R9W/S9

Signal Weak

9/28/92
3/2/93
9/22/93
1/6/94

F

2.6

150.379
CR150.850
CR150.889

T50N/R9W/S9
T50N/R9W/S9
T50N/R9W/S16
T50N/R9W/Sl7

Unknown

2/23/93
.10/26/93
12/6/93
1/6/94
3/9/94
5/22/94
6/19/94

F

7

2.5

150.638

ETR18

2.6

CRlS0.594

T51N/R9W/S29
T50N/R9W/S5
TSON/R9W/SS
TSON/R9W/S5
T50N/R9W/S16
TSON/R9W/S18
T51N/R9W/S29

Alive

2/23/93
10/26/93
12/6/93
1/6/94
3/26/94

M

6
ETR14

8

2.4

3.0

150.468

3.1

CRlS0.189

T51N/R9W/S29
TSON/R9W/S5
TSON/R9W/S5
TSON/R9W/SS
TSON/R9W/S5

�198

Table 2 cont.
5/21/94
6/19/94
4/21/93
9/24/93
10/23/93

TS0N/R9W/S5

TS1N/R9W/S30
12
ETRlS

M

1/6/94
3/26/94

9/20/93
11/9/93
12/14/93
3/31/94

13

M

2.5
2.8

2.7

150.708
CR150.037

150.813

5/21/94
6/19/94

9/30/93

16

M

2.3

150.499

11/22/93

Alive

T50N/R9W/S22
TS0N/R9W/S8
TS0N/R9W/S17
TS0N/R9W/S16
TS0N/R9W/S8
TS0N/R9W/S16

Dead

T50N/R9W/S5
T51N/R9W/S29

Alive

T50N/R9W/S17
TS0N/R9W/S17

Unknown

TS0N/R9W/S16
T50N/R9W/S16
TS0N/R9W/S5

Table 3. Kit foxes trapped in the Montrose East population, Montrose County,
1994. NL= non-lactating females not pups of the year; L = lactating.

Location

Fate

Weight
Kg

Radio Collar
Frequency

F(NL)
21
recaptured

2.5

150.947

·T49N/R9W/S7

F(NL)

22

2.5

150.403

T49N/R9W/S7

Alive

5/29/94

F(NL)

23

2.25

150.33.8

T49N/R9W/S7

Alive

5/29/94

M pup

24

1.75

not-collared

T49N/R9W/S7 .

Alive

5/30/94

F pup Ll76/Rl77 1.5

not-collared

T49N/R9W/S7

Alive

5/30/94

F pup Ll78/R179 1.45

not-collared

T49N/R9W/S7

Alive

5/31/94
6/7/94

F (L) Ll80/Rl81 2.3
recaptured

150.940

T49N/R9W/S7
T49N/R9W/S7

Alive

6/1/94

F pup Ll83/Rl84 1.8

not-collared

T49N/R9W/S7

Alive

6/3/94

M Ad

not-collared

T49N/R9W/S12

Alive

Capture or
Date Located

sex

5/29/94
5/30/94
5/29/94

Ear Tag
Number

L185/R186 3.0

Alive

V

Use of Baits:
Table 4 summarizes the baits used in traps which captured kit fox. Verbeck made
a detailed analysis of what baits were used during his 817 trap nights of effort
and we are following that procedure this field season. Anderson conducted 139
trap nights of effort in Peach Valley with no successful captures during the
month of April. During that period he tried a variety of baits including
commercial fox scent, sardines, commercial raccoon-fox scent, and dead chicks.
Be also put out carcasses of dead white leghorn chickens near several dens in the
Valley with foxes paying little attention to such carrion. Since late May crews
have conducted an additional 798 trap nights using a variety of baits. During

V

�199

trapping efforts at East Montrose, emphasis was given to taking as many animals
as possible in as few a trap nights as necessary. As a result of that effort many
traps were baited with multiple baits consisting of road killed cottontails
and/or prairie dogs and turkeys with the idea being that the foxes might respond
best to a variety of fresh killed meats, a technique that worked well. Although
baits from local road-killed mammals and birds might work better than turkeys or
turkey-lure combinations the numbers of traps being run precludes exclusive use
of such local carrion.
Table 4. Summary of kit fox captures/recaptures and types of baits used. May 14,
1992 to June 30, 1994.
Investigator/Year

Link/ParmetQ.r
92 to July 93

Verbeck
Aug 93 to Jan 94

Present Crews
April - Present

Baits
cottontail
Cottontail/Turkey
Cottontail/Turkey/P. Dog
Prairie Dog/Turkey
Prairie Dog
Turkey
Turkey/Commercial Lure
Pheasant
Turkey/Big Game
Commercial Lure or w Sardines
Chicken/commercial Lure
Total Trap Nights Effort

l/&lt;50

5/77
3/41

5/70
0/39
4/10

0/6
6/&gt;2,600
2/&lt;200

0/408

2/679

1/32
0/66
0/100
0/39
2,725

817

937

Other Activity:
Based on recommendations made by Fitzgerald and presented to CDOW personnel

11/15/93, the Colorado Wildlife commission on 3/10/94 closed the season on kit

fox in Colorado and imposed trap and trapping restrictions for the Peach Valley,
area. The Director of the CDOW on 22 March, placed the kit fox on the list of
species of "special concern." The agency is presently contemplating future
management, including whether it should be listed as "thr~atened." A meeting of
CDOW personnel and the contractor will take place in late summer 1994 to discuss
these issues. Link is finishing her thesis incorporating some of Verbeck' s
findings into the paper. Gill has photographed animals in the Montrose Bast
group.

�253
Colorado Division of Wildlife
Wildlife Research Report
July 1995

JOB PROGRESS REPORT
State of

Colorado

Project No.

W-153-R-7

Mammals Research

Work Plan No.

10A

Kit Fox Studies

Job No.

Period Covered:

Kit Fox (Vulpes macrotis) status
in Colorado

1

July 1, 1994 to June 30, 1995

Author: _J.P. Fitzgerald
Personnel: J.P. Fitzgerald, L. Dent, J. Eussen, M. Link, J. Prather, M.
Reddy, D. Watson, R. Basagoitia, S. Boyle, R. Hays, T . Beck, B. Gill., J.
Olterman

ABSTRACT
In FY1994-95, 2326 trap nights of effort resulted in 46 captures of 31
individual kit foxes . Eighteen were animals not previously captured. Since
work began in March 1992, 6805 trap nights of effort have resulted in capture
of 38 kit foxes : 10 adult males, 7 juvenile males, 14 adult females, and 6
juvenile females. Hundreds of square kilometers of what appears to be suitable
habitat is unoccupied or occupied at low levels. Trapping was conducted in
parts of Mesa, Garfield, Delta, Montrose, and Moffat counties. Captures were
made in Mesa and Garfield Counties (10 kit fox), and in Montrose and Delta
Counties (21 foxes). Most captures were in the Peach Valley and Montrose East
areas. No captures were made in Brown's Park, Moffat County in 171 trap nights
of effort. Attempts to locate foxes during the winter using ATV's were not
successful due to lack of snow. Of 37 collared or ear tagged foxes caught
since 1992, the fate of 23 is unknown, 7 are dead, 7 are alive. Movement of 3
foxes between Montrose East and Peach Valley was documented. Home ranges of
2
Peach Valley and Montrose East foxes were estimated to be from 1.5 to 7.7 km •
Foxes used an average of 3.7 dens per individual during the tracking period.
Reproductive success is low. Of 14 adult females captured since 1992 only 6
litters of pups have been produced. The Wildlife Commission expanded the area
with trap restrictions to portions of Mesa, Garfield, and western Delta
counties. Plans for the next fiscal year are to complete the search effort,
finalize reports, and make recommendations for any continued research on the
species.

m~nm1~111,1~
i~m
BDOWD1 □ 765

�255
KIT FOX (WLPES MACROTIS) STATUS IN COLORADO

James P. Fitzgerald
P. N. Objective
Document the geographic distribution and relative abundance of kit fox in
Western Colorado.
Segment Objectives
1.
2.
3.
4.

Continue to monitor radio-collared foxes in Montrose, Delta, Mesa and
Garfield counties.
Continue search for new kit fox populations.
Complete write-up of earlier field study effort (M. Link Thesis).
Complete plans for 1995-96 field efforts.
Methods

Field methods for live-trapping were similar to those reported previously
(Fitzgerald and Link 1993, Fitzgerald and Verbeck 1993). Live-trapping effort
was concentrated in the Gunnison and Colorado River drainages. Boyle radiotracked foxes in fall and winter in the Montrose East and Peach Valley areas
to estimate home ranges and nightly movements. Boyle, Basagoitia, and Hays
searched for fox tracks in fall and winter months using ATV's. Dent, Eussen
and Hatch have continued the search effort and monitored radioed animals
during this spring and early summer.
Results and Discussion
LIVE TRAPPING EFFORTS:

A total of 2326 trap nights of effort resulted in 46 captures of 31 different
individuals (Table 1). Sixteen were animals captured for the first time.
Table 1. Trapping effort and numbers of individual kit foxes captured by
county and area, 1 July 94 to 30 June 95, westcentral Colorado.
Trap Nights
Captures
County and Area
Mesa/Garfield
West and North of Grand Junction
Mesa/Delta
SE of Grand Junction to Delta
Montrose/Delta
Delta to SE of Montrose
Moffat
Browns Park-Vermillion Creek
Totals

1125

8

528

2

502

21

171

0

2,326

31

Since May 1992 we have captured, marked, and released 38 individual kit foxes.
Baits have usually been road-killed prairie dogs, cottontails, and ground
squirrels supplemented with turkey chicks. A commercial attractor scent
(chicken and fish, Rob Erickson's on Target A.D.C.) has been used in
conjunction with the baits since mid-May 1995 in all traps.
Since March 1992 trapping efficiency and capture rates have increased (Table
2) although much of the increase is probably the result of more concentrated
effort in areas where foxes are known to be present. Seventy percent of

�256

Table 2. Trapping effectiveness and capture rates, March 1992 to July 1,
1995, Kit Fox survey western Colorado.
Trap Period
Trap Nights
# Individual
Total Fox TNE/Indiv TNE/All
Captures*
Fox Captured
Fox
Capt*.
Mar 92-June 93
Peach Valley only

2725
836

9
9

9
9

303
93

303

July 93-June 94

1754

18

21

97

88

July 94-June 95

2326

31

46

75

50

6805

38**

75

179

91

Total

93

*TNE = Trap nights of effort, all captures includes recaptures.
** Total of all individuals captured during the entire project.

captures have been in the months of May, July, August and September, when
recaptures that occur within 2 weeks of the last capture are excluded (trap
happy animals were often caught on consecutive days) (Table 3).

Table 3. Trapping success by age, sex and month of capture, 1992 - July 1,
1995, for foxes captured or recaptured when recaptures occurred at least 2
weeks post capture. No captures were made in October or November.
Jan
Feb
Mar
Jul
Aug
Sep Dec
Month
Apr
May
Jun
Total
Male
Adult
Juv
Female
Adult
Juv
Unknown
Tot

3

1

0

1

3

1

1

1

1

3

4

1

3

3

2

3

2.

4
3

2

4

8

3

11

12

4
0

1

17
6

5
0

1
4

2

l

6

9

1

23
10
1
57

Of 37 foxes (10 adult males, 7 juvenile males, 13 adult females, 6 juvenile
females) captured and collared or ear tagged we have recaptured 14 of them (4
adult males, 2 juvenile males, 6 adult females, 2 juvenile females) at least
once (range 1-6). Of 23 animals captured once, 5 were adult males, 6 adult
females, 6 juvenile males, 5 juvenile females, and 1 sex unknown. Forty-three
percent of our adult animals have been recaptured compared to 31% of the
juveniles. In late spring-early summer 1995 we have not captured any foxes in
almost 400 trap nights of effort including areas known to have foxes. This
may reflect increasing trap wariness as well as a possible decline in
populations. Different trapping methods, including selective use of padded
jaw traps will be tried in some of the areas where we are finding sign of
foxes but not making any catches.
Mesa/Garfield (Wand N of Grand Junction):
Eight kit foxes were captured during 732 trap nights of effort in July and
August (Fig 1, Table 4). An additional 393 trap nights of effort in May and
June 1995 have not resulted in any captures. These 8 fox are the first
captured in 3 field seasons and 2059 total trap nights of effort since 1992.
Seven of the 8 foxes were radio-collared, none have been located since April
1995.

�257

Fig 1. Length of radio-contact and status of collared kit foxes, Mesa and
Garfield Counties, July 1 1994 - June 30 1995.
Month and Year
J

A

1994
O N D J

S

1995
F

M A

M J

Location
Rabbit Valley
M (194/195) 151.244*
F (196/197) 151.221
F (198/199) 151.034
Prairie Canyon/Baxter Pass
U (153/154) 151.082

X------------------------ unknown

x--- unknown

x- unknown

X- unknown

Corcoran Point
F(Jl26/127) 150.834
M(l30/131)
150.468
F(l32/133)
150.638

x---------------------- unknown
x--------------------------- unknown
x--------------------------- unknown

Cheney Res.
M(JlOl/102)

x- unknown

* Ear tags in ( ) followed by radio-collar frequency

\--I
\--I

Three of the 8 animals (1M,2F) were captured in Rabbit Valley close to the
Utah border. Neither female has been located since September 1994. The male
was last located on 10 April 95. An animal of unknown sex was captured and
radio-collared on 21 Aug in Prairie Canyon, Garfield County. It was
accompanied by another fox which was not captured. The collared animal has
not been located since its date of capture. Four foxes (2M, 2F), 2 of them
juveniles (lM, lF), were captured north of Grand Junction near Corcoran Point.
Three of them were radio-collared. Two (Ml50.468, Fl50.638) were last located
9 April 95. The third has not been located since 12 Dec. Two other pups were
observed but not captured at Corcoran Point, Basagoitia photographed kit foxes
visiting guzzlers in this same area in the summer of 1994. Field crews this
spring found fresh kit fox sign at Prairie canyon and Corcoran Point but did
not capture any foxes. The radio-collars on the 7 animals in this portion of
the study region are close to their expected battery life and may no longer be
working. Hundreds of square kilometers of what appears to be suitable range
is unoccupied or inhabited by scattered individuals difficult to detect and
capture.
Mesa/Delta Counties (Grand Junction to Delta):

\--I

Two animals, 1 juvenile male and 1 adult female were captured near Cheney
Reservoir (near the Mesa-Delta County line) in 528 trap nights of effort. The
female broke her jaw in the trap and died during rehabilitation efforts. The
male has not been located since it was collared. A juvenile male (MlS0.980,
ear tag 17) captured 22 Nov 93 by Verbeck in T14S/R95W/S33, northeast of Delta
north of the Gunnison River has not been located since its capture. These 3
foxes are the only captures made in this section of the study area in 1597
trap nights of effort since 1992. Basagoitia reported on 5 Sept 94 seeing a
live fox along Highway 50 south of Cheney Reservoir. On 3 Sept he observed 2
dead kit foxes on the highway in Delta county, 1, 2 km NW of Adobe Flats
reservoir the other by the Alkali Flats road. Basagoitia photographed a kit
fox at a guzzler in Wells Gulch during the summer of 1994. Basagoitia and
Hays spent considerable time live-trapping and searching for fox tracks and
sign using ATV's from Jan-April. They placed 4 road killed deer as baits but
found no evidence of fox visiting the carcasses. Effort suggests few foxes

�258
Table 4. Locations of radioed foxes in the lower Gunnison and Colorado River
Valleys, Mesa and Garfield Counties July 1, 1994 to July 1, 1995.

V

Sex

Ear Tag
Number

Radio Collar
Frequency

M

194/195

151.244

F
F

196/197
198/199

151.221
151.034

Prairie Canyon/Baxter Pass
8/21/94
U
153/154

151.082

T7S R105W S12

150.834

TlOS RlOOW 35
TlOS RlOOW 35
TlOS RlOOW 35
TlOS RlOOW 35
TlOS RlOOW 35
TlOS RlOOW 35
TlOS RlOOW 35
TlOS RlOOW 35
TlOS RlOOW 35
TlOS RlOOW 35
TlOS RlOOW 35
TlOS RlOOW 35

Capture Site
Date, and
Date of Last
Radio-Contact
Rabbit Valley
8/2/94
12/19/94
4/10/95
8/2/94
8/10/94
9/9/94

Corcoran Point
7/15/94
12/19/94
3/20/95
7/15/94
7/17/94
12/19/94
3/20/95
4/9/95
7/19/94
12/19/94
3/20/95
4/9/95
Cheney Res.
7/11/94
7/13/94

F(J)

126/127

M(J)
M

128/129
130-131

F

132-133

M(J)

101-102
150.851
Jaw Broken - Died in Rehab

F(A)

not radio-collared
150.468

150.638

Location

TlOS Rl04W S20
TlOS Rl04W S20
TlOS Rl04W Sl7
TlOS Rl04W 12
TlOS R104W 13
TlOS R104W 13

T13S R98W
Tl3S R98W

V

30
30?

live in this expanse of the Gunnison River basin with many kilometers of
suitable habitat unoccupied or occupied at very low densities.
Peach Valley and Montrose East Populations:
We have spent 2240 trap nights of effort in the region from Delta south of the
Gunnison River to south and east of Montrose since the study began in 1992.
This is the center of our only population of foxes and the site of most of our
radio-tracking effort. Twenty-seven of the 38 individual kit foxes have been
taken from this area. During the 94-95 reporting period, in 452 trap nights
of effort, a total of 8 new foxes were captured. Four were captured in Peach
Valley: adult female (FlSl.083), adult male (Ml51.257) and 2 female pups too
small to radio-collar (they were collared with pink nylon collars). At
Montrose East, 3 adult (MlSl.160, MlSl.107, MlSl.042) and 1 juvenile
(Ml51.131) male were captured.
In Peach Valley 11 adult kit foxes (SF, 6M) have been captured and radioed
since 31 May 1992 (Fig 2, Table 5). Five of those animals, 3 females and 2
males are dead. Two were killed by coyotes, the cause of death of the others
is unknown. The status of 4 animals is unknown. Two animals, male 151.095
and female 151.083) are still alive. Two radio-collared males (Ml51.209,
Ml51.056) have moved from Montrose East to Peach Valley. These 4 animals are
the only radio-collared animals known to be alive in Peach Valley.

V

�259
Fig 2.
1995.

Length of radio-contact with collared kit foxes, Peach Valley, 1992-

* = Animals that have moved to Peach Valley from Montrose East.
1992
MJSN

1993
JMMJSN

1994
JFMAMJJASOND

1995
JFMAMJ

Animal
F0.238 x-------Dead
X-Unknown
M0.309
F0.873
x--------------------- -------------------------------Alive
F0.889
X----------------------------------------------Dead
Fl.009
X-------------------------------------------------Dead
Ml.095
X--------------------------------------------------Alive
M0.037
X----------------------Dead
Ml.177
X--------------------------------Unknown
M0.499
x--Unknown
X------------Unknown
Fl.083
Ml.257
x--------Dead
Ml.209*
X--------------------Alive
Ml.056*
X--------------------Alive

Table 5. Kit fox radio-collared in Peach Valley, 1992 - July 1, 1995, and
dates of last sightings/radio-signals. New radio-collar frequencies are shown
as they are replaced. ETR = ear tag replaced.

~

~

~

~

Capture or
Date Located

Sex

5/31/92
11/23/92

F

9/28/92

M

2

2.7

9/28/92
4/6/94
4/14/95
6/28/95

F

5

2.5

9/28/92
3/2/93
9/22/93
1/6/94
3/15/95

F

Location

Fate

T51N/R9W/S29
T15S/R94W/S27

Dead (C)

150.309

T50N/R9W/S9

Unknown

150.338
150.956
150.873

T50N/R9W/S9
T50N/R9W/S9
T51N,R9W/S32
T51N,R9W/S32

Alive

150.379
150.850
150.889

T50N/R9W/S9
T50N/R9W/S9
T50N/R9W/S9
T50N/R9W/S17
T49N/R8W/S?

Dead

T51N/R9W/S29
T50N/R9W/S5
T50N/R9W/S10
T50N/R9W/S5
T51N,R9W,S29

Dead (C)

T51N/R9W/S29
TS0N/R9W/S5
T50N/R9W/S10
T51N/R9W/S29
T51N/R9W/S29

Alive

T50N/R9W/S22
T50N/R9W/S8
T50N/R9W/S8

Dead

Ear Tag
Number

Weight
Kg

Radio Collar
Frequency

1

2.0

150.238

6

2.4

(moved from PV to SE of Montrose)

2/23/93
12/6/93
9/5/94
2/28/95
4/14/95

F

2/23/93
12/6/93
9/9/94
1/25/95
6/28/95

M

4/21/93
9/24/93
3/26/94

M

7
ETR18

8

2.5
2.6
2.0

3.0
3.1

150.468
150.189
151.095

ETR147/148
12
ETR15

150.638
150.594
151.009

2.5
2.8

150.708
150.037

�260

Table 5 continued.
9/20/93
6/19/94
1/27/95

M

13

9/30/93
11/22/93

M

7/14/94
9/7/94
12/19/94
1/27/95

F

190/191

7/18/94
9/9/94
11/18/94

M(J)

192/193

2.7

ETR46/47
16

150.813
151.177

2.3

150.499

T50N/R9W/S16
T51N/R9W/S29
T51N/R9W/S29

Unknown

T50N/R9W/S17
T50N/R9W/S17

Unknown

151.083

T51N/R9W/S31
T51N/R9W/S31
T51N/R9W/S29,30
T51N/R9W/S29
Unknown

151.257

TS0N/R9W/S10
T50N/R9W/S10
T50N/R9W/S21

Dead

T51N/R9W/S29
M
30/151
151.209
(First captured on 8/26/94 in Montrose East as Ml51.107)
T51N/R9W/S32
4/18/95
T51N/R9W/S32
6/29/95

Alive

151.056
T50N/R9W/S9
M
26/27
(First captured on 8/24/94 in Montrose East as Ml51.131)
T50N/R9W/S9
6/20/95

Alive

1.9

1.6

V

1/27/95

4/13/95

* Dead (C); killed by coyote

V
Adult female (Fl50.873) was captured by Dent in mid-April. He reported she
was lactating but that an injury to her right rear leg was causing her to
limp. She is still alive but not believed to have any pups. Dent recovered
the remains of female 151.009 in Peach Valley on 14 April and judged she had
been killed by a coyote. Peach Valley female (FlS0.889) first captured 28
Sept 1992 was recovered dead on 15 Mar 1995, 19 Jan south of her capture area
and south of the Montrose East population. The area her carcass was recovered
in had been trapped by field crews in the summer of 1994 with no fresh fox
sign reported. Trapping by Hays in the area the carcass was recovered in did
not yield any other foxes.

V

The male foxes alive in Peach Valley include 2 animals (MlSl.209, MlSl.056)
that moved from the Montrose East site to Peach Valley after early January
1995. Basagoitia and Hays on 27 Jan captured a male with only l ear tag (30)
and no radio-collar they recollared the animal (Ml51.209). This animal was
radio-collared (Ml51.107) and ear tagged 30/29 on 26 Aug in Montrose East by
Boyle. Between 10 Jan and 27 Jan he moved from Montrose East to Peach Valley
and lost his collar. Dent recovered collar 151.107 on 18 April close to the
Water Tank in Peach Valley not far from the area Hays and Basagoitia
recaptured and collared the fox as Ml51.209. Male 151.056 moved to Peach
Valley from Montrose East between 10 Jan and 13 April when Dent recaptured him
in Peach Valley. He replaced radio-collar 151.131 with a new unit (Ml51.056).
Boyle first captured this fox in Montrose East on 25 Aug. The third male in
Peach Valley, Ml51.095 is an animal that has stayed in the Valley since first
captured on 23 Feb 1993.
In 1994, the Montrose East population included at least 13 animals (4 ~dult
females, 3 adult males, 3 female pups, 3 male pups) clustered in a 5knt' area
(Fig 3, Table 6). As of 28 June 1995, 5 of 11 animals collared in 1994 are
alive. Three, Fl51.288, Fl51.037, Ml51.237, are at the Montrose East site.
Two males (MlSl.056, Ml51.209) have moved to Peach Valley. Two are dead, the
fate of 4 is unknown. Olterman has made several flights over the study area

ti

V

�261

trying to locate radio-collared foxes. He last flew on 27 June and will be
making other flights in the next few weeks to attempt to locate missing
animals.
Brown's Park, Moffat County:
In the project year we spent 171 trap nights of effort in Brown's Park with no
captures. Clait Braun of the Colorado Division of Wildlife reported seeing a
kit or swift fox near Vermillion Creek in July 1994. Dent in late August
spotlighted a small fox in that area but could not make an identification.
These observations along with reports in 1993 indicate kit or swift foxes live
in Moffat County. Three summers of trap effort with a total of 616 trap
nights have not resulted in any captures.

Figure 3. Length of radio contact and fate of radio-collared kit foxes,
Montrose East population, May 1994 to July 1, 1995.
Month and Year
and Area

M J

Animal ID
Fl51.288
Fl51.146
Fl51.037
Fl50.037
Fl50.940
Fl51.019 ( .020)
Ml51.237
Fl51.056
Ml51.160
Ml51.209
Ml51.042

X---------------------------------------Alive
X------------------------------Unknown
X-------------------------Unknown
X------------------------------Unknown
x------Dead
x---------------Unknown (Collar recovered)
X-----------------------------------Alive
X----------------------------Alive in PV
X--------------Unknown
X----------------------------Alive in PV
x-----Dead

J

1994
A S

O

N D J

1995
F M A M J

Table 6. Kit foxes trapped in the Montrose East population in 1994 and status
on July 1 1995. NL = non-lactating females; L = lactating.
Capture or
Date Located

Sex

Ear Tag
Number

Weight
Kg

Radio Collar
Frequency

5/29/94
8/26/94
12/22/94

F(NL)

21/32

2.5
2.4

150.947

2.8

151.288
150.403

ETR22/38

2.5
2.4
2.3

151.146

23

2.3

150.338

1/10/95
4/17/95

F(NL)

6/27/95

~/

~

5/29/94
8/25/94
1/10/95

F(NL)

22/28

5/29/94
8/28/94
9/15/94

F(NL)

5/29/94

M pup

(recaptured on 7/7/95 - now Fl51.037)
24

1.75

not-collared

Location

Fate

T49N/R8W/S7
T49N/R8W/S7
T49N/R8W/S6,7
T49N/R8W/S6
T49N/R8W/S7
T49N/R8W/S7 Alive

T49N/R8W/S7
T49N/R8W/S7
T49N/R8W/S7

Unknown

T49N/R8W/S7
T49N/R8W/S7

T49N/R9W/S12 Alive
T49N/R9W/S7

Unknown

•

�262

V

Table 6 continued.
5/30/94
8/25/94

F pup 176/177

1.5

not-collared

2.3

150.037

1/10/95

V

T49N/R8W/S7
T49N/R8W/S6
T49N/R9W/S7

Unknown

5/30/94

F pup 178/179

1.4

not-collared

T49N/R8W/S7

Unknown

5/31/94
6/7/94
7/28/94

F (L) 180/181

2.3

150.940

T49N/R8W/S7
T49N/R8W/S7
T49N/R8W/S9

Dead

5/3/94
8/28/94
9/16/94
11/11/94

F pup 182/183

M Ad

8/25/94
12/22/94

M Pup 26/27

1/10/95

not-collared

2.2

151.019( .020)

Collar recovered no trace of carcass

6/3/94
8/25/94
1/10/95
4/18/95
6/27/95

4/13/95
6/27/95

1.8

184/185

3.0

not-collared

2.5

150.708

151.237
2.0

151.131

Moved to Peach Valley

151.056

=

T49N/R8W/S7
T49N/R8W/S7
T49N/R8W/S8
T49N/R8W/S8

Unknown

T49N/RSW/S7
T49N/R8W/S7
T49N/R8W/S7
T49N/R8W/S7
T49N/R8W/S6

Alive

T49N/RSW/S7
T49N/RSW/S7
T49N/R8W/S7
T50N/R9W/S9
T50N/R9W/S9

Alive

8/27/94
12/29/94
1/4/95

M Pup

33/34

1.5

151.160

T49N/R8W/S7
T49N/R8W/S6,7
T49N/RSW/12
Unknown

8/26/94
12/22/94
1/10/95
1/27/95
4/18/95

M Ad

29/30

2.4

151.107

T49N/R9W/S7

151.209

T51N/R9W/S29
T51N/R9W/S32

Alive

T49N/R9W/S7
T49N/R8W/S8
T49N/R8W/S18

Dead(C)

8/27/94
11/9/94
11/22/94

Moved to Peach Valley
M Ad

48/49

2.3

151.042

T49N/R8,9W/S7,12
T49N/R9W/S12,7

V

Behaviors of foxes in Montrose East and Peach Valley:
A report on kit fox activity patterns is appended to this report (Boyle 1995).
Boyle estimated home range size for 7 kit foxes in the Montrose East
population and 2 animals in Peach Valley (Table 7). Animals at Montrose East
averaged 3.6km2 (range 1.5-5.9), those in Peach Valley 7.5-7.7km2 • Home range
sizes may reflect habitat and prey abundance differences between the 2 sites.
Three animals have moved from Montrose East to Peach Valley (Ml51.209,
M151.056) or out of Peach Valley (F150.889). This is the first evidence of
foxes moving between the 2 areas. Boyle (1995) reported fox tracks north of
Flattop Mesa between Peach Valley and Montrose East and did not believe they
were made by collared animals. Scattered individuals may inhabit the area
between these 2 sites but to date we have not captured any and several
landowners have refused permission to cross their properties.
Most radio-collared animals have not moved far from their original capture
locations (Table 5, 6). The eight foxes which we have had radio-collared for
the greatest length of time (Table 8) show little movement from their original

V

�263

Table 7. Estimated home range size for nine kit foxes, Peach Valley and
Montrose East populations, October-January 1994-1995. From Boyle (1995).
Animal No.

Age/Sex

Montrose East
150.037
150.403
150.947
150.708
151.131
151.160
151.107

Ad
Ad
Ad

Peach Valley
151.009
151.083

Ad

F

Ad

F

sites of capture.
predation.

Juv F
F

F
M

Juv M
Juv M
Juv M

Home Range Kmi

# of Locations

56

5.9
4.7
1.5
4.7
2.3
2.5
3.9

53
50
36
38
36

7.7
7.5

22
18

52

Fidelity towards home ranges may reduce the probability for

Home ranges of animals in the Montrose East study area overlapped and the
individuals using different dens varied over the field season (Boyle 1995).
Boyle reported 9 individual foxes used an average of 3.7 dens (range 2-6) from
late September to mid-January. A den complex adjacent to the main road
through the study area was continuously used by 2-4 foxes from late November
to January 10. Previous work by Verbeck (Fitzgerald and Verbeck 1993) and
Link (1995) agree with Boyle's observation of frequent den changes with a
tendency to favor some dens more than others.
Boyle (1995) estimated total minimum distance travelled and straight-line
maximum distances traveled during single night movements of 5 individual foxes
in the Montrose East group. He estimated total minimum distance to average
6.2 Jan and maximum straight line distance to average 2.0 km. Movements of the
observer in tracking foxes may have caused them to increase their movements
more than might occur if undisturbed. Link, Beck and Dent (personal
communications) reported kit foxes being radio-tracked on foot were aware of
their presence and moved rapidly away from them. In the narrow Montrose East
Valley it would be hard to avoid harassing the foxes when tracking their
movements. Boyle's effort confirms our working assumption that foxes do not
travel more than a few Jan's in their nightly forays and traps have to be set
close together and left out for several days.
Reproductive Success:
In December Boyle reported transitory pairing of F150.947 and M 151.131,
followed by F150.947 then denning with F150.403. Dent in April could not
locate any paired animals but did trap a lactating female. Field crews
working in late spring and summer have not located any dens with pups.
Since May 1992, we have captured 14 adult females at times of the year when
reproductive status could be determined. Four have shown evidence of
lactation or contained uterine scars (Fl50.238). In Montrose East in spring
and summer 1994, 4 of 5 adult females were non-lactating. This field season
the only female (150.873) in Peach Valley does not appear to have pups. In
Montrose East female 151.288 did not show signs of pregnancy or lactation in
mid April. Female 150.338 (captured on 7 July 1995) shows no sign of bearing
pups. Since 1992 we know of only 6 litters of pups, 3 in Peach Valley each
with 2 pups, 2 in Montrose East with 7-8 pups using a single den, and 1 at
Corcoran Point with 4 pups. The low numbers of adult females that are
reproducing may be due to a number of different causes including: lack of

�264

Table 8. Estimated size of range of 8 kit foxes radio-collared for at least 7
months, Peach Valley and Montrose East populations.
Fox#

Months Radioed

Estimated Range (km2)

Peach Valley
FlS0.873
FlSl.009
FlS0.889
MlSl.095
MlSl.177

28

16

8
7

Montrose East
FlSl.288
FlSl.037
MlSl.237

13
7+
12+

3
5

33
25+
29+

7
8
8

4

males, lack of adequate food, disturbance from field crews radio-tracking
them, or, in the case of the Montrose East animals high population density in
a limited spacial area.
other Activity:
Link has completed her M.A. Thesis detailing the first 2 years of the
project. Copies are enclosed with this report. The Wildlife Commission acted
in September 1994 to expand the area with trapping restrictions to protect kit
fox. Field plans have been completed for the 95-96 year: 1. We will continue
to radio-collar animals captured in Peach Valley, Montrose East or at Corcoran
Point but will not radio individuals taken elsewhere. All captured animals
will be ear-tagged. 2. We will conclude our extensive trapping efforts with
work to concentrate on the 64 km area along the base of the Book Cliffs from
Corcoran Point to the Utah border and the 38 km long area at the base of Grand
Mesa from Cheney Reservoir to Wells Gulch. 3. We will spend additional time
in Brown's Park trying to resolve if kit or swift foxes live there. 4. From
September 1995 through June 1996 we will use a monthly aerial search as the
primary method for monitoring radioed animals in the Gunnison and Colorado
river drainages. s. Depending on weather we will conduct a limited amount of
snow-tracking during the winter of 95-96. 6. By April, 1996 we will complete
reports and recommendations for continued research on kit fox in western
Colorado.

V
V

By:

James P. Fitzgerald
Contractor, University of Northern Colorado.

V

�313

Colorado Division of Wildlife Wildlife
Wildlife Research Report
July 1996

JOB PROGRESS REPORT
State of

Colorado

Project No.

W-153-R-7

Mammals Research

Work Plan No.

lOA

c!9rt Fox studies

Job No.

Kit fox (Vulpes macrotis) Status

in Colorado
Period Covered: July 1, 1995 to June 30, 1996
Author: J.P. Fitzgerald
Personnel: J . P. Fitzgerald, J. Eussen, c. Hatch, J. Prather, S . Lechman,
L. Dent, D. Finley, J. Olterman, T. Beck.

ABSTRACT
In 1368 trap nights of effort 8 new kit foxes were captured. Five of them were
from a family group (1 adult female, 2 female pups, 2 male pups) captured in
July 1995 in Peach Valley. An adult male was captured at Cheney Reservoir and
a juvenile male pup and adult female were captured at Corcoran Point. The
total number of individual kit foxes trapped since 1992 is 47 with 33 of them
from the Peach Valley-Montrose East complex. A total of 17 individual kit
foxes were radio-tracked during 1995-96. Nine (53%) of the 17 animals died
during the study period. Four deaths were attributed to coyotes, 2 to
drowning, 1 to an automobile, and 2 from undetermined causes . Two litters of
pups were born in the Montrose East area in 1996 with female F23 being killed
by a coyote after her pups came above ground . . The fate of those p~ps is
unknown. One other female living between Peach Valley and Montrose East may
have young. J. Eussen will be working on kit fox food habits as a thesis
project in 1996. The draft final report of project activities was completed
and reviewed by T. Beck. Revisions are being made and the final report wlll be
delivered by August 1.

i]ID1i~Dm1
1
I
BDOW010805

�315

KIT FOX (VULPES MACROTIS) STAms IR COI,9RADO

James P. Fitzgerald

P, N, QBJECTIYE
Document the geographic distribution and relative abundance of kit fox in
Western Colorado.

SEGMENT QBJECTIYES
1.

Continue to monitor radio-collared foxes in Montrose, Delta, Mesa and
Garfield.counties.

2.

Continue search for new kit fox populations.

3.

Compl~te draft of final project report.

METHODS
Field methods for live-trapping were similar to those reported previously
(Fitzgerald and Link 1993, Fitzgerald and Verbeck 1993). Limited trapping was
also conducted using 1.5, soft-catch, leg-hold traps at baited dirt-hole sets.
Trapping efforts were concentrated in the Gunnison and Colorado River
Drainages in Mesa, Garfield, Delta, and Montrose counties and in northwestern
Moffat county. Field personnel continued to monitor and document locatio~s of
radio-collared foxes using searches with a fixed wing aircraft piloted by J.
Olterman, or by ground tracking.

RESULTS AND DJSCQSSIQH
Live ~rapping Bffort

From July 1, 1995 to June 30, .1996 we conducted 1368 trap nights of effort
resulting in capture of 8 new foxes (Table 1.). All trapping was done in
Moffat County.or in the Gunnison River-Lower Colorado River drainages in Mesa,
Garfield, Delta and Montrose counties. Two foxes were captured at Corcoran
Point, a juvenile male and-an adult female. An adult male was captured at
Cheney Reservoir. In Peach Valley, 2 juvenile females, 2 juvenile males, and
an adult female were captured at a whelping den (Table 2). Field crews again.
failed to capture any foxes in Moffat County, although scat believed to be
from kit or swift foxes was discovered and a CDOW biologist (C. Braun)
reported seeing a swift or kit fox crossing the road near Vermillion Creek.
The total number of individual kit foxes trapped since the study began in 1992
is 47. T~irty-three of the captures have been made in the Peach
Valley-Montrose East complex.

�316

Table 1. Trapping effort and numbers of individual kit foxes captured
by county and area, July 1 1995-June 30, 1996.
County/Area

Trap Nights

New· Captures·

Mesa-Garfield Counties
Prairie Canyon to
Corcoran Point Areas

347

2

Mesa-Delta Counties
Cheney Reservoir to
-East of Del ta Airport

493

1

Montrose-Delta Counties
Peach Valley-Montrose
East Complex

368

5

Moffat County
Browns Park-Vermillion
. Creek

160

0

Location, sex, age class, ear-tag·number and radio-collar
frequency for previously uncaptured kit foxes, 1995-96 fiscal year.

Table 2.

Location

Sex/Ear Tag

Radio-collar

Date Captured

Status

M(J)310
F(A)311

150.189

8/12/95

151.-186

11/3/95

Unknown
Dead

M(A)312

151.083

12/4/95

Dead

150.029
150.728
150.004
150.920
151.009

7/28/95
7/26/95
7/.27/95
7/26/95
7/27/95

Alive
Dead
Dead
Dead
Alive

V

V

V

Corcoran
Point
Cheney
Reservoir
Peach Valley
F(A)309
F(J)306
F(J)308
M(J)305
M(J)307

V

�317

Monitoring of Radio-collared Foxes

During the fiscal year, field crews periodically located radioed animals
during ground searches. Jim Olterman also made a number of flights to locate
animals. A total of 17 foxes (9 males, 8 females) were located and monitored
during 1995-96, including 2 male and 2 female pups marked in July 1995, three
of which have died (Table 3). Two litters of pups came above ground in May
1996 in Montrose East, one litter (F23's) had 4 pups, the other litter (F2l's)
has an unknown number of young. F309 living between Peach Valley and Montrose
East is also believed to have pups but the whelping den has not been located.
Nine animals died during the year with deaths of 4 attributed to coyotes
(F306, F308, F23, M312). Two died from probable drowning (M30, F311), 1 was
road killed (M305) and two (M26, F309) died from undetermined causes.
~her Activity

The first draft of the final report wae finished and reviewed by T. Beck. It
is being revised and will be.submitted by the end-o~ August pending receipt of
some additional information from the Montrose Office· of the BLM. The state of
Utah has been contacted to see whether UNC can do some trapping in late summer
along the Utah-Colorado border to assess kit fox populations in Utah that
might provide migrants to Colorado stocks. J~ Eussen is collecting kit fox
scat and will be doing a food habits analysis for a M.A. thesis using his
materials and material collected by other field workers.

By:

James P. Fitzgerald, Contractor,
University of Northern Colorado

�318

Table 3. Kit foxes alive during the 1995-96 fiscal year and their
status as of June 30 1996.
Site &amp; Date
of Capture/
Tracking
Corcoran Point
8/12/95
11/2/95
3/17/96
5/16/96

Sex/Age
Ear Tag#

Radio-collar
Frequency

JM 310
150.189

n.c.

Location

T9S,RlOOW,S25
T9S,RlOOW,S34
TlOS,RlOOW,SlO
signal too weak to locate

Status as
of 30 June

Dead

Cheney Reservoir
12/4/95
AM 312
151.083
5/16/96
moved to Wells Gulch
6/18/96

T3S~R2E,S24
·T4S, R3E, S13
T4S,R3E,S13

Dead

Delta Airport
11/19/95

T14S,R96W,S36

Unknown

AF 311

151.186

collar at private residence

AM 33*

151.160

Peach Valley
9/28/92
AF 5
150.338
4/6/94
• 150.956
4/14/94
150.873
8/15/95
10/11/95
12/4/95
moved to Alkali Gulch
8/26/94
12/22/94
1/10/95
1/27/95
10/11/95
2/14/96
6/18/96
8/24/94
1/10/95
4/13/95
10/11/95
2/14/96
4/9/96
7/26/95
2/14/96
4/9/96

AM 30

151.107

moved to PV from ME
30/151
151.209

collar in Selig ~anal
JM 26
151.131
moved to PV from ME
151.056

JF 306

150.728

V

Unknown

TlN,RlW,SlO
TlOS,RlOOW,SlO
T1N,R1E,S29
TlN,RlW,S36

11/3/95
3/17/96
5/16/96
6/18/96

V

V
V

TSON,R9W,S9
T50N,R9W,S9
T51N,R9W,S32
T51N,R9W,S7
T51N,R9w,s29:..32
Tl5S,R97W,Sl

Unknown

T49N,R9W,S7
T49N,R9W,S12
T49N, R9W, S_12
T51N,R9W,S29
T51N,R9W,S29-32
T51N,R9W,S30
TS1N,R9W,S29

Dead

T49N,R8W,S7
T49N,R8W,S7
T50N,R9W,S9
T51N,R9W,S29
T50N,R9W,S16
TSON,R9W,S16

Dead

TSON,R9W,S16
TSON,R9W,Sl6
TSON,R9W,S16

Dead

V

V

�Table 3 (continued)
Site &amp; Date
of Capture/
Tracking

Sex/Age
Ear Tag#

Radio-collar
Frequency

7/26/95
12/25/95

JM 305

150.920

7/27/95
2/14/96

4/9/96

JF 308
150.004
moved to ME
moved back to PV
JM.307

7/27/95
5/16/96
6/18/96
7/28/95
2/14/96 •
6/18/96

n. c.
151.009

AF 309
150.029
moved to ME
moved between ME and PV

.Montrose East
5/29/94
8/26/94
4/17/95
2/14/96
6/18/96

AF 21

150.947

52/52

151.288
150.098
150.403

Location

T50N,R9W,S16
Tl5S,R95W,S33

Status as
of 30 June

Dead

T50N,R9W,Sl6

T49N,RSW,S24
T51N,R9W,S30

Dead

T50N,R9W,Sl~
· T49N,R9W,S6

T49N,R9W,S6

Alive

T50N,R9W,S16
T49N,R8W,S9
T49N,R8W,S3

Dead

T49N,R8W,S7
T49N,R8W,S7
T49N,R8W,S7
T49N,RSW,S7
T49N,R9W,S6

Alive

T49N,RSW,S7
T49N,R8W,S7
T49N,RSW,S7

Unknown

T49N,R8W,S7
T49N,R8W,S7
T49N,R8W,S5
T49N,R8W,S7
T49N,R8W,S9

Dead

5/29/94
8/25/94
1/10/95

AF 22

5/29/94
9/15/94
7/7/95
2/14/96
6/18/96

AF 23

6/3/94

AM 184

n. c.
150.708
151.237

T49N,RSW,S7
T49N,RSW,S7
T49N,RSW,S7
TS0N,R9W,S18T50N:, R9w·, Sl6
T50N,R9W,S26
T49N,R9W,Sll-12 Alive

JM 33

151.160

moved ~orth of Delta Airport

T49N,RSW,S7
T49N,RSW,S6-7
T49N,RSW,S12
T14S,R69W,S36

moved to Alkali Gulch

Tl5S,R97W,Sl

151.146

151.042

8/25/94
4/18/95
10/11/95
2/14/96
5/16/96
6/18/96
8/27/94
12/29/94
1/4/95
10/11/95
11/19/95
12/4/95

150.338

T14S,R96W,S36
Unknown

������������������������������������������������������������101
Colorado Division of Wildlife
Wildlife Research Report
July 1998

SEGMENT NARRATIVE

State of
Project No.
Work Package No.

Colorado
W-153-R-ll
0663

Task No.

cost center 3430
Mammals Program
Species of Special Concern/Species

at Risk conservation
Kit fox conservation

Period covered: July 1, 1997 - June 30, 1998
Author: T.D.I. Beck
Personnel: T. Beck, G. Bock, D. Coven, J. Garner, R. Gill, M. McLain,
P. Schnurr, L. Willmarth; CDOW

ABSTRACT
The Program Narrative was modified to more clearly outline the multiple
stages of the development of a conservation strategy. The initial phase of
biological assessment was begun this segment. Sixty-three cameras, triggered
by active-infra-red sensors, were deployed throughout the Uncompahgre and
Gunnison valleys. Seven photos of kit fox were obtained; all are believed to
be different individuals. Four of the photos were at or near dens initially
located by ground searches. In addition, 2 active kit fox dens were located;
one of which had 2 individuals and the other only one. Of the 3 dens with
pairs present, none appeared to have young-of-the-year. All but two of the
photos and sightings were in the Peach Valley-Montrose East habitat area.
This isolated area of habitat is only 90 km2 in area. The Gunnison Valley
area comprises 316 km2 of habitat, of which approximately 50\ is deemed
marginally suitable because of lack of den sites. No efforts were made to
trap and collar kit fox during the whelping season.

�103
KIT FOX (VULPES HACROTIS) STATUS IN COLORADO
Thomas D. I. Beck

P,N, Objective
Develop and implement a conservation strategy to recover and conserve
kit fox populations in Colorado.

segment Objectives
1.

Develop a conservation strategy to recover and conserve kit fox in
western Colorado.

2.

Survey for presence of fox in Gunnison valley area with infra-red
activated cameras.

3.

Capture and radio-collar adult kit fox in both the Uncompahgre and
Gunnison valley areas.

METHODS AND MATERIALS
The earlier version of the Program Narrative was modified to more clearly
outline the progressive stages of the conservation strategy development. The
modified document was submitted in May 1998.
Ground searches for kit fox sign and dens were conducted in the Uncompahgre
and Gunnison valleys on 40 days during April-June 1998. Remote 35mm cameras,
activated by active-infra-red sensors, were deployed in areas with fresh kit
fox sign, areas with old fox dens, and likely travel areas. The camera system
was developed by TrailMaster (Lenexa, KS) and was essentially the same system
as used by Beck on black bear (Ursus americanus) studies (Beck 1995).
The distance from the camera to the infra-red transmitter was 2 m; camera
height above ground was 15-30 cm. A pipe was driven into the ground 10 cm in
front of the infra-red transmitter and one of several baits (beaver meat,
chicken flesh lure) were placed down in the pipe to minimize bird conflict.
The recorder unit was programmed so that the infra-red beam had to be broken
for 0.15 sec to be recorded ( value of P = 3) and only a 6 sec delay between
successive pictures. Color print film, ASA 400, in rolls of 24 and 36
exposures were used. Cameras were left at locations for varying periods,
depending on area, work schedule, and need for cameras in other areas.
Observations of active kit fox dens were conducted at dusk on 9 evenings, in
hopes of documenting presence of pups. Observations were made with binoculars
or a night-vision scope at distances of 30 to 100 m.
Maps of areal extent of salt desert shrub communities were obtained from CDOW
Habitat Section. Also, 15-minute quad maps were used for plotting camera
locations and all fresh fox sign.

�104

RESULTS ARD DISCUSSION

Program Narrative Modification
The revised Program Narrative describes 5 phases in the development of a
conservation strategy: Biological Assessment, Socio-Economic Assessment,
Political Assessment, Conservation Planning and Implementation, and
Conservation Evaluation. The development of a formal Conservation strategy
will occur in Phase IV. It is believed that by doing the biological, social,
and political assessments as precursors to the formal plan, support for the
plan will be more wide-based and solid (Clark et al. 1994).

Biological Assessment
Analysis of the work reported by Fitzgerald (1996) suggested that summer was
the period of lowest trap success, and the majority of search effort had been
conducted in the summer. Thus it was deemed prudent to resurvey much of the
available kit fox habitat during spring and fall seasons, utilizing a
different technology than live-trapping. Ground searches for kit fox dens and
spoor were conducted on 40 days during April-June, 1998 by either one or two
researchers throughout the 406 km2 of habitat in the Gunnison and Uncompahgre
valleys. Only 4 active dens were located, all in den complexes previously
identified in the Uncompahgre Valley. Three of the dens supported kit fox
pairs while the other had a single fox. Cameras were set near 3 of the 4
dens. The den in the Montrose land fill (kit fox pair) was not equipped with
a camera because of the high human traffic flow by the den. The camera at the
single den malfunctioned so no photos were made. We obtained 2 photos of kit
fox at each of the other 2 dens. A total of 63 camera sets were made, for
periods ranging from 7 to 28 days. Thirty-five of the sets were for periods
of 10-15 days. Three kit fox photos were obtained in areas where we did not
find active fox dens or spoor. Subsequent searches also resulted in no active
dens found. Based on camera and ground searches, 8 kit fox were located in
the Uncompahgre Valley and 2 in the Gunnison Valley just west of the Delta
airport. Photos were obtained from all active den sites where cameras
operated correctly; thus supporting the use of cameras as an effective survey
tool.
Based on 9 evening observations and 8 daytime examinations of den sites it did
not appear that any of the 3 kit fox pairs produced any pups in Spring, 1998.
Four natal dens of red fox (Vulpes vulpes) were located in the saltbush
habitats in what appeared to be suitable kit fox habitat.
The camera surveys also produced photos of the following: badger (3), house
cat (3), dog (1), raccoon (7), cottontail rabbit (76), prairie dog (3),
antelope ground squirrel (16), striped skunk (3), domestic cattle (6), magpies
(44), horned lark (9), meadow lark (1), and a snake (1). Sixteen cameras
produced no photos, 3 had mechanical malfunctions, and 2 were disturbed and
made inoperable by people.
The Uncompahgre Valley area is comprised of approximately 90 km2 of suitable
kit fox habitat; arranged in an oblong pattern 30 km N-S with an average width
of less than 4 km. Eight of the observed kit fox were in this area. This
area is separated from the Gunnison Valley habitats by agricultural land,
housing developments, a highway, and a river; resulting in a 7-9 km long
obstacle course to inhibit dispersal. Based on the range of kit fox densities
summarized by White and Garrott (1997) (0.16-0.7/km2 ) this area of habitat

�105
would likely only support 14-63 kit foxes.
this lower bound.

Current density appears to be near

The Gunnison Valley area is approximately 316 km2 of apparently suitable kit
fox habitat. Only 2 kit fox were located in this region; both at the same
camera and likely a pair. They were at the southern tip of the habitat area.
Approximately 50% of the habitat is characterized by a volcanic rock cap which
severely limits den sites. No old kit fox dens were located in these
formations and only a few badger and coyote dens. It appears that the lack of
old dens limits the value of this region. The northernmost section of
possible habitat in the Gunnison Valley lies between Kannah Creek and the
Colorado River. It is approximately 74 km2 in area but separated from the
upper valley by extensive irrigated farm lands and new housing developments.
No fresh or old kit fox sign was discovered in this area.
It was decided not to trap and collar adult foxes during the whelping season
because of the added stress of this activity to the individual foxes (Cypher
1997). The small number of kit foxes present seems to justify minimum
intrusion during this period.

Literature cited
Beck, T.D.I. 1995. Development of black bear inventory techniques.
Wildlife, Fed. Aid. Rep. W-153-R-8. llpp.

Colo. Div.

Clark, T.W., R.P. Reading, A.L. Clarke. Eds. 1994. Endangered Species
Recovery:Finding the Lessons, Improving the Process. Island Press,
Washington, D.C. 450 pp.
Cypher, B.L. 1997. Effects of radiocollars on San Joaquin Kit Foxes.
Wildl. Manage. 61(4):1412-1423.

J.

Fitzgerald, J.P. 1996. Status and distribution of the kit fox (Vulpes
Colo. Div. Wildlife, Final Fed. Aid. Rep.
153-R-7. 78 pp.

macrotis) in Western Colorado.

White, P.J. and R.A. Garrott. 1997. Factors regulating kit fox populations.
Can. J. Zool. 75:1982-1988.

Prepared by
Thomas Beck
Wildlife Researcher

w-

�55

Colorado Division of Wildlife
Wildlife Research Report
July 1999

JOB PROGRESS REPORT

State of
Colorado
Project No.
W-153-R-12
Work Package No. __0-=-66=3;;......__ _ _ __
Task No. - - - - ~
1 -------

Cost Center 3430
Mammals Program
Species of Special Concern/Species at Risk
Conservation
Kit fox Conservation

Period Covered: July 1, 1998,. June 30, 1999
Author: T. D. I. Beck
Personnel: T. Beck, D. Coven, P. Creeden, V. Graham, M McLain, P. Schnurr, B. Sommerville, L.
Willmarth; CDOW

ABSTRACT
Biological assessment work was expanded to the Colorado River Valley in this segment Fiftyfour cameras, triggered by active-infra-red sensors, were deployed throughout a nearly 800 km2 area
for 12-30 days each. No photos of kit fox were obtained. Surveys of kit fox dens active in 1998 found
only one den active in 1999; however, the pair apparently did not have any young again this year. A
combination of GAP mapping and ground mapping was used to estimate the habitat potential for
restoration of kit fox in western Colorado. Three distinct areas were identified: the Colorado,
Gunnison, and Uncompahgre Valleys. The Colorado valley is isolated from the other two by urban
development and irrigated agriculture. The Colorado River Valley is the largest contiguous area (685
km2) and has the highest percentage of public land Thus, it is likely the best area for kit fox restoration
efforts. Successful restoration of kit fox throughout the entire 1310 km2 of suitable kit fox habitat in
Colorado could result in kit fox populations varying from 182-728; based on densities reported in the
literature. Primary negative factors to be addressed are housing developments, greater isolation of
habitats, and red fox pioneering into salt desert shrub communities.

�57

KIT FOX (VULPES MACROTIS) STATUS IN COLORADO
Thomas D. I. Beck

P.N. Objective
Develop and implement a conservation strategy to recover and conserve kit fox populations in
Colorado.
Segment Objectives
1.
2.
3.

Conduct the biological assessment work necessary to develop an effective conservation strategy
for the conservation of kit fox in western Colorado.
Survey for presence of kit fox in Gunnison and ·uncompahgre Valley areas with infra-red
activated cameras.
Capture and radio-collar adult and juvenile kit fox in both the Uncompahgre and Gunnison valley
areas.

METHODS AND MATERIALS
Plans for field work were modified significantly in July in response to the dearth of kit fox
activity found in the Gunnison and Uncompahgre Valleys. Additionally, much oftheiandscape in the 2
valleys are either marginally suitable or becoming unsuitable through a combination of natural features
and human development. Therefore, emphasis was shifted to better map the available habitat and
conduct kit fox surveys in the Colorado River Valley.
Ground searches for kit fox sign and dens were conducted in the Colorado River Valley on 40
days during September-November 1998. Remote 35mm cameras, activated by active-infra-red
sensors, were deployed in areas with fresh kit fox sign, areas with old fox dens, and likely travel areas.
The camera system was developed by TrailMaster (Lenexa, KS) and was essentially the same system
as used by Beck on black bear (Ursus americanus) studies (Beck 1995).
The distance from the camera to the infra-red transmitter was 2 m~ camera height above ground
was 15-30_ cm. A pipe was driven into the ground 10 cm in front of the infra-red transmitter and one of
several baits (beaver meat, chicken flesh lure) were placed down in the pipe to minimize bird conflict.
The recorder unit was programmed so that the infra-red beam had to be broken for 0.15 sec to
be recorded ( value of P = 3) and only a 6 sec delay between successive pictures. Color print film,
_ASA 400, in rolls of24 and 36 exposures were used. Cameras were left at locations for varying
periods of 12-30 days, depending on area, work schedule, and need for cameras in other areas.
Observations of an active kit fox den were conducted at dusk on 3 evenings in May 1999, in
hopes of documenting presence of pups. Observations were made with binoculars or a night-vision
scope at distances of30 to 100 m. Historic den sites in the Uncompahgre Valley were visited in May
1999 to check for kit fox activity.
Maps of areal extent of salt desert shrub communities were obtained from CDOW Habitat
Section. Acreage of salt desert shrub and irrigated lands were estimated from the GAP maps. The
land ownership of the primary habitat (salt desert shrub) was also estimated from the GAP maps. Onsite field mapping was conducted to better assess the utility of much of the salt desert shrub component
on private land since much of this land has been undergoing significant housing development. Also,
15-minute quad maps were used for plotting camera locations and all fresh fox sign.

�58

RES ULTS AND DISCUSSION
Biological Assessment

Kit Fox Distribution and Abundance - Analysis of the work reported by Fitzgerald (1996) suggested
that summer was the period of lowest trap success, and the majority of search effort had been
conducted in the summer. Thus it was deemed prudent to resurvey much of the available kit fox
habitat during spring and fall seasons, utilizing a different technology than live-trapping. Ground
searches for kit fox dens and spoor were conducted during spring 1998 in the Gunnison and
Uncompahgre Valleys. Similar searches were conducted in the Colorado River Valley during
September-November 1998.
Fifty-four cameras were placed for periods of 12-30 days. Two camera units were stolen. No
kit fox were photographed at the 52 sites spread throughout the approximately 800 km2 Colorado River
valley. No active fox dens were located during ground searches.
A variety of wildlife was photographed: cottontail rabbits (158),jackrabbits (7), antelope
ground squirrel (2), coyote (6), badger (6), rock squirrel (6), bobcat (1), chipmunk (1), pronghorn (1),
magpie (31 ), owl (1 ), unk. birds (3 ). Frequent rains and cold temperatures resulted in the loss of 38
images during the last 2 weeks of work because the plexiglass dust cover frosted over; causing a frosty
blur on the photograph.
In May, 1999 a dead male kit fox was recovered along a paved road in Colorado National
Monument by DWM Paul Creeden. It was freshly killed when retrieved about 0430. The area is in the
pinon-juniper vegetation community, approximately 500 m higher than the desert floor. About 3 hours
was spent on a ground search in the area looking for any denning activity or otl;ter sign but none was
found It was not the normal vegetation or terrain for kit fox.
All kit fox dens-active in 1998 were checked in May 1999 for fox activity. The Montrose
landfill den again had a pair of kit fox. This pair was observed on 3 evenings in May but there was no
indication of pups. Volunteer observers who work at the landfill reported no pup activity during the
summer. None of the other known kit fox dens checked had any indication of kit fox activity.
Additionally, 3 of the red fox (Vulpes vulpes) dens active in 1998 which were located in the salt desert
shrub community were also active in 1999.
Prey Abundance - Comparative prey surveys were initially to be conducted in Fall 1998. However,
based on the low numbers of kit fox located in Spring 1998 it was decided to expand general surveys
to the Colorado River Valley instead Also, preliminary mapping suggested the Uncompahgre and
Gunnison Valleys provided only modest opportunity for kit fox restoration because of limited habitat.
In addition, the Colorado Legislature debated a bill in the 1999 session which could have
restricted the authority of the CDOW to implement kit fox augmentation. This bill (HB 99-1299) was
passed in late April and signed into law in May. However, final wording did not cover the kit fox
program (in contrast to original language). However, it was decided not to do extensive prey base
work pending resolution of this issue.
Potential Habitat
The western valleys of Colorado which historically supported kit fox were divided into 3 distinct
valley segments: Uncompahgre, Gunnison, Colorado. The Gunnison Valley area was subdivided into 3
segments because the central segment is a region with basalt cap rock close to the surface and den sites
are extremely limited. Even badger diggings are uncommon in this reach; which is also the area where
3 roadkill kit fox have been documented in the past 5 years.

�59

Based on the GAP vegetation maps, there is an estimated 54 7 km2 of salt desert shrub in the
Uncompahgre Valley unit (Fig. 1). This unit also has the highest area of irrigated farm land (528 km2),
all of which historically was salt desert shrub. It also has a high proportion of existing salt desert shrub
in private land status (45.8%). Ground mapping was conducted to exclude peripheral areas of salt
desert shrub as well as areas which have been developed for human housing. Radio telemetry work on
kit fox in this valley strongly indicated the kit foxes did not venture into the developed desert areas but
remained in a relatively small core area Thus, the suitable kit fox habitat for the near future is more
likely about 140 km2. This area is separated from the Gunnison Valley habitats by agricultural land,
housing developments, a highway, and a river; resulting in a 7-9 km long obstacle course to inhibit
dispersal. Based on the range of kit fox densities summarized by White and Garrott (1997) (0.160. 7/km2) this area of habitat would likely only support 22-98 kit foxes.
The Gunnison Valley area has approximately 609 km2 of salt desert shrub vegetation (Fig. 2).
Only 2 kit fox were located in this region in 1998, 5 were trapped here during 1993-1995, and 3 road
kills have been documented. The East Gunnison area (179 km2) only has about 18 km2 of irrigated
land but does have some residential development and the irrigated land may serve as a barrier to
animals moving east of Surface Creek. Thus, suitable kit fox habitat for recovery is closer to 120 km2,
of which 66% is in public ownership.
The Central Gunnison area (250 km2) has about 10 km2 of irrigated farmland. This is the area
of volcanic rock near the surface which appears to severely limit underground dens. Most of this land is
in public ownership (81°/o) and housing development is less a problem here. Thus, about 225 km2of
land is marginally suitable for kit fox recovery. Because of the lack of den sites for escapement, this
area will likely always be a mortality sink for neighboring populations of kit fox. A small area near
Cheney Reservoir has the more typical soil formations found in the salt desert shrub areas and did
support a kit fox family in 1994-95. No kit fox activity has been recorded there since. The area is
private land and the current owner has been unsuccessful at attempts to subdivide for housing,
primarily because of issues of potable water supply. Unsolicited information from local varmint
hunters suggests that red fox have been colonizing this area rapidly during the past 2 years. Earlier
work on kit fox surveys in this area did not document red fox but both dens and red foxes were
observed here in spring of 1998.
The North Gunnison area abuts the Colorado River and Grand Junction urban area to the north.
This area is highly impacted by housing development throughout the salt desert shrub type. Based on
the GAP maps, there are 180 km2 of salt desert shrub in this unit, of which 48% is private. There is an
additional 59 km2 of irrigated farm land. No kit fox have been located in this area by any of our
surveys this decade. Suitable area for kit fox restoration in the near future is probably closer to 140

km2.

Total suitable habitat for kit fox in the Gunnison Valley is approximately 385 km2. It is unlikely
this area would support high densities of kit fox because of the denning problem in the Central area
Thus, a projection of 50-150 kit fox possible should restoration be successful seems to be the best
possible outcome. The housing development in the north coupled with the den problems in the central
suggest that the East unit may be the best area for kit fox populations, which could then support 25-85
kit fox.
The Colorado River Valley supports the largest intact area of salt desert shrub, about 797 km2
based on the GAP map. Most (85%) is in public ownership. Irrigated lands amount to 319 km2,
mostly in the eastern end (Fig. 3). Ten kit fox were captured here in 1994 and 1995. An active den
with a single kit fox was discovered in 1997 near Fruita However, the lack of any photographs of kit
fox or sign at historic kit fox dens in 1998 strongly suggests the current density of kit fox in this valley
is low. This unit appears to have the lowest probability for loss of kit fox habitat and will likely have at
least 685 km 2 of suitable habitat for a long period. Based on kit fox densities reported in White and
Garrott (1997), this area could potentially support 110-480 kit fox if fully occupied.

�60

Capture Efforts
It was decided not to trap and collar adult foxes during the whelping season because of the
added stress of this activity to the individual foxes (Cypher 1997). The small number of kit foxes
present seems to justify minimum intrusion during this period. There have been no juveniles located in
1998 or 1999 to tag.
Literature Cited
Beck, T. D. I. 1995. Development of black bear inventory techniques. Colo. Div. Wildlife, Fed. Aid.
Rep. W-153-R-8. l lpp.
Cypher, B. L. 1997. Effects ofradiocollars on San Joaquin Kit Foxes. J. Wildl. Manage. 61(4):14121423.
Fitzgerald, J.P. 1996. Status and distribution of the kit fox (Vulpes macrotis) in Western Colorado.
Colo. Div. Wildlife, Final Fed. Aid. Rept. W-153-R-7. 78 pp.
White, P. J. and R A Garrott. 1997. Factors regulating kit fox populations. Can. J. Zool. 75: 19821988.

�61

N

A
GREAT OUTDOORS
C0L0llAD0

•

Colorado
Division of Wildlife
May, 1999

e:::::! Irrigated Crop Type
Ill Selected Vegetation Types•

O 1 2 Kilometers
~

• Desert Shrub
Saltbush Fans &amp; Rats
Greasewood Fans &amp; Flats

Figure 1. Selected vegetation types in the Uncompahgre Plateau.

O 1

2

~

3

4 Miles

i,i.iiiiij

�N

A

O'I
t-.J

,,,subUnlt Boundaries

c;J Irrigated Crop Type

,,,.. f

lm1ll Sefected Vegetation Types•

• Desert Shrub
Saltbush Fans &amp; Flats ats
/
Grease~d Fans &amp; Fla:_;

~

o 1 2 Kilometers
~

01234Mlles
,.....-.J

G!UAl" OUl"D00Jl5
Co LORAnO

•

Colorado
Division of Wildlife
May, 1999

Figure 2. Selected vegetation types in the Gunnison River Valley.

DELTA

�N

A

0

Irrigated Crop Type

11111111 Selected Vegetation Types•

Desert Shrub
Saltbush Fans &amp; Flats
Greasewood Fans &amp; Flats
\

0 1 2 Kilometers
~

--

1 2 3 4 Miles

a

GREAT OUTD00ll5.
COLORAnO

(_ '-

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0

of Wildlife

99

Figure 3. Selected vegetation types in the Colorado River Valley.

�25

Colorado Division of Wildlife
Wildlife Research Report
July 2000

JOB PROGRESS REPORT
State of

Colorado

Cost Center 3430

Project No.

W-153-R-13

Mammals Research Program

Work Package No. ___0"""6=-a6=3_ _ _ _ __
Task No.

Kit Fox Conservation
Kit Fox Augmentation Study

1

Period covered: July I, 1999 - June 30, 2000
Author: T.D.I. Beck
Personnel: T. Beck, G. Byrne, CDOW; E. Everett, B. Miller; Denver Zoological Foundation.

ABSTRACT
Relative abundance of kit fox prey surveys were developed as a written protocol. However, administrative
problems prevented conduct of the late-summer 1999 field surveys. Spring 2000 surveys which had been
planned were deferred because of organizational changes within CDOW relative to management of
threatened and endangered species. The new organizational unit is to develop a prioritization process for
allocating resources among species and habitats and it was believed prudent to defer further field work
pending this process since active kit fox augmentation had not begun. Surveys of historic kit fox dens in
Uncompahgre Valley did not find evidence of pup production in 1999 and no active kit fox dens were
located in spring 2000. Data on historic range rehabilitation projects in the shadscale desert communities
of western Colorado was compiled.

�27

KIT FOX AUGMENTATION STUDY
Thomas D. I. Beck

SEGMENT OBJECTIVES

I . Compare relative abundance of potential kit fox prey between Uncompahgre and Colorado river
valleys.
2. Capture as many kit fox as possible in Uncompahgre Valley for DNA work and pup dispersal.
3. Develop a kit fox reintroduction plan for Mesa County.

METHODS AND MATERIALS

Sampling protocols were developed for comparing relative abundance of small rodents and cottontail
rabbits at 2 sites in each valley. Small rodent surveys were to use a 200-trap concentric trapping web.
Snap traps were selected rather than live trapping because of concerns about hantavirus prevalence in these
areas. Because such trapping removes captured individuals, trapping was to be conducted during late
summer; presumably the time of highest animal density. Thus it would be unlikely to create a local
depleted zone. Museum collections from these areas of Colorado are scarce so all trapped animals would
have been saved for museum collections. Rabbit abundance was to be meas_ured by a combination of
mark-resight estimation and spotlight counts. Hopefully the spotlight counts could be indexed to
population estimations to provide a long-term monitoring index. Rabbit population monitoring would be
conducted in early-spring; presumably the time of lowest animal abundance. Selection of only 2 sites per
valley probably would not accurately represent the variation to be expected throughout the valley.
However, this was the most that could be done with manpower and budget.
Weekly precipitation records were collected from 6 stations maintained by NOAA in the Uncompahgre and
Colorado river valleys in Colorado (Montrose, Olathe, Delta, Grand Junction, Fruita, Loma) for the
growing season (March-October) for the period 1970-1998. Not all stations had data for each year.
Historic kit fox dens were visited in July and August 1999 to survey for adult fox presence and pup
•production. Historic dens and den areas were visited in April 2000 to examine for kit fox use.
Records compiled by Ron Kufeld, CDOW retired, were searched to document all range restoration projects
•conducted in the low elevation desert valleys. This data base was believed to be complete for the period
1960-1996. During other field activities, visits were made to most of the range project sites to see if any
noticeable differences could be seen from surrounding desert vegetation.

RESULTS AND DISCUSSIONS

Because of administrative delays in allocating budgets and temporary FTE' s, the trapping webs could not
be set and run prior to the graduate student having to attend classes. Thus the late-summer 1999 prey
studies were deferred to spring of 2000. During late-fall 1999 the Colorado Div. of Wildlife altered its
organizational structure and created a new section to deal with Species Conservation; specifically species

�28
currently on either a federal or state list of threatened or endangered species or a species in decline with
potential for listing. Thus lead role in kit fox restoration shifted to this new section. Discussions among
administrators resulted in the decision to defer further field studies until the new section could develop a
prioritiz.a.tion process for addressing the species conservation needs. Thus prey abundance surveys were
deferred during spring 2000; awaiting the development of the new section priorities. All material collected
during our kit fox research surveys has been copied to the new section.
Den site surveys in summer of 1999 did not produce any evidence of pup production. There was only one
active den found in spring 1999 and for the third consecutive year no pups were produced at this den. No
active dens were located in spring 2000 in a survey of historic den sites. Extensive surveys were not
conducted in areas where we had previously failed to find active kit fox dens based on the rationale that this
declining population will not produce significant dispersal.
Based on the lack of finding any active dens, no trapping operations were conducted in 2000. Earlier
surveys based on trapping and infra-red photography clearly indicate that trapping rarely produced kit fox
captures when field surveys could not find evidence of their presence prior to trapping.
The growing season precipitation data was examined to see if any seasonal patterns emerged. The
variability within a year and among sites was extremely high and no patterns by year or area were
apparent. This is likely a reflection of the nature of the summer precipitation events, which are part of a
regional monsoon pattern dominated by afternoon thunderstorms. These storm events are quite local in
scope yet capable of delivering 2-3 cm of rain in less than an hour.
Casual surveys of range rehabilitation sites indicated no difference from surrounding areas. Thus, when
developing augmentation plans no special accord needs to be given to these historic management sites.
No formal augmentation plan was developed pending results from the new organizational unit on priorities.
However, the material needed to do so is on file. Contacts have been made with 2 surrounding states (Utah
and Arizona) for sources of kit fox should augmentation move forward. Representatives of both states
were confident of being able to provide kit foxes in adequate numbers.

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                  <text>107
Colorado Division of Wildlife
Wildlife Research Report
July 1998

JOB PROGRESS REPORT

State of _____c...o....,.l..,o""'r..,a.,,d..,o"------

cost center 3430

-_1...s...J...-...B...-_.1....1____ :

Mammals Program

Project No.

_ _....,w....

Work Package No.

Species of special concern

0663

Lynx conservation Recovery

Task No.

Period Covered: July 1, 1997 - June 30, 1998
Author: D. F. Reed

ABSTRACT
A conservation strategy/recovery plan for lynx in Colorado was prepared and
the draft revised January 12, 1998 (Chapter 1 in Seidel et al. 1998). This
conservation strategy to recover and conserve lynx populations in Colorado
provided general background on the species and generally identified the
habitat goals and objectives of identifying potential habitat, identifying
linkage zones, selecting suitable habitats, refining habitat suitability
models, and refining habitat protection, as well as, conservation actions to
be taken. Subsequently, more specific protocols were developed to assess
potential lynx habitat based on the species' primary prey, the snowshoe hare.•
The first protocol was for the winter track survey which was conducted during
the winter. The second was for the snowshoe hare pellet counts (Krebs plots)
which were begun toward the end of the segment. The routes selected for the
winter track surveys were based upon accessibility and transportation mode
(snowmobile, cross-country skis, etc.), and hence, were not randomly selected.
Furthermore, sample sizes (routes per forest types) were small. Conclusions
about representativeness should be made with caution.

�109
LYNX CONSERVATION/RECOVERY
Dale F. Reed

P,N, OBJECTIVE
Develop a conservation strategy to recover and conserve lynx populations in
Colorado.

SEGMENT OBJECTIVES
1.

Prepare a conservation strategy/recovery plan for lynx in Colorado.

2.

Assess potential habitat for lynx reintroduction.

STUDY AREA
The study area includes the forests (Aspen, Douglas Fir, Lodgepole Pine, mixed
conifer, mixed forest, Ponderosa Pine, and Spruce-fir) and deciduous oak above
7,500 ft throughout the north-south western half of Colorado.

METHODS AND MATERIALS
The methods used in preparing the "Conservation Strategy/Recovery Plan"
(Seidel et al. 1998) involved extensive literature review, writing, rewriting,
editing, and coordination with the numerous authors, species experts, and
agencies participating in its completion.
The methods used in assessing potential habitat for lynx (Felis lynx) involved
1) a winter track survey where snowshoe hare (Lepus americanus) tracks
(crossings and parallel movements) were counted in snow 24-28 hours after
snowfalls (described by Byrne 1998) and 2) counts of snowshoe hare pellets
(Kreb's plots; Krebs et al. 1987) via randomly selected points in the forest
types and deciduous oak (see Study Area) as determined by statewide GAP data.

RESULTS
Results as in the "Conservation Strategy/Recovary Plan" are summarized in the
following Executive Summary (Seidel et al. 1998:vii-x):
EXECUTIVE SUMMARY
Endangered Species
Since life began on this planet many species have come and gone through
natural changes in physical and biological conditions. Since these extinctions occur naturally why should we spend money and effort to conserve species
that are nearing this end? How do they benefit society if restored? Congress
addressed these questions in the preamble of the Endangered Species Act of
1973, "recognizing that endangered species of fish, wildlife, and plants are
of aesthetic, ecological, educational, historical, recreational, and scientific value to the Nation and its people." Congress further stated its intent
to protect and conserve the ecosystems and habitats. The State of Colorado

�110
has adopted similar protections for species of special concern. The primary
force driving the loss of these species is habitat destruction or human
exploitation. While we do not know the causes for the decline in lynx (Lynx
canadensis) in the Southern Rocky Mountains (SRM) human activity is at least
partly responsible. We have the knowledge to conserve and reestablish these
species. We also have the responsibility.
History and Distribution
Lynx historically occurred, at low densities, as forest carnivores in the SRM.
There have been 12 investigations reported in Colorado since 1979 to document
the presence of lynx or wolverine. Although the presence of both species has
been suspected but not confirmed, and no viable populations have been found.
There have been no field studies in the southern ranges in Wyoming or in New
Mexico. Wyoming conducted a survey in 1986 of reported sightings but few of
these reports were documented (Reeve et al. 1986). This draft does not
include information on the Wyoming and New Mexico portions of the SRM. The
final strategy will include a coverage of these areas. Any future decisions
regarding lynx that affect neighboring states will require further investigation and coordination.
Current Status
At this time the lynx is classified as a federal "candidate" species by the
Fish and Wildlife Service. In Colorado the lynx is classified as state
endangered species and in New Mexico are protected species. Wyoming classifies lynx as Native Species Status Category II (Oakleaf et al. 1996). The
Forest Service classifies lynx as a "sensitive species."
Conservation Strategy
On July 8, 1997, representatives of the U.S. Forest Service, U.S. Fish and
Wildlife Service and the Colorado Division of Wildlife (CDOW) met to discuss
a cooperative program for the conservation and reestablishment of lynx and
wolverine in Colorado. On August 4, 1997, those agencies plus the National
Park Service signed a letter agreeing to jointly prepare "A Candidate Conservation Strategy for Lynx and Wolverine in Colorado." The Colorado Division of
Wildlife is the lead agency for these state listed species.
Species Goal
The goal of this strategy is the conservation and reestablishment of lynx
within their former ranges by establishing populations which reprodu~e
sufficiently to allow emigration into unoccupied suitable habitats. If this
is accomplished, it would permit the downlisting of these species by the
states from endangered. Both species are considered in this document due to
expected economies of scale that will be realized in the habitat assessment,
acquisition, and monitoring portions of this strategy. This document could
serve as the basis for future recovery efforts in Colorado.
Risks to the Species
We can only speculate on the history of lynx populations in Colorado. Some
speculate that trapping, hunting, and poisoning played a significant role in
population reductions.
If so, Amendment 14 approved by the voters of Colorado
in 1996 greatly reduced that threat to future populations because it strongly
restricts the use of poisons, leghold, kill-type and snare trapping devices
in the State of Colorado. Removal of this historical source of mortality
would enhance the probability of success for conservation and/or potential
future reintroductions of lynx. A second primary mortality factor for lynx
populations reported from other sites within their distribution is mortality
of kittens or kits either through starvation or disturbance during rearing.

�111
These are factors that can be addressed by specific management practices.
Most of the potential habitat for these species in the SRM occurs on public
land with the majority on National Forest System lands. Many National Forest
lands in Colorado are designated and managed as wilderness. It is currently
not known how much of that area has potential to support lynx populations.
Habitat Goals for Lynx
The first goal is to describe and map potential habitats for lynx in the SRM.
The second goal is to protect those habitats that may be important for
whatever lynx may still exist in the state and potential habitats for future
reintroduction or reestablishment efforts.
Habitat Evaluation Actions for Lynx
Lynx foraging habitat requirements are inextricably linked to habitat requirements and population distribution of snowshoe hares (Lepus americanus) because
that species is a staple prey item. Therefore habitats with abundant snowshoe
hare populations would be considered the primary criterion for selecting
potential locations for lynx reintroductions. The first step in the strategy
will be to assess the potential habitats both for foraging and denning
potential using GIS vegetation mapping. Key areas will be identified that
contain at least the minimum requirements for species survival. The criteria
used for this selection will come from the significant body of knowledge that
exists for lynx habitats in other regions (Table 1). These same criteria have
been used to develop potential habitat management guidelines that will be
recommended to land managers until information obtained from monitoring
reintroduced individuals suggests changes to those recommendations. Once key
blocks of potential habitat are identified, the CDOW intends to conduct two
surveys to detect snowshoe hare occurrence and estimate densities to validate
or adjust initial habitat assumptions. Data from both surveys will be used to
identify the 2 habitats
with the greatest potential to support Colorado lynx. The actual reintroduction sites will be identified from the field surveys and modified or confirmed
from advice from a peer review panel of qualified scientists with recognized
expertise in lynx ecology and management.
Reestablishment of lynx
Reestablishment of viable lynx populations in Colorado requires reintroductions. A reintroduction would involve assessing potential release sites for
habitat suitability, radio-marking lynx prior to release, and intensive
monitoring of radio-marked animals. Lynx populations in Canada and Alaska
currently are increasing toward peak population levels (Fontana pers. commun.
1997).
Lynx selected for reintroduction otherwise would be killed and sold
as pelts to be traded as fur.
By paying a compensatory price, the CDOW can
obtain lynx for reintroduction at a reasonable price and increase their
chances of survival. When lynx are at the lower end of their population
cycle, population levels would be insufficient to provide sufficient animals
for reintroduction. Since wild lynx populations cycle every 10 to 12 years,
there is a narrow 4- to 5-year window of opportunity to reintroduce lynx in
Colorado's most suitable habitats. It is estimated that
lynx would be
needed to be released each year (
in each of 2 habitats each year) for 2
successive years to establish several viable breeding populations.
Species Monitoring
Radio-marked lynx will be intensively monitored by frequent relocations both
from the air and the ground. Recorded data would include habitat selection
patterns, seasonal home ranges, reproductive success, survival, and probable
cause of death when mortalities are detected. This information would be

�112
evaluated critically to determine if additional releases of these species into
unoccupied habitats is warranted before additional releases are attempted.
Revision

Any strategies for conserving lynx in the SRM must be regarded as tentative
because very little is known about their specific ecology and habitat requirements in the SRM. As the body of knowledge increases and new information is
gained from post-release monitoring of both lynx and wolverine, the Conservation Strategy would be revised. Formal lynx and wolverine status reviews
would be scheduled periodically (e.g., annually) by the Lynx and Wolverine
Conservation Strategy Team to revise the lynx/wolverine Conservation Strategy
as needed.
Budget

A draft budget is included in Appendix B. It is estimated that the cost to
complete the first 3 years of this Conservation Strategy could approximate
$2.5 million. The Division of Wildlife has committed to funding $700,000,
leaving $1.8 million to be acquired from other sources.
Habitat Protection

Following the pre-release habitat suitability surveys, it will be necessary to
develop interim guidelines to delineate, preserve and protect lynx habitats on
public lands that are deemed critical to the conservation of these species.
These interim habitat protection guidelines periodically would be revised as
additional information surfaces from the post-release monitoring of radiomarked individuals. Guidelines will be based on the best scientific and
economic information available; will conform to existing laws and regulations;
and will be subjected to further peer and public review prior to implementation. These guidelines will be developed and amended into this document at a
later date subject to concurrence by all signatories.
Results of the winter track surveys were reported by Byrne (1998). Counts of
snowshoe hare pellets (Kreb's plots; Krebs et al. 1987) were only begun toward
the end of this segment - hence the results from this second method will not
be available until the next segment.

LITERATURE CITED
Byrne, G. 1998. A Colorado winter track survey for snowshoe hares and other
species. Colo. Div. Wildl. 35pp.
Krebs, c. J., B. s. Gilbert, s. Boutin, and R. Boonstra 1987. Estimation of
snowshoe hare density from turd transects. Can. J. Zool. 65:565-567.
Seidel, J., B. Andree, s. Berlinger, K. Buell, G. Byrne, B. Gill, D. Kenvin,
and D. Reed. 1998. Draft strategy for the conservation and reestablishment of lynx and wolverine in the southern Rocky Mountains. U.S. Forest
service, National Park Service, U.S. Fish and Wildlife Service, and
Colorado Division of Wildlife. 115pp.
~·

Prepar:;~:2J/4&amp;5JEU/
Dale F. Reed
Wildlife Researcher

�66

�65

Coiorado Division of Wildlife
Wildlife Research Report
July 1999

JOB FINAL REPORT

State of ------=-=~=="------Colorado
Project No. ----'-W-'---"1""'"53"'""--=-R"--""'12~---Work Package No. _0~6"-'6'""3_ _ _ _ _ __
Task No. _ _ _ _2 " ' - - - - - - - - -

Cost Center 3430
Mammals Program
Species of Special Concern
Lynx Conservation/Recovery

Period Covered: July 1, 1998 - June 30, 1999
Author: D. F. Reed

ABSTRACT

Snowshoe hare pellet counts (Krebs plots) were analyzed and a Division report prepared.

BDOWD14185

�67

LYNX CONSERVATION/RECOVERY

Dale F. Reed

P.N. OBJECTIVE
Task 2 - Develop a conservation strategy to recover and conserve lynx populations in Colorado.

SEGMENT OBJECTIVES
1. Analyze data and prepare report.

STUDY AREA
The study area includes the forests (Aspen. Douglas Fir, Lodgepole Pine, mixed conifer, mixed forest,
Ponderosa Pine, and Spruce-fir) and deciduous oak above 7,500 ft throughout the north-south western
half of Colorado as reported by Reed (1998).

METIIODS AND MATERIALS
The methods used in assessing potential habitat for lynx (Fe/is lynx) involved counts of snowshoe
hare pellets (Kreb' s plots; Krebs et al. 1987) via randomly selected points in forest types and
deciduous oak as determined by statewide GAP data and as reported by Reed (I 998).

RESULTS
The results are in the report titled "Snowshoe hare density/distribution estimates - potential habitat for
reintroduced lynx in Colorado" (Reed and Kindler 1999).

LITERATURE CITED
Krebs, C. J., B. S. Gilbert, S. Boutin, and R. Boonstra. 1987. Estimation of snowshoe hare density
from turd transects. Can. J. Zool. 65:565-567.
Reed, D. F. 1998. Lynx conservation/recovery. Colo. Div. Wildl. Res. Rep. July, 107-l 12pp.
Reed, D. F., and J. Kindler. 1999. Snowshoe hare density/distribution estimates - potential habitat for
reintroduced lynx in Colorado. Fort Collins, CO :Colo. Div. ofWildl. Division report; no. (in
review).

Prepared by _ _ _ _ _ _ _ __
Dale F. Reed

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                  <text>47
Colorado Division of Wildlife
Wildlife Research Report
July 2000
JOB PROGRESS REPORT

State of _ _ _ _ ____.C._.o=lo=rad=o=--------Project No. ________
W__--=-1~53__-___
R----1---4_______

Mammals Research

Work Package No. _ _---'0'-'6a..a.7..a;..0_ _ _ _ __

Lynx Conservation

Task No.

2
--------------

Lynx Veterinary Services and Diagnostics

Period Covered: July 1, 1999 - June 30, 2000.
Author: M. A. Wild.
Personnel: T. Shenk, S. Dieterich, H. Dieterich, T. R. Spraker, D. H. Gould.

ABSTRACT

Fifty-six lynx (34 adult females, 19 adult males, 2 juvenile females, 1 juvenile male) were received from
British Columbia, the Yukon, and Alaska during January - April 2000. Lynx arrived in generally good
condition with the exception of one female lynx that required euthanasia due to an extensive foot lesion
from trapping. All lynx were anesthetized (Telazol 2-3 mg/kg IM) for physical examination and
identification at least twice during the =::3 week acclimation period at the captive holding facility. During
captivity lynx maintained or improved body condition. Using abdominal radiographs, we diagnosed one
female as pregnant and three others were suspicious. Seven lynx had lesions to 1-2 toes that required
treatment. One of these lynx also had two fractured metacarpal bones that required splinting. All
recovered and were released in Spring 2000. One lynx from the 1999 release was recaptured in March
2000. The lynx was emaciated but no other abnormalities were determined. He was released in May 2000
after rehabilitation. Fifteen mortalities were recorded in free-ranging lynx during FY2000. Eight of the
carcasses were in advanced stages of decay (or only the collar was found) and cause of death could not be
determined; however, in three of these cases we were able to rule out starvation as cause of death. Two
lynx died from gunshot wounds, two from trauma, and one from predation. One trauma case and the
predation case were in poor body condition. One male kitten died from starvation about 7 weeks postrelease. A female yearling died of pneumonic plague in Hinsdale County, Colorado.

�48

�49

LYNX VETERINARY SERVICES AND DIAGNOSTICS
Margaret A. Wild

P. N. OBJECTIVES
I.

Provide veterinary care and diagnostic services for reintroduced lynx.

SEGMENT OBJECTIVES
I.

Provide veterinary care and diagnostic services for reintroduced lynx.

METHODS AND MATERIALS
Lynx were trapped in British Columbia (BC) and the Yukon, Canada, and Alaska then transported by truck
and/or airline to holding pens at the Frisco Creek Wildlife Hospital and Rehabilitation Center, Del Norte,
Colorado. Care of lynx during captivity was based on the Husbandry and Management Protocol
(Attachment I of Addendum A).
Post-release, diagnostic and forensic services were provided to support ongoing research and law
enforcement efforts. Carcasses were transported to the Colorado State Diagnostic Laboratory, Fort
Collins, for examination by a board certified veterinary pathologist and a wildlife veterinarian. Complete
post-mortem examination was conducted following the Necropsy Protocol (Attachment 2 of Addendum A).

RESULTS AND DISCUSSION
Results of the 1999 lynx reintroduction are summarized in Addendum A. An additional 56 lynx were
received January-April 2000. Lynx appeared healthy on arrival with no transportation-related injuries.
Captive management and husbandry techniques were similar to those reported in 1999; however, all lynx
were held at least 3 weeks for acclimation and fattening prior to release. Releases occurred in early April
through late May. Daily clinical assessment suggested that lynx adjusted well to confinement in our
isolated holding facility. Daily feed intake was not quantified this year however consumption appeared
similar to the average I 0-15% of body weight/day over a weekly basis that was observed in 1999.
Health Assessment
We anesthetized each lynx with about 2.5-3 mg/kg body weight Telazol IM for initial examination and
sample collection (as described in Attachment 1 of Addendum A). One lynx (BC00F 17) was euthanized
upon initial exam due to extensive foot lesions. The other 55 lynx were anesthetized again with about 2-2.5
mg/kg Telazol IM for placement of a radiocollar just prior to release. In general, lynx arrived in good
condition. Upon arrival, females from British Columbia (BC; n = 9) and The Yukon (n = 20) averaged
8.86 kg (SE 0.28) and 8. 72 kg (SE= 0.22), respectively. At examination prior to release, body weights
had increased to 10.23 kg (SE= 0.19) and 10.28 kg (SE= 0.13) for BC and Yukon females, respectively
(Fig. I). Adult females from Alaska (n = 4) averaged 9.82 kg (SE= 0.67) at arrival and 11.91 (SE= 0.63)
prior to release; however, one of these was known pregnant and three were suspected to be pregnant. Body
weight change was less marked in male lynx. Upon arrival, adult males from BC (n = 9), The Yukon (n =

�50
6), and Alaska (n = 4) averaged 12.2 kg (SE 0.53), 10.64 kg (SE= 0.32), and 11.23 (SE= 0.32)
respectively. At examination prior to release, body weights were 12.93 kg (SE= 0.45), 12.13 kg (SE=
0.17), and 13.27 (SE= 0.63) for BC, Yukon, and Alaska males, respectively (Fig. I). One male kitten
from The Yukon weighed 6.2 kg on arrival and 7.87 kg prior to release. Two female kittens from Alaska
averaged 6.89 kg (SE= 0.34) on arrival and 9.17 kg (SE= 0.08) prior to release.
Using radiographic examination of the growth plates of the distal radius and ulna as an indicator of age
(Nava 1970), we determined that three juveniles were received (YK00M5, AK.00Fl, and AK.00F4).
Apparently, the body length measurements that we collected in 1999 to distinguish kittens from adults
proved useful in field evaluation oflynx and minimized the number of kittens that we received. This year
we also adopted a new approach for estimating age of lynx based on percent pulp cavity in the canine
tooth. This method has been used to age canine teeth collected from lynx carcasses (K. Poole, pers.
comm.), but we attempted to collect the infonnation in situ using skull radiographs. Evaluation of the
method is underway.
Several injuries to lynx were found. Eight lynx had fractured toes or toes previously amputated by
veterinarians in BC or The Yukon. Damage to the foot of one of these lynx (BC00F 17) was severe and
involved the middle three toes on a front paw. Due to the poor prognosis, we euthanized this lynx at the
time of initial veterinary examination. Of the remaining seven lynx, three lynx had one toe amputated (one
of these lynx also had two fractured metacarpal bones that required splinting), two lynx had one toe
amputated and an additional toe damaged, one lynx had two toes amputated, and one lynx had two
fractured toes that were ankylosed but were not treated. Five other lynx had minor lacerations on the legs
or face that healed without complications.
Recapture
On 24 March 2000, we recaptured a lynx (AK.99M9) released in 1999. Field observations by the lynx
monitoring crew suggested that the lynx was severely emaciated. Live trapping the lynx failed, so we
darted the lynx with Telazol (3 mg/kg) using the Dan-Inject CO2 pistol. Physical examination revealed
severe emaciation (6 kg). It can be assumed that the lynx would have died if not recaptured. Blood work
was unremarkable with the exception of a low titer to Toxoplasmosis; however, this was unlikely the cause
of the abnormality. No underlying disease condition was found that would explain the debilitation. The
lynx responded well to supportive care at the holding facility and was released in May 2000.
Post-mortem Examination
Fifteen mortalities were recorded in free-ranging lynx during FY2000 (Table 1; one of these was included
in Addendum A as well). Eight of the carcasses were in advanced stages of decay (or only the collar was
found) and cause of death could not be determined; however, in three of these cases we were able to rule
out starvation as cause of death based on the presence oflipid in bone marrow. Two lynx died from
gunshot wounds, two from trauma, and one from predation (apparently from a bobcat). One trauma case
and the predation case were in poor body condition. One male kitten died from starvation about 7 weeks
post-release. A female yearling died of pneumonic plague. The carcass was recovered in Hinsdale County,
Colorado. Necropsy findings showed an acute fibrinous pneumonia. Plague was diagnosed by fluorescent
antibody test and isolation of Yersinia pestis from lung and spleen samples. After this diagnosis, we
retrieved bone marrow samples to test for plague in six other lynx that had died from unknown causes in
1999 and 2000. Fluorescent antibody test was negative on all of these cases. Plague in rodents is not
uncommon in southwestern Colorado. This lynx most likely consumed a rodent or rabbit infected with
plague.

�51

LITERATURE CITED
Nava, J. 1970. The reproductive biology of the Alaska lynx. M.S. Thesis. Univ. Alas., Fairbanks.
14lpp.

Table l. Summary of mortalities in free-ranging lynx during FY 2000.
Date1

Animal ID

Sex

Age

State of Carcass

Cause of Death

08/26/99
09/15/99
10/22/99
11/03/99
11/17/99
11/24/99
01/26/00
01/29/00
05/23/00
05/23/00
06/08/00
06/15/00
06/15/00
06/22/00
07/29/00

AK.99F18
AK.99F10
BC99-02
AK.99F27
AK.99M6
AK.99F15
YK99F4
AK.99Mll
BCOOF3
YKOOM5
YK.99F3
AKOOF4
YK.99M6
AK.99Fl3
YKOOF17

F
F

2
2
4
1
5
3

Good
Poor
Poor
Good
Good
Good
Good
Minimal remains
Good
Good
Poor
Collar only
Collar only
Minimal remains
Poor

Trauma, emaciation2
Unknown, not starvation2
Unknown, not starvation2
Shot
Shot
Blunt trauma
Predation, emaciation
Unknown
Pneumonic plague
Starvation2
Unknown, not starvation2
Unknown
Unknown
Unknown
Unknown2

M
F

M
F
F

5

M

3
1
0
3
0
4
1
2

F

M
F
F

M
F
F

1 Date mortality confirmed, date of death may have been earlier.
2 Plague negative on FA of bone marrow

14
12
'bl)

c 10

i
·-

8

~

6

"'O
0

4

&gt;.

CQ

I
I
ii

d)

2
0
BC

YK

Females

AK

BC

YK

AK

Males

Fig. 1. Initial body weight (stippled) and body weight at release (solid) of female and male lynx
reintroduced in 2000.

�52

ADDENDUM A

Status Report on the Health of Lynx Reintroduced to Colorado
by
Margaret A. Wild, DVM
Colorado Division of Wildlife
With additional information from
Herman Dieterich, DVM, DACVS and Susan Dieterich
Frisco Creek Wildlife Hospital and Rehabilitation Center
For the 30-31 August 1999 CLAWS/LAT Meeting

GOAL
To assure optimal health of lynx reintroduced into Colorado.
OBJECTIVES
Objectives of the health program were:
1.
2.
3.
4.

To protect the health of wild and domestic animals in Colorado.
To optimize health oflynx released into Colorado.
To optimiz.e welfare oflynx during transport and holding.
To provide diagnostic and forensic services in the case of mortalities.

MATERIALS AND METHODS
Lynx were trapped in British Columbia (BC) and the Yukon, Canada, and Alaska then transported by truck
and/or airline to holding pens at the Frisco Creek Wildlife Hospital and Rehabilitation Center, Del Norte,
Colorado. Care of lynx during captivity was based on the Husbandry and Management Protocol
(Attachment 1).
Post-release, diagnostic and forensic services were provided to support ongoing research and law
enforcement efforts. Carcasses were transported to the Colorado State Diagnostic Laboratory, Fort
Collins, for examination by a board certified veterinary pathologist and a wi_ldlife veterinarian. Complete
post-mortem examination was conducted following the Necropsy Protocol (Attachment 2).
PRELIMINARY RES ULTS AND DISCUSSION
Captive Management and Husbandry
Forty-two lynx were received at the holding facility between 29 January and 14 April 1999. All appeared
healthy on arrival with no transportation-related injuries. Individual lynx were held at the facility for
varying lengths of time based on assigned release protocol. Lynx from BC were held &lt;1- 7 wk (median
6.5 wk), from the Yukon 3 - 10 wk (median 8 wk), and from Alaska 3 - 6 wk (median 5) prior to release.
Daily clinical assessment suggested that most lynx adjusted well to confinement in our isolated holding

�53
facility. However, at least three lynx never adjusted to confinement; two paced the pen causing erosions on
the palmar and plantar surfaces of the pads (AKFX99 and AKF499) and one appeared distressed and
remained in relatively poor body condition (AKF1599). For other animals, clinical observations suggesting
acclimation to confinement were supported by daily feed intake and body weight data. Lynx consumed on
average about 10-15% of their body weight/day over a weekly average (Fig. 1) despite the fact that highly
palatable feed items were not offered ad libitum. Lynx often fasted rather than consume less palatable
items such as the prepared feline diet, fish, or beaver and engorged themselves on highly palatable items
such as wild rabbits (up to &gt;2 kg/day). Most lynx gained considerable body weight while in captivity (Fig.
2).

In 1999, our initial plan was to hold lynx in captivity for as short a period as possible. We assumed that
the animals would be distressed in confinement and would have a greater chance of survival if released
immediately to the wild. However, we found that most lynx appeared to adjust to confinement without
distress. Further, this period in confinement was likely beneficial to the animals in giving them time to
acclimate to Colorado and to gain body weight prior to release.
Health Assessment
We anesthetized all lynx at least once for examination, and most were anesthetized again for placement of a
radiocollar prior to release. We used 3-6 mg/kg body weight Telazol IM to perform 84 anesthetic events
on 42 lynx. Of the 79 anesthesias induced with a single injection, mean induction time was 4.3 min (SE 0.2
min; range 2-10 min). Five other anesthesias required supplementation and mean induction time was
extended to 16.2 min (SE 7.2 min; range 7-29 min). Full recovery was achieved in all cases on average 91
min (range 27-188 min) after initial Telazol injection. All parameters stayed within acceptable limits;
however, lynx receiving 5-6 mg/kg were markedly deeper and oxygen saturation frequently dropped to 70 80%. Supplemental oxygen was administered in these cases.

In general, lynx arrived in good condition. Lynx from the Yukon were in markedly better body condition
than those from other sites (Fig. 2). Using radiographic examination of the growth plates of the distal
radius and ulna as an indicator of age (Nava 1970), we determined that at least six juveniles were received
(two from BC, one from the Yukon, and three from Alaska). Total length of the two juveniles from BC
was markedly less than that of other lynx from BC Guveniles 78 cm, range in adults 87-97.5 cm). The
juvenile from the Yukon was correctly identified using the body length criterion of Slough ( 1996); the
juvenile was 90.2 cm while the adults were all well above Slough's 90.5 cm cut-off for adults (range 96105 cm). Identification of juveniles from Alaska was more difficult, likely in part because evaluation
occurred later in the year. Three juveniles were identified based on lack of closure of the growth plate;
these lynx ranged from 86-89.5 cm in length. Lynx classified as adults ranged from 89.5-106.5 cm. Given
these findings, body length can likely be used as an indicator to classify juveniles; however, site-specific
cut-off points for body length will be required (i.e., while Slough's classification is appropriate in the
Yukon, it appears less reliable for BC and potentially Alaska).
We also used radiography to diagnose advanced pregnancy (&gt;45 days) in lynx. Six lynx (AKF299,
AKF399, AKF499, AKF899, AKF1099, AKF1799) had fetuses with calcified skeletons present and two
other lynx had radiographic evidence suggesting earlier pregnancy (AKF599, YKF599). Of these pregnant
females, three have died as of 28 August 1999 (one starvation, one hit-by-car, one undetermined cause).
Five lynx had lesions or fractures of one to three toes that required medical treatment or surgical
amputation. Two lynx (BC99-8 and AKF499) had minor infections on one toe of a front foot that were
treated medically. These animals recovered fully prior to release. Two lynx had fractures and/or freeze

�54
damage to two toes on a front foot, with one toe amputated from each lynx (AKf 1099, AKf 1899). The
remaining lynx had fractures and freeze damage to three toes on a hind foot that required amputation of all
three toes (BC99-15). Of the three lynx released with toes amputated, two are alive and one has died
(cause of death unknown, although animal was slightly emaciated and had traumatic injuries) as of 28
August 1999.
Sample collection, treatments, and identification were as described in the Husbandry and Management
Protocol; however, eartags were placed only in lynx from BC. An incidental finding observed in the
majority oflynx from the Yukon and Alaska were pinpoint to 2 mm slightly raised lesions on the oral
mucosa, primarily the ventral surface of the tongue. Biopsy samples were submitted to Colorado State
Diagnostic Laboratory for histopathology. Results indicated the plaques were caused by a slightly
thickened epidermal layer, with no specific lesions present.
Otherwise, lynx remained healthy in captivity with the exception of one adult male (YKM 199) and one
adult female (BC99-06). Lynx YKM199 exhibited paresis and muscle weakness of about I wk duration.
Results of diagnostic procedures were unremarkable, with the exception of apparently enlarged kidneys on
radiographs. The lynx was euthanized 29 April 1999 and a thorough post-mortem examination was
performed. No gross or histologic lesions were found (kidneys were normal despite radiographic
interpretation). Kidney lead levels were normal. Serology for Felv/FIV, CDV, FIP and Toxoplasma
gondii were negative. Rabies and parasitology exam were negative. The cause of paresis in this lynx was
undetermined; however, infectious diseases that could have affected other lynx in the holding facility were
excluded from the list of possible causes. Lynx BC99-06 was diagnosed with an abdominal hernia after
recapture. The lynx was initially released under protocol 1, then recaptured in a debilitated, emaciated
state. The lynx was nursed back to health on a diet slowly increasing in amount. Although no adverse
effects were observed during the rehabilitation, an abdominal hernia developed. The rent in the abdominal
wall was surgically corrected without complication.
Post-mortem Examination
In addition to the one lynx euthanized and examined prior to release, as of 28 August 1999 we have
examined 10 mortalities (Table I). Starvation was diagnosed as the cause of death in five lynx based on
extreme emaciation as evidenced by lack of depot fat, muscle atrophy, and serous atrophy of bone marrow.
Three other lynx that died acutely (one shot, two hit-by-car), were in good body condition. Cause of death
in two lynx was undetermined. One lynx (AKF899) had undergone severe autolysis and dehydration prior
to examination. No internal organs or bone marrow remained for examination. Another lynx (AKF1899)
was in a moderate state of autolysis, however, a complete examination was still possible. Gross
examination of this animal revealed slight emaciation and traumatic injuries. Histologic examination of
tissues is pending. All carcasses have been tested for rabies and internal and external parasites. Rabies
examination has been negative in all cases. Incidental findings on parasitology have included Trichinella,
Trichuris, coccidia, Toxascaris, Taenia, giardia, and rodent fleas.

LITERATURE CITED
Nava, J. 1970. The reproductive biology of the Alaska lynx. M.S. Thesis. Univ. Alas., Fairbanks.
14lpp.
Slough, B. G. 1996. Estimating lynx population age ratio with pelt-length data. Wild.I. Soc. Bull. 24:495499.

�55
Attachment 1
Husbandry and Management of Captive Lynx at
Frisco Creek Wildlife Hospital and Rehabilitation Center

Husbandry
Lynx will be held singly or in pairs in holding pens (about 5 m2) with attached nest boxes (about 0.7 m2) at
the Frisco Creek Wildlife Hospital and Rehabilitation Center. Two units, each with 10 pens, are available.
Pens are fully enclosed by fencing and have concrete floors. Straw or hay bedding will be placed in the
nest box as well as in two additional piles in the pen. Pens will be cleaned daily. Fresh water, snow, and
feed will also be provided ad libitum daily. Feed remaining in the pen after 24 hr will be inspected for
quality and discarded if rejected by the animal or if unfit for consumption. Quantity of feed provided and
removed will be measured daily. Type of feed will vary, but will consist primarily of domestic, cottontail,
and jackrabbits, deer and elk meat, and poultry. Additional feeds may include a prepared feline diet, fish,
wild birds, and small mammals (excluding plague vector species, i.e., prairie dogs). Head, kidneys, and
urinary bladder will be removed from domestic rabbits prior to feeding to prevent transfer of
Encephalitozoon cuniculi. Health and behavior oflynx will be observed twice daily. Individual animal
records will be maintained and abnormalities reported to attending veterinarians.
Site Security
Animal housing units will remain under double lock except when access is required for animal care or other
approved activities. Access to the holding pens will be limited to caretakers and visitors with approval
from the Colorado Division of Wildlife (CDOW) Program Manager. Alarms and other security devices
may be installed as needed.
Handling
When handling or transportation is required, lynx will be placed in their individual nest box or
alternatively, a skykennel. If required, the lynx will be transferred from their nest box to a custom squeeze
cage where they can be hand-injected with an anesthetic or other treatments. Lynx will be anesthetized by,
or under the direct supervision of, a veterinarian with 5 mg/kg Telazol, IM. Temperature, pulse,
respiration rate, oxygen saturation, and anesthetic depth will be assessed throughout the anesthetic event.
A record for each anesthetic event will be completed (see attached). Supplemental oxygen will be provided
by mask as needed. Lynx will not be returned to their pens until recovered from anesthesia.
Examination and Animal Identification
Lynx will receive a brief visual examination by a veterinarian upon arrival at the holding facility.
Abnormalities will be noted and appropriate care provided. After 1-7 days rest, each lynx will be
anesthetized for thorough examination. We will obtain a body weight and morphometric measurements,
assess body condition, estimate age (based on tooth wear), take a photograph of the face, collect hair and
whole blood for DNA analysis (R.Ramey, University of Colorado, Boulder) and blood for archiving,
administer penicillin prophylactically (22,000 U/kg, SC), perform a thorough physical examination, and
apply needed treatments and markings for identification. The physical examination will include close
inspection of the condition of toes, claws, and teeth. We will use radiology to augment diagnosis of
injuries, identify juveniles (based on lack of closure of the growth plate of the distal radius and ulna), and
confirm late pregnancy. Other diagnostic samples will be collected as needed if abnormalities are found. If

�56
written documentation is not available to confirm that required anthelmintic treatments have been provided,
we will administer praziquantel (5 mg/kg SC), ivermectin (0.3 mg/kg SC), and topical dusting with
carbaryl. Lynx will be identified with two subcutaneously placed transponders (one on dorsal midline, the
other in the intermandibular area) and an eartag. A radiocollar will be placed on each lynx about 2-14 days
prior to release. If additional anesthesias are required for placement of radiocollar, treatment, etc.,
determination of body weight and other required procedures may be repeated as well.
Treatment and Euthanasia
Medical treatments will be provided by, or under the direct supervision of, the attending veterinarians as
needed. Surgery will be performed by a board certified veterinary surgeon. If euthanasia is required,
ideally it will be performed with the lynx under anesthesia using an overdose of barbiturates. A diagnostic
necropsy will be performed on all mortalities by a board certified veterinary pathologist.

�57

ANIMAL CAPTURE RECORD
Species: -L&lt;
nx- - - - - - - - - - - - - - - - - - - ~

I
I 99
Date:
Name of investigator(s):
Sex:

M 0
F

0

Est

□

Actual

O

Age: _ _

Weight: _ _ __

Est

□

Actual

O

Body Condition:

Animal No.
Excel
Good

O
0

Fair

D

Poor

O

Purpose of Capture: Pre-release exam.
-----------------------------------Location of Capture: _J)ieterich 's Holding Pens
Ambient Temperature: _ _ _ _
Weather Conditions: ____________________
Drug Administration
Time

Drug

Method

Dose

Location

lvermectin
Praziquantel
Penicillin
Event Times
Start Procedures:

Immobilized:

Recovered:

Finish Procedures:

Vital Signs
Time

Temp

Pulse

Respiration

Results of Physical Exam:

Body Measurements:

Samples Taken:

Blood- EDTA
Blood-RU
Hi

Collar

Freq

Markings

D
D
D
D
D
Transponder
Number

BodvLenath
Tai{Lenath

cm
cm
cm
cm
cm

Ear Tag

Location

Number

Color

Left
Right

Comments:

Colorado Division of WIidiife

Revision Date: 08124/00

�58
Attachment 2
Protocol for post-mortem sampling of lynx

Contacts:

Dr. Margaret Wild (CDOW)
Dr. Dan Gould (CSUDL)

All information releases and contact with press need to be through the CDOW. Margaret Wild will
coordinate.
The objectives of the post-mortem examination are to: 1) determine the cause of death and document with
evidence, 2) collect samples for a variety of research projects, 3) archive samples for future reference
(research or forensic). The gross necropsy and histology will be performed by, or under the lead and direct
supervision of, a board certified veterinary pathologist. Preferably, Drs. Margaret Wild and/or Tanya
Shenk of the Colorado Division of Wildlife (CDOW) will also be present. In general, the protocol will
follow standard procedures used for thorough post-mortem examination and sample collection for
histopathology and diagnostic testing. Some other data/samples listed below will be routinely collected for
research, forensics, and archiving. Additional data/samples may be collected based on the circumstances of
the death (e.g., photographs, video, radiographs, bullet recovery, samples for toxicology or other diagnostic
tests, etc.).

Procedures:
1.
2.
3.
4.
5.
6.

Remove the radio collar (animal ID will be the number written on the collar)
Determine the body weight and note general body condition
Note condition of the claws and teeth
Collect external parasites and submit for ID
If the carcass is in good condition, please skin and save the pelt (freeze)
Remove and save PIT tags (about 1.5mm x 12mm rod-shaped transponder~ne under chin, the other
on dorsal midline between the scapulae)
7. Conduct necropsy
8. Collect samples of all major organs including long bone, muscle, spinal cord, etc. (formalin)
9. Collect samples of all major organs including long bone, muscle, spinal cord, etc. (freeze)
10. Collect a 3cm x 3cm section of muscle (freeze)
11. Note condition of bone marrow in femur or other long bone
12. Collect a sample ofvas defcrens and testis (bag with a moist gauze and refrigerate)
13. Bag gut contents that could be used to determine diet (freeze)
14. Collect a fecal sample and submit for parasitology
15. Collect brain. Submit half for rabies exam; save other half in formalin
16. After examination, place the skull in one bag, the pelt in another bag, and other remains in a separate
bag (freeze)

The CDOW will retain all samples and carcass remains with the exception of: tissues in formalin for
histopathology, brain for rabies exam, feces for parasitology, external parasites for ID, other diagnostic
samples.

�59
Table 1. Mortality of lynx reintroduced to Colorado, February-August 1999.
Animal ID
YKM0199
BC99-01
BC99-09
BC99-07
BC99-08
AKM2399
AKF0499
BC99-06
AKF1799
AKF0899
AKF1899

Sex
M
M
F
F
F
M
F
F
F
F
F

Age

Protocol

Date of Death

Weeks Out

Cause of Death

2

NIA

NIA

0

1

04129199
02124199

2

1

02/26199

3

3

1

03116199

6

0

2

7

1

3

04110199
06118199

4

1

3

06112/99

s

Undetennined
Starvation
Starvation
Starvation
Starvation
Shot
Starvation

2

3

07/19199

7

HBC

2

3

07124199

11

HBC

s

3

07131199

12

2

3

08126199

15

Undetennined
Trawna., emaciation

3

1600

-

1400

Q)

1200

&gt;.

800

bl)

--

~ 1000
C

=-@

0

600

~

400
200
0
3110

3117

3/24

I-._

3131

4/7

Males -a- Females

4114

4/21

*

Pregnant

4128

SIS

I

Fig. 1. Average daily feed intake of captive lynx reported weekly from 10 March through 5 May 1999.

�60
16
14

~

12

rn

10

~

8

~

6

,:Q

4

I
0

2
0

YK

BC

I□ Arrival Wt

Im Release Wt

AK

I

Fig. 2a. Body weight of adult male lynx from British Columbia (BC; n = 5 arrival. n = 3 release). Yukon
(YK; n = 7 arrival, n = 5 release), and Alaska (AK; n = 7).

12

~

.l=bO

·-Q)

~
&gt;"'0
0
,:Q

10
8

6
4

2
0

BC

YK

AK

I□ Arrival Wt II Release Wt I
Fig. 2b. Body mass of juvenile female lynx from British Columbia (BC. n = 1), Yukon (YK, n = 1). and
Alaska (AK, n = 3).

�61

14
12

'bi&gt; 10

c

ell

~

~
0
~

8

6

4
2
0
BC-O

YK-P

YK-0

BC-P

AK-0

AK-P

Fig 2c. Body mass of adult female lynx from British Columbia (BC; open n =4 arrival, n = 1, release;
pregnant n = 0), Yukon (YK; open n = 2 arrival, n = 1 release; pregnant n = 1), and Alaska (AK; open n =
3; pregnant n = 7).

6
5
1-4

4

Q.)

1

3

2

1

0
Shot

Starve

Trauma

Cause of Death

I111 !Vele ■ Female
Fig. 3. Lynx mortality by cause through August 1999.

J

HBC

�62

4

3
~

.0

e 2

z

1
0
Feb

111 Starve

Mar

Apr

■ Unk

May

IJJ Shot

Fig. 4. Lynx mortality by month through August 1999.

Jun

IIIHBC

Jul

Aug

■ Trauma

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                  <text>63
Colorado Division of Wildlife
Wildlife Research Report
July 2000

JOB FINAL REPORT
State of

Colorado

Cost Center 3430

Project No.

W-153-R-13

Mammals Research Program

Work Package No. ------"-0___
67"'--0"--_ _ _ _ __
Task No.

Lynx Conservation
Assessing Abundance of Snowshoe Hares

3

Period Covered: July 1, 1999 -June 30, 2000
Authors: D. F. Reed
Personnel: D. F Reed, G. Byrne, T. Shenk, J. Kindler, P. Albers, T. Black, H. McNally, S. Znamenacek,
K. Buell, S. King, G. Patton, J. Zahratka, L. Uphham, B. Andree, J. Hicks, ·L. Green, K. Wright, B.
Heicher, P. Jones, D. Homan, R. Adams, S. Wait, D. Kenvin, B. Woodward, D. Boyer, K. Cordove, B.
Ochs, T. McLean, A. Bellotti, K. Schrollt, G. Cross, F. Kelffuer, G. Madison, L. Dwyer, D. Swanson, D.
Brownne, F. Pusateri, M. Wunder.
ABSTRACT
Data on hare density for this report were derived from pellet surveys using methods describe by Krebs et al.
1987. Samples were distributed among 5 blocks selected by biologist who believed them to be suitable for
sustaining lynx populations. Sample sizes of plot arrays ranged from 62-239 with the most plot arrays
occurring in block 5 (n = 239). Density calculations yielded 0.44 bares per ha for block 5 and lower
densities for the remaining 4 blocks. Hare pellet densities were highest in white fir habitats; followed by
limber pine and Englemann spruce habitats. Pellet densities were lowest in Gambel's oak and ponderosa
pine habitats, but these were also habitats which were not intensively sampled.
The most relevant results in this report are estimates of snowshoe density, the type of overstory in which
. the highest densities occurred (Engleman Spruce, based on those with adequate sample size) and where the
highest densities occurred (National Forests/wilderness areas and counties in Block 5; Figs. 4-8, 9, 10, 12
in Appendix 1). These indicate marginal densities for supporting reintroduced lynx according to the
literature and, professionals working with these species. Granted that most of the work and most of the
.professionals working in the field are in the northern boreal forests where snowshoe populations cycle
dramatically. Poole (1995) reported that concomitant with the first full winter of low bare density in the
Northwest Territories (91-92), all resident lynx died or dispersed in a 135-km2 study area.
Marginal habitat conditions for hares probably result in a scarcity of prey and may explain the relatively
large home ranges (and hence their behavioral adaptations toward dispersal) of the lynx (Koehler 1990,
Roloff 1997). Demographic characteristics of lynx, if any successfully establish home ranges, may be
representative of lynx populations along the southern periphery of their range where habitat conditions are
marginal for snowshoe hares.

�64

�65

SNOWSHOE HARE DENSITY/DISTRIBUTION ESTIMATES AND POTENTIAL
RELEASE SITES FOR REINTRODUCING LYNX IN COLORADO
D.F. Reed

P.N. OBJECTIVES
Analyze, summarize, and organize snowshoe hare survey data into a comprehensive final report for release
to the public (Division Report No. 20).
SEGMENT OBJECTIVES
l. Analyze, summarize, and organize snowshoe hare survey data into a comprehensive final report for
release to the public (Division Report No. 20).
RESULTS
Results of the analysis of snowshoe hare pellet sampling are detailed in the attached Appendix 1. Division
staff contracted with West, Inc. to evaluate and review the adequacy of both the methodology and the
analysis of these data and that report is contained in Appendix 2

�66

�67

APPENDIX 1.

SNOWSHOE HARE DENSITY/DISTRIBUTION ESTIMATES AND POTENTIAL
RELEASE SITES FOR REINTRODUCING LYNX IN COLORADO
Dale F. Reed
FOREWORD

Native wildlife are valuable resources in Colorado. Such values are manifested in several ways. Some
people enjoy seeing or photographing non-hunted species or get satisfaction from merely knowing that they
exist as important components of the ecosystem. During the 1980s and 1990s interest increased in the
concept of ecosystem management and in maintaining or enhancing biodiversity. Furthermore, interest in
enhancing the numbers of or in reintroducing species such as the lynx (Felis lynx) gained momentum in the
late 1990s. To that end, a reintroduction oflynx was planned for the winter and spring of 1999 and a
prerequisite to such an effort should involve examining the distribution and abundance of its principal prey,
the snowshoe hare (Lepus americanus).
TABLE OF CONTENTS

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
METHODS ................................................................... .
Krebs Plots ................................................................... .
Habitat Attributes at Plot Sites ..................................................... .
Model Probability Surface ........................................................ .
Potential Release Sites ........................................................... .
RESULTS AND DISCUSSION ................................................... .
Krebs Plots .................................................................... .
Habitat Attributes at Plot Sites ..................................................... .
Model Probability Surface ........................................................ .
Potential Release Sites ........................................................... .
CONCLUSIONS/SUMMARY .................................................... .
ACKNOWLEDGMENTS ........................................................ .
LITERATURE CITED .......................................................... .
TABLES
1 Number of points and plot arrays ................................................. .
2 Wyoming and Colorado hare densities .............................................. .
3 Probability of suitable hare habitat ................................................ .
FIGURES
l GAP Vegetation Classification and Survey Blocks 1-5 .................................. .
2 Random Sample Points Generated for Krebs plots ..................................... .
3 Krebs Plot Points Completed .................................................... .
4 Map of Snowshoe Hare Density by National Forest .................................... .
5 Graph of Snowshoe Hare Density by National Forest .................................. .
6 Map of Snowshoe Hare Density by County .......................................... .
7 Graph of Snowshoe Hare Density by County ......................................... .
8 Map of Snowshoe Hare Density by Block ........................................... .

�68

9 Graph of Snowshoe Hare Density by Block .......................................... .
IO Snowshoe Hare Density by Block Using "Old" Equation ............................... .
11 Snowshoe Hare Density by Elevation ............................................. .
12 Snowshoe Hare Density by Primary Overstory ...................................... .
13 Snowshoe Hare Density by Forest Structure ........................................ .
14 Snowshoe Hare Density by Primary Understory .................. : ................... .
15 Snowshoe Hare Density by Understory Density ...................................... .
16 Snowshoe Hare Density by Slope ................................................ .
17 Snowshoe Hare Density by Aspect ............................................... .
18 Snowshoe Hare Density by Domestic Grazing ....................................... .
19 Model Probability Surface for Blocks 1-5 .......................................... .
20 Predicted Areas with Greater than 80% Probability of Suitable Hare Habitat in Block 5 ........ .
APPENDICIES
A Krebs Pellet Plot Field Form ..................................................... .
B Selected Data from Block 1 ..................................................... .
C Selected Data from Block 2 ..................................................... .
D Selected Data from Block 3 ..................................................... .
E Selected Data from Block 4 ..................................................... .
F Selected Data from Block 5 ...................................................... .
G Genus-species Understory Abbreviations in Fig. 14 ................................... .
H Summary by Hare Densities per Block, Primary Overstory, National Forest/Wilderness Areas, and by
County ...................................................................... .

�69
SNOWSHOE HARE DENSITY/DISTRIBUTION ESTIMATES AND POTENTIAL
RELEASE SITES FOR REINTRODUCING LYNX IN COLORADO
INTRODUCTION

Based on a renewed interest in the lynx and the possibility of reintroducing the animal in Colorado, four
agencies including the U.S. Forest service, National Park Service, U.S. Fish and Wildlife Service, and
Colorado Division of Wildlife prepared a draft strategy for the conservation and reestablishment of lynx
(Fe/is lynx) in the southern Rocky Mountains (Seidel et al. 1998). This draft outlined generally two
methods for assessing snowshoe hare (Lepus americanus) habitat use or presence and abundance or
population trends as recommended by Weaver (1997). The first method was winter track surveys and the
second was counts of snowshoe hare pellets (fecal droppings).
Tracks in the snow have long been used to note habitat use and the presence of animals (Forrest 1988,
Halfpenny 1986). However, only careful approaches or methods may yield definitive density or population
estimates (Becker et al. 1998). A winter track survey was completed during the winter months of 1998 and
reported by Byrne (1998).
•
Counts of snowshoe hare fecal pellets have been used to estimate population trends or density (Angerbjorn
1983, Krebs et al. 1987, Wolff 1982). Angerbjorn (1983) estimated density in Sweden from counts of
square-shaped quadrats of 0.1 m2 and obtained log-log regression: log (pellets)= 1.02 log (hare density)+
0.44, where hare density is per hectare (ha). He found a close relationship between pellet counts and hare
numbers (r2 = 0.91). Conversely, Wolff (1982:141) indicated that "...pellet counts can be used to indicate
habitat use or population trends, but not to estimate population numbers." Krebs et al. (1987) found a
relationship between mean pellet counts and mean hare density on 50 quadrats of0.155 m2 (5.08 x 305
cm). A modified version of his equation, log10 (hares/ha) = ((log 10 (pellets) - 0.2359] x 2.303) + 0.2773,
was used by Slough and Mowat (1996). Since then, the equation has been modified several times.
The purpose of this document is to report on snowshoe hare pellet counts, the results of estimating hare
densities across major habitat types and associated selected habitat characteristics, and an approach for
estimating hare habitat as it relates to providing the primary prey for reintroduced lynx.
METHODS
Krebs Plots

Five major core areas were delineated for the Kreb's pelletplot counts (Fig. 1). The blocks were selected
based on large contiguous parcels of land that appeared to have suitable habitat (oak, aspen, coniferous
forest type or a mixture of these types). The vegetation data is from the Colorado GAP Analysis project
(Thompson et al. 1993). Natural or manmade barriers, such as Interstate 70, further define the block
boundaries. Small isolated blocks of suitable habitat such as Greenhorn Mountain, the Roan Plateau,
Sangre de Cristos, and the Uncomphagre Plateau were not considered in the hare data collection and the
GIS maps.
Random points for each of the five blocks were generated using a program modified after Zack (pers. com.,
J. Zack) which created a grid for each vegetation type with random numbers between 0 and 100,000. A
sub-program checked the number of cells containing identical values, and aggregated these until a total was
reached that was equal or greater than the required number of random points. The centroids of the cells
with values lower than this cut-off value were then plotted as an Arc/Info coverage.

�70
The number of random points generated across the vegetation types (Fig. 2) were about 200 for blocks l, 4,
and 5, and 100 for blocks 2 and 3 (in some cases random point program generated a few extra points).
Initially, every 4th random point ploted on map (BLM Surface Mangement Status 1:100,000 scale)
overlays were selected to insure wide distribution and randomness in case all points could not be completed.
According to the protocol used, once the location was determined by use of a GPS unit (matching UTM
coordinates generated for a given point as listed on the overlay) or map orienteering, a random bearing (0360 deg) was chosen, and a rectangular array of 10 Krebs plots was set (A), each 30 m apart (rectangular
array= 30 m x 120 m, with 5 plots per side in direction and then in opposite direction of the bearing).
Additionally, a second array (B) was selected at a randomly chosen bearing and distance (10-190 m
inclusive) from the completion point (about 30 m from the beginning of the first array) of the first array
(A). Hence, pellet counts were made for two fairly close areas near each randomly selected point. These
pellets were tallied as either new or old and their means calculated. New and old pellets were differentiated
by color, lighter tan being judged "new" (estimated from current season), and darker gray being judged
"old" (estimated from before current season).
The mean number of pellets (2 sets of 10, i.e. n = 20 plots for each randomly selected point [Fig. 31) was
entered into a published equation to produce an estimated number of hares per hectare. This equation was
a modified version of Krebs et al. (1987) (log 10 hares/ha= {[(0.8127 x log 10 pellets) - 0.2359] x 2.303} +
0.2773, as in Slough and Mowat 1996). Later, the equation was modified (per. com., K. Poole, 9 Nov 98).
Still later, it was modified again (per. com., C. Krebs, 29 Sep 98 and 24 Nov 98). This third iteration, lo&amp;
(hares/ha)= (0.888962 x 10&amp; [pellets] - 1.203391) x 1.567026, was recommended by Charles Krebs (per.
com., C. Krebs, 24 Nov 98) and the one ultimately used for the overall analyses. It was based on his
review of his data (collected samples from the Yukon: 1976-1996, n = 86, calculated from annual pellet
counts in June and average densities of hares from the previous spring and autumn estimated by markrecapture including adding a correction for bias [Sprugel 1983]).
Habitat Attributes at Plot Sites

Categories other than those related to the plot locations (Name of Property, Game Management Unit
[GMU], County, Lynx Survey Block Number, General Location Description, Land Status, and UTM
coordinates) recorded on the field forms (Appendix A) included:
- elevation
- overstory (primary, secondary, and tertiary)
- vegetative structure (e.g. mature, old growth)
- understory vegetation (primary, secondary, and tertiary)
- understory vegetation density (estimated visual obstruction of vegetation from IO m in front of a
vertical I x 6 ft [0.30 x 1.83 m] white panel, marked off in ft2 [0.30 m2], where highest value of
6.0 = no visual obstruction, and to be recorded with photograph)
- slope
- aspect
- overstory and understory distribution (patchy or continuous )
- domestic grazing presence or absence.
Model Probability Surface

A logistic model was used to generate a continuous surface representing the probability of any geographic
location supporting snowshoe hare habitat (pers. com., M. Wunder). The results from the Krebs plot effort
were examined spatially using chi-squared analysis to produce parameter estimates for the model.

�71
Parameter values were estimated for each of vegetation (primary cover type), elevation, slope, and aspect
using the Krebs plot coverage, the vegetation coverage from the GAP analysis project, and a digital
elevation model (DEM) for the study area. The DEM was used to generate separate grids for elevation,
slope and aspect. Parameter estimates with P-values less than 0.05 were then used in the logistic model,
which was then run using the pertinent grids. The model equation follows: 1/l+exp(Ao + Aa *aspect+ Ae
*elevation+ Av* vegetation), where Ao is the overall parameter estimate, Aa is the estimate value for
aspect, Ae is that for elevation, and Av is that for vegetation.
Release Sites

Initially, release sites were selected based on the model probability surface, but for practical reasons of
access and managing the media and number of observers during the releases, private land areas abutting
potential lynx habitat or proximity to the Weminuche Wilderness were given high priority. Potential sites
were inspected and coordinated with landowners and caretakers where appropriate.

RESULTS AND DISCUSSION
Krebs Plots

Paired pellet plot arrays and single plot arrays were completed at 303 and 5 randomly selected points,
respectively. Sample sizes of the number of plot arrays ranged from 62-239 (Table 1, Appendices B-F)
with the most plot arrays (n = 239) completed in block 5 (Appendix F). Distribution of hare densities by
National Forest (Figs. 4-5), by county (Figs. 6-7), and by block (Fig. 8), suggest that block 5 had the
highest hare density.
Density calculations yielded 0.44 hares per ha for block 5 and lower densities for the remaining blocks
(Fig. 9). This mean of hares per ha in block 5 results from using the latest regression equation from Krebs
as discussed under Krebs Plots in Methods. The initial calculation using an.earlier equation (Slough and
Mowat [ 1996]) yielded a mean of almost 1.2 hares per ha (Fig. 10).
Using different equations and possibly using them incorrectly yields substantially different results. Also,
initial analysis of block 5 data using a SAS program used in the Northwest Territories (per. com., K.
Poole, 14 Sep 98) was corrected as were the analyses of data from 2 areas over 2 years in Wyoming,
where lynx were present (per. com., K. Poole, 9 Sep 98; per. com. T. Laurion, 18 May 99) (Table 2). Our
calculations using the latest regression equation from Krebs (per. com., C. Krebs, 27 Oct 98 and 24 Nov
98), matched these same values (0.817, 0.856, 0.694, and 1.429, respectively) (Table 2).
Thus, using the most current accepted calculations, the Wyoming areas having lynx present, had hare
densities ranging from 0.817-1.429, similar to some other densities reported (0.73/ ha, Dolbeer and Clark
1975; 1.40/ha, Lima 1998; 2.40/ha, Meslow and Keith 1968), but subtantially lower than others (12.3/ha,
Bailey et al. 1986), and all higher than that considered the lower "edge" for suppporting lynx (0.5/ha; C.
Krebs, per. comm., 24 Nov 98). Dolbeer and Clark's (1975) 0.73 hares per ha might be considered a
model for habitat in Colorado, but another study using 175 permanent plots, reports lower densities
(0.053/ha in lodgepole pine and 0.068/ha in spruce/fir) (Shivery 1997).
This causes concern that the density of our 0.44 hares per ha in block 5 may not be sufficient as a primary
prey base to support lynx. Part of the problem, however, is that our data were collected randomly across
11 primary overstory types. The Wyoming data were collected from plots ~lected in coniferous forest
types.

�72

It is generally accepted that some of the primary overstory types (probably the 3 non-conifer types [aspen
{Populus tremuloides}, willow {Salix spp}, and Gamble's oak {Quercus gambelii} or mixed mountain
shrub], ponderosa pine (Pinus ponderosa), and bristlecone pine (Pinus aristata) might be expected to have
low hare densities. Apparently this was the case based on our small sample sizes. Most of our samples
were taken in 6 conifer types described below. Hence, the problem remains - we apparently have a
relatively low density of hares if compared to the Wyoming data, but is it comparable? Given that
Wyoming's plots were taken non-randomly in optimal habitats, the extent to which optimal habitat
considerations could induce bias is unknown. It is possible that if we had used our method of selecting
random samples in Wyoming that their means would have been lower. Similarly, it is possible that ifwe
had sampled randomly in "optimal habitats" (whatever those are in Colorado) that our means would have
been higher. In either case, how much lower, or higher, is simply unknown. This probably limits the utility
of comparing these 2 sets of data.

Habitat Attributes at Plot Sites
Attributes from the plot locations as prescribed by data collection (Appendix A) across densities, included
elevation (Fig. 11 ), 11 primary overstory or canopy types,
- Lodgepole pine (Pinus contorta)
- Englemann spruce (Picea engelmannli)
- Subalpine fir (Abies lasiocarpa)
- Douglas fir (Pseudotsuga menziesli)
- Ponderosa pine
- Limber pine (Pinus jlexi/is)
- Bristlecone pine
- White fir (Abies concolor)
-Aspen
-Willow
- Gamble's oak or mixed mountain shrub (Fig. 12), structure (Fig. 13), primary understory vegetation (Fig.
14), vegetation density indices (Fig. 15), slope (Fig. 16), aspect (Fig. 17), and grazing (Fig. 18).

The relationships between hare density and some of these attributes, i.e. elevation, structure, primary
understory, aspect, and grazing, yielded relatively predictable results. Forest types preferred by hares in
Colorado occur at higher elevations (Fig. 11). Limber pine and white fir show the highest hare densities,
but with very small sample sizes these densities are probably not represen~ve (Fig. 12). Conversely,
Englemann spruce had a sample of 220, lodgepole pine 108, subalpine fir 64, and Douglas fir 48 (Fig. 12).
Willow had only one sample where it was considered the primary overstory and is not included in Fig. 12.
For structure, most of the plots completed were in mature or old growth. The small sample of sapling/pole
(n = 49 of 606 records, with only about 50% of the 49 having any pellets) and the even more negligible
sample sizes ofGrass/Forb and Shrub/Seedling, essentially yield zero densities (Fig. 13).
Selected understory species appear to be associated with higher hare densities than others (Fig. 14), but
another measurement, the vegetation density indices, may suggest that the amount and height of the
understory is limited (Fig. 15 and 376 photographs appended to data records). Most of the samples (245
and 97 of 428 records) occurred in the 5.0-6.0 and 4.0-4.9 categories, respectively, where little understory
obscured the panel (Fig. 15). The value for &lt;1.0 is unlikely to be representative.
Other workers have suggested that predation on snowshoe hares may be heaviest in habitats that have little
understory (Sievert and Keith 1985), that snowshoe hares avoided open understories and greater understory

�73
density provided both escape and thermal cover (Litvaitis et al. 1985), and that height ofunderstory was
important (Wolfe et al. [1982] found a strong correlation between hare use and cover densities at heights of
1. 0-2.5 m above ground, and that vegetation types in which cover densities above snow level [ 1. 0-1.5 m]
were at least 40%, accounted for 85% of winter use by hares).
Hare density shows a bimodal response to slope (Fig. 16), but upon inspection of photographs it appears
that at least one field person consistently over-estimated degree of slope, probably skewing these data. In
relation to aspect, hares probably avoided the wanner, dryer, southern exposures (Fig. 17). Hare density
means from plots judged to have domestic grazing or not (Fig. 18) were predictably no different (0.358 vs
0.342, respectively). How recent or the extent of any grazing was not estimated. Judging vegetation
distribution for overstory and understory as patchy or continuous (Appendix A) was largely dependent on
"scale" and was therefore not analyzed. Similarly, "Old" pellets were not analyzed because their age or
persistence could not be determined. Generally, these pellets occurred in low numbers and were noted in
402 of 613 records. Cottontail (Sylvilagus nuttalli) and jackrabbit (Lepus townsendi) pellets were noted in
a low number of records and were not analyzed. Some overlap or abutting of habitat boundaries might be
expected between hares and mountain cottontails, but doubtfully with jackrabbits. One could conclude,
that if you counted jackrabbit pellets, you were in the "wrong" (i.e., non-hare) habitat.
Model Probability Surface

The probability values from the model were naturally distributed across fiv~ range classes (pers. com., M.
Wunder). These were represented as zero percent probability, one to twenty percent, twenty to eighty,
eighty to ninety-three and ninety-three to one hundred percent probability (Fig. 19). The most relevant
results include the areas that were modeled as greater than 80 percent probability of hosting snowshoe hare
habitat. Block 5 included the largest surface area and proportion of area that was modeled greater than 80
percent probability. Areas within a radius of 3.2 km from potential lynx release sites that were predicted
with greater than 80% probability to provide suitable snowshoe hare habitat were delineated (Fig. 20). The
distribution and amount of the area is shown in Table 3.
It should be noted, however, that raw values for area may not be the best (and certainly is not the only)
criterion for drawing conclusions about the suitability of an area for snowshoe hare or lynx. We did not
develop any method for examining the distribution of this area for spatial context. If and when this issue is
addressed in the future, it should be acknowledged that there are many varied factors involved with such an
analysis.
Release Sites

Hence, one of the sites north of the Weminuche Wilderness, Humphreys (Goose Creek), was ultimately
chosen for the initial release February 3-4, 1999. Similarly, other sites northwest, north, south, and
southwest of the Weminuche Wilderness Area, were ultimately chosen for later releases in March.
Release sites in Block 5 located northwest, north, and east (n = 4) and south and southwest (n = 4) of the
Weminuche Wilderness were initially described using a predicted probability surface of snowshoe hare
habitat (per. comm., M. Wunder) and examined using the following criteria:
- ownership, public and private lands where permission for egress was obtained
- access, where at least snowmobiles could be used to gain access
- seclusion, where public access is generally not available
- habitat near release site should have a range of 1,000-10,000 ha of continuous or at least only lightly
broken conifer forests

�74
- connectivity, where forest segments are sufficiently contiguous to allow for traveling lynx to avoid open
areas
The 4 sites northwest, north, and east of the Weminuche Wilderness Area were ranked as follows:
-Humphreys (Goose Creek)
- Red Mountain Ck
- Rio Grand Reservoir, and
- Big Meadows
Similarly, the 4 sites located south and southwest of the Weminuche Wilderness Area were ranked as
follows:
- Weminuche Valley
- Beaver Meadows
- Endlich Mesa, and
- Middle Mtn/Bear Ck
CONCLUSIONS/SUMMARY
The most relevant results in this report are the estimates of snowshoe hare density, the type of overstory in
which the highest densities occurred (Engleman Spruce, based on those with adequate sample size) and
where the highest densities occurred (National Forests/wilderness areas and counties in Block 5; Figs. 4-8,
9, 10, 12, and Appendix H). These indicate marginal densities for supporting reintroduced lynx according
to the literature and professionals working with these species. Granted that most of the work and most of
the professionals working in this field are in the northern boreal forests where snowshoe hare populations
cycle dramatically. Poole (1995) reported that concomitant with the first full winter of low hare density in
the North West Territories (91-92), all resident lynx died or dispersed in a 135-km2 study area.
Marginal habitat conditions for hares probably result in a scarcity of prey and may explain the relatively
large home ranges (and hence their behavioral adaptations toward dispersal) of the lynx (Koehler 1990,
Roloff 1997). Demographic characteristics of lynx, if any successfully establish home ranges, may be
representative of lynx populations along the southern periphery of their range where habitat conditions are
mariginal for snowshoe hares.
ACKNOWLEDGMENTS
We especially thank Pam Albers, Travis Black, Heath McNally, and Steven Znamenacek for the
completion of most of the Krebs plots. Other agency field assistance came from Steve King, Rocky
Mountain National Park; Gary Patton, U.S. Fish and Wildlife; Kit Buell and Jennifer Zahratka, U.S. Forest
Service; and Lee Upham and crews, Bureau of Land Management. Field work by Division personnel
included Bill Andree, Jim Hicks, Larry Green, Kevin Wright, Bill Heicher, Paul Jones, Doug Homan, Rick
Adams, Scot Wait, Dave Kenvin, Dale Reed, Gene Byrne, and Brent Woodward. Gene Byrne organized
and coordinated the field work. Work by volunteers included Don Boyer, K. Cordova, Brett Ochs, Travis
McLean, Amy Bellotti, Kathrin Schrott, Gretchen Cross, Francis Kleffner, Griffin Madison, Lynn Dwyer,
and Dawson Swanson. Geographic Information Systems (GIS) support and cartography provided by Jon
Kindler. Dawn Brownne assisted with data entry. Francie Pusateri provided advice and converted Visual
dBase files to EXCEL. Mike Wunder, Natural Heritage Program, generated the model probability surface
and associated figures. We also thank Tom Beck, Rich Reading, and Tanya Shenk for reviewing the
manuscript. Work reported here was funded mostly by Division GoCo funds and from funds from Vail
Associates.

�75
LITERATURE CITED

Angerbjorn, A. 1983. Reliability of pellet counts as density estimates of mountain hares. Finn. Game
Res. 41:13-20.
Bailey, T. N., E. E. Bangs, M. F. Portner, J. C. Malloy, and R. J. McAvinchey. 1986. An apparent
overexploitated lynx population on the Kenai Peninsula, Alaska. J. Wildl. Manage. 50:279-290.
Becker, E. F., M.A. Spindler, and T. 0. Osborne. 1998. A population estimator based on network
sampling of tracks in the snow. J. Wildl. Manage. 62:968-977.
Byrne, G. 1998. A Colorado winter track survey for snowshoe hares and other species. Colo. Div. Wildl.
35pp.
Dolbeer, R. A., and W.R. Clark. 1975. Population ecology of snowshoe hares in the central Rocky
Mountains. J. Wildl. Manage. 39:535-549.
Forrest, L. R. 1988. Field guide to tracking animals in the snow. Stackpole Books, Harrisburg, PA. 185
pp.
•
Halfpenny, J. 1986. A field guide to mammal tracking in North America. Johnson Publishing Co.,
Boulder, CO. 161 pp.
Koehler, G. M. 1990. Population and habitat characteristics oflynx and snowshoe hare in north central
Washington. Can. J. Zool. 68:845-851.
Krebs, C. J., B. S. Gilbert, S. Boutin, and R. Boonstra. 1987. Estimation of snowshoe hare density from
turd transects. Can. J. Zool. 65:565-567.
Lima, S. L. 1998. Nonlethal effects in the ecology of predatorprey interactions. BioSci. 48:25-34.
Litvaitis, J. A., J. A. Sherburne, and J. A. Bissonnette. 1985. Influence of understory characteristics on
snowshoe hare habitat use and density. J. Wildl. Manage. 49:866-873.
Meslow, E. C., and L.B. Keith. 1968. Demographic parameters ofa snowshoe hare population. J. Wildl.
Manage. 32(4):812-834.
Poole, K. G. 1995. Spatial organization of a lynx population. Can. J. Zool. 73:632-641.
Roloff, G. J., and J.B. Haufler. 1997. Establishing population viability planning objectives based on
habitat potentials. Wildl. Soc. Bull. 25:895-904.
Seidel, J., B. Andree, S. Berlinger, K. Buell, G. Byrne, B. Gill, D. Kenvin, and D. Reed. 1998. Draft
strategy for the conservation and reestablishment of lynx and wolverine in the southern Rocky
Mountains. U.S. Forest service, National Park Service, U.S. Fish and Wildlife Service, and Colorado
Division of Wildlife. 115pp.
Shively, K. 1997. Snowshoe hare density in Vail, Colorado; implications for lynx reintroduction. Unpub.
Rep.:1-7.
Sievert, P.R., and L.B. Keith. 1985. Survival of snowshoe hares at a geographic range boundary. J.
Wildl. Manage. 49:854-866.
Slough, B. G., and G. Mowat. 1996. Lynx population dynamics in an untrapped refugium. J. Wildl.
Manage. 60:946-961.
Sprugel, D. G. 1983. Correcting for bias in log-transformed allometric equations. Ecol. 64:209-210.
Thompson, T. G., W. A. Reiners, and D. L. Schrupp. 1993. Colorado gap analysis vegetation
classification (draft). Unpub. Rpt.
Weaver, J. L. 1997. Reconnaissance oflynx habitat in Colorado. Wildl. Conserv. Soc. lOpp.
Wolff, J. 0. 1982. Snowshoe hare. Pages 140-141 in CRC handbook of census methods for terrestrial
vertebrates. Edited by D E Davis. CRC Press, Boca Raton, FL.
Wolff, J. 0., N. V. Debyln, C. S. Winchell, and T. R. McCabe. 1982. Snowshoe hare cover relationships
in northern Utah. J. Wildl. Manage. 46:662-670.

�76
Table 1. Block numbers, number of points generated, points completed (2 plot arrays for each point with 5
exceptions where only 1 array was completed), and plot arrays completed ( 10 plots for each array).
Block
No. of Points
No. of Points
No. of Plot Arrays
Generated
Completed
(2 x points completed)
1
2
3
4
5
Total

200
100
100
200
200
800

57
31
33.5
64.5
119.5
305.5

114
62
67
129
239
611

Table 2. Mean number of hare pellets per Krebs plot and calculated hare densities per ha in 2 areas over 2
years in Wyoming where l)'TIX occurred and in Block 5 of this study.
Wyoming8
Colorado
Area

DUBOIS97

DUBOIS98

MERNA97

MERN98

BLOCK5

Pellets/plot
Hares/ha

1.86
0.82
(0.64-1.05)b

1.96
0.86
(0.67-1.09)

1.55
0.69
(0.54-0.89)

3.49
1.43
(1.11-1.84)

0.94
0.44
(0.35-0.56)

•Data from T. Laurion, calculations by K. Poole.
b95% CI.

Table 3. Study areas or blocks, areas with greater than 80 percent probability of providing suitable hare
habitat, and the proportion of the study areas involved.
Study Area/Block
Area (ha) with &gt; 80% Probability of
Proportion (%) of Study Area
Providing Suitable Hare Habitat
1
2
3
4
5
Total

460,753
97,920
110,233
587,903
658,258
1 915 067

20.3
11.7
15.7
21.4
24.1
93.2

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-

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■

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(me. Blue Sptueo)

u
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40

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100

I
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SNOWSHOE HARE DENSITY BY NATIONAL FOREST

D 0 Hares/ha

-

-----------

-

0.3 • 0.399 Harea/ha

~ 0.001 • .099 Ham/ha -

0.4 - 0.499 Harea/ha

I ll

0.1 • 0.199 Harea/ha -

&gt;0.5 Harea/ha

0.2 • 0.299 Harea/ha

0
0

-- ,- .. - - -

40
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ARAPAHO NF
BUFFALO PEAKS
WILDERNESS
GRAND MESA NF
GUNNISON NF
LAGARITA
WILDERNESS AREA

6'
~

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CD

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UNCOMPAHGRE
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N

SNOWSHOE HARB DENSITY BY COUNTY

D OHatell'ha
0.3 - 0.399 Hare,/ha
G 0.001 - .099 HIU'ea/ha Ill 0A - OA99 Hare,/ha
flil 0.1 - 0.199 Hatell'ha - &gt;0.$ Hare,/ha
1111 0.2 - 0.299 Hares/ha
0-

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Mean hare density by block using Kreb's oriqinal equation (sample sizes above

5

�86

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&gt;=12,000

El~vation Ranges

Hares per ha

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0

Q.

Fig.12. Hare density by primary overstory (sample sizes above bars).

Q'.

ii:
w

I-

I

~

w

z

a:
Q'.

w
m
::::E
::::;

�87
Hare Density by Forest Structure
16 ,---,-:-=----,----.---,---,
~'.
,[

1.4

1.2

...

~
1/)

.,

:.

:S

:i!- 0.8
'iii

.,

C

C

;

0.6

::c
0.4

0.2

SHRUB/SEEDLING

GRASS/FORS

SAPLING/POLE

MATURE STAND

OLD GROWTH

~orest Structure

1.2

08

"'

a. 0 6

..
1/)

~

::c

04

0.2

AMAL
Fig.

14

ARCO

ARUV

CA spp

JU spp

QUGA

SHCA

SYAL

SYOC

Hare density by selected primary understories (number of records n = 10 or&gt;, and pellets n = 1 or&gt;;
abbr. see Appendix G).

VACA

VASC

�88

OS

Hares per ha

0.3

0.1

0

5.0-6.0

4.0-4.9

3.0-3.9

2.0-2.9

&lt; 1.0

1.0-1.9

Fig. 15. Vegetation density indices by hare deniity.

.;

2

~.,

:.

;;_
~ 1.5

'iii

.,
C:

0
~

"'

:c

0.5

0
&lt; 10

10 - 19

20-29

30-39

40- 49

Slope Range (degrees)

50 -59

60-69

&gt;= 70

�89
Hare Density by Aspect (Area 5)

NORTH

NORTHEAST

EAST

SOUTHEAST • SOUTH

SOUTHWEST

Aspect

0.4

0.35

0.3

0.25

0.2

0.15

0.1

a.as

0

Fig. 1a. Absence or presence of grazing (1st and 2nd bar, respectively) versus hare density.

WEST

NORTHWEST

�rig. 1 CJ. Study area-wide view
showing predicted probability
surface of snowshoe hare
nabitat, study area boundaries,
roads, and municipality
boundaries.
Variable
Ao
Aa
As
Ae
Av

. . - - - - . , r - - : - - - - - - · ·····-· -

............... __
\0
0

Parameter p
0.0001 15.6638
0.2300
0.0503
0.8573
0.0641
0.0001
-0.7106
-1.4909
0.0130

i--.----_J

---~,~
..

I

Model Surface =
1/1 +exp(Ao+Aa* Aspect+Ae"Elevation+Av*Vegetation)

,.J

'

..

•\_,/ Highways
Study Areas
Predicted Probability

-0
-1-20%
1 ·'?~~I 20-80%
.--180-93%
· - 93-100%

'

, .. :&lt;:.
'p-,1

Snowshoe hare data used in this map were collected
by the CDOW, USFS, NPS, USFWS, biologists
and numerous volunteers.

\ J-{ait,y,.:'§,

..~

~

The data were compiled and provided by CDOW staff
The predictive model was constructed by CNHP staff

'

'

'~\

\ e

Co; Oll ;;,i'P

····-·••-···--- ---···----·-······--'

�Fig. 20. Areas within a radius of 3.2 km
from potential lynx release sites that are
predicted with greater than 80%
probability to provide suitable snowshoe
hare habitat.
•

Potential release sites
80-100%Probability within two mile radius
Wilderness and Research Natural Areas
Predicted Probability of Suitable Habitat

D

.

-0
-1-20%
1 :_._;· 120-80%
~80-93%
- - 93-100%

I
I.

!
Hectares

Name
Endlich Mesa

14 63

Weminuche Valley

596

Be aver Meadows

469

Big Meadows

2108

----------------Rio Grande____
Reservo1___..__________
1421
_ i
Humphreys _ _ _ ____..__·"_--•________§_~_J

------.-----

Mosca Divide
Middle Mtn/Tuckervi
Coal Bank/Lime
_____,_____
Middle Mt~/Bear Cr

977 :

Wi 11 i a rn s Cr TH

921 :

West Fork San Juan

912

----~----

---------·--·---

i
I

----------·--·-··----

Red Mountain Creek

----'------····

Transfer Pk.

---------Four mile TH

817.

---·- ----~

794
656

---------------------Middle Fork Piedra

610
---------East Fork Piedra
431
---------------Pl um ta w
120
•••••

.
;

-····--··-·- - - - - - - - - - - - - -

0

40 Kilometers

s

. -·· - - · - - · - · • - · · - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

�92
Colo.--ado Di VI•sion of Wldlife - Krebs Pellet Plot Survey Form
Krebs Plot#
· -

Observer(s):

Slope: (in Degrees)

lime:

Date:
Name of Property
GMU:
Lynx Suivey Block#

(Adual)
County:

Start Location from?
D
General Location Description:

D

GPS

Map

D
D

Aspect

0

UTMY:

UTMX:
Zone:

D
D

12

13

App QH..J,.x A

N

D

s

□

E

D

□

Patchy

□

Continuous

Understory

□

Patchy

D

Continuous

KREBS PLOT DATA:
s,_,, ____

New Old

New Old

J~bbit
New Old

-1 -

--

l

-

-

-

2

-

-

-

-

-j -

--

3

-

-

-!

-

--

_j

-

--

-

--

I

4

-

-

D

-

-

-

• GPS

□

5

-

-

-

6

-

-

-

7

-

-

-

Secondary OVerstory:

8

-

-

Tertiaty OVerstcxy:

9

-

Vegetative Stn.icture Class:

10 _

feet

other

Prima,y Overatory:

GraS$IFOrb

L

Shrublseedrmg
Sapling/Pole
Mature
OldGl"OINth

L

Underatory Vegetative Type:
Common Name
1 (Primary)
2 (8econdary)
3 (Tertiary)
Grazed

D

KrebsFonn

Yes

□

7-8-98

No

i

-

--

-

~1

-

--

-

-

-

-

--

-

-

-

-

-

--

-

-

-

-

-

I

-

,

,' OVerstory Type:

other

-

1

D

Cott&lt;intail

Elevation (MSL):
From:
Topo

-

NE
WN
SE
SW

overstay

J

·NAD27 D
V\GS84 [J
NAD83

i

Rat 0--5
Moderate 6-20
Moderately steep 21-40
Steep 41 degrees or more

Vegetation Distribution:

land status COde:

t

D
D
D
D

w C

D

Datum:

Density
Index

Photo Taken?· D Yes □ No

-..

r-

L
,.

Land Status Codes:

,_

G
~e

Private - P
U.S. F. S. -F
BLM-8
~ State,LaAd Board - S
OON-D
National Park - N
other- O (Explain)

Overstory Veg. Type Codes:
Lodgepole Pine - L
mann S(:)(1!ce - S
~
Su
pine Fir - F •

lasFir-D

~
P
erosa Pine - P
Umber Pine - X
Bristteoone Pine - B

WliteFir-W
Asoen-A
WIICMt-Y

Gamble's Oak or
mixed mountain Shrub - C

Comments (Continue on back if needed): _ _ _ _ _ _ _ _ __

�I

KREBSPL LSBNUM UTMX

FC-21-A
FC-21-B
FC-95-A
FC-95-B
FC-97-A
FC-97-B
FC-101-A

1
1
1
1
1

FC-101-B
FC-178-A
FC-178-B

1
1
1
1
1
1
1
1
1
1
1
1

VA-62-A
VA-62-B
VA-132-A

VA-132-B
VA-144-A
VA-144-B
VA-149-A
VA-149-B
VA-150-A
VA-150-B
VA-155-A
VA-155-B
VA-161-A
VA-161-B
VA-163-A
VA-163-B
EP-40-A
EP-40-B
VA-164-A
VA-164-B
VA-135-B
VA-153-A
VA-153-B
VA-135-A
WA-77-B

WA-81-A
WA-81-B
WA-73-A
WA-73-B
WA-75-A
WA-75-B
VA-166-A
VA-166-B

DW-13-A
DW-13-B
DW-49-A

1
1

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1

446555
446510
448682
448660
428211
428210
425389

UTMY

453580

397240
397326
392830
373296
373376
392913
403816

SN9

MEAN

SN10
1

1
1

I

4489480
4505757 L
4505920 L
4373370 S
4372950 S
4424300 A
394760 4424351 L
371270 4410075 F
371161 4410046 F
406232 4405739 L

5

4

2

6

1

3

1
(,

.. '
1

4405872 S
4405295 L
4405428 L
4394020 L

App~dix (J

2

425240
450931
450870
388866
389100
394594

406200
393331
393518
406653
406432
405438
405303
403862
403935
453565

SNS

SN3

SN2

PRIMOVE SN1

4488703 F
4488640 S
4492238 S
4492180 S
4490776 S
4490840 S
4489448

0

1
1

1
1

1
1

1

43.9.3960 A
43!!6943 S
4386987 S
4384857 F

4364789 S
4442252 F
4442167 L
4381807 F
4381750 F
4419021 F
4399796 F
4399898 L
4419011 L
4528065 L

1

4538167 L
4531982 L
4532088 A
4376295 L
4376415 L
4374855 A

1
1
1

449594 4374855 A
434487 4398253 S

1

1
5
3
•1
2

407484 4521979 S
407495 4522070 S
406978 4538343 L
407057
405250
405123
406867
407088
449594

4

1

21
2

1
1

7
·2
4

1
1
1

2
1
•1

1

1

1
1
1
1
2

1

1
1

3

1
3

2

1

4

1

2
10
1

1

3

4

1

16

4

4
1

. Page 1 of3

2

KREB'SN HARE DEN!- '
0.4 -0.55929
0.2 -0.80394
0.1
-1.0486
0.1 • -1.0486
0
0
0.3 -0.66083
0
0
0
0
0.9 -0.27306
1.2 -0.17152
0
0
0
0
0.1
-1.0486
0
0
0.1
-1.0486
0
0
0
0
0.1
-1.0486
0.2 -0.80394
0.1
-1.0486
0.1
-1.0486
0.2 -0.80394
0
0
0
0
0
0
0
0
0.6 -0.41617
0.1
-1.0486
0.5 -0.48052
0
0
0.6 -0.41617
0.9 -0.27306
2.6 0.101391
1.2 -0.17152
0
0
0.1
-1.0486
0.1
-1.0486
0.1
-1.0486
0.1
-1.0486
0.7 -0.36176
0.3 -0.66083
0
0
0.5 -0.48052
2.1 0.026007
2.5 0.087548
0.9 -0.27306

0.275876311
0.1570576~
0.08941368E
0. 08941368E
(

0.21836012~
(
(

0.53326447&lt;
0.67372666!
(
(

0.08941368(
(

0. 089413681
(
(

0. 089413681
0.1570576!
0.089413681
0.089413681
0.1570576!
I
I
I
I

0.3835557:
0.08941368 1
0.33073167
0.3835557
0.53326447
1.26296421
0.67372666
0.08941368
0.08941368
0.08941368
0.08941368
0.43474840
0.21836012
0.33073167
1.06171345
1.22334116
0.53326M7

w

�KREBSPL LSBNUM UTMX
DW-49-B
DW-50-A
DW-50-B
DW-53--A
DW-53--B

DW-56-A
DW-56-B
DW-145-Jl
DW-145-8
DW-157-A
DW-157-8
EP-30-A
EP-30-B
EP-33--A
EP-33--8
EP-118-A
EP-118-8
EP-38-A
EP-38-B
EP-180-A
EP-180-8
EP-9-A
EP-9-8
EP-31-A
EP-31-B
EP-26-A
EP-26-8
EP-6-A
EP-6-B
EP-27-A
EP-27-8
EP-1-A
EP-1-B
EP-4-A
EP-4-8
EP-28-A
EP-28-8
EP-24-A

EP-24-B
EP-32-A
EP-32-B
EP-11-A
EP-11-B
EP-8-A
EP-8-8
EP-36-A

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1

1
1
1
1
1

434500
426188
426270
435584
435605
454053
453998
451826
451826
461484
461435
444784
444662
451484
451463
451984
452014
450684
450679
450158
450001
442308
442240
445384
445432
452684
452726
437509
437449
438284
438338
427480
427373
422217
422068
425884
426471
431484
431517

432284
432314
425062
424950
433478
433573
429484

UTMY

4398210 S
4396472 S
4396380 S
4388779 S
4388725 S
4379173 S
4379265 S
4410001 L
4410131 L
4390954 L
4390970 L
4470479 S
4470409 X
4460879 X
4460801 X
4448579 F
4448550 F
4448279 F
4448511 F
4474204 L
4478203 F
4465163 S
4464949 F
4470179 L
4470199 L
447.13879 L
4478919 L
4471239 S
4471169 S
4476679 S
4476732 S
4472833 L
4472806 L
4470980 S
4470689 S
4474379 S
4473939 L
4482579 S

4482788 S
4461379 L
4461296 S

SN3

SN2

PRIMOVE SN1
3

1

SN5

SN4

SN6

SN7

SN8

SN9

SN10

1

MEAN
3

1

1

1

2

1
8

1

1
1
1
1
1
2

3
7

1
0

1
0
1
1

3
5
1
2

4
1

1

2
1

1
4
1
1

3
8
1

2
2
4
3

1
~

'

1

2
1

1

1
1

1
1
2
1
2
2
4
1
1

1
4
0
1
1

2
2

1

4
1
4
1
1

1
1
2

1
1

1

2

1
1

1

2

1

2
3
1

1
2
1

1
3
1

.1

1
14

2

0

1
2

1
3

2
1
1

3
1

1
1
1

1

2

2
1

16
1
3

4464125 L
4464089 L
4451783 L
4451435 F
4452379 L
Page2of3

KREB'S N HARE DENSI
0.8 -0.31463
0.5 -0.48052
0.1
-1.0486
1 -0.23587
0.1
-1.0486
0.5 -0.48052
0.8 -0.31463
0.3 -0.66083
0.6 -0.41617
0.3 -0.66083
1 -0.23587
2.1 0.026007
1.5 -0.09275
1.6 -0.06998
1 -0.23587
0.1
-1.0486
0.4 -0.55929
0.2 -0.80394
0
0
0.4 -0.55929
0
0
0.1
-1.0486
0
0
0.9 -0.27306
1 -0.23587
0.3 -0.66083
0.1
-1.0486
0.4 -0.55929
0.1
-1.0486
0.3 -0.66083
0.4 -0.55929
0.1
-1.0486
-1.0486
0.1
0.2 -0.80394
0.1
-1.0486
1.2 -0.17152
2.4 0.073139
0.2 -0.80394
1.6 -0.06998
0.1
-1.0486
0
0
0.3 -0.66083
0
0
0
0
0
0
0
0

0.48458460£
0.33073167E
0.08941368E
0.58093962:
0.08941368E
0.33073167E
0.48458460£
0.218360121
0.3835557c
0.218360121
0.58093962:
1.0617134~
0.807690771
0.85118668:
0.58093962:
0.08941368E
0.275876311
0.15705761
(

0.275876311
(

0.08941368E
(

0.53326447t
0.58093962:
0.218360121
0.08941368E
0.275876311
0.08941368(
0.21836012',
0.275876311
0.08941368E
0. 08941368(
0.15705761
0.08941368(
0.67372666:
1.18342010·,
0.15705761
0.85118668(
0.08941368E
(

0.21836012'.
(
(

(

(

�KREBSPL LSBNUM UTMX
EP-36-8
EP-35-A
EP-35-B
SS-103-A
SS-103-B
SS-107-A
SS-107-B
SS-111-A
SS-111-B
S$115-A
SS-115-B
WA•TT•A
SS-37-A
SS-37-B
VA-11-A
VA-11-B
VA-12-A
VA-12-B
VA-153-A
VA-153-BVA-154-A
VA-154-B

1
1
1
1
1
1
1
1
1
1
1
1
1
1

1
1
1

1
1
1
1
1

429442
434484
434201
406384
408211
386984
387083
413184
413242
406384
406348
403884
401384
401418
366284
365940
387284
387580
373284
373100
367984
368100

UTMY

PRIMOVE SN1

4452678 L
4454279 L
4454346 L
4460379 S
4482059 S
4469379 S
4469472 S
4466179 L
4466143 L
4460379 L
4460391 L
4529079 F
4450579 S
4450424 S
4409979 A
4409800 S
4380379 S
4380600 S
~874 S
4399720 S
4399379 S
4398800 S

SN3

SN2

SN4

SN5

SNS

SN7

SNS

SN9

SN10

MEAN

1

1

3
2

1

1
1
1

1
1

t
1
1

2
2

1

1

2

1
2
1

1
1

1
2

3

5
1

4
2

2

1

1

1

1
3
3
2

KREB'SN HARE DENSll
0
0
0
0
0
0
0
0
0.1
-1.0486
0
0
0
0
0
0
0.1
-1.0486
0
0
0
0
0.3 -0.66083
0
0
0.3 -0.66083
0
0
1.1 -0.20223
0.7 -0.36176
0.2 -0.80394
1.6 -0.06998
0.9 -0.27306
0.6 -0.41617
0.3 -0.66083

(
(
(
(

0.08941368{
(
(
(

0.089413681
I
I

0.21836012
I

0.21836012
I

0.62772865
0.43474840:
0.1570576'
0.851186681
0.533264470.3835557;
0.21836012

\0

V,

Page 3 of 3

�I

KREBSPL LSBNUM UTMX

CG-12-A
CG-12-8
CG-78-A
CG-78-B
SS-21-A
SS-21-B
SS-24-A
SS-24-B
SS-29-A
SS-29-B
SS-31-A
SS-31-B
SS-33-A
SS-33-B
SS-37-A
SS-37-B
SS-91-A
SS-91-B
VA-41-A
VA-41-B
W-5-A
W-5-B
W-13-A
W-13-B
W-53-A
W-53-B
W-81-A
W-81-B
W-82-A
W-82-B
SS-35-A
SS-35-B
S$-65-A
SS-65-B
WA-45-A
WA-45-B
CR-73-A
CR-73-B
CR-46-A
CR-46-B
CR-49-A
CR-49-B

WA-85-A
WA-85-B

SS-66-A
SS-66-B

2
2
2
2
2
2
2
2
2
2
2
2

UTMY

4516720 F
4516636 L
4518850 F
4518851 F
4470720 A
4470747 A
4451320 L
4451400 L
4439720 L
4439703 L
4437620 L
4437718 L
4432620 L
4432676 L
4429320 L
4429389 L
4467220 A
4467128 A
442-0619 L
4425591 L
4533917 L
453.3875 w
4513120 F
451"3062 F
4509020 L
45013942 A
4514220 A
4514433 F
4514120 A
4513955 L
4430920 F
4430965 A
4475620 S
4475833 S
4521319 S
4521281 S
4530820 A

2
2
2

323599
323546
322068
322094
367299
367408
351299
351255
355299
355435
363099
363097
361899
361730
342699
342599
366082
365986
345207
345219
336521
336407
331599
331657
345899
345745
347099
347250
331599
331514
345099
345191
355899
355886
346477
346543
330499

2
2
2
2
2
2
2
2
2

330582 4530639 L
310699 4518920 S
310548 4518948 S
313599 4518520 S
313790 4518470 S
333799 4482873 A
333714 4492646 A
352650 4468880 A
352523 4468800 A

2

2
2
2
2
2
2
2
2
2
2
2
2
2
2
2

2
2
2

2
2
2

SN2

PRIMOVE SN1

SNS

SN3

SN9

AfpluY\,J,·-1. C.

SN10

MEAN

1

1
1

2

1

5
:.!

1

1
1
1
1
1

2

2
3

41
1

1
13

2

1

.. ,

2
1
1

4
1

6

3

2

2
9

1

3

1

2

4
2

1

9

1
11

2
2

9

2

2

1

1

1

9

2
1

1

2
2

4
2

Page 1 of 2

1
3

2
3

KREB'$ N HARE DENS~
0.1
0
0.2
0.1
0
0
1.7
0
0.4
0
0
0
0.1
0.1
0.5
0
0.9
2.7
0
0
5.4
2.2
0.1
1.1
0
0
1.3
1.4
0
0
0
0
0
0
0.4
0.1
0
0
0.1
0
0
0
0.5
1.2
0.2
0

-1.0486
0
-0.80394
-1.0486
0
0
-0.04858
0
-0.55929
0
0
0
-1.0486
-1.0486
-0.48052
0
-0.27306
0.114712
0
0
0.359367
0.042427
-1.0486
-0.20223
0
0
-0.14326
-0.11711
0
0
0
0
0
0
-0.55929
-1.0486
0
0
-1.0486
0
0
0
-0.48052
-0.17152
-0.80394
0

0.08941368€
C
0.15705769
0.08941368€
C
C
0.8941761 OE
C
0.275876311

C
C
C
0.08941368€
0.08941368€
o.33073167e
C
0.533264474
1.302302811
C
C
2.287532027
1.102623281
0.089413686
0.627728653
0
0
0.719011504
0. 76364 7967

C
C
C
C
C
C
0.275876311
0.08941368€
C
C
0.089413686
C
C
C
0.330731678
0.673726665
0.15705769
(\

�l

KREBSPLLSBNUM UTMX
SS-69-A
SS-69-B
WA•1·A
WA-1·8
WA-17-A
WA-17-B
CR-50-A
CR-50-8
CR-83-A
SS-25-A
SS-25-B
WA-61-A
WA-61-8
WA-86-A
WA-9-A
WA-9-B

2
2
2
2
2
2
2
2
2
2
2

2
2
2
2
2

355658
355565
334299
334285
361099
361201
303378
3Q3492
304699
359099
359206
353099
353099
345895
365099
365120

UTMY

PRIMOVESN1

4461691 S
4461595 S
4540420 S
4540385 L
4497920 F
4497971 F
4514532 S
4514404 S
4508720 A
4450020 L
4450122 L
4493520 S
4493520 S
4491620 A
4528020 L
4527890 L

SN3

SN2

SN4

SNS

SN6

SN7

SNS

SN9

SN10

MEAN

1

2
1

1

1

1
1

2

1
2
3

c.;.·..

1

KREB'$ N HARE DENSIT
0
0.1
0.2
0.3
0
0.1
0
0.1
0
0
0
0
0.2
0.1
0.3
0.3

0
-1.0486
-0.80394
-0.66083
0
-1.0486
0
-1.0486
0
0
0
0
-0.80394
-1.0486
-0.66083
-0.66083

0
0. 089413686
0.15705769
0.218360121
C
0.089413686
C

0.08941368€
C
C
C
C

0.1570576~
0.08941368E
0.218360121
0.218360121

l,O

Page 2 of 2

-..J

�•
KREBSPL LSBNUM UTMX
GS-9-A
GS-9-B
GS-13-A
GS-13-B
GS-57-A
GS-57-B
GS-60-A
GS-60-B
GS-61-A
GS-61-B
GS-65-A
GS-65-B
GS-67-A
GS-67-B
GS-93-A
GS-93-B
GS-98-A
GS-98-B
M-25-A
M-25-B
M-71-A
M-71-B
M-73-A
M-73-B
M-1-A
M-1-B
M-74-A
M-74-B
M-77-A
M-77-B
M-79-A
M-79-B
VA-19-A
VA-19-B
ME-29-A
ME-29-B
ME-33-A
ME-33-B
ME-85-A
ME-85-B
ME-26-A
ME-26-B
ME-81-A
ME-81-B
ME-21-A
ME-21-B

3
.3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3

323290
323297
276237
276431
274782
274773
296592
296642
297492
297601
290492
290300
276892
276966
311992
311826
290592
290500
321592
321584
298192
298256
287292
287246
308292
308099
313192
313305
324792
324962
323992
324030
329547
329434
319157
319160
290592
290682
313870
313932
314992
315015
313492
313407
314792
314733

UTMY

PRIMOVE SN1

4412469 F
4412272 F
4395669 0
4395598 0
4408689 S
4408444 S
4403498 S
4403428 S
4402598 S
4402735 S
4399198 S
4399250 S
4396587 A
4396513 0
440!i098 S
4405172 S
4397498 S
4397850 S
444-2998 S
444~917 S
445TT98 A
4457786 A
4455598 A
4455648 A
4448798 A
4448695 A
4454298 A
4454069 A
4452690 L
4452684 L
4450598 A
4450468 A
4416879 A
4416904 F
4435523 F
4435606 F
4432198 A
4432190 F
4440307 A
4440419 F
4441498 S
4441563 S
4448198 F
4448093 A
4446098 S
4446242 S

SN4

SN3

SN2

SN9

SN10

MEAN

Atf'a.~d tx D
1
1

4
4

2
5

3

1

1
8

1

3

1

3
L .. '

7

1

1
1

1

1
1

2

3
3
10

13
1

3
1

3

1

5
5
1

1
4

5

2

1

1
27

23

1
1

1
2

2

2
1

3
1

2
2

2
5
1

1
1
1

1
1
1
1

1

6

1
1

2

1
1
1
1

2
Page 1 of 2

IO

KREB'S N HARE DENSIT'I 00
0.1
-1.0486
0
0
0
0
0
0
0.2 -0.80394
0.5 -0.48052
0.6 -0.41617
0
0
0.9 -0.27306
1.3 -0.14326
0
0
0.4 -0.55929
0
0
0
0
0.9 -0.27306
0
0
0.1
-1.0486
0.5 -0.48052
0.3 -0.66083
1.3 -0.14326
1.3 -0.14326
0
0
0.7 -0.36176
0
0
0
0
0
0
0
0
0
0
4 0.253441
4 0.253441
0
0
0
0
0.6 -0.41617
0.4 -0.55929
0
0
0.1
-1.0486
0.1
-1.0486
0.1
-1.0486
0.5 -0.48052
1.6 -0.06998
0.3 -0.66083
0.2 -0.80394
0.3 -0.66083
0.1
-1.0486
0.1
-1.0486
0.3 -0.66083

0.08941368€
C
C
C

0.15705769
0.330731678
0.38355578
C
0. 5332644 74
0.719011504
C
0.275876311
C

C
0.533264474
C
0.08941368€
0.33073167t
0.218360121
0.719011504
0.719011504
C

0.434748402
C
C
C
C
C

1. 79242672:
1. 79242672:
C
C

0.3835557f
0.275876311
C

0.08941368€
0.08941368E
0.08941368E
0.33073167(
0.85118668:
0.218360121
0.15705761
0.218360121
0.08941368E
0.08941368€
0.218360121

�KREBSPLLSBNUM UTMX
GS-53-A
GS-53-B
GS-69-A
Gs-69-B
GS-17-A
GS-17-B
GS-41-A
GS-41-B
GS-42-A
GS-42-B
GS-43-A
GS-43-B
ME-45-A
ME-45-B
ME-46-A
ME-46-B
ME-89-A
ME-89-B
GS-49-A
ME-30-A
ME-30-B

3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3

315807
315741
303319
303421
283207
283246
319767
319706
320543
320495
3204n
320499
295792
295928
291692
291663
295600
295532
268390
325792
325748

UTMY

PRIMOVESN1

4412384 F
4412364 F
4391172 S
4391426 S
4400690 S
4400732 A
4422156 F
4422201 F
4421864 F
4421868 F
4421531 F
4421391 F
44;.:w98 S
4420845 S
4420398 S
4420254 S
44f6432 A
44~957 A
4415600 A
4433698 F
4433677 L

SN3

SN2

SN4

SNS

SN6

SN7

SNS

SN9

2

2

8

1
2

1

1
0

1

8

2
8

1

SN10

MEAN

1

3

7
5
3
3
1

10
14
4
3

0
1

2
1

3
3

7
1
3

2
5
1

3
3
4
4
1

1
1

3

1
1
5
3
5
2
8

3
6

2

1
4
1

1

-.

1
1
6

KREB'$ N HARE DENSl1"
1.6 -0.06998
0
0
-1.0486
0.1
0.3 -0.66083
0.3 -0.66083
0
0
3.5 0.20631
3.2 0.17468
1.6 -0.06998
3.3 0.185541
2.3 0.058117
2.1 0.026007
0
0
0
0
0
0
0
0
0
0
0
0
0.1
-1.0486
0.1
-1.0486
0.6 -0.41617

0.851186685
0
0.089413686
0.218360121
0.218360121
0
1.60808792
1.495133686
0.851186685
1.532996908
1.143186215
1.061713454
01
0
0
0
0
0
0.089413686
0.089413686
0.38355578

l,C)
l,C)

Page 2 of 2

�KREBSPL LSBNUM UTMX

UTMY

PRIMOVE SN1

PA-12-A
PA-12-B
GU-82-A
GU-82-B
GU-86-A
GU-86-B
SA-14-A
SA-14-8
SA-64-A
SA-64-B
CA-25-A
CA-25-B
CA-27-A
CA-27-B
CA-30-A
CA-30-B
CA-32-A
CA-32-B
CA-38-A
CA-38-B
CA-46-A
CA-46-B

4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4

308071 4273055 D
308068 • 4273008 D
372071 4301755 L
371956 4301612 L
370471 4289955 L
370421 4290005 L
370371 4230655 P
370487 4230576 P
374471 4235455 L
374271 4235529 L
291683 4359468 A
291929 435a523 A
292637 4358699 A
292438 4358853 A
260735 4356491 A
260659 4356410 A
282106 435;!554 0
282058 4352570 0
293676 4335150 A
293766 4335189 A
253361 4321074 A
253422 4320992 A

CA-119-A
CA-119-B
CA-132-A
CA-132-B
CA-141-A
CA-141-B
GU-61-A
GU-61-B
GU-80-A
GU-80-B
GU-82-A
GU-82-B
GU-86-A
GU-86-B
GU-89-A

4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4

283084 4357784 S
283109 4357727 S
307856 4337843 D
307950 4337810 D
313455 4326347 D
313440 4326279 D
412171 4308255 P
412146 4308040 P
398571 4312655 P
398581 4312777 P
372071 4301755 L
371956 4301612 L
370471 4289955 L
370421 4290005 L
394371 4280155 L
394552 4280140 L
372671 4274155 L
372600 4274150 L
364671 4269255 D
364685 4269700 D
292071 4292555 F
292034 4292573 F
290071 4291055 A
290001 4290862 A

GU-89-B

GU-91-A
GU-91-B
GU-92-A
GU-92-B
PA-19-A
PA-19-B
PA-56-A
PA-56-B

4

4

SN3

SN2

SN8

3

0
2
4
18
2

1
0

0
2

6
0
1
0
0

0

0

0

2

1

Apf

Q.M.

d

I.)(

0

SN10

MEAN
3

t
2
0
0

0

SN9

0

0

1
5
12
4
0
0
0
0

1
3

2
0

0
0

0
0

0

0

3
&lt;

•

1

6

1
1

1

2

5

1

3

1

1
6

1

2

1
2
3

3
1
6

7

2

2

1

1

1

3

4
18
2
1

6

1
2

1
2

1

1
2

1
2

2

4
1
5

1

3

12
4
33

1

2

1
1

Page 1 of 3

4

3
1
2

1
1

3
1

KREB'S N HARE DENSl°G:
,-.,
0.38355578
0.38355578
0.627728653
1.495133686
0.978772092
0.434 748402
0.15705769
0.275876311
0
0
0
0
0.218360121
0
0
0
0
0. 089413686
0
0
0
0
0.330731678
0.673726665
0.894176106
0.434748402
0
0.38355578
0.484584609
0.15705769
0.533264474
0.484584609
0.627728653
1.495133686
0.978772092
0.434748402
1. 792426725
0.218360121
C
C
C
C
0.38355578
0.15705769
C
0

0.6 -0.41617
0.6 -0.41617
1.1 -0.20223
3.2 0.17468
1.9 -0.00932
0.7 -0.36176
0.2 -0.80394
0.4 -0.55929
0
0
0
0
0
0
0
0
0.3 -0.66083
0
0
0
0
0
0
0
0
0.1
·1.0486
0
0
0
0
0
0
0
0
0.5 -0.48052
1.2 -0.17152
1.7 -0.04858
0.7 -0.36176
0
0
0.6 -0.41617
0.8 -0.31463
0.2 -0.80394
0.9 -0.27306
0.8 -0.31463
1.1 -0.20223
3.2 0.17468
1.9 -0.00932
0.7 -0.36176
4 0.253441
0.3 -0.66083
0
0
0
0
0
0
0
0
0.6 -0.41617
0.2 -0.80394
0
0
0
0

�I
KREBSPLLSBNUM UTMX
SA-65-A
SA-65-B
SA-69-A
SA-69-8
SA-67-A
SA-67-8
SA-100-A
SA-100-B
SA-102-A
SA-102-B
SA-104-A
SA-104-B
SA-107-A
SA-107-B

SA-108-A
SA-108-B
SA-109-A
SA-109-B
SA-110-A
SA-110-B
VA-1-A
VA-1-B
VA-2-A
VA-2-8
CA-33-A
CA-33-B
LE-3-A
LE-3-8
CA-133-A
CA-133-B
LE-24-A
LE-24-B
LE-116-A
LE-116-8

VA+A-2
VA-111-A
VA-113-A
CA-17-A-

CA-17-B
CA-123-A
CA-123-B
GU-52-A
GU-52-B
GIJ.157•A
GIJ.157•8
GIJ.15a.A

4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
·4
4
4
4
4
4
4

4
4

4
4
4
4
4

UTMY

PRIMOVE SN1

373071
373233
390271
390070
368013
367745
370371
370242
374271
374148
362171
362268
368771
368724
365571
365543
351871
351662
351530
351524
337267
337329
351577
351544
302269
302330
436930
436945
245402
245436
350683
350801
360122
360057
337271
356671
357371
296459

4235355 A
4235373 A
4230055 D
4229851 D
4231272 D
4231280 A
4246555 P
4246541 L
4245655 L
4245672 L
4241955 L
4241864 L
4236155 L
42~_6361 L
4234755 D
4234940 S
4231455 A
4231491 D
4229214 D
4229297 D
4380741 L
4380577 L
4374462 L
4374495 L
4351331
4351244 A
3397400 S
3397800 S
4335106 A
4335245 F
4370138 L
4369892 A
4371050 S
4370936 S
4380755 L
4379855 L
4378955 S
4373781 S

296390
315656
315720
327571
327548
348771
348674
365371

4373800 S
4351061 L
4350930 F
4296255 A
4296315 A
4303555 S
4303630 S
4309155 L

SN2

SN4

SN3

SN5

SN6

SN7

SN9

SN8

SN10

MEAN

1

1
2

1

0

7
2

4
1

2

1
1
1
1

1
2
4

1
C,

,

4
1
13
2

3
2
1

2

1

1
1

2
5

2
11
1

1

1

5

1

1
0

1

1

5
1

2

4

0

1

2

6

1

1

1

3
1

3

4
1
3

1
1

1

Page2of3

3

KREB'S N HARE DENSIT'°
0
0
0.2 -0.80394
1.6 -0.06998
0.3 -0.66083
0
0
0
0
0
0
0
0
0.1
-1.0486
0.1
-1.0486
0.1
-1.0486
0.2 -0.80394
0.3 -0.66083
0.4 -0.55929
0.4 -0.55929
0
0
0.3 -0.66083
0.6 -0.41617
2.4 0.073139
1.4 -0.11711
0.1
-1.0486
0.8 -0.31463
0
0
0.1
-1.0486
0
0
0
0
0
0
0
0
1.1 -0.20223
0
0
0
0
0
0
·O
0
0.5 -0.48052
1.6 -0.06998
0.1
-1.0486
0
0
0.4 -0.55929
0.1
-1.0486
0.7 -0.36176
0.2 -0.80394
0
0
0
0
0
0
0
0
0
0

(

0.1570576~
0.85118668~
0.218360121
(

(
(
(

0.08941368(
0.08941368(
0.08941368(
0.1570576~
0.21836012',
0.27587631,
0.27587631'
(

0.21836012'
0.38355571
1.18342010'
0.76364796;
0.08941368(
0.48458460(
(

0.08941368(
(
(

(
(

0.62772865
I
I
I
I

0.33073167:
0.85118668:
0.089413681
I

0.27587631
0.089413681
0.43474840:
0.1570576'
I
I

I
I

....

--

�-

I

KREBSPLLSBNUM UTMX

GU-153-8
LE-9-A
LE-9-8
LE-73-A
LE-73-B
LE•74•A
LE-74-B
LE-78-A
LE-78-B
LE-128-A
LE-128-B
LE-129-A
LE-129-B
LE-144-A
LE•144-B

PA-18-A
PA-18-B
PA•22·A
PA-22-B
PA-20-A
PA-20-B
PA-21·A
PA-21·8
PA-186-A
PA-186-B
PA·187•A
PA·187•B
SA-106-A
SA-106-B
LE-29-A
LE•29-B
LE-120-A
LE-120-B
C0-148-B
LE-5-A
LE-5-B
CR-83-8

4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4

365558
412871
412756
377871
377906
370877
370998
407171
407263
373571
373292
368871
369228
371171
371104
320871
320822
288076
288225
293771
293804
294371
294368
290271
290372
288471
288585
360209
360219
346471
346471
350771
350771
761178
380700
380520
304199

UTMY

SN2

PRIMOVESN1

4309087 L
4317355 P
4317207 P
4334155 L
4334211 L
4333181 S
4333200 S
4318255 S
4318427 S
4347255 F
4346979 F
434.7155 F
4347084 F
4324855 L
4324853 L
4304655 S
4304619 S
4266178 S
4266146 A
4275055 F
4275216 F
4270255 S
4270108 S
4271155 S
4271208 S
4270055 S
4270239 S
4237602 S
4237494 S
4357055 L
4357055 L
4354155 L
4354155 L
4148888 S
4361960 S
4362240 S
4509001 A

SN4

SN3

SNS

SN6

SN7

SNS

SN9

SN10

MEAN

1

1

1

1
1

2
1

1
1
3

2

1
1

L,,·•

1
1

1

1
6
1

1
2

2
2

1
1

1
1

1
1

1

1

1

3

2

1

1

2

4

1
1

1
1

1

2
1

1

1

1

8

5
1

1

Page 3 of 3

3
1
1

7

KREB'S N HARE DENSll:0
0.1
0
0
0.1
0.2
0.3
0.2
0.1
0.3
0.2
0
0
0.1
0.5
0.7
0.1
0
0.2
0.7
0.3
0.4
0.5
0.2
0.4
0.5
0.2
0.3
0.2
0
0
0
0
0
2.3
0.2
0.2
0

-1.0486
0
0
-1.0486
-0.80394
-0.66083
-0.80394
-1.0486
-0.66083
·0.80394
0
0
·1.0486
-0.48052
-0.36176
-1.0486
0
-0.80394
-0.36176
-0.66083
-0.55929
-0.48052
-0.80394
-0.55929
-0.48052
-0.80394
-0.66083
-0.80394
0
0
0
0
0
0.058117
-0.80394
-0.80394
0

N

0. 08941 368(
(
(

0.08941368(
0.1570576!
0.21836012~
0.1570576!
0.08941368(
0.21836012'
0.1570576!
(
(

0.08941368(
0.330731671
0.43474840;
0.08941368(
(

0.1570576!
0.43474840;
0.21836012"
0.27587631"
0.330731671
0.1570576!
0.27587631 •
0.330731671
0.1570576!
0.21836012"
0.1570576!
(
(
(

(
(

1.14318621 !
0.1570576!
0.1570576!
(

�UTMY

AN-152-A
AN-152-B
AN-156-A
AN-156-B
AN-157-A
AN-157-B
AN-158-A
AN-158-B
AN-160-A
AN-160-B
AN-168-B
AN-168-A
C0-14-A
C0-148
C0-187-A
C0-187-B
DE-8-A
DE-8-8
DE-13-A
DE-13-B
DE-49-A
DE-49-B
DE-54-A
DE-54-B
DE-89-B
DE-89-A
DE-146-A
DE-146-B
DU-30-A
DU-30-B
DU-192-A
DU-192-B
M0-3-A
M0-3-B
M0-28-A
M0-28-8
M0-29-A
M0-29-B
M0-64-A
M0-64-8
M0-66-A
M0-66-B
DU-186-A
DU-186-8
DU-190-A
DU-190-B

4145971 S
4143036 S
4142726 D
4142692 D
41'4'0671 S
4140586 S
4139791 S
4139726 S
4137071 S
4137124 S
4105024 S
4104968 S
4146928A
4146893 A
4145794 A
4145810 A
4189271 D
4189201 D
4151461 S
4151379 S
4205671 S
4205646 S
4158215 P
4158145 P
4203561 B
4203671 B
4152177 S
4152211 S
4135828 0
4135981 0
4134560 P
4134607 P.
4234397 A
4234334 A
4221691 0
4221649 0
4220445 A
4220443 A
4231212 D
4231125 D
4228274 S
4228172 S
4147354 0
4147273 P
4138467 D
4138570 D

5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5

370326
370357
367132
367087
369726
369772
366889
366884
371126
371201
375941
375935
747483
747553
748557
748500
364326
364304
370832
370796
378026
377952
368766
368729
364807
364826
335236
334987
319412
319396
251960
251911
277574
277510
249194
249047
258872
258968
277527
277463
277150
277120
254345
254522
265782
265683

'ffi

SN2

PRIMOVE SN1

KREBSPL LSBNUM UTMX

1

SN3

1
3

1
4
4
2
1
0
1
0
0
0
0
1
2

SNS

3
2
2

6

5

0
0

3
0
1
0

A,o p~d ,·x F

1
5
2

0

0
2
3

0

3
1
0
1
0

1
0

0
1
2

0

0
0
4
0

0

0
1

1
2

5
l

1
0

0
0
11
5

2

0

0

1
3
11

10
2
2
0
0
4

.

0
1

2
1
1
1
0
0

1

0

0
1
1

0

4
3

6
23

SN9

0
0
19
0
1
1
0
0
2
2
0
0

2
1

SN10

MEAN

4
7
5
2

7
5
14

2
12
0
0

1
1
1

2
13
7
0
0
0
0
3
0
6

1
0
0
0
2

0

1
0

Page 1 of 6

KREB'S N HARE DENSITt
0.1
-1.0486
0.1
-1.0486
2.5 0.087548
5.1 0.339192
1.5 -0.09275
0.7 -0.36176
3.5 0.20631
2.5 0.087548
0.4 -0.55929
0.7 -0.36176
2.5 0.087548
3
0.1519
0
0
0
0
0
0
0
0
3.5 0.20631
1.3 -0.14326
0.2 -0.80394
1.3 -0.14326
0.4 -0.55929
0.2 -0.80394
0.4 -0.55929
0.7 -0.36176
0.1
-1.0486
0.1
-1.0486
0.2 -0.80394
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.4 -0.55929
0.8 -0.31463
0
0
0
0
0
0
0
0

0.08941368(
0.08941368(
1.2233411 SL
2.18369704!
0.80769077'.
0.43474840:
1.6080879:
1.22334116'
0.27587631'
0.43474840:
1.22334116'
1.41873187&lt;
(
(

(
(

1.6080879:
0.71901150•
0.1570576!
0.71901150,
0.27587631
0.1570576!
0.27587631
0.43474840:
0.089413681
0.089413681
0.1570576'
I

'

0.27587631
0.48458460

0

�I

KREBSPLLSBNUM UTMX

DU-193-A
DU-193-B
M0--2-B

M0--2-A
M0--60-A
M()..60-B
M0--61-A
M0--61-B

M()..65-A
M0--65-B
M0--68--A
M0--68--B

M0--79-A
M0--79-B
M0--179-A
M0--179-B
DE-144-A
DE-144-B

AN-167-A
AN-167-B
DU-33-A
DU-33-B

M0--4-B
M0--4-A
M0--26-A

M0--26-B
M0--72-A
M0--72-B
M0--77-A

M0--77-B
M()..80-B
M0--80-A
SA-1-A
SA-1-B

SA-39-A
SA-39-B
SA-41-A
SA-41-B

5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5

SA-69-A
SA-69-B
SA-76-A
SA-76-B
SA-78--A
SA-78--B
S1-96-A

5

Sl-96-B

5

5
5
5
5
5

5

UTMY

SN2

PRIMOVESN1

SN4

SN3

SNS

SN6

SN7

SN8

SN9

SN10

MEAN

318011 4134176 P
318116 4134283 P
268285 42;¼~607 A
268326 4238671 A
284257 4241267 A

284212 4241345 A
280720
280683
286117
280095
281510
281561
242213

4234378 S
4234438 S
4229070 S

4229119 S
4225540 S
4225578 S
4211663 S

242282 4211746 S
241604
241618
373926
373904
379909
379825
268426
268396
271352
271426
265626
265631
276226
276156
271726
271755
251688
251626
'337326
337333
332426
332433
339126
339218

4222825 A
4222749 A
4152871 S
4152938 S
4105045 S
4105078 S
4136471 P
4136238 P
4232051 A
4232071 A
4235571 0
4235639 0
4222071 S
4222085 S
4215171 S
4215157 S
4211206 S
4211171 S
4244871 F
4244929 A
4230371 L
4230234 L
4235071 D
4234944 D

331926
332041
341126
341115
327073
327039
267926
267859

4224571 L
4224576 L
4217171 S
4217057 S
4213018 F
4213095 F
4196571 S
4196596 S

3
1
1

0

4
3

4
6

1
3

1
2

0
6

2
1
4

6
7

2
8
2

2

0
1

1
3
1
3
1
0
1

0
0
0
0

0
0
0
0

0
0
0
0

2

2
3
4
2
1
1
1

9

0

0
1

1

1

2
0
1

1
2

0
1
1
1

3
0

0

9
0
8

11

2
0

1

1

7
2

14
8

4
16
0
1
0
0
0
0

6
5
1
0
0
0
0
0
1

3
1

0

5

6
0

2
6

3
5

L

&gt;

4

7

1

13
23

12

1

3
2

6

2
4
2

8
0

5
1

7
0
3
1
1

0
0
0
2

0
0
0
0

2
0
3
7
7

0
5

9
0
0

1
1

2

0

2
3

0
0
0
0

0
0
0
0

0
0
0
0

3
2

1

2

1

1
1

2

3

3
13

1
10

Page 2 of6

7

2
2
2
6

1
1
1
5

5

2

2
1
2

3
2
2
3

4
6

1

KREB'S N HARE DENSIT'
0
0
0
0
0
0
0
0
0
0
0
0
1.2 -0.17152
2.1 0.026007
0.4 -0.55929
0.4 -0.55929
0.9 -0.27306
1.1 -0.20223
2.6 0.101391
2.2 0.042427
0
0
0
0
2.9 0.139934
5.3 0.35277
0.7 -0.36176
0.9 -0.27306
0
0
0
0
0
0
0
0
0
0
0
0
3.5 0.20631
2.2 0.042427
2 0.008786
3.2 0.17468
3.3 0.185541
0.9 -0.27306
1.2 -0.17152
0
0
0
0
0
0
0
0
0.3 -0.66083
0.2 -0.80394
1.8 -0.0284
1.1 -0.20223
1.4 -0.11711
1.4 -0.11711
1.9 -0.00932
1.9 -0.00932
3.1 0.163474

(
(

(

(
(
(

0.67372666'.
1.06171345L
0.275876311
0.275876311
0.53326447.:
o.62772865c
1.26296421;
1.10262328'
(
(

1.38017557(
2.25304338(
0.43474840:
0.53326447 1
(

(
(

(

(
(

1.6080879:
1.10262328 •
1.02043701 I
1.49513368{
1.53299690!
0.53326447&lt;
0.67372666!
(
(

(

I

0.21836012
0.1570576!
0.93669425(
0.62772865:
0. 76364 796'
0.76364796',
0.97877209:
0.97877209:
1.4570481 e·

�KREBSPLLSBNUM UTMX

SI-102-A
SI-102-B
SI-107-A
St-107-B
SI-120-A
S1-120-B
DE-111-A
DE-111-B
DE-112-A
DE-112-B
DE-138-A
DE-138-B
SI-50-A
S1-50-B
SI-86-A
SI-86-B
SI·110-A
S1·110-B
SI-113-A
SI-113-B
SI-122-A
Sl-122-B
SI-126-A
SI-126-B
DC-140-A
DC-140-B
DC-141-A
DC-141-B
SI·12-A
S1-12-B
SI-185-A
. SI-185-B
DU-147-A
DU-147-B
DU-145-A
DU-145-B
DU-151-A
DU-151-B
DU-154-A
DU-154-B
DU-189-A
DU-189-B
SI-123-A
SI-123-B
OE-132-A
DE-132-B

5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5

UTMY

260726 41aa211 o
260809 4193273 D
274226 4188771 S
274147 4188681 S
317826 4171771 S
317901 4171806 S
344226 4185671 A
344198 4185621 A
350326 4183271 S
350264 4183331 S
351826 4157371 S
351853 4157311 S
298726 4201771 S
298652 4201741 S
308226 4206871 S
308294 4206850 S
293526 4186371 A
293451 4186413 A
294626 4182671 S
294582 4182594 S
316126 4171271 S
316056 4171236 S
319126 4168071 S
319118 4168086 S
761926 4156371 F
761750 4156280 F
761426 4156271 F
761350 4156350 F
247730 4156170 A
247800 4156200 A
253126 4155871 P
253110 • 4155730 D
261419 4150956 F
261451 4150964 S
245026 4152171 D
244980 4152260 D
248713 4146127 D
248830 4146020 D
281790 4144654 A
281712 4144508 A
257530 4140571 D
257150 4140565 D
254400 4170897 A
254369 4170937 D
334612 4165099 S
334624 4165200 S

SN4

SN3

SN2

PRIMOVESN1

SN5

SNS

SN7

SNS

SN9

SN10

MEAN

4
2
7

7

4

3
1
2

2
1

1
2
2

1
8
7
1

8

4
5

5
10

1

3
6

4
6
3
5

1
8
5

16

4

6

18

1

1
2

2

3
3
5

1
3
2
14

3
3
9
5
2
8

1
4
5
7

2

5

1

8
1

6
3

1

2

5

4
8

5

,.

2
1
2
10

5

9
3

1
3

12
7

26
7
11

3

4
4
7
3
2

5

1

4
9
14
6
7
6
19
1

7

4

8
2
7

11
12
2

4

6

3

2
1

1
4

3

1
1

19
5
3

1
1

3
2

1
3

1

2
3
3

1

11
1

1
1

2

1

1

3

1

1
1

1

3
4

I

2

8

1

1
Page 3 of 6

2

KREB'S N HARE DENSIT'i
0.4 -0.55929
0.7 -0.36176
0.7 -0.36176
3.3 0.185541
0.9 -0.27306
1.6 -0.06998
1.4 -0.11711
2.1 0.026007
4.3 0.278968
3.2 0.17468
1.6 -0.06998
2.4 0.073139
3.6 0.216253
7.3 0.465777
2.8 0.127548
4.5 0.295014
0
0
0
0
1.4 -0.11711
2.4 0.073139
2 0.008786
3.8 0.235337
1.9 -0.00932
3.3 0.185541
0
0
0
0
0
0
0
0
3.8 0.235337
1.7 -0.04858
0.3 -0.66083
0.4 -0.55929
1.8 -0.0284
0.5 -0.48052
0
0
0
0
0
0
0
0
0.1
-1.0486
0.3 -0.66083
0.9 -0.27306
0.4 -0.55929
0
0
0.2 -0.80394
0.1
-1.0486
1.4 -0.11711

0.275876311
0.434748402
0.43474840,
1.53299690f
0.53326447t
0.85118668:
0.76364796i
1.06171345':
1.90093784i
1.49513368€
0.85118668:
1.183420101
1.645330m
2.92264992'
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1.97248834\
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0.76364796;
1.18342010'
1.02043701\
1.71924109:
0.97877209:
1.532996901
I
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0.894176101
0.21836012
0.27587631
0.93669425 1
0.33073167,

0.08941368
0.21836012
0.53326447
0.27587631
0.1570576
0.08941368
0.7636479fr-,

�KREBSPLLSBNUM UTMX
SI-121-A
SI-121-B
DC-136-A
DC-136-B
AN-163-A
AN-163-B
AN-198-A
AN-198-B
AN-199-A
AN-199-B
AN-200-A
AN-200-8

AN-208-A
AN-208-B

AN-210-A
AN-210-8
DU-149-A
DU-149-B

AN-18-A
AN-18-B
AN-21-A
AN-21-B

AN-23-A
AN-23-8
AN-20-A
AN-20-8

AN-31-A
AN-31-8

AN-37-A
AN-37-B

AN-38-A
AN-38-B
AN-56-A
AN-56-B
AN-153-A
AN-153-B
C0-15-A
C0-15-B

C0-148-A
DC-118-A
DC-118-B
DC-119-A
DC-119-B
DC-100-A
DC-100-8
OC-103-A

5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5

5
5
5
5
5
5
5

UTMY

SN2

PRIMOVESN1

302378
302370
763726
763840
339226
339400
329626
329550
331126
331200
331426
331550
339626
339610
336626
336381
315226
315200
374826
374869
379849
379852
363426
363412
348526
348459
346626
346544
389326
389319
358726
368634
372726
372684
337526
337416
755508
755418

4171441 S
4171435 S
4161571 S
4161650 S
4127771 0
4127800 F
4128671 P
4128600 P
4126371 P
4126400 P
4125971 P
4126000 P
4107771 0
4107779 0
4105271 P
4105136 P
4147571 0
4147900 0
4114271 A
4114352 A
4108329 A
4108424 A
4096771 A
4096848 A
4112171 A
4112107 A
4102771 0
4102762 0
4100371 P
4100270 P
4096271 S
4096289 S
4112271 0
4112332 0
4145471 F
4145472 F
4143632 A
4143617 A

761083
763232
763168
763333
763262
746543
746470
751667

4148897 S
4173781 S
417;~814 S
4171687 S
4171605 S
4192851 S

41si824 s

SN3

'.

SNS

SN4
2

1
2

SN6

SN?

,:•

1

3

1

2

2

1

1

3

5

6

3

7

11

3
5

1
2

MEAN

6

8

2

SN10
1

8

(.

8

SN9
4

1
3
2

2

SN8

3

5

6

3
2

4191077
S
..
Page 4 of 6

2
1
4

1
2

KREB'S N HARE DENSI

1 -0.23587
0.2 -0.80394
1.1 -0.20223
1 -0.23587
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.4 -0.55929
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1.1 -0.20223
0
0
0
0
0.6 -0.41617
2.1 0.026007
0
0
0
0
2.4 0.073139
0
0
0
0
0.5 -0.48052
0.6 -0.41617
1 -0.23587
1.6 -0.06998
0
0

0.580939625
0.15705769
0.627728653
0.580939625
0
0
0

0
0
0
0
0
0
0
0
0
0
0.275876311
0
0

0
0
0

0
0
0
0
0
0
0
0
0.627728653

0
0
0.38355578
1.061713454

0
0
1.183420101
0
0
0.330731678
0.38355578
0.580939625
0.85118668"

�KREBSPLLSBNUM UTMX
DC-103-B
OC-124-A
DC-124-B
DC-128-A
DC-128-8
DE-142-A
DE-142-8
DN-98-A
DN-98-B
DN-99-A
ON-99-8
DU-35-A
DU-35-B
DU-194-A
DU-194·8
DU-195-A
DU-195-B
DU-197-A
DU-197-8
DU-201-A
DU-201-B
DU-204-A
DU-204-B
OC-9-A
DC-9-B
DC-97-A
OC-97-B
DC-101-A
OC-101-B
DC-104-A
DC-104-B
DC·108-A
OC-108-B
Sl-51-A
S1-51-B
Sl-87-A
S1-87-B
S1·90-B
S1-90-A
S1-106-A

SI-106-B
SI-109-A
S1-109-B

SI·114-A
SI-114-B
SI-11-A

5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5

5
5
5
5
5
5

5
5
5

UTMY

SN2

PRIMOVESN1

751699
760062
760116
756231
756142
341726
341679
358626
358674
359126
359063
299926
299861
274126
274131
265726
265795
304326
304386
298826
298965
303126
303137
211626
211613
233026
232894
229826
229820
233926
233885
232026
232125
293005
293126
293826
293746
271226
271226

4191024 S
4169573 D
4169674 D
4166799 P
4166761 P
4154871 S
4154753 S
4195171 S
4195215 S
4194671 S
4194666 S
4130371 P
4130316 P
4132771 P
4132686 P
4132271 P
4132317 P
4130571 P
4130495 P
4124971 D
4125051 D
4119771 P
4119857 P
4181971 A
4181996 A
4196471 S
4196480 S
4193471 S
4193380 S
4190971 S
4190960 S
4188571 S
4188570 S
4199502 S
4199371 S
4206271 S
4206331 S
4203471 S
4203471 S

238966
238966
243126
243560
259926
260012
288426

4189716 S
4189971 S
4187271 S
4187052 S
4181871 S
4181977 S
4157071 A

9

1
5
1
6
1

1
3

'

SN4

SN3

5
4

SN5

3
1
7
9

SNS

2
5
5

SN?

1
3
8

SN8

SN9

4
8
1

8

SN10

MEAN

5
1
2
9

6
7
2

C

0

0

7

2
3

0

6
9

0

5
2

1

3

3

1

1
8

1
3

3

2
5
5
2

24
10
3
5
5
3
1

0

6
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0

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2
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3

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4
2

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5

1
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1
4
Page 5 of 6

2
4

3
6

4

7

1
2

KREB'S N HARE DENSIT'l
0
0
0
0
0
0
0
0
0
0
0
0
2.3 0.058117
1.9 -0.00932
2.8 0.127548
3.5 0.20631
2.8 0.127548
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2 0.008786
2.1 0.026007
3.4 0.196078
1.6 -0.06998
3.1 0.163474
4.7 0.310363
2.2 0.042427
1.7 -0.04858
2.2 0.042427
1.9 ·0.00932
2.4 0.073139
2.1 0.026007
2.2 0.042427
1.6 -0.06998
2.5 0.087548
3.3 0.185541
0
0
0
0
2.4 0.073139
1.8
-0.0284
0
0

0
0
0
0
0
0
1.143186215
0.978772092
1.341369433
1.60808792
1.341369433
0
0
C
C
C
C
C
C
C
C
C
C
C
C

1.0204370H
1.06171345L
1.57064583;
0.85118668'.
1.45704818\
2.04344557!
1.10262328 •
0.89417610{
1.10262328 •
0.97877209;
1.1834201 o·
1.06171345'
1. 10262328 •
0.85118668!
1.22334116,
1.53299690!
(

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1.1834201 o·
0.93669425{

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-.....i

�l

KREBSPLLSBNUM UTMX
Sl-11-B
Sl-125-A
Sl-125-B
Sl-129-A
St-129-B
Sl-133-A
Sl-133-B
Sl-134-A
Sl-134-B

5
5
5
5
5
5
5
5
5

288420
276100
276250
264326
264400
287326
287150
277726
277550

UTMY

PRIMOVESN1

4156972 A
4167900 A
4167850 A
4166571 D
4166500 D
4164071 S
4164100 S
4162971 D
4163000 D

SN2

SNS

SN4

SN3

SN6

SN7

SN8

2
7

SN9

SN10

MEAN

5
7
3

3
1

1

9
2

2
9

Page 6 of 6

1

3

KREB'S N HARE DENSITY~
0.2
1.2
0.7
0.6
1.1
0
0.5
0.2
1

-0.80394
-0.17152
-0.36176
-0.41617
-0.20223
0
-0.48052
-0.80394
-0.23587

0.15705769
0.673726665
0.434748402
0.38355578
0.627728653
0
0.330731678
0.15705769
0.580939625

�109

Appendix G

Genus-species
Abbr.

Name
Scientific

Common

AMAL

Amelanchier
alnifolia

Serviceberry

ARCO

Arnica cordifolia

Heart-leaved Arnica

ARUV

Arctostaphylos uvaursi

Kinnikinnik

CA spp

Carex spp

Sedge

JU spp

Juniperus spp

Juniper

Quercus gambelii

Gambel's Oak

QUGA

"

SHCA

Shepherdia
canadensis

Buffaloberry

SYAL

Symphoricarpos albus

Snowberry

SYOC

symphoricarpos
occidentalis

Snowberry

VA spp

Vaccinium spp

Blueberry

VASC

Vaccinium scoparium

Broom Huckleberry

�110

Appendix I!
SUMMARY
BY FOREST
----

r·

J_

-

-

___j_

J

---

---

j ---- ___

SAMPLE SIZE HARES PER HA

j

-------

- --

------

--

---

------

--------

-- - - - -

--

---

32
03142
ARAPAHO NF------- ------ -----0.5089
____1_l
BUFFALO PEAKS WILDERNESS
21
0.1046
GRAND MESA NF
--------------------~
63
0.3259
GUNNISON NF
--7
0.8712
LAGARITA WILDERNESS AREA
-------89
0.6679
RIOGRANDE NF
31
0.2744
ROCKY MOUNTAIN NATIONAL PARK
22
0.2158
ROOSEVELT NF
83
0.2114
ROUTT NF
16
0.2815
SAN !SABEL NF
92
0.3546
SANJUAN NF
45
0.7032
UNCOMPAHGRE NF
4
0.1352
WEST ELK WILDERNESS
94
0.2632
WHITE RIVER NF
I
SAMPLE SIZE HARES PER HA
95% Cl
SUMMARY BY AR~I
---

---------

---·

----

----

-

----

------

----

-------

-

- -

-

-- -

I

"

114
62
67
129
239

0.29
0.27
0.41
0.28
0.56

0.16
0.14
0.22
0.16
0.35

AREA 1
AREA2
AREA3
AREA4
AREAS
I
SUMMARY BY PRIMARY OVERSTORY

0.2200
0.1900
0.3000
0.2100
0.4400

SAMPLE SIZE HARES PER HA

I
I

105
2
48
64
108
16
41
220
1
3

ASPEN
BRISTLECONE PINE
DOUGLAS FIR
SUBALPINE FIR
LODGEPOLE PINE
GAMBLE'S OAK
PONDEROSA PINE
ENGLEMANN SPRUCE
WHITE PINE
UMBER PINE

0.1558
0.0894
0.3351
0.3301
0.2981
0.0056
0.0737
0.5163
1.1026
0.7466

I
SUMMARY BY COUNTY
-- ·1·

I
_ _ _ j _ __

-

ARCHULETA
------1
BOULDER
CHAFFEE
...
CLEAR CREEK
CONEJOS
DELTA
DOLORES
EAGLE
GARFIELD
GILPIN
GRAND
GUNNISON
HINSDALE
JACKSON
LA PLATA
LAKE
---

--

---

LARIMER
MESA
MINERAL
MOFFAT
MONTEZUMA
OURAY I
PARK
PITKIN
RIO GRANDE
RIO BLANCO
ROUTT
SAGUACHE

SANJUAN
SANMIGUEL

SARATOGA
SUMMIT

---------·-

----------

. -

-

----

---------- - - - - - - - - -

-

-- - - - - - - - --

-------·-

-- ----- - - ---- -------- -

SAMPLE SIZE HARES
PER HA
-

----- - - - - - -

- -

-

----- -

--------- - ~ - -

---

33

~ -

---

-----

- --------

----

-----

i---------

-I-------

- - -

6
-~

-------

17
2
18
35
36
2
31
59
18
8
28

-

8
36
8
18
6
14
16
8
16
14
21
52

45
24
2
2
14

-----

0.0438
0.1659
0.6117
0.3635
0.3642
0
0.6749
0.2941
0.3096
0.3010
0.1955
0.3163
0.9531
0.0769
0.3114

0.1931
0.2840
0.2152
0.7937
0.0874
0.0000
0.2864
0.4260
0.1393
0.9766
0.3316
0.1942
0.4143
0.5622
1.1828
0.1877
0.0888

�111

Review of the habitat assessment study of snowshoe hares by the Colorado
Division of Wildlife •
Shay Howlin
Lyman McDonald
West, Inc.
2003 Central Avenue
Cheyenne, Wyoming 8200 I
(307) 634-1756

February 14, 2000
In our examination of the issues surrounding the snowshoe hare pellet collection in 1998
we have identified 4 major concerns in the use of this data. Here we attempt to clarify
these concerns and offer our analysis of their severity as they relate to the use of the
pellet data as an index to sgowshoe hare abundance.

CONCERNS OF REVIEWERS
•

Failure to validate or accurately duplicate Krebs' protocol
This criticism is based on the premise that the division of wildlife (DOW)
snowshoe bare pellet study intended to use the linear models developed by Krebs et al.
(1996) to estimate snowshoe bare density based on the number of snowshoe hare pellets.
Krebs' model for estimating the density of bares was developed in Canada with different
snowshoe bare ecology and habitat. And the field protocol used by Krebs to develop the
density estimation formula specified the removal of pellets from plots at a set time period
before counting pellets. The DOW study protocol differed from Krebs' protocol in that
they did not clear the study plots of old pellets berore conducting pellet surveys.
The biologists conducting the surveys for the DOW were trained to age pellets
and could identify last year versus current year pellets. In our view, the use of current
year pellets can provide an index to abundance of snowshoe hares. The analysis of the
DOW data does not need to validate or use Krebs' formula if only an index to abundance
is attempted.
•

Failure to follow DOW survey protocol
The DOW generated a random sample of survey points in each of the five study
areas. The number of random points generated for the survey was roughly proportional
to the size of the area. Recognizing the logistical problems associated with visiting all
the random points, the DOW field crews reduced the number ofplots·to visit by selecting
every fourth point from the original random sample (call this subset the reduced sample).
DOW and BLM biologists surveyed additional points from the original random sample
when conveniem. The resuiting dataset contains points in the reduced sample visited by
the field crews, and points in the original sample visited by biologists opportunistically
on the way to other points or other work. Since the resulting sample contains a

�112

disproportionate number of points in block five, reviewers of the study have noted that
the blocks with higher sampling intensity could result in increased chances of finding
pockets of modest hare abundance.
The fact that neither every point in the original random sample nor every point in
the reduced sample was not surveyed resulted in a nonrandom sample of actual data.
Biases associated with the selection of the plots sampled (i.e. closest to roads), makes the
use of the data for an unbiased index to snowshoe hare abundance questionable. The
tables below show the percent of original plots and the percent of the subset of plots that
were surveyed in each block and were entered into the dataset called newform.xls
(obtained from G. Byrne on December 28, 1999).
Percentage of Krebs' plots sampled from original random sample.
Block
Number
l
2
3
4
5

Number of Original Percent of
plots
sample size original
visited
sample
55
200
27.5
32
100
32.0
34
100
34.0
64
200
32.0
121
200
60.5

Percentage of Krebs' plots sampled from the reduced sample(every fourth plot from the
ori inal sam le .
Block
Number

l
2
3
4

5

Number of Reduced Percent of
plots
sample size reduced
visited
le
18
so
36.0
20
25
80.0
22
25
88.0
20
50
40.0
31
so
62.0

•

Time frame of surveys
The DOW conducted the snowshoe hare pellet surveys throughout the summer of
1998. One reviewer of the study contends that plots that were sampled later in the season
had the potential to have more pellets, because there was more time for pellets to be
dropped onto the plots and there are more hares due to the addition of hares to the
population through parturition.
From Figure I, it appears that each block had an even distribution of plots visited
throughout the study period. If there was a time affect influencing the number of pellets
on a plot, it appears it would have approximately the same influence in every block. •

•

Definition of suitable habitat
The DOW protocol details the placement of the Krebs' plots once the randomly
selected point is located. Plots were moved from the starting point to the nearest suitable

�113

habitat (forest, willow, or mountain shrub habitat). A random number table was used to
locate directions and distances to move the point to suitable habitat. If the first randomly
selected direction or distance did not locate suitable habitat~ another direction and
distance was chosen.: '
This protocol effectively reduces the area surveyed during the study to the
"suitable habitat" in the study area. Field personnel made subjective determinations of
suitable versus nonsuitable habitat, because a rigorous definition of suitable habitat is not
easy to follow in the field. The actual size of the area that had a chance of being sampled
is unknown and difficult to define. The size of this area could potentially be determined
by the delineation of suitable habitat on the GIS vegetation coverage if definitions were
consistent throughout the study.

Figure I. Date of Division of Wildlife sampling of plots by block.

- .. ..,..._ -······"· ---··- - - - - - ... - -· ...
.. .. - ...... - - - - ..
- ... --

•

~

0
0

m

3

•

•

•

•

• ••

---

-

..

-

•

•

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Date
CONCLUSIONS
The failure of the DOW snowshoe hare study to validate or follow Krebs'
protocol for the estimation of snowshoe hare density prohibits the use of the data in
Krebs' estimation formulas. We do not feel this criticism discounts the use of the DOW
data for an index of snowshoe hare abundance in the study area.
The criticisms surrounding the time component of the study also do not seem to
pose a critical problem when producing estimates of hare abundance by block. And if an
estimate of suitable habitat can be made using the GIS coverage of the vegetation, the
index of abundance can incorporate the amount of area surveyed.

�114

Our review of the data revealed problems with the quality of the data. There were
twelve missing dates in the dataset, and two dates that were 9 and 49 years before the
bulk of the other observations. There were other simple errors in the plot identification
variable that indicates the dataset was not verified. We recommend the data be checked
for quality control-quality assurance before any analyses are conducted.
If a truly random sample of Krebs' plots could be identified, we would
recommend an analysis of the pellet data using only these plots. But neither all the points
in the entire original sample were visited, nor were all the plots identified in the DOW
biologists subset sample visited. We feel it is impossible to identify a sample of plots
that were selected and visited that do not contain biases associated with the time and
logistical constraints oflocating and sampling the pre-selected Krebs' plots. Therefore,
we do not think this data is capable of producing an index of snowshoe hare abundance
that is unbiased.
The fieldwork associated with the collection of this data has provided information
that can be used to design a study of snowshoe hare abundance that will be adequate to
produce estimates by block. The study provides an estimate of the plot to plot variance in
the number of pellets in the study area, as well as an idea of the number of randomly
placed Krebs' plots that C&amp;l1 be surveyed in a season.
LITERATURE CITED
Krebs, C.J., B.S. Gilbert, S. Boutin and R. Boonstra. 1987. Estimation of snowshoe hare
population density from turd transects. Canadian Journal of Zoology. 65: 565567.

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                  <text>113
Colorado Division of Wildlife
Wildlife Research Report
July 1998
JOB PROGRESS REPORT

Colorado

state of

cost center 3430

Project No. _,_,W~--1~5~3--~R~--l_l~-----

Mammals. Research

Work Package No. _ _~P~B~B~O,_______ :

Black-footed Ferret Recovery

Task No. __....;.._ _,,,_________

Monitoring and Managing Disease in

Black-footed Ferrets
Period Covered:
Author:

July 1, 1997 - June 30, 1998.

M.A. Wild and K. T. Castle

Personnel:

E. Wheeler.

ABSTRACT
We prepared a Program Narrative describing research to support black-footed
ferret (Mustela nigripes) recovery efforts in Colorado. The black-footed
ferret is a federally listed endangered species in the United States. Blackfooted ferrets have been extirpated from Colorado, but are scheduled to be
reintroduced to the wild at the Little Snake Management Area (LSMA) in Moffat
County, Colorado in 1999. Our research can be sub-divided into two broad
sections: disease monitoring and flea control as a tool to manage sylvatic
plague in prairie dogs and black-footed ferrets. Disease monitoring will be
performed using collection of carnivores (primarily coyotes) from the LSMA
twice per year. Carnivores will be examined post-mortem for signs of active
disease and serology will be performed to test for exposure to diseases
potentially threatening black-footed ferrets. Results of testing in FY97/98
show that toxoplasmosis and tularemia are present at LSMA, but potential
impact on black-footed ferrets is unknown. Two potentially devastating
diseases, canine distemper and plague, are also present at LSMA. Although
prevalence of titers to canine distemper virus (CDV) in coyotes appears low at
LSMA, an increasing trend.in prevalence is suggested .. Titers to plague
(Yersina pestis) were found in 65% and 48% of coyotes tested in the summer and
winter collections, respectively. Titers were present in both adult and
juvenile animals, suggesting ongoing plague activity in some areas. The
second section of our Program Narrative describes experiments with captive
white-tailed prairie dogs to evaluate insect growth regulators (IGRs) on
control of prairie dog fleas (genus Oropsylla). Preliminary work to establish
a captive colony of &gt;30 white-tailed prairie dogs and to develop techniques to
rear Oropsylla in an insectary have been initiated this fiscal year.

��115

MONITORING AND MANAGING DISEASE IN BLACK-FOOTED FERRETS
Margaret A. Wild and Kevin T. Castle

P. N. OBJECTIVES
1. Monitor enzootic disease activity threatening survival of black-footed
ferrets reintroduced into the LSMA.
2. Write a Final Program Narrative describing an experiment to develop and
evaluate management techniques to minimize disease-related mortality of
reintroduced black-footed ferrets.

SEGMENT OBJECTIVES
1. Determine the level of activity of canine distemper virus, Aleutian
disease, toxoplasmosis, tularemia, and leptospirosis in carnivores and
plague in prairie dogs (using coyotes as sentinels) in the LSMA by sampling
~20 coyotes in summer and winter.
2. Write a Final Program Narrative describing an experiment to develop and
evaluate management techniques to minimize disease-related mortality of
reintroduced black-footed ferrets.

METHODS AND MATERIALS
Carnivore Disease Survey
Infectious diseases can severely impact the success of black-footed ferret
(Mustela nigripes) reintroduction efforts. As part of the black-footed ferret
reintroduction protocol, we monitored disease activity in carnivores in the
Little Snake Management Area (LSMA), Colorado. Coyotes (Canis latrans) were
collected during a summer and winter sampling period. Post-mortem examination
and sample collection was performed as described in the Planning Program
Narrative (Wild 1997). In addition to serologic assay for plague (Yersina
pestis) using the passive hemagglutination inhibition test (PHA/PHI), sera
collected in the winter sampling were also tested using the plague ELISA test.
Proposed Research Experiments
We compiled data and performed literature searches and interviews to prepare a
Program Narrative. We initiated work on Phase I--Pilot Study as per the
Program Narrative and captured white-tailed prairie dogs using techniques
described in the attached protocol (Attachment 1).

Black-footed Ferret Reintroduction
We assisted in preparation of the Black-footed ferret allocation request
submitted to the US Fish and Wildlife Service by the Colorado-Utah blackfooted ferret recovery working team in 1997 and 1998.

�116

RESULTS AND DISCUSSION
Carnivore Disease Survey
With the assistance of USDA Wildlife Services and the Bureau of Land
Management (BLM) we collected 20 coyotes from the LSMA between 21-25 July 1997
and 21 coyotes between 10-11 February 1998. Coyotes were collected using a
combination of calling and aerial gunning. Death occurred rapidly and the
collection technique was adequate, but much less efficient in summer than when
used in the winter months. Coyotes were collected from various locations in
the &gt;4700 mi 2 management area; however, we focused on the Powderwash area and
near the site of the pre-conditioning pens. No lesions indicative of active
disease were noted on gross examination of carcasses. We found no serologic
evidence of exposure to leptospirosis (serovars canicola, grippe, hardjo,
ictero, and pomona). Coyotes were not tested for Aleutian Disease (a mustelid
disease). Serologic titers were positive to toxoplasmosis in two coyotes (one·
adult, one juvenile) collected in the winter sampling. Fifty percent of the
coyotes sampled during the summer had positive titers to tularemia, while &lt;5%
of those sampled in winter were positive. Positive titers could have been
associated with predation on rabbits, prairie dogs, or other rodents or
exposure to ectoparasites. Duration of titers to tularemia are likely of
short duration (&lt;6 mo). The impact of tularemia or toxoplasmosis on blackfooted ferrets is not currently known; however, ferrets and humans are
susceptible to these diseases. Although a relatively small proportion of
coyotes had positive titers (~1:16) to canine distemper virus (CDV), data
collected over the last 18 mo suggest a trend toward increasing prevalence of
CDV at the LSMA (Fig. 1). Because CDV is a serious disease threat to blackfooted ferrets, a priority in the coming year will be to monitor the trend of
CDV prevalence. Likewise, plague activity on the LSMA is of concern. In the
summer collection, both juvenile (7/13) and adult (5/7) animals showed
evidence of exposure to plague (titers &gt;1:8; Fig. 2). Seropositive juveniles
indicates that some active plague is continuing in the area. Samples
collected in the winter were tested using the standard PHA/PHI test and also
an ELISA test. The ELISA test may be more specific than the PHA/PHI test;
however, it has not been fully validated and accepted (H. Edwards, pers.
commun.). Results of the standard PHA/PHI test indicate about half (10/21) of
the animals samples had positive plague titers (Fig. 2). Alternatively,
results of the ELISA test suggest that 81% (17/21) of animals samples were
positive. Anecdotal evidence suggests that localized outbreaks of plague may
be occurring in some areas of the LSMA, while plague activity may be lesser in
the other areas (M. Albee, pers. commun.). This localization of plague
activity is not uncommon.
Proposed Research Experiments
Given the results of these initial surveys, plague appears to be the most
significant disease threat currently to black-footed ferrets reintroduced into
the LSMA. Further, it is now more apparent that research emphasis needs to be
placed on management and control of plague in prairie dogs and black-footed
ferrets.
The Program Narrative describing this research is attached
(Attachment 2).
To support this research, we captured 34 white-tailed prairie dogs from the
Arapaho National Wildlife Refuge (ANWR), Colorado. Initially, four adult
males were captured in April to evaluate methodology. Thiry juveniles were
then captured in June. Spring/summer capture is required because white-tailed
prairie dogs hibernate. Further, juveniles can be easily differentiated from

�117

adults in early summer (June). One prairie dog died from trauma at FWRF, but
all prairie dogs remained healthy during the quarantine period. The housing
and care protocol (see Program Narrative) appears sufficient for maintaining
prairie dogs. The white-tailed prairie dogs are more fractious than
anticipated; however, training continues in an attempt to habituate the
animals to handling.
We also initiated investigation of maintaining prairie dog fleas (.Oropsylla
spp.) in artificial insectaries. Flea mortality has been high immediately
after capture from ANWR and transport to Fort Collins. We will continue to
modify our protocols to increase survival. Fleas that survive transport have
been successfully maintained in the rearing medium. Pinky (neonatal) mice are
provided to the fleas for a 24-hr period every 2-3 days as a blood source.
Fleas have been observed to lay eggs, but the numbers (a few/day) are, as
expected, low.
Black-footed Ferret Reintroduction
The U.S. Fish and Wildlife Service approved an allocation of black-footed
ferrets for reintroduction into the LSMA in fall 1997; however, due to delay
in publishing the final rule on experimental designation of the joint
Colorado-Utah reintroduction sites, black-footed ferrets were not received
this year. The Colorado-Utah site has received conditional approval for
allocation of 20 black-footed ferrets later in 1998.

LITERATURE CITED
Wild, M.A. 1997. Monitoring and managing disease in black-footed ferrets.
Colorado Div. Wildl. Res. Rep., 0880-1, Jul 1996 - Jun 1997, Fort Collins.

Prepared by

M~tJLJ
Magaret A. Wild
Wildlife Researcher

��119
ATTACHMENT 1
PROTOCOL FOR LIVE-TRAPPING PRAIRIE DOGS
Prepared by: Kevin T. Castle, M.S.
17 March 1998
The following procedures are based on my personal experience with trapping a
variety of mammals, and on the prairie dog trapping experiences of Hoogland
(1995) and A. Schwartz (pers. commun.). Hoogland reported only 12 trap-related
deaths in over 10,000 captures, and Schwartz observed only 5 deaths in
approximately 1,700 captures; the average mortality rate is approximately 0.1%,
so trapping mortality is unlikely if these procedures are followed.
If an
animal is severely injured (fracture, severe laceration), such that its ability
to survive is markedly impaired, or it would suffer undue misery and stress, it
will be euthanized. Euthanasia will be performed using an overdose of inhalant
anesthetic, by placing the prairie dog in an induction chamber with a
halothane-soaked gauze.
If two trapping-related deaths occur, trapping will
cease and the protocol will be reviewed and modified. Minor injuries or
metabolic imbalances will be treated by, or under the supervision of, a
veterinarian.
One or two single or double-door Tomahawk traps (6" x 6" x 24") are placed near
active burrows; single door traps seem to selectively capture juvenile prairie
dogs, whereas double-door traps will capture both juveniles and adults. Traps
are baited with rolled oats and/or "horse sweet mixture"; horse sweet mixture is
sticky, and therefore tends to stay in place, rather than roll or blow away.
During a 1-2 week "prebaiting" session, the traps are wired closed (to prevent
unwanted, accidental entry), and bait is spread around the traps and burrows.
Prebaiting allows the prairie dogs to become accustomed to having strange
objects in their environment, and lets them associate the traps with the
presence of food.
In addition, the traps "weather" and take on a more natural
scent; this is especially important for new, unused traps that may smell of
oils used in the manufacturing process.
After the prebaiting session, traps are set (opened and baited) just prior to
sunset, and checked (minimally) at noon and at dusk the following day.
It is
better to set the traps at night rather than in the morning, to avoid
disturbing any animals that become active early. Once disturbed, it may take
from 15 minutes to several hours for an animal to re-emerge from its burrow,
and any other animals may become more wary. Prairie dogs are diurnal, and are
typically not seen above ground in inclement weather, so it is unlikely that
any will be captured at night or when temperatures are very cold or very hot.
Nonetheless, traps are not set during rain or snow, or when daytime ambient
temperature is expected be below 20°F or above 90°F.
Prairie dogs should be handled by experienced mammal trappers, wearing heavy
leather or welder's gloves. Upon capture, each animal is placed into a coneshaped nylon or canvas bag for non-chemical immobilization. They are sexed and
weighed, and age is determined (Hoogland 1995; cox and Franklin 1990). A
numbered monel ear tag is attached to each animal. Released animals should be
tagged also, to minimize the handling of animals recaptured at a later date.
Animals are then transferred to individual mesh-bottom holding cages (minimum
size= 18" x 18" x 18"), and the cages are covered for transport. At least
part of the holding cage should remain covered at all times, to provide a
hiding place for the animal; if possible, a nest box containing bedding
material (e.g. "Bed-o'-cobs", care Fresh, hay) should be provided. Rodent chow,

�120
alfalfa cubes, and water are provided ad lib. if transport/holding time will
exceed 2 h. Animals held in the field should be kept indoors if possible, but
minimally need to be protected from the elements and from potential predators.
They should be checked every 3-4 h the first 1-2 days after capture, to assess
health and acclimation to captivity, and at least once per day thereafter.
Literature Cited:
Hoogland, J. L. 1995. The black-tailed prairie dog: social life of a burrowing
animal. University of Chicago Press, Chicago, 557 pp.

�121
ATTACHMENT 2
PROGRAM NARRATIVE

State of

Colorado

cost center 3430

Project No.

W-153-R

Mammals Program
Black-footed Ferret conservation

Work Package No._-P-8~8~0,..__ _ _ __

Task No. ______________

:

Monitoring and Managing Disease

in Black-footed Ferrets
A.

NEED

The mission of the Colorado Division of Wildlife (CDOW) is to "perpetuate the
wildlife resources of the state and provide people the .opportunity to enjoy
them" (State of Colorado, 1994). Further, the CDOW Long Range Plan established
a goal directing the Division to "cooperate with federal, state, county and
local government agencies, private landowners and other organizations in
evaluating the potential for restoration of extirpated species" (State of
Colorado, 1994; Goal 8).
The black-footed ferret (Hustela nigripes) is a federally listed endangered
species in the United States. Black-footed ferrets have been extirpated from
Colorado, but are scheduled to be reintroduced to the wild at the Little Snake
Management Area (LSMA) in Moffat County, Colorado in 1999. Coyote Basin, Utah
and White River Resource Area, Colorado are also under consideration for blackfooted ferret reintroduction efforts in the near future. The overall goal of
ferret reintroduction is to contribute to the national black-footed ferret
recovery plan objectives (U. s. Fish and Wildlife Service, 1988). The specific
reintroduction objective for LSMA is to sustain a natural breeding population
of 30 adult black-footed ferrets.
success of ferret reintroduction programs in Wyoming, south Dakota, and Arizona
have been hampered by multiple factors. Mortality rates, primarily from
predation and disease, have been high (D. Biggins, pers. commun.; P. Marinari,
pers. commun.). It has become apparent that improved methods for
preconditioning ferrets prior to release, predator management, and disease
management are prerequisite to success of future reintroduction efforts.
Here, we will begin investigating the potential for impact of diseases on
black-footed ferrets in the LSMA reintroduction site. Disease, primarily
canine distemper and sylvatic plague, has been a significant factor limiting
captive as well as free-ranging black-footed ferret populations. Mortality of
black-footed ferrets from infection with canine distemper or sylvatic plague is
extremely high (Williams et al., 1988; Williams et al., 1994). Further,
mortality from sylvatic plague in prairie dogs can markedly impact prey base
for black-footed ferrets.
Before black-footed ferrets are reintroduced to the
site, data on these potentially devastating diseases must be collected and
unique plans for their management devised.
B.

OBJECTIVES
1.

Monitor enzootic disease activity threatening survival of black-footed
ferrets reintroduced into the LSMA.

�122

2.
C.

Develop techniques to manage plague in the LSMA using insect growth
regulators applied orally to prairie dogs.

EXPECTED RESULTS AND BENEFITS

Disease Monitoring
Improved techniques for disease management will likely be required for the
successful reintroduction of the extirpated black-footed ferret to Colorado.
We must monitor enzootic disease activity to determine immediate risks to
black-footed ferrets. Monitoring will also provide information on the
epizootiology of diseases that will assist in formulating management plans for
black-footed ferrets and may also aid in understanding population dynamics of
other inhabitants. of the short grass prairie.
Performance Indicator: Monitor disease status of ~40 carnivores in the LSMA
annually and based on these findings make disease management recommendations to
the Colorado-Utah black-footed ferret recovery working team.
Flea control
We believe that the proposed research will provide a novel and effective means
of controlling plague in prairie dogs and black-footed ferrets. Sylvatic
plague is transmitted primarily via the bite of infected fleas. Control of
flea populations can be used to break the cycle and reduce the occurrence of
disease. Products, such as lufenuron and pyriproxyfen, administered orally to
pet animals have effectively controlled fleas (Blagburn et al, 1994; Hink et
al., 1994; Palma et al., 1993). If these products are efficacious and safe in
prairie dogs, and to black-footed ferrets which consume treated prairie dogs,
then they could be used to control fleas, and plague, at reintroduction sites.
Further, these products could be used as an alternative method of wildlife
management in areas where sylvatic plague is a threat to public health.
Performance Indicator: Provide a novel technique for the management of plague
in the LSMA to protect the endangered black-footed ferret.

D.

APPROACH

Disease Monitoring

Rationale:

Infectious diseases can severely impact the success of black-footed
ferret reintroduction efforts. Canine distemper and sylvatic plague pose the
greatest threats to black-footed ferret survival (Williams et al, 1988;
Williams et al, 1994). Wild canids and mustelids, as well as domestic dogs,
are susceptible to canine distemper and can serve as reservoirs for infection
(Williams, 1982). Plague is maintained primarily in rodent populations, such
as prairie dogs (Quan, 1982). Therefore, prior to reintroduction, status of
diseases such as canine distemper and plague in sympatric wildlife populations
must be determined to assess the risk to black-footed ferrets. We will monitor
activity of canine distemper in carnivores, primarily coyotes (Canis latrans),
by determining serologic titers and performing postmortem examination. Titers
are useful in ascertaining if carnivores have recently been exposed to the
virus. Postmortem examination is required to determine if carnivores have
active infection with canine distemper. We will monitor plague activity in
prairie dogs using coyotes as sentinels. Although coyotes are rarely involved
in plague transmission, serologic testing of coyotes for titers to plague can

�123
help define the extent of plague activity in rodent prey populations (Thomas
and Hughes, 1992). Moreover, by sampling juvenile animals in the summer,
recent plague activity can be identified. This survey of carnivores, combined
with collaborative work by the Bureau of Land Management investigating changes
in prairie dog numbers, will provide important information on activity of
diseases that are potentially devastating to black-footed ferrets. Disease
management activities will be driven by these findings.

Methods:

We will use survey of carnivores as a tool to determine status of
canine distemper and sylvatic plague in LSMA. Surveys will be performed
annually in January-March and July-September. Each survey will consist of a
minimum sample of 20 coyotes. Aerial gunning will be used as the primary means
of sample collection. Summer collections will focus on juvenile animals.
Animals will be located by personnel in a fixed wing aircraft. Personnel from
USDA Wildlife Services skilled in coyote control will fly over and shoot
animals at close range (about 10-45 m) using a 12 g shotgun loaded with copper
coated BB's or #4 buck shot. Multiple shots will be fired at the head of the
animal. Ground crews will locate and recover the animal carcass. If the
animal was not fatally wounded, ground crews will euthanatize animals with a
shot to the neck or chest. Location of carcass collection will be recorded
within 1/4 section. Surveys will be supplemented with additional samples
collected opportunistically from carcasses of coyotes and other carnivores,
including badger (Taxidea taxus), red fox (Vulpes vulpes), and striped skunk
(Mephitis mephitis), killed as a result of hunting or by unintentional
vehicular collision.
Diagnostic techniques will include collection of blood samples for serology,
collection of lower jaw for age determination, and postmortem examination to
detect evidence of active disease. Serum will be harvested from blood samples,
frozen, and submitted to Wyoming state Diagnostic Laboratory (WSVL, Laramie)
for determination of titers to canine distemper using the serum neutralization
test and to plague (Yersinia pestis) using the passive hemagglutination
inhibition test. Titers to toxoplasmosis, tularemia, Aleutian disease
(mustelids only), and leptospirosis will also be determined using samples
collected during the initial carnivore survey. Gross necropsy will be
performed by or under the direct supervision of a veterinarian. Routine tissue
collection will include: samples of gross lesions, kidney, urinary bladder,
lung, and brain placed in 10% buffered formalin; samples of lung, small
intestine, and brain frozen; and samples of lesions stored fresh for immediate
analysis. Samples of parasites will also be collected opportunistically;
however, all badgers with dermatitis will be sampled for Filaria taxideae.
Fixed tissues will be submitted to Dr. E. s. Williams, WSVL for histologic
examination. Frozen samples will be stored by Colorado Division of Wildlife
for analysis as needed (i.e., as indicated by histologic·or serologic
findings). Fresh samples will be submitted to WSVL or Colorado State
Veterinary Diagnostic Laboratory (CSVDL, Fort Collins). Parasites will be
stored and submitted to WSVL or CSVDL as needed. Additional blood samples will
be collected for serology as available from carcasses harvested by local
hunters and from unintentional vehicular collision. Serum samples will be
handled as previously described.

Analysis: A titer of ~1:16 will be considered positive for antibodies against
canine distemper virus or for antibodies against Yersinia pestis. We will use
Fisher's exact test (or extensions) to statistically analyze the prevalence of
antibodies among age classes and over time.

�124

Flea Control

Rationale:

Mortality of black-footed ferrets from infection with sylvatic
plague is extremely high (Williams et al., 1994). Further, mortality from
sylvatic plague in prairie dogs can markedly impact prey base for black-footed
ferrets.
Plague has severely hampered reintroduction efforts in other states
(P. Marinari, pers. commun.) and preliminary data suggest that plague activity
is present in some areas of the LSMA (M. Albee, unpub. data). Successful
reintroduction will likely require management techniques to control plague.
Plague i~ maintained primarily in rodent populations, such as prairie dogs,
where it is transmitted via the bite of an infected flea.
Fleas of the genera
Opisocroscis and Oropsylla have been associated with plague transmission in
prairie dogs (Ubico et al., 1988). Insecticide dusts have been applied to
prairie dogs burrows in an attempt to kill fleas and thus control plague.
Carbary! has been the most commonly used insecticide; however, application is
labor intensive and activity is short-lived (Barnes, 1993). Permethrin has
been shown effective up to 84 days after application, but the authors warn that
application at the recommended dosage rate would be highly laborious (Beard et
al., 1992). Recently developed compounds used to control fleas in pet animals
offer a promising alternative to insecticide dusts. Although topically applied
flea adulticides, such as imidacloprid, are not feasible for use in wildlife,
insect growth regulators (IGRs) with ovicidal and/or larvicidal activity could
be delivered orally to free-ranging animals via bait. The IGR lufenuron is a
benzoylphenylurea derivative which inhibits formation of chitin in the
exoskeleton of insects (Cohen, 1987). A single oral dose of lufenuron has been
shown effective in controlling the cat flea (Ccenocephalides felis felis) for
at least 30 days in treated dogs (Hink et al., 1994) and cats (Blagburn et al.,
1994). Davis (1997) reported a significant reduction in fleas on ground
squirrels (Spermophilus beecheyi) that had been treated with lufenuron.
Another IGR, pyriproxifen, exerts activity by mimicking natural insect juvenile
hormones. Pyriproxifen has been shown effective in vitro in inhibiting normal
egg production for 80 hr post-treatment (Palma et al., 1993) and may have other
longer lasting means of control as well (T. Miller, pers. commun.). If these
compounds proved efficacious over a period of time(~ 1 mo) when administered
orally to prairie dogs, they could be applied over large areas of prairie dog
habitat via a treated bait. However, prior to management application, the
products should be evaluated in a controlled laboratory setting to determine an
effective dose, duration of efficacy, product safety, and to formulate an
acceptable bait carrier. If results of laboratory tests are positive, the
products should be tested in a controlled field study to determine efficacy
under natural conditions. Without this evaluation, the management potential of
IGRs for controlling plague and protecting the health of the endangered blackfooted ferret, as well as human health, will be difficult to discern.
Our work will be divided into three phases. Phase I will be pilot work to
establish a colony of captive prairie dogs and to develop an environment
suitable for flea survival and reproduction both on the prairie dogs (and in
their bedding) and in an artificial medium. Before we can evaluate the
efficacy of IGRs, we must be sure that fleas will survive and reproduce on our
captive prairie dogs. Further, we will need to artificially rear prairie dog
fleas for infestation of prairie dogs and assessment of egg viability. These
techniques are not currently available (Barnes, 1993). Phase II will evaluate
efficacy and safety of lufenuron and pyriproxifen fed to captive prairie dogs.
Finally, in Phase III we will evaluate potentially efficacious IGRs (from phase
II) in a limited field application. White-tailed prairie dogs (Cynomys
leucurus) will be used as the study animal because this is the species of
prairie dog present at the LSMA black-footed ferret reintroduction site.

�125
Phase !--Pilot Study

Methods:
Capture of prairie dogs. White-tailed prairie dogs will be captured at the
Arapaho National Wildlife Refuge, Colorado. One or two single or double-door
Tomahawk traps (15 cm x 15 cm x 60 cm) will be placed near active burrows.
Traps will be baited with horse sweet mixture (sweetened grain mixture).
During a 1-2 week prebaiting session, the traps will be wired closed (to
prevent unwanted, accidental entry), and bait will be spread around the traps
and burrows. After the prebaiting session, traps will be set (opened and
baited) just prior to sunset, and checked (minimally) at noon and at dusk the
following day. Prairie dogs are diurnal, and are typically not seen above
ground in inclement weather, so it is unlikely that any will be captured at
night or when temperatures are very cold or very hot. Nonetheless, traps will
not be set during rain or snow, or when daytime ambient temperature is expected
be below -6 C or above 32 c. Prairie dogs will be handled by experienced
mammal trappers, wearing heavy leather or welder's gloves. Upon capture, each
animal will be physically restrained in a cone-shaped nylon or canvas bag.
They will be sexed and weighed, and age determined (Hoogland, 1995; Cox and
Franklin, 1990). A numbered monel ear tag will be attached to each animal.
The animals will then be transferred to an individual mesh-bottom holding cage
(minimum size= 45 cm x 45 cm x 45 cm) with nest box and covered for transport.
Feed (e.g., rodent chow, alfalfa cubes) and water will be provided ad lib if
transport/holding time will exceed 2 hr.
care and housing of prairie dogs. Prairie dogs will be maintained indoors in
individual cages (45 cm x 90 cm x 45 cm) with nest boxes at the Foothills
Wildlife Research Facility (FWRF). Animals will be quarantined for 14 days
upon return to FWRF to assess disease (plague) status. Due to our study needs,
prairie dogs will not be treated to control external parasites. During the
quarantine period, all personnel will be required to wear room-specific gloves
and coveralls when in the room, whether observing animals or cleaning cages.
Personnel will be informed of the clinical signs of plague in prairie dogs and
humans and instructed to monitor themselves and their clothing for fleas.
If
plague is diagnosed in a prairie dog, all animals in the building will be
euthanized with an overdose of halothane inhalant anesthetic.
Our custom cage design is based on specific study needs (providing the prairie
dogs with sufficient living space, while allowing us to rear and collect
fleas), discussions with M. Metzger, and the published work of Hilton (1971).
Individual prairie dog cages will be constructed of wood and wire fencing, with
"no-see-um" netting over the top and covering potential flea escape routes.
Half of the cage serves as a nest box, and the other half serves as a feeding
area. Two hinged doors allow access to each half of the cage for cleaning or
animal handling. The nest box is a 40 x 28 x 23 cm plastic container fitted
with a wooden lid. The nest box has a 10 cm diameter hole in one wall to
provide access to the feeding area; a 10 cm diameter piece of PVC tubing joins
the nest box to the feeding area. The access hole can be covered to confine
the animal to either side of the cage as necessary. Previous work on ground
squirrels (Hilton, 1971) suggests that the animals are unlikely to
defecate/urinate in the nest box, and Hoogland (1995) noted that there was
little fecal matter in the burrows and nests of black-tailed prairie dogs he
studied. Our preliminary work shows that defecation in the nest box is
minimal, and that urination is very rare; we therefore do not expect the nest
boxes to become soiled during experiments.

�126

The floor of the feeding area consists of 1 cm mesh wire fencing, to allow
feces, urine, and spilled food to fall through to a pan below. This mesh size
prevents the animal's feet from becoming wedged in the floor, but may encourage
the animal to spend most of its time in the nest box when not feeding.
It is
important for us to keep the animal in the nest box as much as possible, in
order to enhance flea reproduction; many fleas of the genus Oropsylla are "nest
fleas" and are associated with the host's body only when feeding (Hilton, 1971;
M. Metzger, pers. comm.). Confining the prairie dogs and fleas to the nest box
will also facilitate collection of fleas and.their eggs. A food dish and water
bottle will be wired to the side of the feeding area.
A 2.5 cm deep, removable, galvanized sheet metal pan will be placed under the
entire cage to catch food, feces, urine, and any fleas that escape the nest
box.
All prairie dogs will be checked at least once per day. Fresh feed (rodent
chow, alfalfa cubes) and water will be provided daily, and cage bottoms will be
cleaned of feces each day. Pans will be cleaned and bedding will be replaced
as needed, but a minimum of 2 times per week. Rooms (or nest boxes) will be
maintained at approximately 24 C and 75% relative humidity to ensure flea
survival and reproduction (M. Metzger, pers. commun.; Metzger and Rust, 1997).
Two south-facing windows in the animal room should provide sufficient light for
these fossorial animals, and will allow us to maintain the animals on a natural
photoperiod.
We do not anticipate any prairie dog mortality due to capture or experimental
procedures.
If an animal becomes sick or injured, and recovery is not likely,
it will be euthanized with an overdose of halothane inhalant anesthetic.

Pilot study. We will capture and house 3-5 prairie dogs for initial evaluation
of our methods. Prairie dogs will be observed daily and weighed at least once
per week, to help assess health and acclimation to captivity.
If two or more
animals do not adjust to our captive conditions (they refuse food and/or water
or appear sick) we will review and modify our procedures. All prairie dogs
that die in captivity will undergo a full post-mortem examination. Minor
adjustments to husbandry may be made as needed to meet animal needs.
One objective of the pilot study is to determine if prairie dogs can be trained
to allow repeated grooming by handlers, without being chemically immobilized.
Hoogland (1995) successfully groomed black-tailed prairie dogs without chemical
immobilization, and one of us (KTC) repeatedly handled captive black-tailed
prairie dogs that were distracted with a treat, such as a carrot. We will
therefore attempt to handle each animal on a daily basis, in order to establish
a routine whereby they become accustomed to being groomed. If we can train the
animals to allow grooming, chemical immobilization will not be necessary. If
chemical immobilization appears necessary, we will test the following methods
to determine which to use in Phase II: 1) animals will be placed in an
induction chamber and anesthetized with isoflurane. The animals will be
removed from the chamber within 15 seconds after cessation of movement and
anesthesia will be maintained via a mask; or 2) animals will be placed into a
restraining cone and injected intramuscularly (IM) with a combination of
ketamine (30 mg/kg) and diazepam (0.5 mg/kg) (Kreeger, 1997). During
anesthesia, animals will be monitored visually for respiration, heartbeat, and
signs of distress. Trained or immobilized prairie dogs will be groomed with a
fine-toothed flea comb for 3 minutes; grooming will take place up to 3 times
per week. After immobilization, each animal will be returned to its cage, and
closely observed until it regains normal functions.

�127
Concurrent to establishing the captive prairie dog colony, we will develop a
technique to artificially rear prairie dog fleas of the genus Oropsylla.
Although prairie dogs can harbor several genera of fleas, we have selected to
maintain only Oropsylla because they are among the most common fleas of prairie
dogs and they have been implicated in the transmission of plague (Ubico et al.,
1988). Fleas will be collected by combing trapped prairie dogs and by swabbing
of burrows (Barnes et al., 1972). Fleas will be placed in 500 ml glass jars
each containing about 125 g of larva-rearing media consisting of wheast (Red
Star Biologicals), dried beef blood (Monfort Biologicals), powdered dog chow,
and sand. In the laboratory, live fleas will be anesthetized with CO2 and
identified by comparison to a reference collection of preserved fleas.
Because
fleas are sensitive to changes in temperature and humidity, they will be
maintained in an incubator at about 23-24 c and ~70% relative humidity
(Metzger, pers. commun.). Appropriate relative humidity will be maintained
using a super-saturated solution of potassium chloride (Winston and Bates,
1960). A natural photoperiod will be approximated within the incubator through
the use of fluorescent lights and a timer. Fleas will be monitored daily for
survival and reproduction. Modifications will be made as necessary to optimize
flea performance.
To determine adequacy of the cage environment for flea survival and
reproduction, we will infest prairie dogs with about 20-50 male and female
fleas. We will collect and count fleas from prairie dogs and their bedding at
weekly intervals. Fleas will be collected from prairie dogs by combing (while
distracted with a treat or while under anesthesia) for 3 min and from bedding
by sifting and visual inspection. Fleas will be returned to the prairie dog
after counting. Collections, and if needed reinfestations, will be continued
until successful colonization occurs. If a severe allergic reaction or other
health problem associated with flea infestation occurs, the prairie dog will be
removed from the study and provided veterinary care or euthanized.

Analysis: Evaluation of husbandry techniques and artificial flea rearing
procedures will be subjective.

No statistical analyses will be performed.

Phase II--Laboratory Evaluation of IGRs

Methods: Prairie dogs will be captured and maintained in captivity as described
in Phase I. Laboratory evaluation of pyriproxifen and lufenuron will be
divided into four experiments--efficacy dose titration, efficacy of controlling
flea infestations in a simulated burrow environment, product safety, and bait
formulation. Detailed Study Plans will be written for each of these
experiments based on results of the Pilot Study; however, general procedures
will be as follows.

Efficacy dose titration. In this experiment we will determine an effective
dose of pyriproxifen and of lufenuron to interrupt reproduction in prairie dog
fleas and monitor duration of the products' efficacy. Prairie dogs (n = 21)
will be blocked by sex and randomly divided into two treatment groups and a
control group. In the first experiment, lufenuron will be evaluated at two
dose rates. Treatment group 1 (n = 7) will receive 15 mg/kg and treatment
group 2 (n = 7) will receive 45 mg/kg lufenuron PO. The control group (n = 7)
will receive excipient suspension without lufenuron PO. After a sufficient
washout period, the experiment will be repeated using pyriproxifen at
anticipated dosages of 50 mg/kg and 100 mg/kg PO for treatment groups 1 and 2,
respectively. Prairie dogs will be infested with fleas prior to treatment and
periodically after treatment to maintain flea infestations. We will collect
flea eggs prior to treatment and at 5 weekly intervals and determine egg

�128
viability by rearing in artificial media. Number of eggs hatching in a
specific time period (to be determined in Phase I) will be determined and
compared between groups and over time. We may also collect blood from prairie
dogs during the weekly samplings if an assay to determine serum levels of test
product can be developed. Development of a successful artificial rearing
system for prairie dog fleas is prerequisite to the performance of this
experiment. If such a protocol is not developed, we will attempt to determine
an effective dose using the methods described below for evaluation of efficacy
in a simulated burrow environment. In this case, duration of efficacy will be
more difficult to determine.

Efficacy of controlling flea infestations in a simulated burrow environment.
If results of the efficacy dose titration experiment suggest that a single oral
dose of pyriproxifen and/or lufenuron is effective in controlling reproduction
of prairie dog fleas for at least 4 wk, we will further evaluate the product(s)
in a simulated burrow environment. The purpose of this experiment is to
evaluate the ability of the test products to control prairie dog flea
populations over an extended period. Prairie dogs (n = 20) will be blocked by
sex and divided into treatment and control groups. They will be infested with
fleas and treated monthly with pyriproxifen or lufenuron. Adult fleas on the
animal and in the cage will be counted at 1-2 wk intervals for 12 wk. After
counting, fleas will be returned to the animal. Number of fleas recovered will
be compared between treatment groups and over time.
Product safety. We will determine safety of an overdose of pyriproxifen and/or
lufenuron. Prairie dogs (n = 20) will be divided into a treatment and control
group. Prairie dogs in the two groups will be maintained similarly except the
treatment group will receive an amount of product equal to that contained in
the maximum calculated daily intake of treated bait. Overdose feeding will
continue for a 3 day period. Health, attitude, and weight change of prairie
dogs in the treatment and control groups will be monitored during, and for 1 wk
following, this treatment. Based on type of action, these products should be
safe in mammals (Blagburn et al., 1995; T. Miller, pers. commun.); however, if
animals become moribund, they will be euthanatized. All dead animals will
receive a complete postmortem examination. If the overdose of test product is
safe in prairie dogs, product safety will be tested in black-footed ferrets or
black-footed ferret x Siberian polecat hybrids. Ferrets maintained at other
research facilities will be used as test animals and will be divided into a
treatment and control group. Prairie dogs treated with three times the maximum
daily dosage of test product (as described above) will be fed to ferrets in the
treatment group for 7 days. Health, attitude, and weight change of ferrets in
the treatment and control groups will be monitored during, and for 1 wk
following, this treatment.
Bait formulation. When an effective dose of pyriproxifen and/or lufenuron is
determined, we will begin investigating formulation of a bait carrier. Because
of differences in the chemical properties of the test products, unique
formulations will likely be required for each product. Due to its high
palatability, we will initially attempt to incorporate the test product into
horse sweet feed (sweetened grain mixture); however, incorporation into a
pelleted feed may be required to adequately deliver the product. Palatability
of treated bait will be evaluated in feed-deprived (hungry) prairie dogs as
well as those fed ad libitum maintenance diets (satiated). Blood samples may
be collected from prairie dogs to determine serum level of test product after
bait consumption.

�129

Analysis:
Efficacy dose titration. Efficacy of test product will be determined by
comparing developmental success of eggs produced by fleas exposed to treated
prairie dogs vs. eggs produced by fleas exposed to control group prairie dogs.
These formulas will be used in efficacy determination:

Developmental success= number emergent adult fleas x 100
number eggs collected
Percentage efficacy= mean developmental success (control)-

mean develqpmental success (treated)

x 100

mean developmental success (control)
Mean developmental success values for eggs collected from prairie dogs in each
of the treatment groups will be analyzed using analysis of variance.
Efficacy in a simulated burrow environment. Efficacy of test product will be
determined by comparing number of fleas recovered from treatment and control
prairie dogs and their cages on each sampling day using analysis of variance.
Significant reductions in numbers of fleas on treated prairie dogs would
signify interruption of the flea life cycle attributable to treatment with the
test product.
Product safety and Bait formulation: Evaluation of product safety and
acceptability of bait will be subjective. No statistical analyses will be
performed.

Phase III-Field Evaluation of IGRs

Methqds: Based on results of laboratory evaluations, we will evaluate
pyriproxifen and/or lufenuron in a limited field application. Only product(s)
that significantly reduced flea numbers on treated hosts for ~1 mo and that
showed no adverse effects on captive prairie dogs and ferrets will be field
tested. We will identify similar, yet geographically distinct, colonies of
healthy prairie dogs for evaluation of the test product(s). Treatment
colony(s) will receive bait fortified with the test compound while the control
colony will receive bait only. Treatments will be applied at monthly intervals
during the summer. Observations will be made to determine prairie dog numbers
and consumption of bait by prairie dogs and non-target species. Flea indices
(number of fleas per individual and number of fleas per burrow) will be
determined by counting and identifying fleas collected by combing live-trapped
prairie dogs and by swabbing burrows (Barnes et al., 1972). Blood samples may
also be collected from prairie dogs to determine serum level of test product.
Collections will be made at monthly intervals beginning ~l mo prior to
initiation of treatment, continuing through the active season of prairie dogs
(September), and resuming the following summer. Flea indices will be compared
between treatment and control colonies and over time.
Analysis: Efficacy of test product will be determined by comparing flea
indices of control and treatment colonies at each sampling using analysis of
variance. Significant reductions in numbers of fleas on prairie dogs at
treated sites would signify interruption of the flea life cycle attributable to
treatment with the test product.

�130
schedule:
Objective
1. Disease survey
2. Phase I--Pilot study
3. Phase II--Laboratory study
4. Phase III- Field study
5. Analyze data, report results
E.

Fiscal Year
1998-2002
1998-1999
1999-2000
2000-2001
2001-2002

LOCATION

Planning, captive animal research, data analysis, and reporting will be carried
out at the COlorado Division of Wildlife's Foothills Wildlife Research
Facility, 4330 w. Laporte Ave., Fort Collins, Colorado.
Carnivore disease survey will be conducted at the Little Snake Management Area,
Moffat County, Colorado.
Capture of prairie dogs to establish a captive colony will be at Arapaho
National Wildlife Refuge, Jackson County, COlorado.
Location of Phase III (field study) is yet to be determined, but will be
reported in the detailed Study Plan for that experiment.

F.

ESTIMATED COST

Fiscal Year

Estimated costs

1998
1999
2000
2001
2002
G.

$13,000
20,500
21,400
21,400
13,000

llE ReW,1irements
PFTE
0.5
0.5
0.5
0.5
0.5

PERSONNEL
Margaret A. Wild1
Kevin T. Castle1
Thomas A. Miller2
Craig Parks3

co-principal investigator
Co-principal investigator
CO-investigator
CO-investigator

Colorado Division of Wildlife, Fort Collins, COlorado
Virbac, Inc., Fort Worth, Texas
3 Novartis Animal Health U.S., Greensboro, North Carolina

1
2

TFTE
0.25
0
0.5
0.5
0

�131
H.

LITERATURE CITED

Barnes, A. M. 1993. A review of plague and its relevance to prairie dog
populations and the black-footed ferret. Proceedings of the symposium on
the management of prairie dog complexes for the reintroduction of the blackfooted ferret. J. L. Oldemeyer, D. E. Biggins, B. J. Miller, and R. Crete,
eds. 96pp.
Barnes, A. M., L. J. Ogden, and E.G. Campos. 1972. Control of the plague
vector, Opisocrostis hirsutus, by treatment of prairie dog (Cynomys
ludovicianus) burrows with 2% carbaryl dust. Journal of Medical Entomology
9: 330-333.
Beard, M. L., s. T. Rose, A. M. Barnes, and J. A. Montenieri. 1992. Control
of Oropsylla hirsuta, a plague vector, by treatment of prairie dog burrows
with 0.5% permethrin dust. Journal of Medical Entomology 29: 25-29.
Blagburn, B. L., J. L. Vaughan, D.S. Lindsay, and G. L. Tebbitt. 1994.
Efficacy dosage titration of lufenuron against developmental stages of fleas
(Ctenocephalides felis felis) in cats. American Journal of Veterinary
Research 55: 98-101.
Blagburn, B. L., C. M. Hendrix, J. L. Vaughan, D. s. Lindsay, ands. H.
Barnett. 1995. Efficacy of lufenuron against developmental stages of fleas
(Ctenocephalides felis felis) in dogs housed in simulated home environments.
American Journal of Veterinary Research 56: 464-467.
Cohen, E. 1987. Interference with chitin biosynthesis in insects. In Chitin
and benzoylphenyl ureas, series entomologica, vol. 38, J.E. Wright and A.
Retnakaran (eds), Dr. W. Junk, Publishers, Boston, pp. 33-42.
Cox, M. K. and W. L. Franklin. 1990. Premolar gap technique for aging live
black-tailed prairie dogs. Journal of Wildlife Management 54:143-146.
Davis, R. M. 1997. Use of an orally administered insect development inhibitor
(lufenuron) as a flea control agent in the California ground squirrel,
Spermophilus beecheyi. Fourth International Symposium on Ectoparasites of
Pets, pp 31-35.
Hilton, D. F. J. 1971. A method for rearing fleas of ground squirrels.
Transactions of the Royal Society of Tropical Medicine and Hygiene 66: 188189.
Hink, w. F., M. Zakson, ands. Barnett. 1994. Evaluation of a single oral
dose of lufenuron to control flea infestations in dogs. American Journal of
Veterinary Research 55: 822-824.
Hoogland, J. L. 1995. The black-tailed prairie dog: social life of a burrowing
animal. University of Chicago Press, Chicago, 557 pp.
Kreeger, T. J. 1997. Handbook of Wildlife Chemical Immobilization.
International Wildlife Veterinary Services, Inc., Laramie, WY. 342 pp.
Metzger, M. E. and M. K. Rust. 1997. Effect of temperature on cat flea
(Siphonaptera: Pulicidae) development and overwintering. Journal of Medical
Entomology 34: 173-178.

�132
Palma, K. G., s. M. Meola, and R. w. Meola. 1993. Mode of action of
pyriproxifen and methoprene on eggs of Ctenocephalides felis (Siphonaptera:
Pulicidae). Journal of Medical Entomology 30: 421-426.
Quan, T. J. 1982. Plague. In Diseases of wildlife in Wyoming, E.T. Thorne,
N. Kingston, w. R. Jolley, and R. c. Bergstrom (eds), Wyoming Game and Fish
Department, Cheyenne, pp. 67-71.
Rust, M. K. 1992. Influence of photoperiod on egg production ·of cat fleas
(Siphonaptera: Pulicidae) infesting cats. Journal of Medical Entomology 29:
242-245.
state of Colorado. 1994. Long Range Plan.
Division of Wildlife. 32pp.

Department of Natural Resources,

Thomas, c. U., and P. E. Hughes. 1992. Plague surveillance by serological
testing of coyotes (Canis latrans) in Los Angeles County, California.
Journal of Wildlife Diseases 28:610-613.
Ubico, S. R., G. O. Maupin, K. A. Fagerstone, and R. G. McLean. 1988. A
plague epizootic in the white-tailed prairie dogs (Cynomys leucurus) of
Meeteetse, Wyoming. Journal of Wildlife Diseases 24: 399-406.

u. s. Fish and Wildlife Service.

1988.

Black-footed Ferret Recovery Plan.

87pp.
Williams, E. s. 1982. Canine distemper. In Diseases of wildlife in Wyoming.
E.T. Thorne, N. Kingston, W.R. Jolley, and R. c. Bergstrom (eds), Wyoming
Game and Fish Department, Cheyenne, pp. 10-13.
Williams, E. S., K. Mills, D.R. Kwiatkowski, E.T. Thorne, and A. BoergerFields. 1994. Plague in a black-footed ferret (Hustela nigripes). Journal
of Wildlife Diseases 30:581-585.
Williams, E. S., E.T. Thorne, M. J. G. Appel, and D.·W. Belitsky. 1988.
Canine distemper in black-footed ferrets (Hustela nigripes) from Wyoming.
Journal of Wildlife Diseases 24:385-398.
Winston, P. w., and D. H. Bates. 1960. saturated solutions for the control of
humidity in biological research. Ecology 41: 232-237.

�133
SEGMENT NARRATIVE
state of
Colorado
Project No.
W-153-R
Work Package No. __0_8-8-0'------Task No.

cost center 3430
Mammals Program
Black-footed Ferret conservation
Monitoring and Managing Disease

in Black-footed Ferrets
Planning Program Narrative Objectives:
1. Monitor enzootic disease activity threatening survival of black-footed
ferrets reintroduced into the LSMA.
2.

Develop techniques to manage plague in the LSMA using insect growth
regulators applied orally to prairie dogs.

Segment Objectives:
1. Determine the level of activity of canine distemper in carnivores and
plague in prairie dogs (using coyotes as sentinels) in the LSMA by
sampling ~40 coyotes.
2.

Establish a colony of captive white-tailed prairie dogs that can sustain
infestation with fleas of the genus Oropsylla.

3.

Develop techniques to artificially rear fleas of the genus Oropsylla.

4.

Determine an effective dose of pyriproxifen and of lufenuron to control
fleas of the genus Oropsylla on prairie dogs.

Estimated segment costs= $46,540
Personal Services
Permanent employees (0.5 FTE)
Temporary employees
Contracts
Total Personal Services
Operating supplies and services
Travel expenses

capital eq,uipment

$26,040
0

10.000
$36,040
$ 8,300
2,200

0

Total Operating

$10,500

Total Costs

$46,540

�69

Colorado Division of Wildlife
Wildlife Research Report
July 1999

JOB PROGRESS REPORT

------~~-----

State of
Colorado
Project No. _ _ _ _W'------1=5-=-3--=-R___--=-l=-2_ _ __
Work Package No . _..;;.0""'"88~0'--_ _ _ __
Task No. ______I.___ _ _ _ _ __

Mammals Research
Black-footed Ferret Recovery
Monitoring and Managing Disease in
Black-footed Ferrets

Period Covered: July 1, 1998 - June 30, 1999.
Authors: .M. A. Wild and K. T. Castle
Personnel: E. Wheeler.

ABSTRACT
The black-footed ferret is a federally listed endangered speci~s in the United States. Blackfooted ferrets-have been extirpated from Colorado, but are scheduled to be reintroduced to the wild at
the Little Snake Management Area (LSMA) in Moffat County, Colorado in the near future. Our
research can be sub-divided into two broad sections: disease monitoring in the proposed release area
and flea control as a tool to manage sylvatic plague in prairie dogs and black-footed ferrets. Disease
monitoring was performed using collection of carnivores (primarily coyotes) from the LSMA in July
1998 and February 1999. Two potentially devastating diseases, canine distemper and plague, are
present at LSMA. Prevalence of titers to canine distemper virus (CDV) in coyotes are low ~10%).
Prev~ence of titers to plague (Yersina pestis) were found in 60% and 20% of coyotes tested in the
summer and winter collections, respectively. Titers were present in both adult and juvenile animals,
suggesting ongoing plague activity in some areas. We began investigations into the bioavailability of
lufenuron to orally dosed prairie dogs. A test dose of300 mg/kg body weight was determined and
administered to 30 captive prairie dogs. Prairie dogs were divided into two groups (one group torpid,
the other non-torpid). Blood samples for lufenuron assay were collected pre-treatment, at 1 wk postdosing, then at 2-wk intervals through week 9 post-dosing. No adverse affects to lufenuron were
observed. Lufenuron assay is pending. We also attempted to establish a colony of fleas of the genus
Dropsy/la for artificial infestations on captive prairie dogs. Although we were unsuccessful in
establishing self-sustaining colonies of 0. tuberculata (the prairie dog flea) from wild populations, we
did establish a thriving colony ofinsectary-reared 0. montana (the ground squirrel flea). These fleas
will be used in future investigations into the efficacy of lufenuron to control fleas on captive prairie
dogs.

f

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WH

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BDOW014186

��71

MONITORING AND MANAGING DISEASE IN BLACK-FOOTED FERRETS
Margaret A. Wild and Kevin T. Castle

P. N. OBJECTNES
1. Monitor enzootic disease activity threatening survival of black-footed ferrets reintroduced into the
LSMA.
2. Develop techniques to manage plague in the LSMA using insect growth regulators applied orally
to prairie dogs.

SEGMENT OBJECTNES
1. Determine the level of activity of canine distemper virus in carnivores and plague in prairie dogs
(using coyotes as sentinels) in the LSMA by sampling &gt;40 coyotes.
\"'
2. Establish a colony of captive white-tailed prairie dogs that can sustain infestations ~eas__of.the
genus Oropsylla.
3. Develop techniques to artificially rear fleas of the genus Oropsylla.
4. Determine an effective dose ofpyriproxifen and oflufenuron to control fleas of the genus
Oropsylla on prairie dogs.

METHODS AND MATERIALS
Carnivore Disease Survey
Infectious diseases can severely impact the success of black-footed ferret (Mustela nigripes)
reintroduction efforts. As part of the black-footed ferret reintroduction protocol, we monitored disease
activity in carnivores in the Little Snake Management Area (LSMA), Colorado. Coyotes (Canis
latrans) were collected.in July 1998 and February 1999. Post-mortem examination and sample
collection was performed as described in the Program Narrative (Wild 1998).
Black-footed Ferret Reintroduction
We assisted in preparation of the black-footed ferret allocation request submitted to the US
Fish and Wildlife Service by the Colorado-Utah black-footed ferret recovery working team in 1999.
We prepared a protocol for the care of captive black-footed ferrets at the LSMA {Attachment 1).
Consultation on health matters and veterinary care were.provided for captive black-footed ferrets.
Artificial Rearing of Oropsylla fleas
In summer 1998 and spring 1999 we collected Oropsylla spp. fleas from prairie dog burrows
at Arapaho National Wildlife Refuge. We attempted to maintain and propagate these wild fleas under

�72

insectary conditions (Wild 1998). Additionally, we attempted to produce self-sustaining populations of
0. tubercu/ata within the nest boxes of four quarantined prairie dogs. To enhance flea survival, we
placed a wooden box fitted with a screen top into each nest box. The wooden "flea refuge" allowed
fleas to jump on or off the animal at will, and kept the prairie dog from stepping on fleas and eggs. We
placed "bed-o-cobs" bedding material on the refuge floor in order to provide hiding places for the fleas.
Each prairie dog was infested with up to 60 adult fleas (about 3:2 females:males). To count fleas, we
anesthetized and groomed each animal periodically, and noted the number of surviving fleas found on
the animal and in its nest box.
Because of the decline in 0. tuberculata availability in the field and the low survivorship and
reproduction of that species in the lab, we decided to explore the use oflaboratory-reared 0. montana
for experimental purposes. 0. montana is generally found on ground squirrels, such as Spermophilus
beecheyi (California ground squirrel); it should be able to reproduce when fed on the closely-related
prairie dogs. Other researchers have maintained lab colonies of 0. montana for a number of years, and
have found that the species readily reproduces when fed in artificial systems, and when fed on captive
neonatal or adult rodents. While we would rather utilize true prairie dog fleas, such as 0. tuberculata,
in our experiments, the use oflab-reared 0 montana offers some advantages over 0. tubercu/ata: 1)
0. montana is readily available; 2) the temperature and humidity preferences of the species are wellcharacterized, so it reproduces well in an insectary; and 3) lab-reared 0. montana are plague-free. In
summer 1999 we acquired a small colony of about 400 0. montana from the Centers for Disease
Control (CDC), Fort Collins. These fleas were maintained under insectary conditions (Wild 1998).
Flea Control In Prairie Dogs
Thirty-three white-tailed prairie dogs (Cynomys leucurus) collected in June 1998 from
Arapaho National Wildlife Refuge were maintained at Foothills Wildlife Research Facility (FWRF).
Details of animal husbandry and health are reported by Wild (1999). Initially, we planned to evaluate
two insect growth regulators in captive prairie dogs: lufenuron and pyriproxyfen. However, after
reviewing the literature, contacting product manufacturers, and investigating methods to measure
efficacy, we have determined that lufenuron holds the most promise for effective application.
Lufenuron is longer lasting than pyriproxyfen (Palma et al. 1993, Hink et al. 1994), researchers with
Novartis (the manufacturer oflufenuron) are interested in collaboration, and a blood assay is available
to measure lufenuron but not pyriproxyfen.
We performed two studies to begin evaluating lufenuron in white-tailed prairie dogs. First, a
pilot study to determine bioavailabilty oflufenuron administered orally to captive prairie dogs at three
dosages: 20 mg/kg, 60 mg/kg, and 300 mg/kg (n = I at each dosage). Blood samples were collected
for lufenuron assay pr~treatment and 1, 7, 28, 42, and 56 days post-dosing. Lufenuron assay using
HPLC was performed by En-Cas Laboratories. Results of this pilot study were used in planning the
following study to determined the seurm profile oflufenuron during active and torpid periods in orallydosed white-tailed prairie dogs:
Bioavailability of lufenuron administered orally to captive
white-tailed prairie dogs (Cynomys leucurus)
Kevin T. Castle 1, Margaret A. Wild 1, and S. Craig Parks2
1
Colorado Division of Wildlife, 317 W. Prospect,
Ft. Collins, CO 80526
2
Novartis Animal Health, P. 0. Box 26402, Greensboro, NC 27404

�73

Introduction
Mortality of black-footed ferrets (Mustela nigripes) from infection with sylvatic plague is
extremely high (Williams et al., 1994). Further, mortality from sylvatic plague in prairie dogs
(Cynomys spp.) can markedly impact the prey base of black-footed ferrets. Plague has severely
hampered reintroduction efforts in other states (P. Marinari, pers. comm.) and preliminary data suggest
that plague activity is present in some areas of the Little Snake Management Area (Wild, unpub. data)
where black-footed ferrets are scheduled to be released in late 1999. Successful reintroduction will
likely require management techniques to control·plague. We believe that the proposed research will
provide a novel and effective means of controlling plague in prairie dogs and black-footed ferrets.
Plague is maintained primarily in rodent populations, where it is typically transmitted via the •
bite of an infected flea Fleas of the genera Opisocrostis and Dropsy/la have been associated with
plague transmission in prairie dogs (Ubico et al., 1988). Insecticide dusts have been applied to prairie
dogs burrows in an attempt to kill fleas and thus control plague. Carbaryl has been the most commonly
used insecticide; however, application is labor intensive and activity is short-lived (Barnes, 1993).
Permethrin has been shown effective up to 84 days after· application (Beard et al., 1992), but the
authors warn that application at the recommended dosage rate would be highly laborious.
Recently developed compounds used to control fleas in pet animals offer a promising
alternative to insecticide dusts. Although topically applied flea adulticides, such as imidacloprid, are
not feasible for use in wildlife, insect growth regulators (IGRs) with ovicidal and/or larvicidal activity
could be delivered orally to free-ranging animals via bait. The IGR lufenuron is a benzoylphenylurea
derivative which inhibits formation of chitin in the exoskeleton of insects (Cohen, 1987). A single oral
dose oflufenuron has been shown effective in controlling the cat flea (Ctenocephalidesfelisfelis) for at
least 30 days in treated cats (Blagburn et al., I 994) and dogs (Hink et al., 1994). Davis (1997)
reported a significant reduction in fleas on free-ranging ground squirrels (Spermophi/us beecheyi) that
had been treated with lufenuron. Iflufenuron proves efficacious over a long period of time~ I mo)
when administered orally to prairie dogs, it could be applied over large areas of prairie dog habitat via a
treated bait.
Prior to management application, lufenuron should be evaluated in a controlled laboratory
setting to determine an effective dose, duration of efficacy, product safety, and to formulate an
acceptable bait carrier. If results of laboratory tests are positive, lufenuron should be tested in a
controlled field study to determine efficacy under natural conditions. Without this evaluation, the
management potential ofIGRs for controlling plague and protecting the health of the endangered blackfooted ferret, as well as human health, will be difficult to discern.
We have proposed studies to test the efficacy oflufenuron for controlling fleas on artificiallyinfested captive white-tailed prairie dogs (Cynomys leucurns; Wild and Castle, 1998); however,
laboratory rearing of fleas has proven difficult thus far. Further, because Dropsy/la and Dpistocrostis
fleas are most readily collected in spring and early summer, our lufenuron-efficacy work is limited to
the summer months. As an alternative, preliminary, means oflufenuron evaluation, we will conduct a
bioavailability study oflufenuron administered orally to captive white-tailed prairie dogs.
Prescribed oral doses of lufenuron for domestic cats and dogs are 30 mg/kg and IO mg/kg
body weight, respectively. The concentration oflufenuron in blood of protected animals is somewhat
variable, but protection seems to be conferred to dogs and cats when blood levels reach at least 50-100
parts per billion (B. Blagburn, pers. comm.). No data are available regarding the bioavailability of
ingested lufenuron in any wild rodent species; however, assay results are pending from a recent pilot
study (Castle and Wild, 1998). Based on results from this pilot study and assuming 100 ppb as the
efficacious blood level, we will determine the test dose for this experiment. Although the correlation
between blood levels oflufenuron and efficacy of flea control in prairie dogs will need to be determined
in future experiments, this preliminary work will provide insights into: 1) between-animal variability

�74

and 2) features of the decay curve oflufenu~on (e.g. peak concentration and duration oflevels over 100
ppb) in the blood of prairie dogs.
Because white-tailed prairie dogs are spontaneous, obligate hibernators, they exhibit marked
changes in activity and physiologic function seasonally (Harlow, 1997). These activity and physiologic
changes may influence lufenuron bioavailability. Throughout much of their range, adult white-tailed
prairie dogs enter hibernation in August or early September, and juveniles begin hibernation in late
September or early October. Before hibernating, they store large amounts of body fat, to provide
energy during their winter-long fast (Harlow, 1997). It is possible that as fat is mobilized during
hibernation and upon arousal, lipid-soluble materials that were ingested and stored during late summer
and fall may also be mobilized. Because lufenuron is highly lipid-soluble (Blagburn et al., 1994),
white-tailed prairie dogs fed treated bait prior to hibernation could potentially store the compound over .
winter, and therefore be protected during winter and when they arouse in spring. If prairie dogs were
thus protected, flea population increases could be pre-empted, and management of plague outbreaks
would be enhanced. To test this hypothesis, we will compare blood lufenuron levels in active vs torpid
prairie dogs in a controlled laboratory setting.
To summarize, the objective of this study is to determine the serum profile oflufenuron during
active and torpid periods in orally-dosed white-tailed prairie dogs. These data will be used in the
design of future experiments to evaluate lufenuron in captive and free-ranging prairie dogs, and will
provide insights on the between-animal and seasonal variation that is to be expected. When combined
with efficacy information, blood assay for lufenuron would provide a useful tool for evaluating
lufenuron treatment programs involving free-ranging animals.
Methods

Care and housing ofprairie dog
All captive prairie dogs will be pair-housed in cages under the same conditions described in
Castle and Wild, 1998. Prairie dog cages (46 x 91 x 46 cm) are constructed of wood and wire fencing.
Half of the cage serves as a nest box, and the other half serves as a feeding area Two hinged doors
allow access to each half of the cage for cleaning or animal handling. The nest box is a 40 x 28 x 23
cm plastic container· fitted with a wooden lid. The nest box has a 10 cm diameter hole in one wall to
provide access to the feeding area; a 10 cm diameter piece of PVC pipe joins the nest b.ox to the
feeding area The access hole can be covered to confine the animals to either side of the cage as
necessary. Our preliminary work shows that defecation and urination in the nest box are minimal, so
we do not expect the nest boxes to become soiled during experiments.
The floor of the feeding area consists of 1cm mesh wire fencing to allow feces, urine, and
spilled food to fall through to a newspaper-lined metal pan below. This mesh size prevents the
animal's feet from becoming wedged in the floor, but may encourage the animal to spend most of its
time in the nest box when not feeding. Newspaper in the metal pan will be changed daily if soiling
occurs.
Food (Teklad Rodent Blocks) will be provided ad libitum except as noted below. Water will
be available at all times. Prairie dog cages will be kept in two similar buildings. Temperature in each
building is thermostatically controlled, and artificial lighting is controlled with timers.
Health and attitude of prairie dogs will be assessed daily during the experimental period. Body
weight will be measured at 1-2 week intervals while each animal is anesthetized for blood collection.

�75

Experimental Design
Thirty captive white-tailed prairie_ dogs (16 males and 14 females) less than one year old will
be blocked by sex and randomly divided into two treatment groups (n = 13 each) and two control
groups (n = 2 each). Treatment group 1 and one control group (active-group animals) will be housed
in a building under conditions that inhibit hibernation (14L: 1OD photoperiod plus natural lighting
through windows, ambient temperatures above 15 °C). Treatment group 2 and a second control group
(torpid-group animals) will be housed in a second building under conditions that promote hibernation
(1 0L: 14D photoperiod, ambient temperature of 5-6 °C). Intermittent fasting of up to 2 d per 7 d period
will also be used in some individuals to promote hibernation if temperature and photoperiod changes
prove insufficient. Our goal is to expose the two groups to the most extreme conditions known to
inhibit or promote torpor. We do not expect food deprivation to harm the torpid-group animals,
because food intake between torpor bouts is minimal (Harlow, 1997).
We have determined that these experimental conditions allow us to inhibit or promote
hibernation in a majority of our white-tailed prairie dogs; however, despite our efforts, some animals
housed under hibernation-promoting conditions remain active, while some housed under hibernationinhibiting conditions become torpid. We will therefore assess each animal daily, and record its activity
level. Active-group prairie dogs that become torpid will be aroused by gentle shaking and rubbing;
torpid-group animals that remain active will not be disturbed. We will assess the duration of torpor in
torpid-group animals by placing a small amount of sawdust on the back of each torpid individual; the
presence of sawdust on the back at subsequent checks will be interpreted to mean that the individual
was torpid the entire period (Harlow, 1997).

Dosing Methods
Prairie dogs will be fasted for 24 h, then weighed prior to dosing; water will be available
during the fast. After the fasting period, each individual in a cage will be confined to one-half of the
cage by blocking off the nest box access hole, and temporarily removing the nest box. Each animal in
treatment groups 1 and 2 will be fed a bolus dose of lufenuron (20-300 mg/kg dose, pending pilot trial
results) mixed thoroughly in a highly palatable bait (ground rat chow and molasses). Control animals
will receive the bait only. The bait will be offered in each animal's feeding dish. We previously
determined that fasted prairie dogs consume up to 2 g of such a bait within about 30 min, and will
consume up to 13 gin less than 12 h. We will observe the progress of bait ingestion in each animal to
determine when the dose is ingested. We will weigh the bait/lufenuron mixture before and after the
prairie dogs are dosed, in order to calculate the actual dose ingested. After both animals in a cage have
consumed their dose, the nest box will be returned and they will again be pair-housed.

Blood Collection
We will collect 3 ml of blood from each prairie dog prior to lufenuron dosing, one week after
dosing, then at 2 week intervals through week 9 post-dosing, or until torpor bouts are no longer
observed. Anesthesia is required for blood collection. We have determined that prairie dogs respond
very well to isoflurane anesthesia. Induction and recovery are quick (approximately 3-5 min for each),
and we have detected no adverse effects. All prairie dogs will be aroused from torpor prior to
anesthesia, in order to assure sufficient blood pressure for blood collection. Prairie dogs_will be placed
into a plastic chamber for induction at a concentration of 4% isoflurane in oxygen, then anesthesia will
be maintained via mask at about 2-2.5% isoflurane. Heart rate and respiration will be monitored
during anesthesia. Blood will be collected by jugular venipuncture and placed into a glass vacutainer
blood tube (without anticoagulant). Alternatively, if we are unable to collect an adequate blood sample

�76

peripherally, we will collect blood from the vena cava or directly from the heart. Although cardiac
puncture is considered to be a safe procedure for collection oflarge volumes of blood from laboratory
rodents (CCAC, 1984), due to the increased risks involved with cardiac puncture (5-10% mortality
expected; J. Wimsatt, pers. comm.), we will use this technique only to obtain critical samples. Serum
will be harvested and frozen within 4 h of collection. Serum lufenuron concentration will be
determined by HPLC at Novartis Laboratories.

Product safety
Based on mode of action, chitin inhibitors should be safe in mammals, even at very high doses
(Blagbum et al., 1995; T. Miller, pers. comm.). Cats have been fed more than 5 times the prescribed
dose oflufenuron without showing adverse side effects (B. Blagburn, pers. comm.). The high dose to
which our prairie dogs may be exposed (300 mg/kg) is based upon our estimate of the maximum
amount of bait a prairie dog might eat in a day in the field (40-60 g) and a reasonable lufenuron
concentration in the bait (5 mg/g). We did not detect adverse effects from lufenuron administration
during our pilot study, when 3 prairie dogs received doses of20-300 mg/kg.
We do not anticipate any prairie dog mortality due to the dosing regime or blood collection.
However, if an animal becomes sick or injured, and recovery is not likely, it will be euthanized with an
overdose of inhalant anesthetic. A complete post-mortem examination will be performed on any
animal that may die during the experimental period.

Data Analysis
We will compare lufenuron blood concentrations of the torpid- and active-group prairie dogs
over time by conducting a profile analysis of the lufenuron decay curves. In addition, we will use
analysis of covariance to compare: 1) peak concentrations obtained in each group, and 2) the duration
of concentrations above 100 ppb in each group. The number of days an animal was observed to be
active will serve as the covariate in our analyses. Group responses will be considered significantly
different at p 0.05.
Literature Cited
Barnes, A. M. 1993. A review of plague and its relevance to prairie dog populations and the blackfooted ferret. Proceedings of the symposium on the management of prairie dog complexes for
the reintroduction of the black-footed ferret. J. L. Oldemeyer, D. E. Biggins, B. J. Miller, and R
Crete, eds. 96pp-. •
Beard, M. L., S. T. Rose, A. M. Barnes, and J. A. Montenieri. 1992. Control of Oropsylla hirsuta, a
plague vector, by treatment of prairie dog burrows with 0.5% permethrin dust. Journal of
Medical Entomology 29:25-29.
Blagbum, B. L., J. L. Vaughan, D.S. Lindsay, and G. L. Tebbitt. 1994. Efficacy dosage titration of
lufenuron against developmental stages of fleas (Ctenocephalidesfelisfelis) in cats. American
Journal of Veterinary Research 55:98-101.
Blagburn, B. L., C. M. Hendrix, J. L. Vaughan, D. S. Lindsay, and S. H. Barnett. 1995. Efficacy of
lufenuron against developmental stages of fleas (Ctenocephalidesfelisfelis) in dogs housed in
simulated home environments. American Journal of Veterinary Research 56:464-467.
Castle, K. T. and M. A. Wild. 1998. Safety and efficacy of pyriproxifen and lufenuron for the control
of prairie dog fleas: a pilot study. Colorado Division of Wildlife Animal Care and Use
Committee Study Plan.
Canadian Council on Animal Care (CCAC). 1984. Guide to the care and use of experimental
animals, Vol. 2. Ottawa, Ont., Canada

�77

Cohen, E. 1987. Interference with chitin biosynthesis in insects. In Chitin and benzoylphenyl ureas,
series entomologica, vol. 38, J.E. Wright and A. Retnakaran (eds), Dr. W. Junk, Publishers,
Boston, pp.33-42.
Davis, R. M. 1997. Use of an orally administered insect development inhibitor (lufenuron) as a flea
control agent in the California ground squirrel, Spermophilus beecheyi. Fourth International
Symposium on Ectoparasites of Pets, pp. 31-35.
Harlow, H. J. 1997. Winter body fat, food consumption, and nonshivering thermogenesis of
representative spontaneous and facultative hibernators: the white-tailed prairie dog and blacktailed prairie dog. Journal of Thermal Biology 22:21-30.
Hink, W. F., M. Zakson, and S. Barnett. 1994. Evaluation of a single oral dose of Iufenuron to control
flea infestations in dogs. American Journal of Veterinary Research 55:822-824.
Ubico, S. R, G. 0. Maupin, K. A. Fagerstone, and R. G. McLean. 1988. A plague epizootic in the
white-tailed prairie dogs (Cynomys leucurus) of Meeteetse, Wyoming. Journal of Wildlife
Diseases 24:399-406.
Williams, E. S.; K. Mills, D. R Kwiatkowski, E.T. Thome, and A. Boerger-Fields. 1994. Plague in a
black-footed ferret (Mustela nigripes). Journal of Wildlife Diseases 30:581-585.
Wild, M. A. and K. T. Castle 1998. Monitoring and managing disease in black-footed ferrets.
Colorado Division of Wildlife Program Narrative, Project# W-153-R

RESULTS AND DISCUSSION
Carnivore Disease Survey
With the assistance of USDA Wildlife Services and the Bureau of Land Management (BLM) we
collected 19 coyotes and 4 badgers from the LSMA between 27-30 July 1998 and 20 coyotes between
11-12 February 1999. Coyotes were collected using a combination of calling and aerial gunning.
Death occurred rapidly and the collection technique was adequate, but much less efficient in summer
than in the winter months. Coyotes were collected from various locations in the &gt;4 700 mi 2
management area; however, we focused on the Powderwash area and near the site of the preconditioning pens. No lesions indicative of active disease were noted on gross examination of
carcasses. We found no serologic evidence of exposure to leptospirosis serovars canicola, grippo,
hardjo, and pomona; however, low positive titers to serovar ictero were found in nine coyotes (five in
July and four in February). No serologic titers to toxoplasmosis were found. Coyotes were not tested
for Aleutian Disease (a mustelid disease), but all four badgers were sei-onegative for the disease. All
badgers and 20% of coyotes sampled during the summer had positive titers to tularemia, while 10% of
the coyotes sampled in winter were positive. Positive titers could have been associated with predation
on rabbits, prairie dogs, or other rodents or exposure to ectoparasites. Duration of titers to tularemia
are likely of short duration (&lt;6 mo). The impact of tularemia or leptospirosis on black-footed ferrets is
not currently known; however, ferrets and humans are susceptible to these diseases. Canine distemper
virus (CDV) and plague are serious threats to survival of black-footed ferrets. The prevalence of
coyotes with serological titers to CDV was .:S,10%; markedly lower than in previous years (Fig. 1).
However, plague activity continues in LSMA as evidenced by titers in sampled coyotes (Fig. 2).
Black-footed Ferret Reintroduction
Nineteen black-footed ferrets (8 adult females, 5 juvenile females, 6 juvenile males) were
received from the National Black-footed Ferret Conservation Center in November 1998 and placed in
breeding pens at LSMA. Seventeen ferrets remained in good health with minimal health treatment

�78

required. One adult female ferret died of a biliary adenocarcinoma and one juvenile female is missing
and presumed dead. Ten female ferrets were paired with males and five of these gave birth. One litter
was apparently consumed by the female when &lt;l day of age. Toe· other four litters yielded 13 pups.
Artificial Rearing of Dropsy/la fleas
Although fleas had been abundant in the spring of 1998, in July fleas seemed to disappear from
the field. Burrow swabs consistently returned 0, 1, or 2 fleas per burrow. Because most burrows had
no fleas, the ratio of fleas/burrow dropped to less than 0.5. The cause of decline is unclear. One
possibility is that because many burrows were filled in by prairie dogs escaping the summer heat, the
nest areas that house a majority of fleas were no longer accessible from the surface. It is also possible
that the flea populations experienced a real decrease during the summer, and that decrease was
reflected in swabbing success.
Our attempts to artificially rear Oropsylla fleas during summer 1998 met with limited success.
We had successful completion of the life cycle within our rearing jars, but only about 4 adult fleas were
produced from eggs laid in captivity. Our overall success was limited by low flea survival during
transport to the lab, and the relatively low numbers of fleas available for collection in late summer
when our facilities were readied for use (virtually no fleas were available in the field after 30 June). By
the end of October 1998, no fleas were alive in our insectary.
We resumed field collections of fleas on 5 April 1999, when snow cover had receded and
prairie dog burrows were open. We inade five more trips to the field through the middle of May. A
total of 1645 fleas (906 of these 0. tuberculata) were collected. We successfully increased flea
survival during transport from the field to the lab by keeping fleas under cooler and more humid
conditions. Most fleas collected were alive when they arrived at the lab. Unfortunately, adult flea
mortality in the insectary was high, despite our attempts to keep the fleas well-fed and under optimal
temperature and humidity conditions. Reproduction within the insectary was therefore limited. We
collected 8 larva from the insectary jars, and placed them into a separate dish containing rearing media;
none of the larva pupated.
Attempts to produce self-sustaining populations of 0. tuberculata on prairie dogs were also
disappointing. While a few fleas survived for 21-24 days on the prairie dogs, it became clear that selfsustaining populations were not possible under our conditions. Our lack of success was most likely
due to our inability to properly mimic natural burrow conditions required by fleas (constant
temperature and high humidity). We attempted to simulate burrow conditions by attaching insulation
to each nest box (to maintain temperature), and by placing a screen-covered petri dish of moist
vermiculite into the flea refuge (to increase humidity). We were able to keep temperatures fairly
stable, but were not able to maintain high relative humidity within the nest boxes.
Survival and reproduction of 0. montana in the insectary has been high. We will use 0.
montana in future experiments investigating flea control in captive prairie dogs.
Flea Control In Prairie Dogs
In the pilot study we observed no adverse affects with any of the lufenuron dosages. Previous
researchers have shown lufenuron to be efficacious for controlling fleas in cats and dogs when serum
concentration is 50-100 parts per billion (ppb) (C. Parks, Pers. comm.). Our results indicate that, as
expected, baseline samples contained no lufenuron, but that one day after dosing, blood concentration
was at or above efficacious levels at all treatment levels. After one week, blood concentrations had
decreased considerably; serum concentration in the animals dosed with 20 mg/kg and 60 mg/kg had
fallen below the efficacious level, while the concentration in the animal fed 300 mg/kg remained well
above the efficacious level at 220 ppb. Analyses of remaining blood samples are pending.

�79

In January 1999, we performed the experiment titled "Bioavailability oflufenuron administered
orally to captive white-tailed prairie dogs". All prairie dogs except for two non-torpid group animals
ingested &gt;95% of their bait within 18 h; all remaining bait was removed and weighed after 18 h. We
observed all prairie dogs twice daily (8:00 am. and 4:00 p.m.) during the experiment for overall health
and to quantify length of torpor bouts. Animals that were torpid for two consecutive observations were
considered to have been torpid the entire time between observations, unless a small amount of sawdust
placed on the back of torpid animals had been displaced. Animals that were torpid at one observation
time then awake the next were considered to have awakened at the midway point between
observations. Torpid-group animals found hibernating were allowed to remain torpid, while non-torpid
group animals were awakened if found hibernating. All torpid animals were awakened prior to
anesthesia and blood collection. The duration of the study was 1512 hours; torpid group animals were
torpid for an average of 406 h (range= 0 - 936 h), while non-torpid group animals averaged 7.5 h
torpid (range= 0 - 36 h).
We detected no detrimental effects of lufenuron in any prairie dog, nor were any animals
harmed by repeated anesthesia and blood collections. HPLC analysis for blood lufenuron
concentrations is pending.

LITERATURE CITED
Hink, W. F., M. Zakson, and S. Barnett. 1994. Evaluation of a single oral dose oflufenuron to control
flea infestations in dogs. Am. J. Vet. Res. 55:822-824.
Palma, K. G., S. M. Meola, and R W. Meola 1993. Mode of action of pyriproxifen and methoprene
on eggs ofCtenocephalides felis. J. Med. Entomol. 30:421-426.
Wild, M. A 1998. Monitoring and managing disease in black-footed ferrets. Colorado Div. Wildl.
Res. Rep., 0880-1, Jul 1997 -Jun 1998, Fort Collins.
Wild, M. A 1999. Animal and pen support services for mammals research. Colorado Div. Wildl.
Res. Rep., 8160-1, Jul 1998 - Jun 1999, Fort Collins.

25
20
uQ,)

~ 15

ro

U)

'Q,)

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E
~

z

5

. . . .. . . .
1997-W

......

1997-S

1998-W

■

••

1998-S

1999-W

Sample period
8 CDV positive

□ CDV negative

I

Fig. 1. Prevalence of exposure to canine distemper virus (CDV) in coyotes from the Little Snake Management
Area, Colorado, from winter 1997 through winter 1999. All positive coyotes were adults with the exception
of one juvenile in summer 1998. Data from winter 1997 (age class unknown) provided by M. Albee.

�80

A

20

15

....
Q)

e 10
::J

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0+-------~1997-W

1997-S

1998-W

1998-S

1999-W

Sampling period

B

20

15

....

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Q)

:::,

z

5

1997-W

1997-S

1998-W

1998-S

1999-W

Sampling period

I mPlague-Pos £3 Plague-Neg I
Fig. 2. Prevalence of exposure to plague in coyotes (A= juveniles~ B = adults) from the Little Snake Management Area, Colorado, from winter 1997 through winter 1999. Data from winter 1997 (age class unknown)
provided by M. Albee.

�81

ATIACHMENT I

HUSBANDRY PROTOCOL FOR CARE OF CAPTIVE BLACK-FOOTED FERRETS
AT THE LIITLE SNAKE MANAGEMENT AREA
Pen Construction
Breeding pens will be constructed over established prairie dogs towns. If an active prairie dog
colony is not present, prairie dogs from plague-free areas will be reintroduced to the pen site prior to
construction. Individual pens will be about 1500-5000 ft2 and constructed in clusters of four (four-plex
design). Generally, females will be housed in three of the pens and a male in the fourth pen. Each pen
will contain a vault capable of holding a buried insulated wooden nest box (about 12" x 20" x 16"),
which will be covered with a roof to provide shade and to keep runoff away from the nest box. In the
females' pens, the vault will be contained a sub-enclosure, or whelping pen, about 100 ft2 in size.
A perimeter fence will be constructed around each four-plex or group offour-plexes. Tubing
and traps will be placed at intervals along the fence to protect and capture potential escapees.
Additionally, prior to initial introduction of breeding-age ferrets, the burrows will be checked using a
"smoke test" and then radio-collared ferrets will be placed in the pens to further check pen sec~ty:
Site Security
Breeding pens will be located in a remote area with access limited to authorized personnel.
Visitors will be allowed only on a limited basis and when accompanied ~y-site personnel. Human
activity near the pens will be limited strictly to ferret husbandry and management practices. No_dogs
will be allowed in the pen area Use of motorized vehicles in the pen ar~a, will be minimized. The
perimeter fence will serve to contain escaped ferrets and as a deterrent to entrance of wild and feral
carnivores; however, other means of carnivore control (nonlethal and lethal) may be necessary to
protect ferrets.
Biosafety protocols will include the use of site specific coveralls and boots by personnel
handling ferrets or entering ferret pens. Treatment of shoe soles with a bacteriocidal/virucidal solution
(e.g., Roccal-D) may substitute for designated footwear. Personnel will not enter ferret pens or handle
ferrets if they are experiencing flu symptoms (fever, chills, body aches, respiratory signs); caretakers
with cold symptoms should wear a mask and gloves when working around ferrets. Ideally, caretakers
should receive flu shots annually. Only prairie dogs from the immediate vicinity of the pen site or those
completing quarantine-will be provided to ferrets. Personnel will not handle carnivores or prairie dogs
( except those completing the quarantine period) during the work day prior to entering the pen site
unless they shower and change clothes. Pets of site personnel should be vaccinated annually against
canine distemper.
General Husbandry
Ferrets will be checked daily at dawn or dusk by trained caretakers. Caretakers should
minimize contact with ferrets, but should observe ferrets directly or with binoculars to assess health
status daily. Abnormalities will be noted in animal records and, if necessary, the attending veterinarian
notified. If a ferret is not observed (directly or via sign, e.g., consumed food) for 3 consecutive days, a
trap (attached to a nest box via tubing) will be placed in the pen. Traps will be checked at intervals
appropriate to assure that the ferret is not adversely affected by temperature, weather, or restraint time

�82

(generally, every 2-6 hr). Trapped ferrets will be weighed and examined grossly. Additional
examination and treatment will be administered if necessary under the direction of the attending
veterinarian. Body weights will be obtained monthly (and anytime the ferret is handled for other
reasons) to monitor health status and to evaluate feeding programs. Ferrets will be trapped, weighed,
briefly examined, and released qack to the pen. Transponder function will be checked at least once
monthly and transponders will be replaced (with the ferret under anesthesia) if needed.
Nest boxes will be provided only during periods when the ferret is confined to the whelping
cage, e.g .. , the breeding and whelping period or during required confinement to prevent escape or
enhance treatment. Nest boxes will be cleaned every other day ( excepting during breeding period
when male and female are housed together and immediately prior to and following parturition) using
pen-specific instruments, bedding, and trash can when kits are present or if a contagious disease is
suspected. Wood shavings (not cedar) will be placed about 3-4 inches deep on one side of the nest box
and about l inch deep of al phi-dry will be placed on the other side. A minimum-maximum
thermometer will be placed on the roof of one nest box in each four-plex. Temperatures will be
checked during nest box cleaning or daily during periods of extreme weather. Modifications to the nest
box insulation may be needed if temperatures in the nest box are extreme.
Maintenance diet will include live prairie dogs supplemented with frozen prairie dog and rabbit
carcasses, hamsters, and dry ferret food (Totally Ferret). Dry ferret food will be used only a
supplement if insufficient supplies of prairie dogs are available as food. Dry ferret food will not be
provided as a sole feed source, but as a supplement to the meat diet. Prairie dogs will be collected,
quarantined, and processed as described in the protocol by Marinari and Williams (1998). Rabbits will
be procured from breeders and processed as prairie dogs; however, additionally the head and kidneys
will be removed. Dry feed will be stored in rodent-proof containers prior to feeding. Whenever
possible, live prairie dogs will be provided to ferrets; however, we will avoid offering large, aggressive
prairie dogs and any prairie dog surviving &gt; 3 days will be trapped and removed from the ferret pen.
These prairie dogs will be euthanized and fed as meat. Female ferrets will be provided with. an average
of 100 g feed/day and males will receive 125 g feed/d; however, ferrets may not be provided fresh feed
daily (e.g., if a 500 g prairie dog is provided). Amount of feed provided to individuals will vary based
on assessment of physical condition. Frozen prairie dogs will be thawed about 48 hr in a refrigerator
prior to feeding. Feed may at times be provided in a trap (with the doors wired open) for training
purposes. Unconsumed meat left in the pen will be discarded after 24 hr. Water will be injected into
prairie dog carcasses during the winter or when available water is minimal. A water source will be
provided, but may be frozen during the winter. If snow cover is not present, fresh water will be
provided daily. Waterers will be cleaned weekly or more frequently if needed. Records will be
maintained to document feed offered and estimate feed consumed by ferrets in each pen.
During gestation, whelping, and lactation, modifications of the maintenance diet will be
required. About 2 wk following breeding, feed will be increased 1.33 times the base diet. About 4 wk
following breeding, feed will be increased to I .66 times the base diet. From whelping to weaning, feed
will be offered ad libitum. Ideally, only live prairie dogs and hamsters should be offered, but if
unfeasible, ferrets will be supplemented with prairie dog or rabbit meat or dry feed initially, then when
kits begin to kill prey, only live prairie dogs (about 150 g/ferret) will be offered until release.

as

Breeding Management
Adult males and females will be housed in separate pens except during the breeding period.
The breeding period will vary annually based on weather, so multiple handling of ferrets may be
required to assess reproductive status. Beginning about 1 February, or when signs of breeding
behavior are noted (increased digging, marking, etc), males will be trapped weekly for breeding

�83

soundness examination. With ferrets restrained in handling cages, the testes will be measured (width,
depth) and tested for firmness. After testes are firm for 1 mo, males will be considered ready for
breeding. When males are showing signs of reproductive activity (testes firm and about &gt;20 mm width
or depth), females will be trapped for signs of estrous. The females will be restrained in a handling
cage and the vulva measured. If the vulva is small (&lt;2 mm x 3 mm), the female will be trapped and
measured again in about 7 days. If the vulva is beginning to swell, the female will be handled again at
3 day intervals to monitor the trend in change of the vulva Vaginal cytology may be used when the
vulva shows a trend toward increasing size (generally to about 4 x 7 mm). When vaginal cytology
indicates &gt;90% comified cells, we will wait 5 days, then introduce the male to the females whelping
pen (male and female will be restricted to whelping pen). The male and female will be monitored
remotely using a pen camera or by watching from a distance and listening for vocalizations to
determine compatibility and breeding activity. Breeding activity is assumed if chuckling is heard,
copulation observed, and/or a neck stain is present on the female. In this case, the male will be
removed 3 days after introduction. Function of the females transponder will be checked after
copulation and replaced if necessary. If breeding activity is not observed, the male may be left with the
female up to 7 days; however, if the male and female show no interest in one another (in separate areas
of pen, no neck stain), the male may be removed after 24 hr and a new male introduced 1-2 days later.
The male will be removed immediately if it shows aggressive behavior that threatens the female.
Males will be given 3-4 days rest after each breeding. A male may be brought from a separate fourplex to breed a female if the resident male is incompatible or unavailable. The female will be trapped
7-10 days following suspected breeding for vaginal cytology. If cells remain highly cornified, breeding
likely did not occur and the female will be re-paired. Records will be kept on results of breeding
soundness exams, vaginal cytology, pairings, and breedings.
The female will be restricted to the whelping area beginning 35 days post-breeding. A waterer
will be placed in the whelping area and bedding material placed in the nest box. Vitamin K will be
supplemented to the females diet at the rate of 5 drops/day from 5 days_prior to whelping to day 35
following whelping. On day 42 post-breeding, we will begin listening daily for sound from the nest
box. If sounds are heard, the animals will be left undisturbed for 5 days. On day 5, the nest box will
be cleaned using pen-specific bedding, instruments, and trash can. The nest box will be cleaned again
on day 10 and the door to the whelping area opened. The nest box will be cleaned at 2 day intervals
until the female moves the kits from the nest box. Prairie dogs and hamsters will be the only feed
offered until kit release. If females do not whelp a second breeding will be attempted. About 10 days
following the calculated whelping date we will again begin monitoring vaginal cytology. When 90%
cornified cells are present, a male will be paired with the female as described previously.
Kits will be trapped on day 90 for physical examination, marking with transponders, and
vaccination against canine distemper virus (if vaccine available). Kits will be trapped subsequently for
booster vaccines if needed.
Care of Sick Animals
Health status of ferrets will be checked daily (or as possible). Healthy ferrets should be active,
consume feed, have a clean haircoat, and be free of physical abnormalities (lameness, cuts, swellings,
etc.). The pen floor should also be examined for abnormal feces, blood (not from prey item), vo,mit,
etc. Any abnormalities will be noted on the daily observation forms and the attending veterinarian
notified. If there is any likelihood that the condition could be contagious, the caretaker will disinfect
their hands and boots and ideally change coveralls before proceeding to other pens. If an animal is
known to be sick, that animal will be cared for last (or by an alternative caretaker) using good
sanitation techniques and any equipment used in the pen will be disinfected. Sick animals may be

�84

confined to the nest box and whelping pen to aid in care and treatment. Alternatively, critically ill
animals may be placed indoors in quarantine for treatment. If coccidiosis is suspected (lack of appetite,
mustard-like feces) and the attending veterinarian cannot be reached, treatment can be initiated using
50 mg/kg Albon orally on day 1 followed by 25 mg/kg Albon orally daily for about 7 days. Fresh
water must be available at all times when animals are treated with Albon (parenteral fluid therapy may
be needed as well). Specimens (feces, discharges) should be obtained opportunistically if possible
(using good sanitation practices) and placed in a whirlpack and refrigerated until further instructions
are obtained. If a ferret is found dead, it should be double or triple bagged (e.g., in a ziplock or trash
bag), labeled with animal ID, pen, and date and refrigerated. The carcass will be boxed in a cooler and
submitted via overnight Federal Express to Dr. Beth Williams, Wyoming State Veterinary Laboratory
for necropsy. The facility supervisor, attending veterinarian, and BFFCC should be notified for further
instructions. Prairie dogs found sick or dead in the pen area should also be collected and submitted for
necropsy. Caretakers should wear gloves and practice good sanitation measures whenever dealing
with sick or dead animals.
Release
We will attempt to maintain 20 breeding animals of various ages: ideally, 5 female and 1 male
I-year-olds, 5 female and 2 male 2-year-olds, 5 female and 1 male 3-year-old, and 1 male 4-year-old.
Animals will be redistributed to pens each fall to maximize diversity in breeding pairs. Older adults
and excess young of the y~ar will be released each fall when young are about 20 weeks of age. Prior to
release, all ferrets will be fitted with radiocollars.

�115
Colorado Division of Wildlife
Wildlife Research Report
July 2000

JOB PROGRESS REPORT
State of ----~~=~-----Colorado
Project No.

W-153-R-13

Mammals Research

Work Package No. ___
0_88_0_ _ _ _ _ __
Task No.

1

Black-footed Ferret Recovery
Monitoring and Managing Disease in
Black-footed Ferrets

Period Covered: July. 1, 1999 - June 30, 2000.
Authors: M.A. Wild and K. T. Castle
Personnel: E. Wheeler, E. Schmal, and S. Kasven.
\

)

ABSTRACT

\

)

The black-footed ferret is a federally listed endangered species in the United States. Black-footed ferrets
have been extirpated from Colorado, but were scheduled to be reintroduced to Moffat County, Colorado in
1999. However, due to high plague activity and low prairie dog densities at the Little Snake Management
Area (LSMA), black-footed ferret reintroduction was postponed indefinitely at the site. The secondary site
at Coyote Basin, Utah was readied and reintroduction of ferrets was performed there in 1999. The Wolf
Creek site in Moffat County, Colorado is also being readied for reintroduction of ferrets, likely in 2001.
Our work in support of black-footed ferret reintroduction can be sub-divided into three broad sections:
disease monitoring in the proposed release areas in Colorado, care of black-footed ferrets, and flea control
as a tool to manage sylvatic plague in prairie dogs and black-footed ferrets. Disease monitoring was
performed using collection of coyotes from LSMA in July 1999 and from the Wolf Creek site in February
2000. Two potentially devastating diseases, canine distemper and plague, are present at LSMA. Although
prevalence of positive titers to canine distemper virus (CDV) in coyotes ·have been relatively low over the
last 3 years (:S33%), the prevalence of positive titers to plague (Yersina pestis) have been high (up to 89%
positive). Titers were present in both adult and juvenile animals, suggesting ongoing plague activity in at
least some sections of the management area. Samples collected from coyotes at the Wolf Creek site
indicated substantially lower disease activity than at LSMA. Prevalence of positive titers to plague and to
CDV was 7% of samples collected in February 2000. In general, captive black-footed ferrets maintained at
the LSMA breeding and preconditioning pens remained healthy. One ferret died and another was presumed
dead in the burrow system after a severe hailstorm. Of 13 kits born at the pens in spring 1999, 12 survived
to weaning in fall 1999. These 12 kits in addition to 50 other black-footed ferrets were released at the
Coyote Basin site in fall 1999. Twenty ferrets were maintained in the pens overwinter and produced 11
kits in spring 2000. We summarized research results and presented a paper titled "Dose titration and
safety of lufenuron fed to captive white-tailed prairie dogs (Cynomys leucurus)" at the 2000 meeting of the

�116
Wildlife Disease Association, Jackson, Wyoming. We also performed a trial to test' the efficacy of
lufenuron in controlling fleas on captive prairie dogs. One week post-dosing, fleas that fed on prairie dog
treated with 500 mg/kg lufenuron prcxiuced a lower proportion (p &lt; 0.05) of viable rggs than those fed on
control prairie dogs (mean 0.16 vs. 0.39, respectively). However, the proportion of viable eggs prcxiuced
during week 2 post-dosing was low for each group (0.24 treatment vs. 0.17 control). By week 4 postdosing, egg prcxiuction had fallen to nearly zero in each group; however, the three eggs produced by fleas
fed on treated prairie dogs were all viable. Although further, similarly controlled investigation is
warranted, preliminary results suggest that given current techniques, the likelihood of lufenuron limiting
fleas populations and breaking the plague cycle is not extremely promising.

�117

MONITORING AND MANAGING DISEASE IN BLACK-FOOTED FERRETS
Margaret A. Wild and Kevin T. Castle

P. N. OBJECTIVES

1. Monitor disease activity threatening survival of black-footed ferrets reintroduced into the Little Snake
Management Area (LSMA).
2. Develop techniques to manage plague in the LSMA using insect growth regulators applied orally to
prairie dogs.
SEGMENT OBJECTIVES

1. Provide ;ete~ care to captive and reintroduced black-footed ferrets.
2. Monitor and manage plague activity in LSMA.

METHODS AND MATERIALS

Carnivore Disease Survey
Infectious diseases can severely impact the success of black-footed ferret (}Juste/a nigripes) reintroduction
efforts. As part of the black-footed ferret reintroduction protocol, we monitored disease activity in
carnivores at proposed ferret reintroduction sites: in July 1999 at the Little Snake Management Area
(LSMA), Colorado and in February 2000 at the Wolf Creek Management Area (WCMA), Colorado.
Coyotes (Canis latrans) were collected for post-mortem examination and samples collected as described in
the Program Narrative (Wild and Castle 1998).
Black-footed Ferret Reintroduction and Veterinary Care
I assisted in preparation of the black-footed ferret allocation request submitted to the US Fish and Wildlife
Service by the Colorado-Utah black-footed ferret recovery working team in 2000. I provided veterinary
care and consultation on health matters for captive black-footed ferrets and black-footed ferret releases.
Animal care was performed in accordance with the established protocol (Wild and Castle 1999).
Flea Control In Prairie Dogs
We completed the experiment "Bioavailability of lufenuron administered orally to captive
white-tailed prairie dogs (Cynomys leucurus)" and performed a follow-up experiment "Efficacy of
lufenuron for the control of fleas in white-tailed prairie dogs (Cynomy leucurus)". These studies were
outlined in Wild and Castle 1998. The detailed study plan for the lufenuron bioavailability study and
e:fp.cacy trial are reported in Wild and Castle 1999 and in Attachment 1, respectively.

�118
RESULTS AND DISCUSSION
Carnivore Disease Survey
With the assistance of USDA Wildlife Services and the Bureau of Land Management (BLM) we collected
16 coyotes from the LSMA between 26-30 July 1999 and 14 coyotes from the Wolf Creek site on 8-9
February 2000. Coyotes were collected using a combination of calling and aerial gunning. Further
collections were not possible due to weather constraints and aircraft availability. No lesions indicative of
active disease were noted on gross examination of carcasses.
Of the coyotes collected from the LSMA, 31 % (5/16) had positive titers to plague (Fig. I) using the
standard HA/HI test while one additional coyote was positive using the ELISA test. Interestingly, all
juveniles sampled this summer (n = 9) were negative to plague. Because the juvenile coyotes have
consumed (sampled) prairie dogs from this summer only, lack of exposure may indicate that the prevalence
of plague in prairie dogs in the area is declining. If this is the case, titers in adults would likely be from
exposure in previous years. Alternatively, the prey base of the coyotes may have shifted to species that are
less commonly infected with plague (e.g., rabbits) if the density of prairie dogs has been greatly reduced by
plague. Forty-three percent of coyotes sampled (6/14 usable samples) had positive titers to tularemia. In
contrast to plague, all positive titers to tularemia were observed in juvenile coyotes. As previously
observed, tularemia appears to elicit a serologic response of short duration in coyotes. The impact of
tularemia on black-footed ferrets and prairie dogs is unknown and warrants investigation. A titer to canine
distemper virus (CDV) was found in only one of 14 serum samples tested (Fig. 2).
Samples collected from coyotes at the Wolf Creek site indicate substantially lower disease activity than at
LSMA. A 9-year-old male coyote had positive titers to plague and to CDV, but all other coyotes (n = 13)
were negative to plague and CDV (7% positive; Fig. 3). The adult male and one additional juvenile coyote
also had titers to tularemia (14% positive).
Black-footed Ferret Reintroduction and Veterinary Care
In general, captive black-footed ferrets maintained at LSMA remained healthy. One adult female was
treated for an apparent mite infection and secondary bacterial pyoderma. Unfortunately, samples to
confirm this diagnosis could not be collected prior to treatment; however, the ferret responded quickly and
completely to therapy with ivermectin and amoxicillin. Additional cases of crusty skin have been
successfully treated with ivermectin but confirmation of the etiology has not yet been made. A I-yr-old
male was found dead and a 4-yr-old female was missing and presumed dead after a severe hailstorm.
Necropsy results revealed death from blunt trauma. The death(s) occurred in the new pen complex where
shallow burrow systems may have been flooded forcing ferrets to the surface in the severe weather. To
avoid this problem in the future, additional above ground shelter will be provided. Of 13 kits born at the
pens in spring 1999, 12 survived to weaning in fall 1999. One kit disappeared and is presumed dead in the
burrow system.
Based on results of carnivore disease monitoring over the past 3 years and prairie dog inventories
performed in summer 1999, LSMA was determined to be currently unsuitable habitat for the release of
black-footed ferrets. Prairie dog inventories performed by Utah Division of Wildlife showed insufficient
densities of prairie dogs to support black-footed ferret reintroduction. As a result, ferrets were not released
into LSMA but instead were released into Coyote Basin, Utah. Continued monitoring will determine when
(if) LSMA can support reintroduction of black-footed ferrets. A secondary site in Colorado, (Wolf Creek)
is also being readied for reintroduction of black-footed ferrets in fall 2000 or 2001.

_ _,

�119
The 12 kits produced onsite, in addition to three 1-yr-old males, and five 3-yr-old females from the LSMA
pens were released at Coyote Basin in November 1999. Additionally, 19 kits and five 3-yr-old females
from other captive breeding sites were pre-conditioned at the LSMA prior to release at Coyote Basin. The
reintroduction was further supplemented with 28 ferrets released immediately upon arrival from other
captive breeding sites without pre-conditioning at LSMA. Prior to release, ferrets were trapped for routine
examination, treatment, and identification (Wild and Castle 1999) and a health certificate was issued for
each individual. All appeared healthy except for the presence of ectoparasites (ticks, mites, fleas).
Individual ferrets were treated with ivermectin and pen dusting was advised.
In an attempt to meet our ideal age and sex structure of captive black-footed ferrets (Wild and Castle
1999), we retained seven ferrets and supplemented the population with 13 additional ferrets from other
captive breeding facilities. Seven black-footed ferrets (five 1-yr-old females and two males) were retained
in captivity at the LSMA pens. In November 1999, six adult females,'three female kits, and four male kits
were added to this breeding group bringing the total number of ferrets at the LSMA pens to 20. Ferrets
were maintained under the standard care protocol (Wild and Castle 1999). Females were paired with males
in spring 2000, and four litters resulted. One litter was apparently consumed by the female when about 1
day of age. The other three litters yielded 11 kits.
Flea Control In Prairie Dogs
We presented results of the lufenuron dose titration study at the 2000 meeting of the Wildlife Disease
Association, Jackson, Wyoming. The abstract of that presentation read:
DOSE-TITRATION AND SAFETY OF LUFENURON FED TO CAPTIVE WHITE-TAILED PRAIRIE IX&gt;GS (CYNOMYS

LEUCURUS)

KEVIN T. CASTLE Colorado Division of Wildlife, 317 W. Prospect St. Fort Collins, CO, 80521,
MARGARET A. WILD, Colorado Division of Wildlife, 317 W. Prospect St. Fort Collins, CO, 80521, and S.
CRAIG PARKS, Novartis Animal Health, P.O. Box 26402, Greensboro, NC 27404.
Plague is a zoonotic disease that impacts populations of prairie dogs (Cynomys spp.) and other species, such as
black-footed ferrets, that rely on them for food and shelter. Yerstnia pestis, the etiological agent of plague, is
transmitted primarily by the bite of an infective flea. Recently developed compounds used to control fleas in
pet animals offer a promising alternative to insecticide dusts for the control of fleas in wild rodents.
Lufenuron is a lipid-soluble insect growth regulator with ovicidal and larvicidal activity. Lufenuron is
efficacious for controlling fleas in cats and dogs at blood concentrations above 50-100 parts per billion
(ppb). A single oral dose oflufenuron has been shown to be effective in controlling the cat flea (Ctenocephaltdes
felts felts) for at least 30 days in treated cats and dogs. To date, there have been no studies conducted to detennine
the duration oflufenuron blood concentrations in any prairie dog species. We compared lufenuron blood
concentrations in white-tailed prairie dogs (C. leucurus) during periods of activity (nontorpid group) and
hibernation (torpid group) during January-March 1999. We hypothesized that if high serum concentrations
of lufenuron could be maintained over winter during hibernation or for &gt; 1 mo in active prairie dogs, the
compound may be effective for use in breaking the plague cycle. Thirty captive WTPD were fed 300
rrig/kg lufenuron; half the animals were allowed to become torpid, while the other half were kept awake.
All animals remained healthy throughout the 9 week study period. Prairie dogs in the active group gained
weight, while those in the torpid group lost weight over the 9 weeks. Blood was drawn from each animal
prior to dosing, one week after dosing, then every other week until week 9 post-dosing. Serum was
harvested and tested by HPLC for lufenuron concentration. Blood lufenuron concentration did not differ
between the groups one week post-dosing. Concentration in both groups decreased over time, but the

�120
concentration in torpid animals declined at a more gradual rate; after weeks 3, 5, and 7, lufenuron levels in
torpid WfPD were significantly higher than levels in nontorpid WfPD. After nine weeks, blood levels
were again similar, and had approached the limit of detection (10 ppb). Blood levels in nontorpid WfPD
declined to &lt;50 ppb after 3 weeks, while levels in torpid WfPD declined to &lt;50 ppb after 7 weeks. Future
studies will be required to determine efficacy of lufenuron in controlling fleas on WfPD. If effective blood
concentrations are similar to dogs and cats, however, frequent dosing would be required to control flea
numbers on prairie dogs and thus break the plague cycle.
Results from this experiment indicated that blood concentrations of lufenuron did not reach initial levels as
high as anticipated, nor were the concentrations maintained above 50 ppb for as long as anticipated (Fig.
4). The most likely cause of these low concentrations was poor absorption of the drug by prairie dogs.
lbis may be due to the difference in gut morphology between rodents and carnivores. Alternatively, other
aspects of pharmacokenetics may have been responsible for the low serum levels in prairie dogs despite
dosing at rates 10-30 times higher than those recommended for cats and dogs, respectively.
We followed up the dose titration experiment with an experiment to test the efficacy of oral lufenuron to
control fleas on captive prairie dogs. Based on data from the bioavailability study, we increased the
lufenuron dose to 500 mg/kg. Serum samples from the study have been submitted for lufenuron assay.
Results are pending. Interpretation of efficacy results will rely on these serum lufenuron levels; however,
we were able to make some preliminary comparisons between performance of fleas fed on treatment and
control prairie dogs. One week post-dosing, fleas that fed on treated prairie dog produced a lower
proportion (p &lt; 0.05) of viable eggs than those fed on control prairie dogs (mean 0.16 vs. 039,
respectively). Unfortunately, the proportion of viable eggs produced during week 2 post-dosing was low
for each group (0.24 treatment vs. 0.17 control). By week 4 post-dosing, egg production had fallen to
nearly zero in each group; however, the three eggs produced by fleas fed on treated prairie dogs were all
viable. We are uncertain of the cause of the dramatic reduction in egg production and viability observed
during the course of the experiment. Anecdotal reports suggest that flea production may be influenced
seasonally (or at least cyclically) despite attempts to maintain controlled environmental conditions in the
insectary (Metzger, Pers. Comm.). Regardless, it is unfortunate that serum levels oflufenuron decreased
more rapidly than we had expected and that data did not support the hypothesis that lufenuron would be an
effective means to significantly reduce flea production over the summer. Although further, similarly
controlled investigation is warranted, preliminary results suggest that given current techniques, the
likelihood of lufenuron limiting fleas populations and breaking the plague cycle is not extremely promising.
Therefore, experiments into efficacy of controlling flea infestations in simulated burrow environments and
in the field (described in Wild and Castle 1998) will not be performed.

LITERATURE CITED
Wild, M.A. and K. T. Castle. 1998. Monitoring and managing disease in black-footed ferrets. Colorado
Div. Wildl. Res. Rep., 0880-1, Jul 1997 - Jun 1998, Fort Collins.
Wild, M.A. and K. T. Castle. 1999. Monitoring and managing disease in black-footed ferrets. Colorado
Div. Wildl. Res. Rep., 0880-1, Jul 1998 - Jun 1999, Fort Collins.

�121
Attachment l
Kevin T. Castle, Margaret A. Wild, and S. Craig Parks
Colorado Division of Wildlife
Foothills Wildlife Research Facility (KTC and MAW)
Novartis Animal Health, Greensboro, NC (SCP)

Introduction
Black-footed ferret (Mustela nigripes) recovery plans call for the reintroduction of ferrets to sites
characterized by the presence of viable populations of prairie dogs (Cynomys spp.), which provide food and
shelter for ferrets. Unfortunately, prairie dogs inhabiting many potential reintroduction sites carry fleas
that can serve as vectors ofYersinia pestis, the causative agent of plague (Ubico et al, 1988). Prairie dogs
and ferrets are both highly susceptible to plague (Barnes, 1993; Williams et al., 1994) so the chances of
successful ferret reintroduction will be enhanced if the numbers of fleas infesting a prairie dog colony can
be significantly reduced.
Lufenuron is a benzoylphenylurea derivative which inhibits formation of chitin in the exoskeleton of insects
(Cohen, 1987). A single oral dose oflufenuron has been shown effective in controlling the cat flea
(Ctenocephalides felts felis) for at least 30 days in treated cats (Blagburn et al., 1994) and dogs (Hink et
al., 1994; Blagburn et al., 1995). No studies on the efficacy oflufenuron have been conducted with prairie
dogs; however, Davis ( 1997) reported a significant reduction in fleas on free-ranging ground squirrels
(Spermophilus beecheyi) that had been treated with lufenuron.
We are performing a series of experiments to test the applicability oflufenuron to control fleas in captive,
and ultimately wild, white-tailed prairie dogs (Cynomys leucurus). Thus far in pilot studies we have
determined standard husbandry, maintenance, and handling protocols for captive prairie dogs and
determined a test dose oflufenuron based upon a bioavailability study. We have also attempted to
establish an insectary colony of a flea species (0ropsylla tuberculata) that naturally infests prairie dogs
and their burrows. Oropsylla fleas are among the most common prairie dog fleas, and have been
implicated in the transmission of plague in prairie dogs (Ubico et al., 1988). Fleas of this genus are nest
fleas that infest the host only to obtain a blood meal. At other times the fleas select microenvironments
within in the burrow system that are conducive to successful reproduction and survival. In pilot studies we
were unable to develop methods to successfully maintain and produce self-sustaining populations of 0.
tuberculata in an insectary. However, a related species, 0. montana, which naturally infests ground
squirrels (e.g. Spermophilus beechyi) has been successfully maintained in the insectary using methods of
M. Metzger and K. Gage (pers. comm). These fleas will feed on prairie dogs and successfully reproduce
after ingesting a blood meal. Because of its similarity to 0. tuberculata, we will use 0. montana as a
model to determine if flea reproduction can be controlled in lufenuron-treated prairie dogs.
A chambered-flea system has been used to test on-host viability and fecundity of fleas on cats (Thomas et
al. 1996) and laboratory mice (D. Engelthaller, pers. comm.). In this system, fleas are contained in a
chamber attached to the host, and can obtain a blood meal through a mesh screen. This system has several
advantages over other methods of artificial infestation. First, because a known number of adults can be
placed into the chamber, flea mortality is easily noted, and survivorship can be determined. Second, sex
ratios can be adjusted to maximize egg production. Third, eggs can be recovered readily, to determine
viability. Fourth, the environment in the chamber will be warm and humid, and therefore conducive to
adult and egg survival. Finally, fleas will not be able to leave the prairie dog, and therefore will not be able
to infest caretakers or other animals.

�122
In this study we will: 1) develop techniques for artificially infesting white-tailed prairie dogs with
chambered populations of fleas, 2) test the flea control efficacy oflufenuron fed to white-tailed prairie dogs
artificially infested with fleas, and 3) compare efficacy of flea control with serum lufenuron levels. Our
working hypothesis is that fleas which feed on lufenuron-dosed prairie dogs will have reduced survival of
eggs and larvae compared to fleas which feed on control animals that receive no lufenuron.
Methods
Prairie Dog Maintenance
We will use 31 captive white-tailed prairie dogs maintained at the Foothills Wildlife Research Facility in
Ft. Collins in our experiment. Prairie dogs will be housed singly (if used in experiments) or in pairs (if
used for flea colony maintenance) in custom-designed cages (100 cm x 500 cm x 600 cm; Wild and Castle
1998). Prairie dogs will be observed daily, and will have ad libitum access to Teklad Rodent Blocks and
water. Windows will provide a natural photoperiod, and a combination of timed heaters and air
conditioners will be used to keep ambient temperature between 10 and 25° C.
Twenty prairie dogs (10 males and 10 females) will be blocked by sex and randomly divided equally into a
treatment group and a control group for the experiment. The treatment group will receive lufenuron while
the control group will not. Because all animals cannot be housed in one building due to space limitations,
the groups will be split evenly between two separate but similar buildings, to help control for any interbuilding differences (e.g. temperature, humidity) that may exist. The sample size of20 prairie dogs will
allow us to detect a ~91 % reduction in the number of eggs that successfully hatch in the treated group
given alpha = 0.10 and beta = 0 .90. An additional 11 captive prairie dogs will be maintained under similar
conditions, but will not participate in the experiment. Instead, they will be used in the maintenance of the
flea colony (see below).
Lufenuron Dosing
Prairie dogs in the experimental group will be fasted for 24 h prior to dosing; water will be available during
the fast. After the fasting period (day 0), each experimental animal will be weighed, then offered a bolus
dose oflufenuron (300 mg/kg body mass). Lufenuron will be mixed thoroughly in approximately 10 g of
highly palatable bait (ground rat chow and molasses); control animals will receive bait only. We
previously determined that a majority of fasted prairie dogs consume about 90-95% of their dose in less
than 12 h. We will observe the progress of bait ingestion in each animal to determine when the dose is
ingested. Remaining bait will be removed after 24 h. We will weigh the bait/lufenuron mixture before and
after the prairie dogs are dosed, in order to calculate the actual dose ingested. After dosing, normal feeding
will resume.
Flea Infestation
An initial stock of laboratory-reared, disease-free fleas (0. montana) will be obtained from Dr. Kenneth
Gage at the Centers for Disease Control and Prevention (CDC) in Ft. Collins. Fleas will be housed in 500
ml glass jars containing larva-rearing media, to allow the population to be self-sustaining . Rearing media
consists ofwheast (Red Star Biologicals), dried beef blood (Monfort Biologicals), powdered dog chow, and
sand. Fleas will be maintained in an incubator at about 22-23° C and ~70% relative humidity (M.
Metzger, pers. comm.) to ensure optimal reproduction. A natural photoperiod will be approximated within
the incubator using fluorescent lights and a timer.
Adult fleas must ingest a blood meal in order to reproduce. We will use two methods to provide blood
meals to fleas held in the insectary for propagation of the colony. The first 1:11ethod will follow an
established protocol (Castle and Wild 1998) to provide blood to the adult fleas in each rearing chamber,
using neonatal rodents. Briefly, when fleas are in need of a blood meal (1-2 times per week), we will obtain

�123
neonatal rodents from a private colony. The neonates will be placed into the insectaries with fleas for up to
24 h; previous work has shown that over 80% of the neonates are alive after 24 h. No food or water will
be provided for the neonates, as they are strictly dependent on nursing. After feeding by the fleas, neonates
will be euthanized by an overdose of inhalant anesthetic.
Once per week, for 7 weeks, we will utilize the 11 non-experimental prairie dogs as blood sources, using
the chambered flea technique described below. While the use of neonatal rodents is an efficient, approved
method of providing blood to fleas, neonatal rodents are not always available from private colonies. Prairie
dogs will therefore serve the dual purposes of providing blood meals when neonates are unavailable, and
minimizing the number of neonatal rodents sacrificed.
One week prior to study initiation, and on study days 2, 7, 14, 21, 28, 35, and 42 we will place flea
chambers on experimental prairie dogs. Fleas feeding on treated prairie dogs will potentially be exposed to
lufenuron from this blood meal. W.e will collect 50 adult female and 30 ad~lt male fleas from the insectary
and place them"into a chamber (2.5 cm diameter). Each chamber will be-attached to a prairie dog so the
fleas can obtain a blood meal. To attach the chambers, prairie dogs will be anesthetized using isoflurane
delivered by a vaporizer. Respiration and depth of anesthesia will be monitored. A patch of fur on the
dorsal thorax caudal to the shoulders will be shaved. A flea chamber will be placed on the skin, and taped
into place using Elastikon and Vet-rap. The prairie dog will then be placed in a 30 cm x 20 cm x 20 cm
holding box to recover from anesthesia, and will be monitored while the chamber is attached.
Chambers will remain on each prairie dog for 30 min. At the end of the feeding time, the prairie dog will
again be anesthetized with isoflurane, and the tape and chamber will be removed. Prairie dogs will be
returned to their cages after recovery from anesthesia. Fleas will be observed for evidence of feeding by
observation under a 10-20x ,;nicroscope, and blood-filled fleas will be placed in plastic vials and put into
our insectary for egg recovery. 0. montana fleas typically lay eggs within 2-3 days of a blood meal (M.
Metzger, pers. comm.), so adult dishes will be monitored every day for 7 days to monitor egg production.
Eggs will be removed from the adult dish and placed in new vials inside the insectary; they will be observed
every day for larval emergence. The total number of eggs produced by fleas from each prairie dog will be
recorded, as will the number of larva that emerge each ·day. Unfed adult fleas will be returned to the
insectary (prior to lufenuron dosing) or preserved in alcohol (after lufenuron dosing).
Blood Collection
Concentration of lufenuron in the blood may be an indicator of efficacy of flea control. To determine the
relationship between blood lufenuron concentration and egg viability and larval development, we will
collect 3 ml of blood from each anesthetized prairie dog prior to chamber attachment on each sampling day.
Blood will be collected by jugular venipuncture and placed into a glass vacutainer blood tube without
anticoagulant. Alternatively, ifwe are unable to collect an adequate blood sample peripherally, we will
collect blood from the vena cava or directly from the heart. Although cardiac puncture is considered to be
a safe procedure for collection of large volumes of blood from laboratory rodents (CCAC, 1984), due to
the increased risks involved with cardiac puncture, we will use this technique only to obtain critical
samples. Serum will be harvested and frozen within 4 h of collection. Serum lufenuron concentration will
i&gt;C? determined by HPLC at Novartis Laboratories.
Based on our pilot studies and other literature (Blagbum et al. 1994, 1995; Thomas et al. 1996) we do not
anticipate any prairie dog mortality due to the flea infestations, lufenuron dosing regime or blood collection,
but if a severe allergic reaction or other health problem associated with our procedures occurs, the prairie
dog will be removed from the study and provided veterinary care or euthanized with an overdose of inhalant
anesthetic or barbiturate. A complete post-mortem examination will be performed on any animal that may
die during the experimental period.

�124
Data Analysis
Efficacy of lufenuron will be determined by comparing developmental success of eggs produced by fleas
exposed to treated prairie dogs vs. eggs produced by fleas exposed to control group prairie dogs. These
formulas will be used in efficacy determination:
Developmental success =

number of larvae hatched x 100
number of eggs collected

Percentage efficacy=mean developmental success (control) - mean developmental success (treated) x 100
mean developmental success (control)
Mean developmental success values for eggs collected from prairie dogs at each sampling period will be
analyzed using analysis of covariance, using blood lufenuron concentration at each time step as the
covariate. Group responses will be considered significantly different ifp &lt; 0.10.
Literature Cited
Barnes, A. M. 1993. A review of plague and its relevance to prairie dog populations and the black-footed
ferret. Proceedings of the symposium on the management of prairie dog complexes for the
reintroduction of the black-footed ferret. J. L. Oldemeyer, D. E. Biggins, B. J. Miller, and R. Crete,
eds. 96pp.
Blagburn, B. L., J. L. Vaughan, D.S. Lindsay, and G. L. Tebbitt. 1994. Efficacy dosage titration of
lufenuron against developmental stages of fleas (Ctenocephalides felis felis) in cats. American
Journal of Veterinary Research 55: 98-101.
Blagburn, B. L., C. M. Hendrix, J. L. Vaughan, D.S. Lindsay, and S. H. Barnett. 1995. Efficacy of
lufenuron against developmental stages of fleas (Ctenocephalides felis felis) in dogs housed in
simulated home environments. American Journal of Veterinary Research 56: 464-467.
Castle, K. T. and M.A. Wild. 1998. Protocol for the use of neonatal rodents as a blood source for
insectary-reared fleas. Colorado Division of Wildlife Animal Care and Use Committee Study Plan.
Canadian Council on Animal Care (CCAC). 1984. Guide to the care and use of experimental animals,
Vol. 2. Ottawa, Ont., Canada.
Cohen, E. 1987. Interference with chitin biosynthesis in insects. In Chitin and benzoylphenyl ureas, series
entomologica, vol. 38, J.E. Wright and A. Retnakaran (eds), Dr. W. Junk, Publishers, Boston, pp.3342.
Davis, R. M. 1997. Use of an orally administered insect development inhibitor (lufenuron) as a flea control
agent in the California ground squirrel, Spermophilus beecheyi. Fourth International Symposium on
Ectoparasites of Pets, pp. 31-35.
Hilton, D. F. J. 1971. A method for rearing fleas of ground squirrels. Transactions of the Royal Society of
Tropical Medicine and Hygiene. 66: 188-189.
Hink, W. F., M. Zakson, and S. Barnett. 1994. Evaluation of a single oral dose oflufenuron to control
flea infestations in dogs. American Journal of Veterinary Research 55: 822-824.
Thomas, R. E., L. Wallenfels, and I. Popeil. 1996. On-host viability and fecundity of Ctenocephalides
felis (Siphonaptera: Pulicidae), using a novel chambered flea technique. Journal of Medical
Entomology 33: 250-256.
Ubico, S. R., G. 0. Maupin, K. A. Fagerstone, and R. G. McLean. 1988. A plague epizootic in the whitetailed prairie dogs (Cynomys leucurus) of Meeteetse, Wyoming. Journal of Wildlife Diseases 24:
399-406.
Williams, E. S., K. Mills, D.R. Kwiatkowski, E.T. Thome, and A. Boerger-Fields. 1994. Plague in a
black-footed ferret (Mustela nigripes). Journal ofWildlife Diseases 30:581-585.
Wild, M.A. and K. T. Castle 1998. Monitoring and managing disease in black-footed ferrets. Colorado
Division of Wildlife Program Narrative, Project# W-153-R.

\
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�125

20 ~ - - - - - - - - - - - - - i ■ Plague-Neg&gt;----------~
□ Plague-Pos
15
L.

(1)

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::::,

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5

1997-W

1997-S

1998-W

1998-S

1999-W

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Fig. la. Prevalence of exposure to plague in juvenile coyotes from the Little Snake Management Area,
Colorado, from winter 1997 through summer 1999.

II Plague-Neg

20

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Fig. lb. Prevalence of exposure to plague in adult coyotes from the Little Snake Management Area, Colorado, from
winter 1997 through summer 1999. Data from winter 1997 (age class unknown) provided by M Albee.

�126

25 - . - - - - - - i □ CDV positive II CDV negative

20
t&gt; 15

J

10
5
0
1997-W

1997-S

1998-W

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1999-W

1999-S

Fig. 2. Prevalence of exposure to canine distemper virus (CDV) in coyotes from the Little Snake
Management Area, Colorado,' from winter i 997 through smnmer 1999. All positive coyotes were adults
with the exception of one juvenile in summer 1998. Data from winter 1997 (age class unknown) provided
by M. Albee.
20 , - - - - - - - - - - - , Ill Negative f - - - - - - - ,
□ Positive

15

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Plague

Fig. 3. Prevalence of exposure to plague and canine distemper virus in adult coyotes from the Wolf Creek
site, Colorado in winter 2000.

200
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Fig. 4. Mean serum lufenuron concentrations of active ( ♦) and torpid (■) prairie dogs orally dosed with
300 mg/kg lufenuron.

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I

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Colorado Division of Wildlife
Wildlife Research Report
July 2000

I
\

JOB PROGRESS REPORT
State of _ _ _ _ _-=C=o=lo=ra=d=o'-------

Cost Center 3430

Project _ _ _ _.....W-'---"-1=5=-3-"""'R=--=13~----

Mammals Research

Work Package ---"""'3::....:0:....:;0""'1_ _ _ _ __

Deer Management

Study No. -------=RMA==-=-------

Technical Support for Deer Population
Management at the Rocky MoW1tain Arsenal
National Wildlife Refuge, Denver Colorado

Period Covered: July 1, 1999 - June 30, 2000
Author: Dan L. Baker
\

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Personnel: M.A. Wild, T. M. Nett, J.C. Ritchie, D. Finley, M. Conner, L. Wheeler

ABSTRACT
We provided technical support for the management of mule and white-tailed deer populations at the Rocky
Mountain National Wildlife Refuge, Denver, Colorado. Deer population demographics information was
summarized from 1995-1999 and used to develop a simulation model to assist wildlife managers in
evaluating alternative strategies for population control. As an alternative to annual culling of overabundant
deer, we developed and tested a fertility control technology in captive mule deer. This contraceptive agent
, was demonstrated to be 100 % effective in preventing pregnancy when delivered prior to the breeding
season. Effective duration of the contraceptive was approximately 153 days. No negative effects on the
nutrition, physiology, and general health of the treated animals were observed, however, breeding behavior
of treated females was significantly (P :S 0.001) different from untreated co~trols.

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m~i11~1i1mrnmnr
BDOW016784

��217

TECHNICAL SUPPORT FOR DEER POPULATION MANAGEMENT AT THE ROCKY
MOUNTAIN ARSENAL NATIONAL WILDLIFE REFUGE, DENVER, COLORADO
Dan L. Baker

P. N. OBJECTIVES
l. Provide technical support for the management of mule deer, white-tailed deer populations and their
habitats at the Rocky Mountain Arsenal National Wildlife Refuge (RMA).
2. Develop a practical and acceptable technology to inhibit reproduction in mule deer and whitetailed deer populations at the RMA.
3. Develop a simulation model to predict impacts of alternative population control strategies at RMA.
4. Demonstrate the feasibility of population control strategies in a field application.

SEGMENT OBJECTIVES
l. Provide professional consultation relevant to the development of a deer management plan at the
Rocky Mountain Arsenal National Wildlife Refuge.
I

2. Develop and test a practical and acceptable technology to inhibit reproduction in captive mule deer.
3. Evaluate the effects of contraceptive technology on mule deer nutrition, physiology, general health,
and breeding behavior.

INTRODUCTION
Deer Population Management Plan

The Rocky Mountain Arsenal National Wildlife Refuge (RMA) has the potential to become one of the
premier wildlife viewing areas in the United States. However, realizing that potential depends on wise
management. In particular, the mule deer population contained within the boundary fence must be
regulated in balance with the resources available. Experience with enclosed deer populations elsewhere has
revealed that unregulated population increases will lead relentlessly to degradation of habitat, to widespread
starvation, and eventually to catastrophic declines in animal numbers.
Professional culling and fertility control offer alternative management strategies for regulating deer
populations at the RMA. However, until fertility control technology is demonstrated to be a feasible and
efficacious method for controlling free-ranging wild ungulate populations, annual culling of mule deer is
the only viable management option available to resource biologist.at the RMA.
Using either culling or contraceptives to meet deer population objectives will require, wildlife managers to
choose specific tactics of treatment. Choices must be made on the number and age to treat, frequency of
treatment, species, sex, etc. Decisions on the best tactics will depend on comparing the effects of

�218
alternative management actions on population behavior. To assist in these decisions, we developed an
interactive simulation model of deer population dynamics to allow managers to evaluate alternative
treatment regimes on simulated populations before applying them to real animals. Critical to model
performance is knowledge of population demographics of the RMA deer herds and requires information on
sex and age composition, recruitment, pregnancy rates, fetal sex ratio, and estimates of population density.
1bis information together with knowledge of the habitat resources available to deer will provide a sound
biological basis for management of deer populations at the RMA.
Deer Fertility Control
Contraception offers a viable alternative to culling as means oflong-term control of overabundant wild
ungulates. During the last decade, research aimed at developing effective contraceptives for free-ranging
wildlife populations has accelerated. These efforts have resulted in development and testing of a wide
variety of potential contraceptive agents (Kirkpatrick and Turner 1985, Warren et al. 1995).
One of the most promising new non-steroidal, non-vaccine, approaches to contraception involves synthetic
analogs of gonadotropin-releasing hormone (GnRH). GnRH is a molecule produced in the hypothalamus of
the brain. It directs specific cells in the pituitary gland to synthesize and secrete two important
reproductive hormones; follicle stimulating hormone (FSH) and luteinizing hormone (LH). These latter
two hormones, known as gonadotrophs, control the proper functioning of the ovaries in the female and
testes in the male.
Inhibition of ovulation caused by chronic administration of GnRH analogs has been successful in several
species, including dogs (Vickery et al. 1989), cattle (Herschler and Vickery 1981), sheep (McNeilly and
Fraser 1987), white-tailed deer (Becker and Katz 1995), and elk (Baker and Nett, unpublished data).
Evidence from studies confirm that sustained release is the most effective approach for temporarily
suppressing pituitary-gonadal function. The practicality of this approach, however, is dependent upon
development of a long-acting, slow-release analog that can be remotely delivered.
Recently, a practical mode of administration using subcutaneous implants has overcome the need for
constant mechanical infusion of the analog. Slow release formulations of superactive GnRH analogs are
now commercially available and have been shown to be effective in suppressing the pituitary-ovarian axis
for up to 6 months in a variety of mammalian species (Fraser et al. 1987).
To our knowledge, only limited investigations have been conducted to evaluate the effectiveness ofGnRH
analogs in wild ungulates (Becker and Katz 1995, Baker and Nett 1998 unpublished data), however, the
minimum dose of GnRH analog required for maximum pituitary stimulation is known for mule deer (Baker
et al. 1995) and the minimum effective duration of controlled release GnRH-agonist implants has been
determined to be at least 130 days in captive elk (Baker and Nett 1999, unpublished data). Additional
research is needed to determine the effectiveness of these contraceptive agents in preventing pregnancy in
mule deer and their maximum effective duration. Research is also needed to identify any nutritional,
physiological or behavioral side-effects that may result from treatment. Thus, the objectives of our research
are:
1) To evaluate the effectiveness and effective duration of GnRH analog in preventing
pregnancy in mule deer.
2) To evaluate the effects ofGnRH analog on nutrition, physiology, general health and
breeding behavior of captive mule deer.

�219
We will test the null hypothesis ofno effect of GnRH analog on luteinizing hormone (LH) levels,
pregnancy rates, social behavior, and general health of captive female mule deer.

MATERIALS AND METHODS
Deer Population Management Plan.

The primary deer population management objective for the RMA is to maintain a healthy and productive
mule and white-tailed deer population that is in balance with its habitat resources.
Specific objectives include:
1) Manage total deer population levels at approximately 50% of habitat carrying
capacity with a mule deer : white-tailed deer population ratio of 2: 1. The total winter
population goals will be 550-650 mule deer and 250-350 white-tailed deer.
2) Manage sex and age composition of deer to achieve a high proportion of mature
males relative to adult females. The sex and age composition goals will be 90 to
120 bucks:100 does with at least 50% of males older than 2 years of age.
The status (population siz.e, condition, general health) of the deer population at the RMA was evaluated on
an annual basis from 1995 to 1999 using the following demographic information. This information was
incorporated into a culling/fertility contrbl simulation model that allowed RMA biologist to evaluate
alternative population control strategies for meeting deer population objectives.
Census. A total count of all deer on the RMA was conducted each winter from 1989 to 1998. Procedures
were standardized for all counts by 1) conducting at least two consecutive aerial surveys each winter, 2)
conducting surveys after trees and shrubs had dropped their leaves, 3) conducting surveys when snow cover
was at least 95-100 %, 4) using the same 2 observers whenever possible, and 5) using a Bell Soloy
helicopter that was flown at an average ground speed of 60 km/hr at altitudes from 24 to 35 m above
ground. The helicopter flew transects approximately 400 m apart beginning on the south perimeter and
preceding north along east to west transects. Observers searched areas on their respective sides of the
helicopter. Temperature, visibility, and percentage snow cover were recorded for each flight. Deer were
tallied by species but not classified by sex and age.
Sex and Age Classification. Sex, age, and species composition of deer at the RMA were sampled each
November. Three permanent survey routes were established by dividing the RMA into 3 separate
geographical areas and identifying a permanent route within each area. Each route followed established
roads and was chosen to observe the maximum number of deer within the area. The length of each route
was determined by the driving distance that could be covered by one vehicle during the period 0700-1200.
One pair of previously trained observers sampled each of the three areas each day~ the same pairs of
observers were consistent across all days.
Classifications were conducted at the peak of the breeding season (approx. Nov 22) to increase the
probability of observing all age classes. Observations were made from a vehicle using 8 x 50 binoculars
and 10-60x. spotting scopes. No classifications were attempted for deer that were farther than 200 m from
the observer or for deer that were bedded. Deer were classified by species as either mule or white-tailed
deer, and sex, and age as immature buck, mature buck, doe, fawn, and abnormal buck (Dasman and Taber
1956). Each year, prior to conducting surveys, observers independently classified the same deer from as
many groups of deer as required to consistently obtain identical classifications.

�220

Reproductive Parameters. We detennined pregnancy rates, fetal rates, fetal sex ratio, and average
conception date for adult female mule deer collected from 1995 to 1999. Deer were shot through the spine
in the cervical region with a high powered rifle at distances ranging from 30 - 75 m. Reproductive tracts
were removed and examined for evidence of fetuses. Does lacking identifiable embryos or fetuses after
January I were regarded as current breeding failures. If corpora lutea were present, we used only those
does in which there was gross evidence, through presence of embryos or pigmented degenerating corpora
lutea, that the doe either had been or was currently pregnant.
During 1994 we measured fetal growth rates to estimate breeding dates. Adult does were collected at 4 time
periods during gestation: January 25, February 16, March 9, and April 19. -Fetuses from each doe were
removed in the field and transported to the laboratory for determination of sex and age. Fetal foreheadrump (mm), hind leg length (mm), and body mass (g) measurements were made according to methods
described by Armstrong (1950). Measurements of twins and triplets were averaged to provide a single
estimate of fetal age for each doe. We estimated the age of each fetus by using the linear regression of
forehead-rump length (mm) (Y) and age (days) (X) established from known-age mule deer fetuses (Y = 124.6 + 3.2lx) (Hudson and Browman 1959).

Culling/Fertility Control Model. We developed an interactive simulation model to allow RMA biologist to
evaluate alternative mule deer culling strategies. This model combined extant knowledge of mule deer
population biology with measured population parameters at the RMA to predict the proportion of male and
female deer that need to be removed each year to accomplish management objectives.

Table 1. Principal parameters in culling simulation model for mule deer at RMA.
Reference
Definition
Value
Measured
Whittaker, 1992
Adult/yearling female survival
0.90
No
Whittaker, 1992
Adult/yearling male survival
0.90
No
Bartmann et al., 1992
Fawn survival coefficient a:
1.20
No
Bartmann et al., 1992
Fawn survival coefficient P
-0.053
No
Fetal sex ratio(% males)
0.47-0.62
Yes
December recruitment
0.59-0.72
Yes

Deer Fertility Control
Mule deer (OdocoUeus hemionus hemionus) are polyestrus owlators that exhibit highly seasonal patterns
of reproduction that are controlled by photoperiod regimens. The onset of the breeding season occurs
during decreasing daily photoperiods of autumn and is preceded by a period of deep anestrous in summer
(Plotka et al.1977). The first ovulation of the breeding season is usually preceded by one or more silent
ovulations associated with the formation of short-lived corpora lutea that serve to synchronize the first
overt estrus within a herd (Thomas and McT.Cowan 1975). In temperate North America, the majority of
conceptions occur in late November, but recurrent estrous cycles of 24 -28 days are possible through
March if females fail to conceive (Knox et al. 1988). In early spring, coincidental with increasing day
length, reproductive cycles cease and females remain anestrous until October. For pregnant females,
parturition generally occurs in late May or early June, after a gestation period of about 200 days (Anderson
and Medin 1966).

Experimental Animals. We conducted two experiments to evaluate GnRH analog in captive tame and wild
female mule deer. Experiment I was a highly controlled experiment using IO tame, adult females and 2
wild, adult male mule deer. Experiment 2 attempted to simulate the appli~on of contraceptive treatments

�221
to free-ranging mule deer at the RMA. This effort involved 9 wild, adult female mule deer and 5 wild,
adult male mule deer. These studies were conducted from November 3, 1999 until August 15, 2000 at the
Colorado Division of Wildlife's Foothills Wildlife Research Facility (FWRF), Fort Collins, Colorado.
Experiment 1: Protocol
Reproductive Status. Before randomly assigning animals to treatment groups, we detennined the
reproductive status of all does by measuring serum progesterone levels at weekly intervals beginning
November 10. For this sampling, deer were moved from 5 ha pastures to individual isolation pens, sedated
(40-100 mg xylazine (100 mg/ml), IM) and blood samples collected (5ml). Animals were reversed with
yohimbine (0 .125 mg/kg, IV) and returned to paddocks the same day. Sedation of deer was done in order to
minimize potential adrenal secretion of exogenous progesterone during handling and blood sample
collections (Plotka et al.1983, Asher et al. 1989).
Treatments. Following fertility evaluations, 5 does were randomly selected to receive an analog of GnRH
(LUPRON) and 5 does were assigned to a control group. Treatment does \,\'.ere given a subcutaneous
implant containing 10 mg of LUPRON one week prior to being exposed to male deer. Based on previous
studies with mule deer (Baker et al. 1994), and elk (Baker and Nett 1999), approximately 3-4 animals per
treatment are sufficient to establish statistically significant differences among treatment means.
Hormonal Evaluation. Prior to application of the contraceptive treatment, we measured the LH response
of each doe in both LUPRON and CONTROL groups to a challenge dose of GnRH analog (1 ml/50 kg
BW, IV) . Results from this trial provided a pretreatment baseline for comparison to future posttreatment
LH responses. This and succeeding LH 1challenge trials were conducted as follows: On Day 1 of the trial,
mule deer were moved from 5 ha pastures to individual isolation pens, sedated (4-6 ml, 5: 1 ketamine
(lOOmg/ml):xylazine hydrochloride (100 mg/ml, IM), and fitted nonsurgically with indwelling jugular
catheters. Animals were be reversed with yohimbine (0.125 mg/kg, IV). On Day 2, we administered GnRH
analog (1µ /50 kg BW) through the cannula and collected blood samples (5 ml) at 0, 60, 120, 180, 240,
300, 360, and 480 minutes postinjection. Following the last blood collection, catheters were removed and
each animal given Naxel (3 ml/deer, (50 mg/ml, I.V.). Animals were then returned to 5 ha pastures. Serum
was stored at - 20 °c until analyzed for LH. The duration of contraceptive effectiveness was assessed by
conducting GnRH challenge trials each month from November 1999 to April 2000.
Hormonal Assays: After collection, blood was held at 4 °C for 24 h until serum was obtained by
centrifugation. Serum progesterone concentrations was determined using RIA procedures (Niswender
1973). Sensitivity of the progesterone assay was 0.12 ng/ml. Female mule deer with progesterone levels
above 1 ng/ml were considered reproductively active (Plotka et al. 1977). 1990). Mule deer with
progesterone levels below 1 ng/ml were sampled 7 days later. If after three consecutive blood collections,
progesterone levels remained lower than 1 ng/ml the animal was be removed from the experiment. Serum
concentrations of LH were quantified by means of ovine LH RIA (Niswender et al. 1969). The limit of
sensitivity of the assay was 0.4 ng/ml.
Response Measurements. The effects of LUPRON on female mule deer were assessed by comparing
responses of treated and control deer by the following methods:
a) Hormonal response. Responsiveness of the pituitary to GnRH challenge were determined in three
ways: 1) maximum LH (ng/ml) response achieved postinjection minus baseline, 2) time (hr) required to
reach maximum LH, and 3) total amount ofLH secreted (ng/ml/min).
b) Pregnancy rates. We assessed contraceptive effectiveness by determining the pregnancy rates in treated
and control deer. A single blood sample (10 ml) was taken via jugular venipuncture from each animal for

�222
pregnancy- specific protein B (PSPB) analysis approximately 60, 90, and 180 days post-conception
(Willard et al. 1998). Animal handling and blood collections for PSPB follpwed methods previously
described for hormonal assessment and were collected in conjunction with these measurements. Neonates
born to any experimental animal were incorporated into the resident FWRF mule deer herd with the
exception of fawns born after August 15. Because late born fawns may experience higher than nonnal
over-winter mortality, and potentially compromise body condition and short-term fertility of the dam,
neonates were removed from the dam and either bottle-raised or euthanized according to ACUC
procedures.
c) General health. Knowledge of the effects ofGnRH analogs on nutrition, body weight dynamics, blood
chemistry and general health of mule deer is unknown. Previous experiments with domestic livestock
(Herschler and Vickery 1981), companion animals (Vickery et al. 1989), white-tailed deer (Becker and
Katz 1995), and elk (Baker and Nett 1999) have reported no measurable short-term physiological effects.
We evaluated these potential side-effects by monitoring body weight, blood chemistry, hematology and
overall health of all female deer. We collected blood (10 ml) for blood chemistry and hematology prior to
treatment, and at 30, 90, and 180 days posttreatment. We weighed deer at monthly intervals and monitored
feed intake on a weekly basis ..
d) Breeding behavior. The effects of the GnRH analogs on breeding behavior of mule deer are not known.
However, if gonadotroph cells are desensitized by long-acting synthetic GnRH analogs, down-regulation
and diminished LH and FSH secretion can be induced. Reduced secretion of LH and FSH could decrease
or disrupt ovarian function, estrus cycles and secondary sex characteristics. Furthermore, if pituitary
responsiveness returns following depletion of GnRH analog implants, treated females could resume estrous
cycles and become pregnant late in the l1reeding season. This, in turn, could have survival consequences for
both the pregnant female and her neonate.
We evaluated these potential effects by monitoring maintenance and sexual behavior of male and female
mule deer during the nonnal breeding period and at the end of the predicted depletion of the GnRH analog
(March-April). Each animal in each treatment and the breeding males was individually identified using
color-coded neck bands or ear tags. We tested the null hypothesis that the frequency of sexual interactions
between males and treated females would be similar to those of males and untreated females. We tested this
hypothesis using focal-animal sampling procedures and discriminant function analysis (Lehner 1987). The
exact experimental design depended on time-of-day effects, number of observers, length of required
sampling period, number of bucks in pasture, and the number of bucks observable by one observer.
Statistical All;Olysis. We analyzed data using least squares ANOVA for General Linear Models and the
SAS Interactive Matrix Language. Response to contraceptive treatments was analyzed with two-way
factorial analysis of variance for a randomized complete block design with repeated measures structure.
Levels of GnRH analog were treatments; individual animals were blocks. Factors in the analysis were
treatment and time. Treatment effects were tested using the animal-within-treatment variance as the error
term. Time was treated as a within subject effect using a multivariate approach to repeated measures. We
used orthogonal contrast to test for differences among individual means (Morrison 1976, Miller 1966).

Experiment 2 : Protocol
Treatments. Nine captive wild adult female deer (previously captured and currently being used in a
companion study under an approved ACUC protocol) were systematically assigned to either the control (4
animals) or LUPRON treatment (5 animals). During October 21 - November 1, in association with routine
FWRF management procedures, control females plus 5 wild adult male mule deer were sedated (0.075
mg/kg medetomidine and 2 mg/mg ketamine or 4.4 mg/kg Telazol and 2.2 mg/kg xylazine) via projectile

�223
darts, and individually marked. Male deer were marked with color-coded ear tags and females with colorcoded neck bands. All deer were reversed using atipamezol (0.38 mg.kg) or yohimbine (0.15 mg/kg). On
November 3, treatment females were captured and individually marked (following the same tranquilization
procedures as previously described), and given a subcutaneous implant of LUPRON (10 mg/animal).
Based on previous studies with mule deer (Baker et al. 1994), and elk ( Baker and Nett 1999)
approximately 3-4 animals/treatment are adequate to detect statistically significant differences between
treatment means.
Response Measurements. The effects of LUPRON on female mule deer were assessed by comparing the
responses of treated and control deer by the following methods:
a). Fawning rates. We determined contraceptive effectiveness by comparing the fawning rates of treated
and control deer. Beginning in early June, all does were observed for behavioral and clinical evidence of
parturition. In addition, fawning paddocks were searched daily for neonates. Any treatment female that
had not fawned by August 15, was tested for pregnancy using PSPB analysis (Willard et al. 1998). Any
fawn born after August 15 was removed from the dam and either bottle-raised or euthanized according to
ACUC procedures.
b) Breeding behavior. Procedures for comparing breeding behavior of control and treated does was similar
to those described in Experiment 1.
Statistical Analysis. Differences among fawning rates between control and treated females was analyzed
using unpaired ttest (p &lt; 0.05) (Steel and Torrie 1960).
!

RESULTS AND DISCUSSION
Deer Population Management
Census. Mule and white-tailed deer populations generally increased from 1989 to 1998 with relatively
large fluctuations in total numbers from year to year, particularly for white-tailed deer (Table 2). Mule
deer numbers increased by 75 .6 % and white-tailed deer by 77.1 % during the eight year measurement
period. For mule deer, most of the increase in population size occurred between 1990 and 1993. During
this time period, the population grew at a rate of about 20% per year. After annual culling was
implemented in 1994, the annual growth rate of the population was reduced to approximately 4% per year.
Presently (1998), mule deer numbers (637) are within the population objective set for this species (550650).
The white-tailed deer population at the RMA has shown large fluctuations in size from year to year. It's
not known if these annual fluctuations are due to actual changes in population numbers, measurement
error, or a combination of these factors. Regardless, white-tailed deer appear to be increasing with the
greatest increase occurring between 1997 and 1998 (+ 44.9 %). The current (1998) population size (318)
is within the management objective set for this species (250-350) and is near the population ratio objective
of 2: 1 mule deer:white-tailed deer. Due to lack of snow cover no winter counts were conducted in 1999.
Biologist at the RMA generally believe that the total counts of white-tailed deer are less reliable than those
for mule deer because of the different habitat types preferred by this species and differences in behavior
during helicopter surveys. Mule deer are generally more gregarious in winter than white-tailed deer and
found in more open habitats where they are more easily observed and accurately counted. They appear to
be less fearful of helicopter flights and tend to stay in one place during surveys, thus minimizing duplicate
counts. In contrast, white-tailed deer are more solitary and generally found in dense vegetation near streams

�224
Table 2. Total counts of mule and white-tailed deer at the RMA during 1989 to 1999.
Mule deer
White-tailed deer
Year
Number
Number
%Change
%Change
1990
154
73
1991
200
+23.0
72
-1.4
1992
286
+30.0
35
-51.4
1993
397
84
+58.3
+27.9
1994
1995
550
+62.3
+27.8
223
1996
501
168
-24.6
- 8.9
1997
657
175
+4.0
+23.7
1998
632
318
+45.0
-3.8
1999
No winter counts

and woodlands. They are more easily frightened by low the flying helicopter and tend to run when being
counted. For population management purposes. we assumed that helicopter surveys accounted for 90-95%
of the total mule deer population and 80-85% of the total white-tailed deer population.
Ser and Age Classification. We determined the species, sex. and age composition of deer at the RMA
during November 1996 to 1999 (fable 3). An average of 466 (se ± 58) individual mule deer and 153 (se ±
22) white-tailed deer were observed and classified each year during this period.
Mule Deer: Bucks. The proportion of male mule deer in the population remained relatively constant ( x =
42%, se ± 1.8) from 1996 to 1998 (fable 3). However, the composition of young and mature males in the
herd changed over this same time period. The proportion of young male mule deer increased from 8% of the
total population in 1996 to 17% in 1998 while mature males declined from 35% to 23%. Most of the

decline occurred between 1996 and 1997. The increase in young males in the population is also
reflected in the total male mule deer population.
The ratio of young males:mature males increased from 26 to 72:100 mature males between 1996 and 1998
(fable 3). Surprisingly, the increase in young males occurred despite selective culling of this cohort each
year. Clearly, the trend over the last three years has been an increasing proportion of young males and a
decreasing proportion of mature males. Reasons for this trend are unknown.
Currently, mature males comprise 57 % of the total male population which meets the objective for this
segment of the population. However. management intervention may be needed to reverse this trend in order
to meet current deer population objectives.
Mule Deer: Does. The proportion of adult does in the population has remained relatively constant (x =
31%, se ± 3.1) during 1996 to 1998 (fable 3). Buck:doe ratios declined by 20% from 1996 to 1998 in
large part due selective annual culling of young males. The 1998 buck:doe ratio is within management
objects for this segment of the population.
Mule Deer: Fawns. The proportion of fawns in the RMA mule deer population remained relatively stable
(x = 23 %, se ± 0.67) from 1996 to 1998 (fable 3). However, mean fawn:doe ratios over this time period
have steadily declined (27 %) suggesting a substantial reduction in fawn recruitment into the population.
Reasons for this decline are unknown and may need to be addressed in the near future.

�225
Table 3. Sex and age comeosition of the mule deer eoeulation at RMA during November 1996 to 1998.
Mule Deer
1998
1996
1997
Means
Mean
S.E.
S.E.
S.E.
Mean
Category:
71.3
Young bucks
36.3
1.7
87.3
6.8
4.4
Mature bucks
Adult does
Fawns
Abnormal bucks
Animals observed
Groues observed
Ratios:
Bucks: 100 does
Fawns:100 does
Young bucks:
100 mature bucks

139.0
124.3
98.3
3.3
401.3
109.3

10.6
11.8
4.7
0.9
25.7
11.3

150.0
197.0
140.3
6.3
581.0
247.6

1.7
2.0
5.8
2.2
7.0
11.7

98.0
153.0
91.6
3.3
417.3
182.6

9.6
7.8
10.0
0.9
27.2
14.7

142
81

23
8

120
71

30
3

113
59

76
4

25

1

58

4

72

6

White-tailed Deer: Bucks. Unlike male mule deer, the proportion of male white-tailed deer in the total
population increased from 30% 1996 to 42% 1998 (fable 4). Almost all of the increase occurred from
1997 to 1998. Similar to male mule deef, this increase was primarily associated with an increase in the
proportion of young bucks and a decrease in mature bucks in the total buck population. As of November
1998, mature bucks comprised approximately 62% of the bucks in the total buck population.
White-tailed Deer: Does. The proportion of adult white-tailed does in the RMA herd was relatively
constant from 1996 to 1998 (x = 43%, se ± 1.5) (fable 4). However, with the apparent increase in bucks
over this same time period the buck:doe ratio increased dramatically from 65 bucks: 100 does in 1996 to
103 bucks:100 does in 1998.
White-tailed Deer Fawns. The proportion of fawns in the total population increased for 22% in 1996 to
27% in 1997 and 1998 (fable 4). Fawn:doe ratios fluctuated from between 40 and 65 fawns:100 does
during 1996 to 1998.
Reproductive Parameters
Pregnancy Rates: Reproductive data was collected from 164 adult female mule deer from 1995-1999
(fable 5). Mean pregnancy rate during this period was 91.4 %(se ± 4.0) and ranged from a low of 80 % in
1999 to a high of 100 % in 1997 and 1998. Average fetal rate for pregnant does was 1.72 fetuses/doe (se
± 0.05), and 1.54 fetuses/doe (se ± 0.09) for all does combined.
Fetal Growth Rates and Estimated Conception Dates: We observed a significant (P = 0.001) linear
relationship between fetal age and fetal body length (Fig. 1). The fetal growth rate for mule deer at the
RMA was similar (P = 0.65) to the growth rates reported for known age mule deer fetuses (Hudson and
Browman 1959) and greater (P = 0.01) than the growth rates for mule deer fetuses in the Piceance Basin,
Colorado (Bartmann 1986).
A common use of fetal growth rate is to estimate breeding dates. The growth rate for mule deer fetuses
derived from data of Hudson and Browman (1959) was applied to fetal data collected from the RMA.

�226
Linear regression of estimated breeding date on collection dates was calculated to estimate the breeding
season (Fig. 2). The slope of this regression line was not significantly different from 0 (P = 0.034)
indicating that fetal length measurements are a predictable indicator of conception dates for the period of
gestation sampled. However, it should be noted that this relationship was established for adult female mule
deer in good to excellent body condition. Other studies have shown that estimated breeding dates will vary
during the gestation period depending on winter severity and its effect on fetal growth rates, particularly
during the last trimester of pregnancy (Bartmann 1986). Based on calculated conception dates, we estimate
that 95% of the breeding occurred between November 21 and December 1. Conception dates ranged from
November 14 to December 7. The breeding season for does at RMA appears to be somewhat earlier
(November 25 - December 15) and shorter in duration than the breeding season reported for mule deer in
the Cache la Poudre drainage of north-central Colorado and from studies in west central Colorado
(Anderson and Medin 1966).
Table 4. Sex and age composition of the white-tailed deer population at RMA during November 1996 to
1998.
Mule Deer
1998
1996
1997
Mean•
S.E.
Mean
S.E.
S.E.
Mean
Category:
21.0
6.5
Young bucks
6.0
20.7
3.2
1.5
33.7
34.0
2.9
Mature bucks
10.4
39.7
3.5
53.0
2.08
Adult does
61.3
83.7
6.8
9.3
36.3
Fawns
29.7
52.7
7.4
3.9
1.ft
0.0
0.0
0.0
0.0
0.0
0.0
Abnormal bucks
130.3
6.01
131.7
197.0
17.3
Animals observed
24.3
73.3
4.8
46.0
6.9
105.3
3.3
GrouES observed
Ratios:
103
8
Bucks:100 does
65
15
2
71
42
2
63
8
Fawn: 100 does
47
6
Young bucks :
20
1
65
22
100 mature bucks
51
3

Fetal Sex Ratios: We examined 251 mule deer fetuses for evidence of sex during 1995 to 1999 (fable 6).
Of these, 140 were males and 114 were females resulting in a pooled fetal sex ratio of 56% males and 44%
females. The pooled fetal sex ratio for mule deer at the RMA is within the range of values reported
elsewhere for Rocky Mountain mule deer (Medin and Anderson 1979, Robinette et al. 1955) and was not
significantly different from unity (P = 0.23). However, fetal sex ratios deviated from 50:50 in 2 out of 5
years and favored males over females (P = 0.023). In only 1 year out of 5 did the fetal sex ratio favor
females.
Disease: 1998. During August 1998, epiz.ootic hemorrhagic disease virus (EHD) was diagnosed as the
probable cause of death in 19 white-tailed deer and 21 mule deer at the RMA. However, the extent of deer
mortality from this disease is unknown and was probably much greater than the 40 individual deer that
were actually found.
Culling Model. Professional culling of adult mule deer at the RMA was implemented on a prescribed basis
beginning in November 1994. Prior to 1994, the mule deer population was increasing at a rate of
approximately 20 % per year. Since 1994, annual culling has reduced the population growth rate to 4%
per year and allowed resource managers to meet deer management objectives for this herd. To meet these

�227
Table 5. Pregnancy and fetal rates of adult female mule deer collected at the RMA during 1995 to 1999.

Fetal Rate &lt;fetuses/doe}
Year
1995
1996
1997
1998
1999
Mean
SE
n

Sample Size
39
46
26
38
15

Pregnancy Rate(%)
92.3
84.9
100.0
100.0
80.0
91.4
4.0
5

Pregnant Does
1.61
1.59
1.88
1.63
1.91
1.72
0.07
5

Table 6. Fetal sex ratio for adult mule deer on the RMA during 1995 to 1999.
Year
Sample size
Males(%)
1995
58
60.4
1996
62
62.9
1997
49
53.2
1998
62
47.4
1999
20
60.0

Total Does
1.48
1.34
1.88
1.63
1.53
1.54
0.09
5

Females(%)
39.6
37.1
47.8
52.5
40.0

objectives has required that resource mapagers remove approximately 10- 15% of the adult females and 610% of the young males from the popul!tion each year. These estimates vary each year depending on
productivity of the population, changes in sex and age ratios, and deer habitat resources.
The mathematical model used to estimate the number of animals that must be culled annually to maintain a
target, steady state population appears to provide a reasonably accurate representation of mule deer
population dynamics at the RMA. The efficacy of this model, however, is dependent on intensive
monitoring of the population and adapting management actions to a changing environment.
Deer Fertility Control

Pregnancy Rates and Hormonal Responses
In both Experiment 1 and 2, the LUPRON subcutaneous implant was 100% effective in preventing
pregnancy in all female mule deer (n = 9) that were treated. Untreated control deer (n = 10) all delivered
normal fawns. Duration of effectiveness varied among deer and ranged from 118 days to 210 days.
Serum progesterone (P4) concentrations of treated females remained below 0.1 ng/ml for at least 118 days
posttreatment (Fig. 1). Serum P4 levels in two out of three does remained below 0.1 ng/ml for at least 174
days and for at least 210 days in one doe. Administration of the depot formulation of LUPRON resulted
in a significant (P :!&gt; 0.001) decline in serum luteinizing hormone (LH) concentration after 47 days
posttreatment (Fig. 2). Similar to P4 levels, LH remained below 1 ng/ml until 153 days posttreatment.
These results suggest that GnRH induced interruption of reproductive cycles and pregnancy is associated
with diminished progesterone and LH production, implying defective function of the corpus luteum. These
luteolytic effects have been attributed to the well recognized desensitizing actions of elevated LH levels on
ovarian LH receptors.

�228
Breeding Behavior

We collected data for 59 sampling periods: 24 morning periods totaling 37.0 hrs, 18 mid-day periods
totaling 36.0 hrs, and 17 evening periods totaling 52.2 hrs, for an overall total of 125.2 hrs of observation.
Time of day, date, and the interactions were not significant effects and were.dropped from the ANOVA
model. The behavior rate of does treated with Lupron SQ was not different than for control does for
copulatory or general breeding behaviors (fable 3). However, male pre-copulatory and female precopulatory behavior rates were higher for the Lupron SQ group compared to the control group (fable 3).
If Lupron had no treatment effect, then the difference between behavior rates of control and treatment
groups will equal zero. The difference in behavior rates for does treated with Lupron SQ and control does
was not equal to zero for male pre-copulatory behaviors and was borderline significant at a 0.10 alphalevel for female pre-copulatory behaviors (fable 4).
Behavior rates were almost identical for the control and Lupron SQ groups for copulatory and general
breeding behavior categories. However, male and female pre-copulatory behavior rates for the Lupron SQ
group were 2.0-5.5 times higher than for the control group. It is unclear why the Lupron SQ group had
higher pre-copulatory be~vior rates, but similar rates of copulatory behavior. It is possible that sampling
variation is responsible, especially given the small sample sizes.
The rate of male pre-copulatory behavior was significantly higher toward the Lupron SQ group than the
control group. Male pre-copulatory behavior rates were 2 times higher toward the Lupron SQ group.
Although the rate of female pre-copulatory behavior was 5.5 times higher for the Lupron SQ group
compared to the control group, this difference was not significant.

6

---

Deer K95

- -0- -

Deer G96

84

118

-......-- DeerN93

5

~

E
oi
.s
"&lt;t

a..

4

3

E

:l

ai

Cl)

2

0

....

' ' ''
' ',"'
''
"

Pretrmt

47

153

174

210

Days Posttreatment

Figure 1. Serum progesterone (P4) levels in female mule deer before and after treatment with a
subcutaneous implant containing 10 mg ofLUPRON. Each line and symbol represents an individual deer.

�229
As with the elk, rates of general breeding behavior were similar for the 2 treatment groups. Although deer
do not have a harem breeding system, the general breeding behaviors may be more concerned with
dominance and represent indirect reproductive behaviors.

----

Deer K95

-¾-

--0--

DeerG96

Deer N93

30

4
~

E
CD
.s

20

I

...I

.

E
::,

cii

en

Q

.:,,:
t'G

Cl)

\

10

(l_

\

\
\

·\
\

\

\

\

\

\ \
'I:\

'I'

0
Pretrmt

47

84

118

153

174

210

Days Posttreatment

Figure 2. Serum luteinizing hormone (LH) levels in female mule deer before and after treatment with a
subcutaneous implant containing 10 mg ofLUPRON. Each line and symbol represents an individual deer.

Table 3. Mean rate of behavior and standard error for control and treatment deer groups; mean and
standard error were estimated using type ill least-squares.
Behavior category
Treatment Group
Copulatory
Control
Lupron SQ
Male Pre-Copulatory
Control
Lupron SQ
Female Pre-Copulatory
Control
Lupron SQ
General Breeding
Control
Lupron SQ

Mean
SE
(# behviors/h r')

0.010
0.011

0.007
0.010

0.466
0.944

0.124

0.010
0.055

0.004
0.028

0.107

0.029
0.021

0.111

0.101

�230
Table 4. Difference in deer behavior rates(# behaviors/hr) between control and treatment groups, standard
error of the difference, and P-value of the difference (the probability that the behavior rates were equal);
statistics were estimated using type III least-squares.
Behavior Category

Treatment Group
Copulatory
Control - Lupron SQ
Male Pre-Copulatory
Control - Lupron SQ
Female Pre-Copulatory
Control - Lupron SQ
General Breeding
Control - Lupron SQ

Mean
Difference

SE

P-Value

-0.001

0.013

0.944

-0.478

0.162

0.003

-0.045

0.030

0.129

-0.004

0.035

0.900

LITERATURE CITED
Adam, C. L., C. E. Moir, and T. Atkinson. 1985. Plasma concentrations of progesterone in female red
deer (Cervus elaphus) during the breeding season, pregnancy, and anoestrus. J. Reprod. Fertil.
74:631-636.
Anderson, A. E., and D. E. Medin. 1966. The breeding season in migratory mule deer. Colorado Division
of Wildlife, Game Information &amp;aflet No. 60.
Armstrong, RA. 1950. Fetal development of the northern white-tailed deer (Odocoileus virgin/anus
borealis, Miller). American Midland Naturalist 43:650-666.
Asch, RH., F. J. Rojas, T. R Tice, and A. V. Schally. 1985. Studies of a controlled- release
microcapsule formulation of an LH-RH agonist in the rhesus monkey menstrual cycle. Int. J. Fert.
30:19-26.
Asher, G. W. 1985. Oestrous cycle and breeding season of farmed fallow deer, Dama dama. J. Reprod.
Fertil. 75:521-529.
Baker, D. L., M. W. Miller, and T. M. Nett. 1995. Gonadotropin-releasing hormone analog-induced
patterns ofluteinizing hormone secretion in female wapiti (Cervus elaphus nelsoni) during the
breeding season, anestrus, and pregnancy. Biol. ofReprod. 52:1193 - 1197.
Bartmann, RM. 1986. Growth rates of mule deer fetuses under different winter conditions. Journal of
Wildlife ~ement 46:245-248.
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�231
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�232
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•
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Prepared by _ _ _ _ __
DanL. Baker
Research Biologist

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                  <text>135
Colorado Division of Wildlife
Wildlife Research Report
July 1998

JOB PROGRESS REPORT

State of

Colorado

cost center 3430

Project No.

W-153-R-ll

Mammals Program

3001

Deer conservation

Work Package No.

Task N o . - - - - - - - - ~ - - - - - Period Covered:
Author:

Experimental Deer Inventory

July 1, 1997 - June 30, 1998.

R. M. Bartmann, T. M.. Pojar.

Personnel: R. Arant, L. Bennett, G. Bock, D. c. Bowden, D. coven, M. Leslie,
D. Masden, K. Miller, J. Olterman, M. Potter, G. Schoonveld, H.
Spear, s. Steinert, J. Thomson, B. Watkins, G. c. White, and D.
Younkin.

Abstract
An inventory system was developed to enable more precise monitoring of
mule deer (Odocoileus hemionus) population status. It was implemented in 2
Data Analysis Units (DAU) in late 1997. A spreadsheet model was used to
identify key parameters for model inputs. Allocation of sampling effort among
the surveys required to obtain parameter estimates was based on annual
variability associated with those estimates and sensitivity of the model to
change in those estimates. Key parameters are· annual doe survival~ overwinter fawn survival, fawn:doe ratio and proportion of does in the population
obtained from age/sex surveys, population size, and harvest. In D4, the
fawn:doe ratio estimate was 58.8:100. None of 30 radiocollared does died
during the segment and 10 of 38 fawns died for a 74% survival. In D19, the
fawn:doe ratio estimate was 34.2:100. Five of 31 does died for an 84%
survival and 20 of 39 fawns died for a 49% survival. A quadrat census to
estimate population size could not be done in either DAU.

�137

EXPERIMENTAL DEER INVENTORY
Richard M. Bartmann and Thomas M. Pojar

P. N. OBJECTIVES
1.

Develop and test an experimental deer inventory system in 5 DAU's in
western Colorado to determine efficacy in monitoring deer population
status.

2.

Publish results in a peer-reviewed scientific journal.

SEGMENT OBJECTIVES
1.

Estimate the annual doe survival rate in DAU's D-4 (Red Feather) and D-19
(Uncompahgre).

2.

Estimate the over-winter fawn survival rate in DAU's D-4 (Red Feather) and
D-19 (Uncompahgre).

3.

Estimate the December fawn:doe and buck:doe ratios in DAU's D-4 (Red
Feather) and D-19 (Uncompahgre).

4.

Estimate winter deer density in DAU's D-4 (Red Feather) and D-19
(Uncompahgre).

5.

Develop a spreadsheet model for predicting deer population performance in
DAU's D-4 (Red Feather) and D-19 (Uncompahgre).

6.

Analyze data and prepare an annual Federal Aid Job Progress report.

INTRODUCTION
During the early 1990's, mule deer populations in much of Colorado and the
west began declining. The Colorado Division of Wildlife (CDOW) has collected
data on deer populations for many years. These data consist primarily of
harvest estimates collected state-wide every year, age/sex classifications
made in most Game Management Units (GMU) every 1 or more years, and population
estimates made in a few GMU's or DAU's infrequently. These data were
assembled to try and determine if and when a deer decline occurred and its
magnitude (Colo. Div. Wildl., unpubl. rep.).
It was concluded the occurrence
of a large-scale deer decline might be inferred but evidence was weak. This
was partly because the data were inconsistent in the timing and manner in
which they were collected, and also because additional key data on survival
rates were not available. Thus, a new deer monitoring system was needed that
would enable assessing deer population performance in a more timely and
precise manner.

STUDY AREAS
It was originally planned to establish a new deer inventory system in 5 DAU's
around the state. Later, it was decided that for evaluation purposes, 3 would
suffice. Because of financial constraints, the system was implemented in 2

�138
DAU's the first year with the third DAU to be included the second year. The 2
DAU's selected for initial implementation of a new deer inventory system were
D-4 ( Red Feather) in the northern front range and D-19 (Uncompahgre) in
southwest Colorado. DAU D-4 consists of GMU's 7, 8, 9, 19, and 191. Winter
range is a mountain shrub type with Ponderosa pine (Pinus ponderosa)- Douglas
fir (Pseudotsuga menziesii) overstory in many places. DAU D-19 consists of
GMU's 61 and 62. Winter range is primarily a pinyon (Pinus edulis)-juniper
(Juniperus osteosperma)-sagebrush (Artemisia tridentata) type with
considerable oakbrush (Quercus gambelli) interspersed.

METHODS

survival
Basic methods for both DAU's were the same, although timing of their
implementation varied. Annual doe survival and over-winter fawn survival were
estimated from a sample of radio-collared animals. Seventy radiocollars were
available the first winter and allocated to 30 does and 40 fawns. Deer were
captured in early winter by netgunning from a helicopter. Annual doe survival
was estimated for the period 1 December to 30 November. over-winter fawn
survival estimated from 1 December to 15 June when they were considered
adults.
Capture locations were originally randomized throughout the winter range in
each DAU, but problems developed with private land access and finding deer.
Consequently, the helicopter crew was sent to accessible areas where deer were
known present and instructed to put out a certain number of doe and fawn
radiocollars. Each radiocollar had a mortality mode set for a 3-4-hour delay
with frequencies in the 148-151 MHz range. Fawn collars were a drop-off type
so they could be retrieved and reused. This precluded getting survival
information on yearling females from 15 June to 30 November. Data from
Piceance Basin indicates this is not a critical period from a survival
standpoint, except during the hunting season, and hunting mortalities are
censored anyway.
Radiocollared deer were monitored from the air a minimum of once every 2 weeks
from December through June. Each mortality was checked as soon as possible to
try and determine cause of death.

A~e/sex classifications
Age/sex classifications were used to estimate fawn recruitment to December and
post-season buck:doe ratios. A random-route survey was already in place in D4 and was used without modification for this study. Fifteen existing census
quadrats were randomly selected and a route passing through each quadrat
devised. The route was flown with a Bell Soloy helicopter using a GPS unit
for navigating from point to point.
In D-19, a random-route survey was designed similar to that in D-4. Each GMU
was divided from north to south into strata at 1,000-meter intervals along UTM
coordinates. Two existing census quadrats were randomly selected in each
strata within a GMU and, starting at the top of the GMU, a line was drawn to
connect quadrats in a zig-zag pattern from north to south. The process was
then repeated for the other GMU.

�139
Deer in groups encountered along the flight path were classed as fawns, does,
bucks, or unknown. Estimates of fawn:doe and buck:doe ratios were based on
groups using the estimator developed by Bowden et al. (1984).

Population Size
Deer population size was estimated from counts of deer on 0.65-km2 quadrats
using procedures described by Kufeld et al. (1980).
A quadrat census system was established in D-4 in 1985 and has been flown 7
times, the last in January 1997. The current design includes 98 quadrats in
15 strata, but the original data on the total sample area and strata
poundaries could not be found. There was not enough time to gather the needed
data to define a new total sample area and re-stratify, so the quadrat census
was to be flown as in the past. The exception was that a Bell Soley
helicopter was to be used instead of a Jet Ranger. Snow conditions along the
front range are undependable. When adequate snow does occur to provide a good
counting background, it usually lasts only a few days. Helicopters need to be
scheduled in advance, so the chance of encountering good counting conditions
was minuscule. Therefore, it was decided the D-4 survey would be flown
regardless of snow cover.
A quadrat census was established in GMU 62 in 1976. It was expanded to
include GMU 61 in 1981. There are 346 quadrats in 13 strata which took -70
hours to survey. Only 30 hours were allocated for the census, so the number
of quadrats was reduced to 140 by random selection.

Population Model
The POPII model is currently used to help manage deer populations. The model
is complex and requires numerous parameter estimates with no supporting data.
As a result, people are free to manipulate various parameters to try and make
the model fit their preconceived ideas. A much simpler model is needed for
which key inputs are derived from sample-based estimates. The new model will
help determine the key types of data required and how to allocate costs and
effort to obtain them.

RESULTS

Doe survival
P.=.i: Thirty does were captured and radiocollared from 4-7 January 1998. The
delay from the desired late November period was caused by contract problems.
Monitoring was done from a fixed-wing aircraft about once every 2 weeks
through June 1998. No does died during that period (Table 1).

12=.l.2.: Does were captured and radiocollared from 15-20 December 1997.

Here
again contract problems delayed the process. The first two does captured were
given fawn radiocollars by mistake. Consequently, 31 does were finally
radiocollared. Monitoring from a fixed-wing aircraft was done weekly the
first month, but was increased to twice weekly the rest of the winter and
spring to try and locate mortalities quicker. As of 30 June, 5 of the 31 does
had died for a survival estimate of 84%. Annual doe survival is monitored
until 30 November, so this rate could go lower.

�140
Table 1. Fates of mule deer does and fawns radiocollared in DAU's D-4 (Red
Feather) and D-19 {Uncompahgre) during the 1997-98 winter.
D-4
Fate

D-19

Does

Fawns

Does

Fawns

30

28

26

19

Coyote

3

3

10

Lion

1

1

1

Survived

Bobcat
Unknown Predator

1
2

1

Starvation

1
1

Accident

1

1

Undetermined

3

5

Fawn survival
~ : Thirty-eight fawns were captured and radiocollared during the same period
as for does. Two collars were temporarily misplaced and not put out. Ten
fawns died for an over-winter survival rate of 74%.
~ : A doe radiocollar was erroneously placed on a fawn. This, together with
the 2 fawn collars placed on does, resulted in only 39 fawns being
radiocollared. Twenty fawns died by 15 June for an over-winter survival rate
of 49%. The fawn that received a doe collar was 1 of the mortalities which
eliminated the need to recapture it to prevent choking when it got older.

Age/Sex Classifications
D.=_4: The classification survey was flown 16-18 December.

There were 950 deer
classified for a fawn:doe ratio of 58.8 (95% CI= 52.9-65.2) and buck:doe
ratio of 23.8 {95% CI= 19.4-28.6).

~ : The classification survey was flown 11-13 December. The random routes
only took about 5 hours to complete with 358 deer classified. To use more of
the 15 hours allocated for the survey, a non-random route was flown through
the longer north-south length of each GMU. This produced another 831 deer in
abo_ut •the same amount of time as for the random routes.
For all data combined, the fawn:doe ratio estimate was 34.2 {95% CI= 30.937.7) and the buck:doe ratio estimate was 11.1 (95~ CI= 8.9-13.4). Comparing
results from 2 route types, the fawn:doe ratio estimate was marginally higher
(35.3 vs. 31.8) while the buck:doe ratio was nearly twice as high (12.8 vs.
7.0) on the non-random routes. Thus, the observer's knowledge about where to
find large numbers of deer could bias ratio estimates, particularly for bucks.

Population size
D.=_4: contract problems prevented getting a helicopter before the mid-January

cutoff date for conducting the survey, so it was not flown.

�141

D.=.J..2.: Adequate snow conditions did not occur until late January.

A population
estimate has not been made since 1994, so it was decided to do the survey even
though it was past the 15 January cutoff. Work was started 27 January, but
weather and other problems prevented the survey from being completed in a
reasonable time span, so it was canceled on 12 February after 63 quadrats had
been flown. A valid population estimate cannot be made based on this
incomplete data.

Population Model
Development of a population model to identify key inputs for refining the deer
inventory system was begun with cooperators from Colorado State University.
Deer population dynamics are much more complicated than the model portrays,
but routine measurement of the wide array of inputs required for a more
complicated model is unrealistic. Thus, it is a reasonable trade-off between
what we can measure from a practical standpoint and what is needed to predict
deer population status for management purposes.
The model concentrates on predicting changes in the adult doe portion of the
population as this is the key to evaluating population status. The model has
only 2 age classes (fawns and adults) assigned to 3 categories (fawns, does,
and bucks). Fawns are initially recruited to the population on 1 December
when the fawn:doe ratio is estimated from age/sex classifications.
The model contains 4 parameters that are year-specific: annual buck survival,
annual doe survival, over-winter fawn survival, and December fawn recruitment.
Buck survival has no influence on population status unless their numbers drop
low enough to affect breeding; a phenomenon yet to be documented in hunted
populations. Therefore, there is no real need for an estimate of buck
survival. An indication of status can be derived from the buck:doe ratio
estimate obtained from age/sex surveys, and the number of new bucks recruited
is estimated from male fawns that survive to become yearlings. Thus, only the
last 3 parameters need to be considered for the model.
The strategy for managing a mule deer population is to estimate the doe
segment so harvest can be adjusted to maintain the December doe population at
some desired level. To do this, 3 more parameters have to be estimated in
addition to the 3 mentioned above: total population size, the proportion of
the population that is does, and doe harvest. A harvest estimate is already
available from another source and fawn recruitment and the proportion of does
in the population are obtained from the same survey, so we only need to
consider 4 surveys to obtain 5 parameter estimates.
The problem now comes down to how to allocate costs and effort to these 4
surveys to derive estimates of the 5 parameters that will result in the most
precise prediction of the December doe population or, alternatively, the
annual rate of population increase. Either will indicate the number of does
that must be harvested to maintain the desired doe population level. This
process is ongoing and will be completed in the next segment.

�142

LITERATURE CITED
Bowden, D. c., A. E. Anderson, and D. E. Medin. 1984. Sampling plans for mule
deer sex and age ratios. Journal of Wildlife Management. 48:500-509.
Kufeld, R. c., J. H. Olterman, and D. c. Bowden. 1980. A helicopter quadrat
census for mule deer on Uncompahgre Plateau, Colorado. Journal of
Wildlife Management. 44:632-639.

/?

~repared by

~

~~\;£:::;______
WildLi.fe Researche~

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Wildlife Researcher

��85

Colorado Division of Wildlife
Wildlife Research Report
July 1999

JOB FINAL REPORT

State of:
Colorado
Project No.
W-153-R-12
Work Package No._3~0~0~1~-----Task No.
I

Cost Center 3430
Mammals Program
Deer Conservation
Experimental Deer Inventory

Period Covered: July 1, 1998 - June 30, 1999
Authors: R B. Gill, and T. M. Pojar
Personnel: G. Schoonveld, S. Steinert, J. Olterman, C. Wagner, B. Watkins, R Bartmann, G. White

ABSTRACT
Over-winter (Nov-May) survival rates were estimated for 3 Data Analysis Units: Red Feather
(D-4), Middle Park (D-9), and Uncompahgre (D-19). Overall 3 study areas, doe survival averaged
91.7% and fawn survival averaged 79.4%. Population estimates were obtained for D-9 in late January,
1999 by flying square mile quadrats allocated according to a stratified random sampling scheme. Deer
density averaged 12.93 deer/km2 and projected to a total population of 11,016 deer± 2,337 (90% CI).
Estimates of the ratios of bucks and fawns:100 does were obtained from helicopter counts conducted in
December 1998. The buck:doe ratio was estimated to be 27 bucks: I 00 does. The fawn:doe ratio was
estimated to be 62 fawns: I 00 does.

�87

EXPERIMENTAL DEER INVENTORY
R. Bruce Gill and Thomas M. Pojar

P.N. OBJECTIVES

I.

Develop and test an experimental deer inventory system in 5 DAUs in western Colorado to
determine efficacy in monitoring deer populations.

2.

Publish results in a peer-reviewed scientific journal.

SEGMENT NARRATIVES

I.

Estimate the annual doe survival rate in DAUs D-4 (Red Feather), D-9 (Middle Park), and D-19
(Uncompahgre).

2.

Estimate over-winter fawn survival rate in DAUs d-4 (Red Feather), D-9 (Middle Park), and D19 (Uncompahgre).

3.

Estimate the December fawn:doe and buck:doe ratios in DAU D-9 (Middle Park).

4.

Estimate winter density in DAU D-9 (Middle Park).

5.

Develop a spreadsheet model for predicting deer population performance in DAUs D-4 (Red
Feather), D-9 (Middle Park), and D-19 (Uncompahgre).

6.

Analyze data and prepare an annual Federal Aid Job Progress Report.

INTRODUCTION
Initial plans called for the development and testing of experimental inventory systems on 5 deer
_Data Analysis Units (DAUs) across Colorado's important deer herds. Manpower and financial
constraints limited the scope to 3 DAUs: Red Feather (D-4), Middle Park (D-9), and Uncompahgre
(D-19). Measurements on each DAU were to continue for a period of 3-5 years before deciding
whether to expand implementation of the experimental deer inventory system. However, the project's
principal investigator, Richard M. Hartmann, retired during the segment and his vacancy remains
unfilled. Consequently, it was decided to terminate the R&amp;D component of the inventory system at the
end of the current segment. This report, therefore, constitutes the Final Report of activities
accomplished under Work Package 3001, Task I.

STUDY AREAS
Study aras D-4 and D-19 were described previously (Hartmann and Pojar 1998). Study area
D-9 is situated in the headwaters area of the the Colorado River drainage encompassing areas below
approximately 2,600 min elevation in Grand and Summit Counties. Winter range is primarily

�88

sagebrush steppe vegetation type characterized by low growing(&lt; 1 m) shrubs. Sagebrush species
(Artemisia tridentata tridentata andArtemisia tridentata vaseyana) predominate with other shrub
species such as rubber rabbitbrush (Chrysothamnus nauseosus), sticky-flowered rabbitbrush
(Chrysothamnus viscidifloris), mountain snowberry (Symphoricarpus oreophilus), bitterbrush
(Purshia tridentata), serviceberry {Amelanchier alnifo/ia), and chokecherry (Prunus virginiana)locally
abundant (scientific names ·according to Weber 1976). Mule deer winter over approximately 850 km2
below 2600 m in elevation.

METHODS
Bartmann and Pojar (1998) thorougly described the methods used in this investigation, so they
will not be repeated here.

RESULTS
Doe Survival
Across all 3 study areas, doe survival during winter 1998-99 averaged 91. 7% with 121 of 132
does surving from November 1998 through May 31, 1999. This compares to an over-winter survival
rate of 90.1 % for adult does throughout the previous winter (Bartmann 1998). No single source of
mortality stood out as a primary {Table 1) which was similar to results from 1997-98.
Fawn Survival
In general, fawn survival throughout winter 1998-99 increased compared to 1997-98. In 199899, 127 of 160 radio-collared fawns survived from November 1, 1998 through May 31, 1999 for an
overran survival rate of 79. 4 %. In 1997-98, 61. 0% of radio-collared fawns overall survived the
winter.
Sex and Age Composition
Classification counts of mule deer in Middle Park Data Analysis Unit (D-9) were conducted
during the period December 22-24, 1998 and included a total of912 deer, of which 15.9% were bucks,
32. 0% were fawns, and 52.1 % were does (Table 2). The ratio of bucks per 100 does computed to
30.5 ±4.8 bucks: 100 does and 61.5 ±7.5 fawns:100 does.
Population Density
Middle Park Data Analysis Unit (D-9) deer census quadrats were flown during the fourth week in
January, 1998. Counting conditions and deer distribution were both ideal. Overall, 2,415 deer were
tallied on 56 sample quadrats. Number of deer/km2 averaged 12.93 with a standard error of 4.00.
When projected over the entire winter range ofD-9, the deer population was estimated at 11,016 deer
±2,337 (90% {Table 3).

en

�89

Table l. Fates of mule deer does and fawns radiocollared in DAUs D-4 (Red Feather), D-9 (Middle
Park}, and D-19 (Uncomeahgre} during the 1998-99 winter.
Red Feather
Fate

Uncompahgre

Middle Park

Does

Fawns

Does

Fawns

Does

Fawns

Total Radiocollared

S2

so

40

so

40

60

Survived

4S

40

39

44

37

43

Coyote predation

l

4

0

l

l

7

2

0

0

0

2

1

0

3

0

2

2

0

0

0

0

0

0

0

0

0

0

2

Accidents

0

0

0

0

0

Unknown

2

0

0

2

4

10

1

6

J

17

Mtn. lion predation
Other predators

0

Road kills

0

Hunter kills

2

Starvation

0

7

Total Mortality

1Total does not equal 100% because of rounding error.

Table 2.- Results of mule deer classification counts in Middle Park Data Analysis Unit (D-9),
December 22-24, 1998.

GMU

I-yr
bucks

2-yr
bucks

Adult
bucks

Total
bucks

Does

Fawns

Total

12/23/98

27

6

6

·3

15

66

44

12S

12/22-24/98

37

27

23

19

69

17S

98

342

12/23-24/98

181

6

5

2

13

44

17

74

12/23-24/98

28

7

12

3

22

130

92

244

12/24/98

18

11

10

5

26

60

41

127

-. - &lt;ih

Date

Totals

32

145

47S

292

D-9 Swrunary

1-yr
bucks:
100 does

2-yr
bucks:100
does

Adult
bucks:100
does

Total
bucks:100
does

Fawns:100
does

Ratio estimates

12.0

11.8

6.7

30.S

61.S

Lower90%CI

9.3

9.1

4.8

2S.9

54.3

Upper9O%CI

14.8

14.6

8.8

35.5

69.4

S7

56

�90

Table 3. Deer quadrat census results for Middle Park Data Analysis Unit (D-9), January 1998.
Stratum

Strata

Deer
Counted

(km2)

Population
Estimate

N

n

Total

Dccr/km2

SE

Total

±_90%

80.3

28.5

582

20.43

12.34

1640

629

2

222.7

10.4

13

1.25

3.17

280

449

3

189.1

46.6

. 730

15.66

7.64

2961

918

4

121.7

15.5

144

9.27

9.84

1128

761

5

72.5

15.5

378

24.33

26.41

1764

1216

6

88.1

15.5

494

31.79

24.59

2799

1375

7

77.7

12.9

74

5.71

5.40

444

266

Overall

852.1

145.0

2415

12.93

4.00

11016

2337

Spreadsheet Models
A spreadsheet population model was developed in a Quatro Pro spreadsheet format for Red Feather (D-4),

Middle Park (D-9), and Uncompahgre (D-19) Data Analysis Units. Disk copies of spreadsheets for each
DAU were sent to Area Biologists responsible for managing each DAU. Copies of the spreadsheet fonnat
may be obtained by writing to:
Dr. Gary C. White
211 B JVK Wagar Bldg.
Department of Fishery and Wildlife Biology
Colorado State University
Fort Collins, CO 80523

LITERATURE CITED
Bartmann, R. M., and T. M. Pojar. 1998. Experimental deer inventory. Colorado Division of Wildlife.
Wildlife Research Report, July, 1998, Part II: 135-142.
Weber, W. A. I 976. Rocky mountain flora. Colorado Associated University Press. Boulder, CO.

Prepared by _ _ _ _ _ _ _ _ _ __

R. Bruce Gill
Wildlife Research Leader

Thomas M. Pojar
Wildlife Researcher

�</text>
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                  <text>145
DEER REPRODUCTION ASSESSMENT
Richard M. Bartmann and Thomas M. Pojar

P, N, OBJECTIVES
1.

Estimate the variation in pregnancy-specific protein B (PSPB) levels in
mule deer does in Game Management Unit (GMU) 19 (Poudre).

2.

Develop a study plan to compare current mule deer reproductive rates to
historic data to determine if differences exist that might contribute to
the recent decline in deer populations in Colorado.

SEGMENT OBJECTIVES
1.

Estimate the variation in PSPB levels in mule deer does during 2 winter
periods in GMU 19.

2.

Test for differences in pregnancy rates of mule deer does between the 2
winter sample periods.

3.

Develop a study plan to compare current and historic reproductive rates of
mule deer in at least 2 areas of Colorado.

4.

Analyze data and prepare an annual Federal Aid Job Progress report.

INTRODUCTION
An assessment of mule deer population status during the early to mid-1990's
indicated that many populations across western Colorado had declined to
various extents. However, the cause(s) was not identified. One indication of
a problem was detection of a significant decline in December fawn:doe ratios
in some DAU's over the past 20+ years. This suggested a possible problem with
reproduction or neonatal mortality.
A logical starting point to try and identify a problem was the breeding
season--were does being bred? This was also the easiest aspect to investigate
because it did not require killing deer to obtain samples.

STUDY AREAS
GMU 19 was selected for study because there was historic data for comparison.
Winter range along the northern front range is a mountain shrub type with
Ponderosa pine (Pinus ponderosa)-Douglas fir (Pseudocsuga menziesii)
overstory.

METHODS
Pregnancy detection was via blood analysis to determine levels of PSPB. PSPB
levels in blood have been used to detect pregnancy with a high degree of
accuracy in various species including mule deer (Wood et al. 1986). Detection
times post-conception have varied among species, but is generally considered
reliable after about 24 days with cattle (Sasser et al. 1986). Therefore,
delaying blood sample collection until early January was considered to provide
an adequate interval post-breeding for detecting PSPB. Delaying the second
set of collections until early February would detect pregnancies from

�146
conceptions during the second estrus and provide an indication of the extent
of late breeding.
From 15-20 does (~1-year-old) were to be captured with Clover traps in early
January and again in early February. However, helicopter netgunning of deer
for survival work in DAU D-4, of which GMU 19 is part, was delayed until early
January, so it was decided to collect blood samples from does captured for
that project. Blood samples were submitted to BioTracking in Moscow, Idaho to
assess levels of PSPB to determine pregnancy status.

RESULTS
Blood samples were obtained from 29 does captured 4-7 January 1998. Twentyseven were considered pregnant and 2 not pregnant. One doe was at the cut-off
point of 93% (93.1%) and may have been a late breeder. The range in values
for the pregnant does was 84.3-93.l with mean 88.5 and SE 0.36. Values for
the 2 non-pregnant does were 102.6 and 102.8. The 27 pregnancies yielded a
93% pregnancy rate with all except possibly 1 apparently bred during the first
estrus. Thus, late breeding did not appear a problem so no collections were
done in February.
The 93% pregnancy rate is barely significantly lower (P = 0.062) than the 100%
rate derived from data for 49 does collected in GMU 19 from January-May 196165 (Anderson 1965a, 1965b, 1966). However, it is still considered a high rate
with the conclusion that conception is apparently not a problem in DAU D-4.
A next step would be to determine fetal rates, but this would involve
euthanizing a large number of does during mid to late winter. One option is
to have hunters collect does, but hunting seasons that late in winter are not
well accepted. Therefore, no further work is planned to evaluate reproductive
status until a satisfactory collection method is found for estimating fetal
rates.

LITERATURE CITED
Anderson, A. E. 1965a. Reproductive studies. Colo. Dep. Game, Fish and Parks,
Game Res. Rep. January:165-195.
Anderson, A. E. 1965b. Reproductive studies. Colo. Dep. Game, Fish and Parks,
Game Res. Rep. January:522-543.
Anderson, A. E. 1966. Reproductive studies. Colo. Dep. Game, Fish and Parks,
Game Res. Rep. January:275-307.
Sasser, R. G., C. A. Ruder, K. A. Ivani, J.E. Butler, and w. C. Hamilton.
1986. Detection of pregnancy by radioimmunoassay of a novel pregnancyspecific protein in serum of cows and a profile of serum concentrations
during gestation. Biol. Reprod. 35:936-942.
Wood, A. K., R. E. Short, A. Darling, G. L. Dusek, R. G. Sasser, and C. A.
Ruder. 1986. Serum assays for detecting pregnancy in mule and whitetailed deer. Journ:il of Wildlife Management. 50:684-687.

,,.71__

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Prepared by .J(~~~,-_hJ:.~~d~;_:z.iiB~artm;;;zt.~~;n~n=··-=···=····==···=·:--:==::::::==-==WildLi.fe Researche~

Wildlife Researcher

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                  <text>147
Colorado Division
Wildlife Research
July 1998

of Wildlife
Report

JOB PROGRESS REPORT

State

of

Project
Work

No.

Package

Colorado

Cost Center

W-153-R-ll

Mammals

No.

~3~0~0~1L_

Task No.

Period

_

3430

Program

Deer Conservation
Monitoring and Managing Chronic
Wasting Disease in Deer

Covered:

July

1, 1997 - June 30, 1998

Authors:

M. W. Miller

Personnel:

S. Berry, K. Larsen,
Wheeler, M. A. Wild,

K. 1. O'Rourke, T. R. Spraker,
and E. S. Williams

S. Tracy,

E.

ABSTRACT
Deer from throughout Colorado were examined for occurrence of chronic wasting
disease using a combination of targeted surveys and harvest/road-kill
surveys.
We continued to develop and modify a statewide targeted surveillance program
for acquiring, examining, and reporting on CWO suspects submitted from
Colorado.
Between June 1997 and May 1998, 6 chronic wasting disease (CWO)·
cases were diagnosed among 16 "suspect" deer submitted from known endemic
portions of northeastern
Colorado; CWO was not diagnosed in any of 7
additional "suspect" deer submitted from elsewhere in Colorado.
All confirmed
CWO cases originated in game management units (GMUs) where the disease had
been detected previously.
Harvest and road-kill surveys were used to estimate CWO prevalence in enzootic
management units.
About 4.2% of deer harvested in Larimer County data
analysis units (DAUs) (D4 or D10) and about 1.1% of deer harvested in South
Platte River bottom units (DAU D44 plus GMUs 87, 90, 93, and 95) tested
positive for CWO via immunostaining;
none of the 171 deer harvested or culled
in other select GMUs outside known enzootic areas tested positive for CWO.
Prevalence estimates may be somewhat liberal because subclinical cases where
either histopathological
lesions or anti-PrP immunostaining
reactions in brain
tissue were included; of the 44 cases identified, ~none appeared to be
suffering from clinical CWO and only 26 of 44 (59%) "positive" deer showed
both histopathological
lesions and immunostaining.
In contrast to earlier observations derived from targeted surveillance data,
CWO prevalence among male and female mule deer did not differ (P = 0.86).
Age
distribution
of CWO-positive
mule deer did not differ from sex-specific age
distributions
of negative animals.
These data support the belief that CWO
epidemiology
is driven primarily by lateral transmission.

�148
Requiring head submissions increased survey sample sizes for deer &gt;4-fold
compared to voluntary submissions in 1996. Based on harvest estimates from
surveyed GMUs, compliance with mandatory submission regulations was about 75%.
Unstaffed barrel sites still appear to be the most efficient method for sample
collection~
Data from both targeted surveillance and surveys indicate that eastern Larimer
County remains the most significant focus of CWO in Colorado, although some
natural spread may be occurring both southward and eastward.
Targeted
,surveillance of clinical suspects appears to be the most sensitive approach
for initially detecting CWO in deer (and elk) populations throughout Colorado,
and should be continued statewide.
Once detected, combinations of harvest and
road-kill surveys will be employed to estimate prevalence, monitor prevalence
trends, and compare prevalence among DAUs. 'Because CWO appears to be more
prevalent in deer than in elk in endemic areas, it follows that harvest
surveys in high-risk areas should focus on deer rather than elk to be most
effective in confirming absence of CWO in nonendemic areas.
Cwo affected about 25% (5/25) of the adult (~1-yr-old) mule deer and about 46%
(5/11) of the adult white-tailed
deer in resident Foothills Wildlife Research
Facility herds during the last biological year; CWO accounted for 83% of adult
mule deer mortality and 100% of adult white-tailed deer mortality. Resident
mule deer also represented the source of infection (treatment) in an ongoing
10-yr study of cattle susceptibility to CWO.
No signs of neurological disease
were observed in any of the 12 calves (subjects) or 12 mule deer fawns from
the Rocky Mountain Arsenal National Wildlife Refuge (contact controls) housed
with naturally~infected
resident deer since July 1997; one calf died from
gastrointestinal
obstruction and bloat about 2 wk after entering the deer
paddocks, and one fawn that apparently failed to adjust to captivity died
about 1 mo after capture, presumably from hypothermia secondary to
malnutrition.

�149
MONITORING

AND MANAGING

CHRONIC

WASTING

DISEASE

IN DEER

M. W. Miller

P. N. OBJECTIVES
(1) Design,

conduct,

and report

results

of:

(a) targeted surveillance to estimate and detect changes in distribution
of chronic wasting disease (CWO) in free-ranging deer populations;
and
(b) harvest or road-kill surveys to estimate and detect
prevalence of CWO in enzootic deer populations.
(2) Design,
captive

changes

in

conduct, and report results of experimental
studies using
deer naturally or experimentally
infected with cwo.
SEGMENT

OBJECTIVES

(1)

Conduct and report results of targeted surveillance to estimate and
detect changes in distribution of CWO in free-ranging deer populations
statewide.

(2)

Conduct and report results of harvest surveys to estimate prevalence
of CWO in DAUs D4, D10( +GMU 29), and D44 (+ GMUs 87, 93, and 95).

(3)

Continue experimental
evaluation
natural contact exposure.

of cattle

(4)

Observe
deer.

of naturally-occurring

epizootiological

features

susceptibility

to

cwo via

CWO in captive

INTRODUCTION
Chronic wasting disease (CWO) affects native deer and elk, causing behavioral
changes and progressive
loss of body condition that invariably lead to the
death of affected animals (Williams and Young 1992).
Neither the causative
agent nor its mode of transmission
have been identified.
There are no tests
currently available for diagnosing CWo in live animals, and postmortem tests
require microscopic
examination of brain tissue.
There are no known
treatments for cwo. Previous attempts to eradicate CWO from research
facilities failed on at least 2 occasions (Williams and Young 1992; Miller et
al., 1998).
Although similar in some respects to other transmissible
spongiform encephalopathies
that affect domestic sheep (scrapie) and cattle
(bovine spongiform encephalopathy;
"mad cow disease"), there is no evidence
suggesting cwo can be naturally transmitted to domestic livestock, or that
scrapie or SSE can be transmitted to native cervids.
Moreover, there is no
evidence suggesting that cwo presents a threat to human health.
"Chronic wasting disease" was first recognized by biologists in the 1960's as
a disease syndrome of captive deer held in wildlife research facilities in Ft.
Collins, CO, and was subsequently recognized in captive deer, and later in
captive elk, in wildlife research facilities near Ft. Collins, Kremmling, and
Meeker, CO and Wheatland, WY (Williams and Young 1980, 1982).
Since 1981, CWO
has also been diagnosed in free-ranging mule deer, white-tailed
deer, and elk
from northcentral
Colorado; most of these diagnoses have been made since 1990

�150
(Spraker et al. 1997). Although CWO was first diagnosed in captive cervids,
the original source of CWO is unknown; whether CWO in captive cervids really
preceded CWO in wild cervids, or vice versa, is equally uncertain
(Spraker et
al. 1997).
At present, the known world-wide distribution of CWO in wild cervids appears
to be limited to northeastern
Colorado and southeastern Wyoming.
In
Colorado, free-ranging
CWO cases have primarily originated from along the
Front Range near Estes Park and west of Ft. Collins-Loveland.
Cases were
diagnosed in 6 different game management units (GMUs)(191, 9, 19, 20, 94, and
96) prior to 1996, but two GMUs (19, 20) yielded about 85% of the documented
cases; the affected GMUs comprise portions of 3 deer (04, 010, 044) and 2 elk
(E4, E9) data analysis units (DAUs).
There is no evidence that wild deer or
elk outside northeastern
Colorado are infected with CWO.
The significance of CWO and its impacts on native deer and elk populations are
unclear.
Simulation models of CWO dynamics predict that this disease could
cause significant declines in affected deer and elk populations
(Miller and
McCarty, unpublished
data).
In light of CWO's potential impacts on wildlife
resources and the difficulties
inherent in eliminating CWO from captive or
wild cervid populations
once established,
it seems most prudent to assume CWO
could adversely affect native deer and elk populations and manage to reduce
its occurrence and prevent its further spread.
A more complete understanding
of CWO is fundamental to developing a
comprehensive
management program.
In 1996, ongoing surveillance efforts were
enhanced to provide a better tool for estimating and monitoring changes in CWO
prevalence in enzootic areas and for potentially detecting emergence of CWO in
new areas.
Reliable estimates of CWO prevalence are particularly
critical to
detecting"trends,
predicting potential impacts of disease on long-term
population performance,
and assessing efficacy of management interventions;
moreover, such data are needed to guide policy decisions and to provide
information to hunters and other publics.
Ultimately, surveillance data will
"be the foundation of an adaptive resource management plan for CWO in deer and
elk; that plan will provide a mechanism for incorporating
new knowledge gained
through surveys, modeling, and experimental studies into a continuously
evolving management program formulated to reduce the occurrence of CWO and
minimize the risk of its spread to other native deer and elk populations
in
Colorado.
MATERIALS

AND METHODS

Surveillance
We monitored deer populations throughout Colorado for occurrence of CWO using
a combination of targeted surveillance and harvest or road-kill surveys.
These were organized and conducted as follows:
Targeted (= clinical disease) surveillance: Deer showing clinical signs
consistent with those seen in chronic wasting disease were collected by field
personnel statewide and brain tissues examined for evidence of spongiform
encephalopathy.
The "suspect case" profile was defined as follows:
•

•

Species:

Age:

mule deer
white-tailed
~ 18 months

deer

�151
•

Signs:

emaciated and
abnormal behavior &amp;/or
indifference to human activity &amp;/or
increased salivation &amp;/or
tremor, stumbling, incoordination
&amp;/or
difficulty or inefficiency
in chewing/swallowing
increased drinking and urination

&amp;/or

Where possible, submissions were subjected to complete necropsy; in some
situations, only heads were available for examination
and sampling.
In all
cases, histopathology
of brain tissue (Williams and Young 1993) was used to
diagnose CWO; in some cases, immunohistochemistry
or other ancillary tests
were used to confirm or support diagnoses.
Harvest surveys: In order to obtain reliable estimates of CWO prevalence that
will serve as a basis for monitoring responses to management
interventions,
we
continued conducting harvest surveys on select deer populations.
During the
1997-1998 hunting seasons, fresh brain and select lymphatic tissues were
collected from deer harvested in enzootic GMUs; deer harvested or culled in
other select GMUs throughout Colorado were also sampled as negative controls.
Brain tissues were examined at the Colorado State University Diagnostic
Laboratory for histopathological
lesions (Williams and Young, 1993)or anti-PrP
immunostaining
reactions (O'Rourke et al., 1998) consistent with CWO
infection.
Because sample sizes for most individual GMUs were too small to
provide reliable prevalence estimates by GMU, we pooled data by DAU for
comparisons within and among species. We estimated specificity of
imunohistochemistry
using data from deer harvested outside known enzootic
areas. Ages were estimated via replacement
(4-6-mo-old, 16-18-mo-old,
~28-moold) and cementum annuli using first incisors from all positive deer and a
random sample of negative deer (103 males and 100 females) harvested in four
GMUs (9, 191, 19, 20); using these data, we compared sex-specific
age
frequency distributions
for CWO-affected
and unaffected male and female mule
deer.
Epizootiological
Studies
Epizootology
of naturally-occurring
CWO in captive mule deer and white-tailed
~
(Miller and Wild): Naturally-occurring
CWO was a sporadic disease of
resident FWRF mule deer prior to 1985 (Williams and Young, 1992), and also has
occurred sporadically
since 1994; no cases had been observed in resident
white-tailed
deer since their addition to FWRF in 1993.
We maintained and
observed 25 ~1-yr-old mule deer and 11 ~l-yr-old white-tailed
deer in paddocks
at CDOW's Foothills Wildlife Research Facility (FWRF) during July 1997-June
1998; 10 fawns were also born and recruited into the resident mule deer herd.
Deer received natural forage, pelleted rations (high energy supplement and
"browser" diet), and alfalfa hay; water and mineralized
salt were available ad
libitum. All deer were evaluated daily for clinical signs of CWO (and other
health problems) in conjunction with routine feeding and handling activities.
Resident mule deer also represented the source of infection (= "treatment") in
an ongoing study of cattle susceptibility
to CWO (see below).
Cattle susceptibility
to CWO (Williams and Miller): We continued monitoring
cattle for clinical evidence of natural CWO transmission
as part of a
coordinated
interagency effort to study cattle susceptibility
to CWO.
Twelve
4-mo-old calves purchased from a private ranch located near Sheridan, WY, were
placed in paddocks at the FWRF with naturally-infected
captive mule deer in
July 1997 (see above for description of resident deer herd). Twelve 4-mo-old
mule deer fawns were captured at the Rocky Mountain Arsenal National Wildlife

�152
Refuge (RMANWR) in late September and placed in the same paddocks as contact
controls for natural transmission
(extensive ongoing surveillance of RMANWR
deer has continued to confirm that this population is free of CWO).
In a separate but related study, 20 additional 6-mo-old mule deer fawns were
captured at the RMANWR in early December.
Each
fawn was given a single oral
dose of about 5 g of fresh brain tissue homogenate from captive mule deer with
clinical CWO.
Fawns were then released into a separate paddock physically
removed from the contact transmission
study.
These experimentally-infected
fawns will serve two purposes: as controls for domestic calves orally
inoculated with a single oral dose of about 50 g of this same CWO brain
homogenate
(Williams et al., 1998), and as subjects of a study on the
pathogenesis
of CWO in mule deer (Appendix A).

RESULTS AND DISCUSSION
Surveillance
Targeted (= clinical disease) surveillance: Between June 1997 and May 1998, 6
chronic wasting disease (CWO) cases were diagnosed among 16 "suspect" deer
submitted from known endemic portions of northeastern Colorado; CWO was not
diagnosed in any of 7 additional "suspect" deer submitted from elsewhere in
Colorado.
All confirmed CWO cases originated in game management units (GMUs)
where the disease had been detected previously. Males and females were
represented equally. All CWO cases were observed and submitted during
November-February,
well within the October-April
timeframe of most clinical
case submissions
(Spraker et al., 1997; Miller, 1997).
Encephalitis,
intoxication,
neoplasia, and pneumonia were diagnosed among the 17 suspects
not suffering from CWO; for most (9/17) non-CWO cases, no definitive
explanation
for clinical signs and condition could be determined from the
samples submitted.
Harvest surveys: We sampled and examined 1421 deer harvested in enzootic GMUs
during 1997 archery, muzzleloader,
and rifle seasons (Table 1). About 4.2%
.(39/933) of deer harvested in Larimer bounty DAUs (04 and 010) tested. positive
for CWO via immunostaining.
Four GMUs (9, 191, 19, 20) yielded all of the
positive deer detected in Larimer County units (04 and 010) (Table 1; Fig. 1);
among these units, prevalence ranged from about 3-16%. Prevalence in sympatric
elk populations
(0-0.2%; Miller, 1998) was much lower than in deer (P &lt;
0.009).
Based on data from 1997 archery, muzzleloader,
and rifle seasons,
combined estimated mean CWO prevalence in 04 and 010 deer populations
(4.2%)
appeared to be essentially unchanged from 1995 (5.9%) and 1996 (5.7%); for the
3 GMUs (191, 19, 20) where sufficient samples sizes were available for 3
successive years (1995-1997), prevalence has not differed over time (P ~ 0.3).
CWO was detected in about 1.1% (5/449) of deer harvested in South Platte River
bottom units (DAU 044 plus GMUs 87, 90, 93, and 95·) (Table 1). Among river
bottom and adjacent plains units, positive deer were harvested in GMUs 91, 95,
951, and 96 (Table 1; Fig. 1).
None of the 171 deer harvested or culled in other select GMUs (mainly
and 104) outside known enzootic areas tested positive for CWO.

66, 67,

�153

rg 00o

o
o
o

• MD PositiveMdpos.txt
• ELK PositiveElkpos.txt
.•. WTD PositiveWtdpos.txt
WTD NegativeWtdneg.tx
o MD NegativeMdneg.txt
RiverColo riv
CountiesCounties
A

.

/\I

o

\1---'

___,
s

Figure 1. About 4.2% of deer harvested in larimer County data analysis units (OAUs) (04 or 010) and about 1.1% of
deer harvested in South Platte River bottom units (OAU D44 plus GMUs 87,90, 93, and 95) tested positive for CWO via
immunostaining. Most positive cases were from eastern larimer County.

As reorted previously
(Miller, 1997), the foregoing prevalence estimates may
be somewhat liberal because the definition of "positive" included subclinical
cases where either histopathological
lesions or anti-PrP immunostaining
reactions in brain tissue were observed.
Of the 44 cases identified, none
appeared to be suffering from clinical cwo. Twenty-six of the 44 (59%)
positive deer showed both histopathological
lesions and immunostaining;
the
other 18 were classified as positive solely on the basis of immunostaining
reactions.
Although no known "false positives" were identified among the 171
deer examined from outside known enzootic DAUs (specificity ~0.979), further
evaluation of both sensitivity and specificity of existing diagnostic
techniques still appears warranted.
In contrast to observations
derived from targeted surveillance data (Spraker
et al., 1997; Miller, 1997), CWO prevalence among male (5.5%) and female
(4.8%) mule deer did not differ (P = 0.86) for animals harvested in four
Larimer County GMUs (9, 191, 19, 20).
Antlerless permit numbers issued for
1997 failed to produce targeted sample sizes of 250 adult (~1 yr) does/DAU: we
received 195 usable samples from 04 and 151 from 010, including samples from
archery, muzzleloader,
and rifle seasons.
Additional does will be examined
during 1998 to increase sample sizes for comparison of prevalence between
sexes.
Age distribution
of CWO-positive mule deer did not differ from respective sexspecific age distributions
of negative animals (Fig. 2). These data support
the belief (Miller et al., 1998) that CWO epidemiology
is driven primarily by
lateral transmission.
If maternal transmission were the primary mode of
transmission
(as is believed to be the case in scrapie of domestic sheep),
then an age distribution
skewed toward younger aged animals would be expected,
particularly
among does where older-aged animals are more abundant. In light
of an estimated 18-24 mo incubation period for CWO in deer (Williams et al.,
1998), the rarity of preclinical disease in yearlings
(-16-17-mo-old deer)

�154
appears to be the strongest argument
against maternal transmission being the
most common route for CWO transmission.
Although survival rates for male mule
deer are substantially
lower than for
females, CWO appears equally prevalent
among males and females and uniformly
distributed
among respective age
classes.
These data may reflect the
potential inefficacy of random culling
in reducing CWO prevalence, although
relatively high female densities and
the potential for female-male
transmission
could confound such
interpretations.
Requiring head submissions increased
survey sample sizes &gt;4-fold compared to
voluntary submissions in 1996: in
04/010, we collected 938 deer heads, as
compared to -200 collected in 1996.
Limited licenses also may have aided in
increasing deer submissions.
Based on
harvest estimates from surveyed GMUs
(COOW, unpubl. data), compliance with
mandatory submission regulations was
about 75%.
Unstaffed barrel sites
still appear to be the most efficient
method for sample collection.
Epizootiologieal
Studies
Epidemiology
of naturally-occurring
CWO in captive mule deer and whitetailed deer (Miller and Wild):
Five
mule deer and 5 white-tailed
deer
developed clinical cwo during the last
biological year (May, 1997-April 1998)
(Fig. 3); two additional mule deer
cases and one additiona white-tailed
deer case occurred during May-June
1998.
In all, CWO affected about 20%
(5/25) of the adult (~l-yr-old) mule
deer and about 46% (5/11) of the adult
white-tailed
deer in resident FWRF
herds during the last biological year;
CWO accounted for 83% of adult mule
deer mortality and 100% of adult
white-tailed
deer mortality.

~

CWO-poalilv.

D

N.D.1I •.•

~

...••
r:::

•
~•
:::J
1:r

7-'D

••,D

B. Female mule d.er

Age cia ••

Rgure 2. Age frequency distributions did not differ
between CWO-positive and negative (A) male or (8)
female mule deer sampled via harvest surveys.

A.ilule

du,

·

."

'0

-·,."
z

, •• ,

, •• 7

, •• 3

·

...
'0

.!

,."

z

V •• r

Since mule deer were reintroduced
into
Figure 3. Both mule deer and white-tailed deer herds
FWRF in late 1990, 17 of 59 (29%)
resident at CDOW's Foothills Wildlife Research Facility
animals that survived to &gt;1 yr of age
are now infected with chronic wasting disease.
have succumbed to CWO.
The index case
in the most recent epizootic occurred
in October 1994; 4-5 clinical cases
Annual clinical
have occurred in each subsequent biological year (Fig. 3A).
prevalence has ranged from 2-20% (Fig. 4). Generating comparable epizootic

�155
behavior in a forecasting model (Miller
and Mccarty, unpubl. data) requires a
transmission
coefficient
(~) of about 3.5
infectious contacts/infectious
animal/yr
(Fig. 4); two assumptions of this
spreadsheet model, no environmental
source of infection and a l2-mo
incubation period prior to onset of
clinical disease, seem somewhat
questionable
in light of recent
experiences and may need to be
reevaluated.

_a-wd,.."..DldMr

50

40

~ 30

fI)
'0

[EJ~~oI"

25

20

15 ~

B
r::::

'0

~

fI)

..D

E 20

::::J
Z

10 ~

l:.

Based on observations
made over the last
5
10
12 mo, CWO apparently can be an explosive
disease 'in white-tailed
deer populations.
It follows that the relative rarity of
o
o
1995
1994
1996
1997
CWO in free-ranging white-tailed
deer is
Year
probably more a function infrequent
exposure rather than natural species
resistance; white-tailed
deer are
relatively rare in the foothills of
Figure 4. Modeled CWO dynamics
eastern Larimer county where CWO is most
simulated
trends observed in FWRF deer
prevalent.
The source of infection for
since 1994 when relatively high transmission
our captive white-tailed
deer herd is
coefficients (13 = 3.5) were used.
unclear.
One possibility
is introduction
via two breeding males (C93, W93) that
were intermittently
housed with CWO-infected mule deer males; another
possibility
is transmission
from infected mule deer via fenceline contact or
environmental
contamination.
The essentially simultaneous occurrence of CWO in
two does that had never been housed with mule deer seems to support the latter
alternative. Cases in two additional animals 9 and 11 mo after the index case
could be consistent with either a point source of exposure and variable
incubation period or lateral transmission with a relatively short (-12 mo)
incubation period.
Data on pathogenesis,
incubation periods, agent shedding,
potential environmental
sources of infection, and the relationship between
infectiousness
and onset of clinical signs for CWO in both white-tailed
and
mule deer are clearly needed to improve understanding
of CWO epizootiology
in
both captive and free-ranging deer.
Cattle susceptibility
to CWO (Williams and Miller):
One calf died from
gastrointestinal
obstruction
and bloat about 2 wk after entering the deer
paddocks, but the other 11 remained healthy throughout the first year of this
10-yr experiment.
Similarly, 11 of the 12 control fawns from RMANWR remained
healthy; one fawn that apparently failed to adjust to captivity died about 1
mo after capture, presumably from hypothermia secondary to malnutrition.
Seven of the 25 &gt;1-yr-old naturally-exposed
resident FWRF deer developed
clinical CWO and died or were euthanized during the first 12 mo of the study,
thereby ensuring calves and control deer received some exposure to CWO.
ACKNOWLEDGMENTS
The statewide CWO monitoring and surveillance program described here relies
heavily on efforts of dedicated field personnel throughout the Colorado
Division of Wildlife, and truly represents a division-wide
effort to improve
our understanding
and management of this important disease problems.
In
addition to those specifically
listed, we collectively thank all of those

�156
regional and area biologists, district and area wildlife managers, volunteers,
deer and elk hunters, and others who assisted by submitting suspect cases,
harvested animals, or road-killed animals throughout the year.

LITERATURE CITED
Miller, M. W.
1997.
Monitoring. and managing wildlife chronic wasting disease
in Colorado. in Wildlife Research Report, Mammals Research, Federal Aid
Projects, Job Progress Report, Project W-153-R-10, WP2, J17.
Colorado
Division of Wildlife, Fort Collins, Colorado, USA, pp. 37-46.
1998.
Monitoring and managing wildlife chronic wasting disease in
elk. in Wildlife Research Report, Mammals Research, Federal Aid Projects,
Job Progress Report, Project W-153-R-11, WP3002, T3.
Colorado Division of
Wildlife, Fort Collins, Colorado, USA, in press.
, M. A. Wild, and E. S. Williams.
1998.
Epizootiology
of chronic
--wasting disease in captive Rocky Mountain elk.
J. Wildl. Dis. 34: 532-538.
O'Rourke, K. I., T. V. Baszler, J. M. Miller, T. R. Spraker, I. SadlerRiggleman, and D. P. Knowles. 1998. Monoclonal antibody F89/160.1.5 defines
a conserved epitope on the ruminant prion protein. J. Clin. Microbiol. 36:
1750-1755.
Spraker, T. R., M. W. Miller, E. S. Williams, D. M. Getzy, W. J. Adrian, G. G.
Schoonveld, R. A. Spowart, K. I. O'Rourke, J. M. Miller, and P. A. Merz.
1997.
spongiform encephalopathy
in free-ranging mule deer (Odocoileus
hemionus), white-tailed
deer (Odocoileus virginianus),
and Rocky Mountain
elk (Cervus elaphus nelsoni) in northcentral Colorado.
J. Wildl. Dis.
33:1-6.
Williams, E. S., and S. Young.
1980.
Chronic Wasting disease of captive mule
deer: A spongiform encephalopathy.
Journal of Wildlife Diseases 16: 89-98.
, and
1982.
Spongiform encephalopathy
--Journal of Wildlife Diseases 18: 465-471.
__

~' and
Scientifique

of Rocky

Mountain

elk.

1992.
Spongiform encephalopathies
in Cervidae. Revue
et Technique Office International des Epizooties 11: 551-567.

, and
1993.
Neuropathology
of chronic wasting disease in mule
--deer (Odocoileus hemionus) and elk (Cervus elaphus nelsoni). Veterinary
Pathology

30: 36-45.

, M. W. Miller, T. J. Kreeger, H. Van Campen, and T. R. Spraker. 1998.
--Susceptibility
of cattle to cervid spongiform ~ncephalopathy.
unpublished
grant proposal, submitted to USDA, CSREES,
Competitive Grants Program, 88 pp.

c
Wildlife

Research

Veterinarian

National

Research

Initiative

�157

Table 1. Results of 1997 CWD harvest surveys -- archery, muzzleloader, &amp; rifle seasons.
DEER

DAU

GMU

# Examined

# Positive

D4

7

29

0

8

160

0

191

212

10

9

74

12

19

123

6

Total

598

28

20

335

11

Total

335

11

29

39

0

Total

39

0

87

37

0

90

1

0

91

54

1

. 92

41

0

93

53

0

94

55

0

95

97

2

951

56

1

96

55

1

Total

449

5

DI0

Boulder

Plains

Prevalence

(95% CI)

0.047

(0.031-0.067)

0.033

(0.016-0.058)

0

(0-0.09)

0.011

(0.004-0.025)

�158

�159

AJ;lpendix A
STUDY PLAN

Pathogenesis
Elizabeth

of Chronic

Wasting

S. Williams

Disease

and Michael

in Mule Deer
W. Miller

Need
Chronic wasting disease (CWO) is a transmissible
spongiform encephalopathy
(TSE)of native North American deer and elk (Williams and Young, 1980, 1982,
1992).
The neuropathology
of clinical CWO is well-described
(Williams and
Young, 1980, 1982, 1992, 1993; Spraker et al., 1997), but CWO pathogenesis
remains largely unstudied.
Among clinical CWO cases, the parasympathetic
nucleus of the vagus and the olfactory stria are most consistently
and
severely affected (Williams and Young, 1993).
Typical but less abundant
lesions occur in the parasympathetic
nucleus of the vagus, and sometimes the
olfactory stria, in apparently subclinical CWO cases detected during harvest
surveys (E. S. Williams, unpubl. data; T. R. Spraker, pers. comm.).
Brain and
various lymphoid tissues often stain intensively with anti-prion protein (PrP)
immunostaining
in clinical cases (Williams and Young, 1992; Spraker et al.,
1997; E. S. Williams, unpubl. data; T. R. Spraker, pers. comm.).
Immunostaining
of brain and select lymphoid tissues, particularly tonsil, are
usually positive in subclinical cases.
Positive staining of tonsil and brain
tissue can occur in the absence of spongiform lesions.
Lymphoid Prpsc
propagation
apparently precedes development of detectable neurological
lesions
in scrapie (Schreuder et al., 1996, van Keulen et al., 1995, 1996), but not
bovine spongiform encephalopathy
(Wells et al., 1996).
The presence of Prpsc
in central nervous system and peripheral tissues has lead to development of
immunohistochemistry
(Miller et al., 1993; van Keulen et al., 1995, 1996;
Schreuder et al., 1996) and immunoblotting
(Farquhar et al., 1989; Ikegami et
al., 1991; Race et al., 1992) as preclinical and clinical diagnostic tests for
scrapie in sheep. These antemortem tests are based on biopsy and examination
of lymphoid tissues, typically tonsil, lymph node, and spleen for Prpsc•
Positive staining of lymphoid and salivary gland tissues in the absence of
either lesions or staining in brain tissue has also been observed in deer and
elk, but interpretation
of these observations remains equivocal.
Improved understanding
of CWO pathogenesis would clearly facilitate the
interpretation
of diagnostic findings in subclinical CWO suspects detected via
harvest surveys.
Such understanding
would also enhance interpretation
of data
being gathered in studies designed to evaluate antemortem diagnostic tests for
CWO.
Moreover, reliable pathogenesis data may offer valuable insights into
initiation, duration, and routes of agent shedding, as well as other important
aspects of CWO epizootiology.
Here, we propose to study the pathogenesis
of
CWO in mule deer after oral exposure to infectious brain material.
Objectives
The specific objectives of this study are to:
(1) describe the pathogenesis
of CWO in mule deer after oral exposure to
infectious material using histopathology,
immunohistochemistry,
and
Western blot analyses; and
(2) compare susceptibility,
pathogenesis,
and incubation periods between
male and female deer.
Additionally,
animals challenged in this study will serve as controls for
ongoing cattle challenge trials (Williams et al., 1997).

�160
Materials and Methods
We will study the pathogenesis
of CWO in mule deer after oral exposure to
infectious brain material.
Twenty 5- to 6-mo-old mule deer fawns (10 males,
10 females) will be captured from the Rocky Mountain Arsenal National Wildlife
Refuge (RMANWR) and transported to the Colorado Division of Wildlife's
Foothills Wildlife Research Facility (FWRF) in Fort Collins, Colorado.
Previous surveillance work has revealed that deer residing at RMANWR are
presently unaffected by CWO, thereby ensuring fawns will not be exposed to CWO
until inoculated experimentally.
For capture, fawns will be anesthetized with tiletamine HCl and zolazepam
(Telazol~; 5 mg/kg) and xylazine HCl (2.5 mg/kg) or carfentanil HCl (0.03
mg/kg) and xylazine (1 mg/kg) delivered intramuscularly
(1M) via projectile
syringe; if carfentanil
is used, anesthesia will be antagonized with
naltrexone HCl (100 mg/mg carfentanil) delivered intravenously
(IV)(25%) and
subcutaneously
(SC) (75%) after initial handling and processing.
Additional
xylazine (20-100 mg IV or 1M) will be administered as needed to keep fawns
sedated until they arrive at FWRF.
(See appendix for detailed capture
protocols.)
Upon arrival at FWRF, residual sedation will be antagonized with IV yohimbine
HCl (0.25 mg/kg).
Once fawns are able to swallow effectively, each will
receive about 5 g of homogenized brain material pool collected from mule deer
previously diagnosed with spongiform encephalopathy;
presence of scrapieassociated fibrils in this homogenate was previously confirmed via negativestain electron microscopy
(E. S. Williams, unpubl. data).
This homogenate is
the same being used for oral and intracranial cattle challenges
(Williams et
al., 1997). Homogenate will be deposited into the posterior oropharynx using a
modified syringe.
Once fawns have swallowed the homogenate, they will be
released into a 3 ha paddock.
Alfalfa hay, pelleted supplemental diets (highenergy and "browser" rations), mineralized salt blocks, and water will be
provided ad libitum.
All fawns will be observed daily by animal caretakers
and evaluated at least monthly by an attending veterinarian
for signs of CWO.
To study CWO pathogenesis,
two fawns' (one male, one female) will be randomly
sacrificed at 3, 6, 12, 18, 24, 30, 36, or 42 mo after oral challenge.
At the
time of sacrifice, fawns will be anesthetized with tiletamine HCl and
zolazepam (Telazol~; 5 mg/kg) and xylazine Hel (2.5 mg/kg) delivered via
projectile syringe.
We will collect blood, saliva, feces, and cerebrospinal
fluid from each fawn, then administer about 400 mEq KCl intravenously to
induce cardiac arrest.
The incubation period of CWO after oral challenge is
unknown; however, because clinical CWO developed in mule deer 18 to 24 mo
after intracranial challenge (E. S. Williams, unpubl. data), we anticipate
that most study animals surviving &gt;24 mo will develop Cwo 24 to 36 mo after
oral challenge.
Deer developing severe clinical CWO (characteristic
behavioral changes accompanied by estimated &gt;20% weight loss) will be
euthanized as described above.
Two age-matched control deer (one male, one
female) will be collected from the RMANWR on the same schedule as challenged
deer are sacrificed.
Control deer will be anesthetized
in the field as
described above, sampled, and euthanized with KCl; if field anesthesia becomes
infeasible, control deer will be killed by shooting in the neck with a highpowered (~0.223 cal) rifle.
Saliva, feces, blood, and cerebrospinal
fluid will be stored at -70 C for
potential evaluation via Western blot or infectivity studies.
Carcasses will
be transported
to the Wyoming State Veterinary Laboratory
(WSVL) for complete
necropsy and tissue sampling.
Samples collected will include brain, spinal

�161
cord, and numerous other tissues (Table 1). These tissues will be divided and
subsamples fixed in 10% neutral phosphate-buffered
formalin or in PLP solution
(periodate, lysine, paraformaldehyde)
at a concentration
of 2%
paraformaldehyde
(van Keulen et al., 1996); additional subsamples will be
stored unfixed at -70 C for studies of Prpsc accumulation.
Carcasses will be
incinerated once sampling is completed.
Tissues will be examined via histopathology,
immunocytochemistry,
Western
blot, and/or negative-stain
electron microscopy.
Histopathology
will be
conducted as previously described (Williams and Young, 1993). Central nervous
system tissues will be removed within 4 hr following euthanasia. Brains will
be sagittally sectioned and half fixed in 10% neutral phosphate-buffered
formalin. Samples of spinal cord and other tissues (Table 1) will be similarly
fixed. The other half of the brain and portions of the spinal cord will be
frozen at -70 C. Paraffin blocks will be prepared from olfactory tubercle and
cortex; cerebral cortex (frontal, parietal, temporal, and occipital lobes);
basal ganglia; three levels of thalamus; two levels of mesencephalon;
three
levels of pons and cerebellum; medulla oblongata at the obex; medulla caudal
to the obex; and multiple levels of spinal cord to include cervical, thoracic,
and lumbar regions. Tissues will be sectioned at 5-6 ~m and stained with
hematoxylin and eosin, Bodian's silver stain, luxol fast blue stains, and
glial fibrillary acidic protein (Dako, Carpinteria,
California)
immunocytochemistry
for astrocytosis as appropriate. Lesions will be compared
to those previously described for CWO in mule deer and elk and other natural
TSEs of animals (Williams and Young, 1993; Hadlow, 1996).
We will test for Prpsc in formalin- or PLP solution-fixed,
paraffin embedded
tissues using minor modifications
of the technique of van Keulen et al.
(1995). We will use a polyclonal rabbit antiserum against ME7 scrapie strain
passaged in mice (Rubenstein et al., 1986) (Department of Virology, New York
State Office of Mental Retardation and Developmental
Disabilities,
Staten
Island, New York) or mouse monoclonal antibody against ovine Prpsc
(F89/160.1.5; O'Rourke et al., 1997) (USDA/ARS, Pullman, Washington).
Briefly, paraffin embedded tissue sections will be deparaffinized,
treated
with 99% formic acid for 30 minutes, rinsed with PBS, and autoclaved for 10
minutes at 122 C in 10 x Automation buffer. Sections will be incubated in 4%
normal goat serum for 20 minutes, incubated overnight at 4 C in primary
antibody at 1:1500 dilution, rinsed, and incubated for 30 minutes with
biotinylated
anti-rabbit or anti-mouse IgG (Vector Laboratories,
Burlingame,
California).
Slides will be rinsed, and ABC reagent (Vectastain Elite ABC kit,
Vector Laboratories)
applied for 30 minutes, rinsed and incubated with AEC
substrate solution (Dako Laboratories,
Carpinteria,
california)
for 10
minutes. Slides will be counter stained with Harris hematoxylin,
rinsed,
"blued" with lithium carbonate, rinsed again, and coversli~d.
Positive and
negative brain sections, normal rabbit serum, and PBS will be used as
controls.
Adequate primary antibody is available for the entire study.
L

Western blot assays will be conducted with modifications
of the techniques of
Rubenstein et al. (1986) and Collinge et al. (1996). Brain or lymphoid tissues
will be homogenized
in Tris buffer saline (TBS) at 50 mg/500 ~l followed by a
5 minute low speed centrifugation.
100 ~l supernatant is combined with 6 ~l
22% sarcosyl in TBS, mixed, 4 ~l (5mg/ml) proteinase K is added, mixed again,
then incubated at 37 C for 1-2 hours. Aliquots will be collected for protein
concentration
determination
using Pierce's Micro BCA protein assay. Equal
volume of concentrated
sample buffer (120 roM Tris-HCl pH 6.8, 142 roM BME, 200
roM DTT, 4% SDS, 0.02% BPB, 20% glycerol) will be added and the sample boiled
for 5 minutes. Hot samples will be loaded on Mini-Vertical
4%/12% SDS-PAGE

�162
(Laemmli). The samples will be electrophoresed
at 100 v for 1.5-2 hours with
BioRad's Protein SOS-PAGE molecular weight markers.
A semidry transfer to
0.45 ~m pure nitrocellulose
will be conducted using Towbin buffer according to
manufacturer's
instructions.
Post-transfer,
the gel will be Coomassie Blue G250 stained while the membrane is floated on TBST20 (10 roM Tris pH 8.0, 150 roM
NaCI, 0.1% Tween2o) until wet, then submerged and rinsed. The membrane will be
incubated in 1% NGS -TBST2o for 30 - 60 minutes at room temperature, washed
two-three times for 10 minutes each in TBST2o, and TBST20 1:5,000 diluted
primary antibody (polyc1onal rabbit or monoclonal mouse anti-Prpsc)
added to
the blot and incubated 2 hours at room temperature or overnight at 4 C. The
antibody will be removed, the membrane washed two-three times for 10 minutes
each, and secondary antibody (Promega's goat anti-rabbit conjugated alkaline
phosphatase)
diluted in TBST20 (per manufacturer's
instructions)
added and
incubated 2 hours at room temperature. The membrane will be again washed two
to three times followed by three 2 minute washes in distilled water and then a
5 minute TBS wash done twice.
Promega's BCIP/NBT color development solution
(made according to manufacturer's
instructions) will be added and development
monitored. The reaction will be stopped by several distilled water rinses. The
membrane and stained gel will be recorded via CCO camera, digitized, and
quantitated
(Bio-Rad Molecular Analysis System).
Scrapie-associated
fibrils will be purified using a modification
of the
techniques of Hilmert and Oiringer (1984).
One to two g of brain will be
homogenized
in 10% sarcosyl (pH 7.4) and N-octano1 added for a 30 minute
incubation at room temperature.
The homogenate will be centrifuged for 10
minutes at 3,000 x G (JA-20 rotor, J-21 Beckman centrifuge) and supernatant
collected and centrifuged
for 30 minutes at 22,000 X G. The supernatant will
then be transferred to Beckman quick seal tubes and centrifuged at 215,000 X G
(75T rotor, L8-80 Beckman centrifuge) for 2 hours. The pellet will be
resuspended
in 1% sarcosyl and 10% NaCI, stirred for 60 minutes at 37 C, and
microfuged
for 15 minutes. The pellet will then be resuspended -in 1% sarcosyl,
10% NaCI, and 5 ~g proteinase Klml added and stirred for 2 hours at 37 C. The
suspension will be microfuged for 10 minutes. Negative staining will be
conducted according to Scott et ale (1987, 1990). The pellet will be
resuspended
in 50 ~l distilled water and a 300 mesh plastic coated, carbon
stabilized grid floated on a drop of suspension for 10 seconds, blotted and
negative stained with 2% potassium phosphotungstate,
pH 6.6. Some additional
modifications
of the procedures for SAF detection (Stack et al., 1995; 1996)
are currently being tested at WSVL.
We will describe distribution
of Prpsc and microscopic
lesions as determined
by each of the foregoing assays, and relate these to both the chronological
progression of clinical CWO and the potential shedding of agent from infected
deer.
Because our study is largely descriptive, no statistical analyses of
pathology data will be attempted.
Among fawns surviving long enough to
develop clinical CWO, mean incubation times for males and females will be
compared using Student's t-test (a = 0.1), and the proportions of males and
females developing clinical cwo will be compared using Fisher's exact
probability
test (a
0.1).

=

Literature Cited
Collinge, J., K. C. L. Sidle, J. Meads, J. Ironside, and A. F. Hill. 1966.
Molecular analysis of prion strain variation and the aetiology of 'new
variant' CJO. Nature 383: 685-690.
Farquhar, C. F., R. A. Somerville, and L. A. Ritchie. 1989. Post-mortem
immunodiagnosis
of scrapie and bovine spongiform encephalopathy.
Journal
of Virological Methods 24: 215-222.

�163
Hadlow, W. J. 1996. Differing neurohistologic
images of scrapie, transmissible
mink encephalopathy,
and chronic wasting disease of mule deer and elk. In
Bovine spongiform encephalopathy
The BSE dilemma,
Vol. C. J. Gibbs, Jr.
(ed.). Springer-Verlag,
New York, New York, pp. 122-137.
Hilmert, H., and H. Diringer. 1984. A rapid and efficient method to enrich
SAF-protein
from scrapie brains of hamsters. Biosciences Reports 4: 165170.
Ikegami, Y., M. Ito, H. Isomura, E. Momotani, K. Sasaki, Y. Muramatsu, N.
Ishiguro, and M. Shinagawa. 1991. Pre-clinical
and clinical diagnosis of
scrapie by detection of PrP protein in tissues of sheep. Veterinary
Record 128: 271-275.
Miller, J. M., A. L. Jenny, W. D. Taylor, R. F. Marsh, R. Rubenstein,
and R.
E. Race. 1993. Immunohistochemical
detection of prion protein in sheep
with scrapie. Journal of Veterinary Diagnostic Investigation
5: 309-316.
Race, R. E., D. Ernst, A. L. Jenny, W. D. Taylor, D. Sotton, and B. Caughhey.
1992. Diagnostic implications of detection of proteinase K-resistant
protein in spleen, lymph nodes, and brain of sheep. American Journal of
Veterinary Research 53: 883-889.
Rubenstein, R., R. J. Kascsak, P. A. Merz, M. C. Papini, R. I. Carp, N. K.
Robakis, and H. M. Wisniewski.
1986. Detection of scrapie-associated
fibril (SAF) proteins using anti-SAF antibodies in non-purified
tissue
preparations.
Journal of General Virology 67: 671-681.
Schreuder, B. E. C., L. M. J. van Keulen, M. E. W. Vromans, J. P. M. Langveld,
and M. A. Smits.
1996.
Preclinical test for prion diseases.
Nature
381: 563.
Scott, A. C., S. H. Done, C. Venables, and M. Dawson. 1987. Detection of
scrapie-associated
fibrils as an aid to the diagnosis of natural sheep
scrapie. Veterinary Record 120: 280-281.
Scott, A. C., G. A. H. Wells, M. J. Stack, H. White, and M. Dawson. 1990.
Bovine spongiform encephalopathy:
Detection and quantitation
of fibrils,
fibril protein (PrP) and vacuolation in brain. Veterinary Microbiology
23: 295-305.
Spraker, T. R., M. W. Miller, E. S. Williams, D. M. Getzy,
W. J. Adrian, G.
G. Schoonveld, R. A. Spowart, K. I. O'Rourke, J. M. Miller, and P. A.
Merz. 1997. Spongiform encephalopathy
in free-ranging mule deer
(Odocoileus hemionus), white-tailed deer (0. virgianus), and Rocky
Mountain elk (Cervus elaphus nelsoni) in northcentral
Colorado. Journal
of Wildlife Diseases 33: 1-6.
Stack, M. J., A. M. Aldrich, A. D. Kitching, and A. C. Scott. 1995.
Comparative
study of electron microscopal techniques for the detection of
scrapie-associated
fibrils. Research in Veterinary Science 59: 247-254.
Stack, M. J., A. M. Aldrich, A. D. Kitching, and A. C. Scott. 1996. Comparison
of biochemical
extraction techniques for the detection of scrapieassociated fibrils in the central nervous system of sheep naturally
affected with scrapie. Journal of comparative Pathology 115: 175-184.
van Keulen, L. J. M., B. E. C. Schreuder, R. H. Meloen, M. Poe len-van den
Berg, G. Mooij-Harkes,
M. E. W. Vromans, and J. P. M. Langerveld.
1995.
Immunohistochemical
detection and localization of prion protein in bran
tissue of sheep with natural scrapie. Veterinary Pathology 32: 299-308.
van Keulen, L. M. J., B. E. C. Schreuder, R. H. Meloen, G. Mooij-Harkes;
M. E.
W. Vromans, and J. P. M. Langveld.
1996.
Immunohistochemical
detection
of prion protein in lymphoid tissues of sheep with natural scrapie.
Journal of Clinical Microbiology
34:1288-1231.
Wells, G. A. H., M. Dawson, S. A. C. Hawkins, A. R. Austin, R. B. Green, I.
Dexter, M. W. Horigan, and M. M. Simmons. 1996. Preliminary observations
on the pathogenesis
of experimental bovine spongiform encephalopathy.
In

�164
Bovine spongiform encephalopathy
The BSE Dilemma,
Vol. C. J. Gibbs, Jr.
(ed.). Springer-Verlag,
New York, New York, pp. 28-44.
Williams, E. S. and S. Young. 1980. Chronic wasting disease of captive mule
deer: A spongiform encephalopathy.
Journal of Wildlife Diseases 16:
89-98.
Williams, E. S. and S. Young. 1982. Spongiform encephalopathy
of Rocky
Mountain elk. Journal of Wildlife Diseases 18: 463-471.
Williams, E. S., and S. Young. 1992. Spongiform encephalopathies
of Cervidae.
Scientific and Technical Review Office of International
Epizootics 11:
551-567.
Williams, E. S. and S. Young. 1993. Neuropathology
of chronic wasting disease
of mule deer (Odocoileus hemionus) and elk (Cervus elaphus nelsoni).
Veterinary Pathology 30: 36-45.
Williams, E. S., M. W. Miller, T. J. Kreeger, and H. Van Campen.
1997.
Susceptibility
of cattle to cervid spongiform encephalopathy.
Unpublished
study plan, 66 pp.

Table 1. Tissues to be collected
and detection of Prpsc.

Nervous Tissue
brain (multiple levels)
pituitary
CSF
dura
spinal cord (cervical, thoracic,
lumbar)
dorsal root ganglia
trigeminal ganglia
stellate ganglia
sciatic nerve
radial nerve
Muscle Tissue
diaphragm
semitendinosus
muscle
triceps muscle
longissimus dorsi muscle
Alimentary Tissue
tongue
submandibular
lymph node
parotid salivary gland
esophagus
rumen
omasum
abomasum
duodenum
distal ileum and Peyer's patches
spiral colon
feces
pancreas
liver

from deer exposed

to CWO for histopathology

Lymphoid Tissue
spleen
thymus
tonsil
submandibular
lymph node
retropharyngeal
lymph node
bronchial lymph node
mediastinal
lymph node
hepatic lymph node
mesenteric lymph nodes
ileocecal lymph node
hepatic lymph node
superficial cervical lymph node
popliteal lymph node
Other Tissues
kidney
urine
adrenal gland
.lung
nasal mucosa
left ventricle
blood (serum, buffy
bone marrow
skin (head)
bone (rib)

coat,

clot)

�91

Colorado Division of Wildlife
Wildlife Research Report
July 1999

JOB PROGRESS REPORT

State of
__,..--!:C~o~lo::.!.r=ad...,o,,-_
Project No. __
-..l..W!--...:..1=.:53:!...-~R~-~12~_
Work Package No. _---"'-30;:....;0::..,:1'-_
Task No.
3

------~---------

Period Covered:

Cost Center 3430
Mammals Program
Deer Management
Monitoring and Managing
Disease in Deer

Chronic Wasting

July 1, 1998 - June 30, 1999

Authors:

M. W. Miller, C. T. Larsen, and J. Gross

Personnel:

R Kahn. M. Leslie, K. I. O'Rourke,
Williams

T. R Spraker, E. Wheeler, M. A. Wild, and E. S.

ABSTRACf
.
Deer from throughout Colorado were examined for occurrence of chronic wasting disease
using a combination of targeted surveys and harvest/road-kill surveys. Between June 1998 and May
1999, 8 chronic wasting disease (CWD) cases were diagnosed among 25 "suspect" deer submitted
from known endemic portions of northeastern Colorado; CWD was not diagnosed in any of 10
additional "suspect" deer submitted from elsewhere in Colorado. All confirmed CWD cases originated
in game management units (GMUs) where the disease had been detected previously.
We sampled over 1800 harvested or road-killed deer to randomly survey for CWD in select
DAUs. Immunohistochemistry
(llIC)-based prevalence in Larimer County (5%; 39/780) and South
Platte River bottom/plains (1.6%; 5/315) DADs were unchanged from previous years. We detected no
evidence ofCWD in any of369 samples from Middle Park, or in any of over 300 samples from other
GMUs outside northeastern Colorado. Late doe hunts in Larimer County DAUs provided an
additional 212 samples for comparison of CWD prevalence between sexes; based on data compiled
over the last 2 years, CWD prevalence does not differ between male and female mule deer (P = 0.72).
Since June 1998, CWD affected 8 of 29 adult (z l-yr-old) mule deer in the resident Foothills
Wildlife Research Facility herd. No signs of neurological disease were observed in any of the 11 cattle
(subjects) or 11 mule deer from the Rocky Mountain Arsenal National Wildlife Refuge
(RMANWR)(contact
controls) housed with naturally-infected resident deer since July 1997.
Using mc, Prpres was detected in brain tissue (medulla oblongata at the obex) from 1 of2
mule deer experimentally inoculated with a 5 g oral dose of brain tissue
homogenate from
CWD-infected deer 6 or 9 mo earlier. One of two deer examined 16 mo after inoculation (Pl)
had lesions of spongiform encephalopathy, and both were mC-positive. Two deer examined 3 rno PI
and 2 examined 12 rno PI were negative, as were all 10 uninoculated controls collected from
RMANWR at the same intervals. One of the 8 remaining deer inoculated in December 1997 began

�92
showing early clinical signs of CWD ~ 15 mo PI; a second began showing early signs 2-3 wks later,
and subtle signs were noted in at least 4 of 8 inoculated deer alive 18 mo PI.
An epidemic model of
was developed to simulate the dynamics of chronic wasting
disease in mule deer populations. As seen in earlier modeling exercises, simulations resulted in
projections wherein either the disease or the deer population was eliminated; stable coexistence of
chronic wasting disease could not be achieved in simulated populations. Productivity (i.e., harvest)
was reduced in populations by very low rates of prevalence. Spread of CWD within a simulated
population was highly sensitive to transmission rate, and very small decreases in transmission
efficiency resulted in notable decreases in prevalence. Simulated test and slaughter programs revealed
the importance of initiating control while CWD prevalence was low « 0.05). Low rates of test and
slaughter (e.g., &lt; 20% of the infected population) effectively eliminated wasting disease in simulated
populations if control measures were initiated while prevalence was low (i.e., 0.01), but the likelihood
of control diminished rapidly as disease prevalence increased. Test and slaughter programs will
require an effort sustained over many decades to ensure elimination of chronic wasting disease.
A statewide plan for monitoring and managing CWD in deer and elk was drafted. The plan has
been distributed for internal and limited external review, and will be finalized by 30 September 1999.

cwn

�93

MONITORING

AND MANAGING CHRONIC WASTING DISEASE IN DEER
M. W. Miller and C. T. Larsen

P. N. OBJECTIVES
'"1. Design, conduct, and report results of:
a. targeted surveillance to estimate and detect changes in distribution of chronic wasting disease
(CWD) in free-ranging deer populations; and
b. harvest or road-kill surveys to estimate and detect changes in prevalence of CWD in enzootic
deer populations.
,2. Design, conduct, and report results of experimental studies using captive deer naturally or

experimentally infected with CWD.

AGREEMENT

OBJECTIVES

1. Conduct and report results of targeted surveillance to estimate and detect changes in distribution of
CWD in free-ranging deer populations statewide.
2. Conduct and report results of harvest surveys to estimate prevalence ofCWD in DAUs D4, D9
(GMUs 18,28,37,371), DI0( +GMU 29), and D44 (+ GMUs 87, 90, 93, arid 95).
3.

Continue an experiment evaluating cattle susceptibility to CWD via natural contact exposure.

4.

Continue to study pathogenesis ofCWD in mule deer.

5. Develop an epidemic model ofCWD dynamics in deer populations.
6.

Observe epidemiology of naturally-occurring CWD in captive deer.

MATERIALS AND METHODS
Surveillance
We monitored deer populations throughout Colorado for occurrence of CWD using a
combination of targeted surveillance and harvest or road-kill surveys. These were organized and
conducted as follows:

�94

Targeted (= clinical disease) surveillance: Deer showing clinical signs consistent with those seen in
chronic wasting disease were collected by field personnel statewide and brain tissues examined for
evidence of spongiform encephalopathy. The "suspect case" profile was defined as follows:
• Species:

mule deer
white-tailed deer

• Age:

::::18 months

• Signs:

emaciated and
abnormal behavior &amp;lor
indifference to human activity &amp;lor
increased salivation &amp;lor
tremor, stumbling, incoordination &amp;lor
difficulty or inefficiency in chewing/swallowing
increased drinking and urination

&amp;lor

Where possible, submissions were subjected to complete necropsy; in some situations, only heads were
available for examination and sampling. In all cases, histopathology of brain tissue (Williams and
Young 1993) was used to diagnose CWO; in some cases, immunohistochemistry (ll:IC) or other
ancillary tests were used to confirm or support diagnoses.
Harvest surveys: In order to obtain reliable estimates of CWO prevalence that will serve as a basis for
monitoring responses to management interventions, we continued conducting harvest surveys on select
deer populations. During the 1998-1999 hunting seasons, fresh brain and select lymphatic tissues were
collected from deer harvested in enzootic GMUs; deer harvested or culled in other select GMUs
throughout Colorado were also sampled as negative controls. Brain tissues were examined at the
Colorado State University Diagnostic Laboratory for anti-PrP immunostaining reactions (O'Rourke et
al., 1998) and histopathological lesions (Williams and Young, 1993) consistent with CWO infection.
Epizootiological Studies
Epizootology of naturally-occurring CWO in captive mule deer and white-tailed deer: Naturallyoccurring CWO was a sporadic disease of resident FWRF mule deer prior to 1985 (Williams and
Young, 1992), and also has occurred sporadically since 1994; no cases had been observed in resident
white-tailed deer since their addition to FWRF in 1993. We maintained and observed 29 ~ l-yr-old
mule deer and 5 ~ l-yr-old white-tailed deer in paddocks at CDOW's Foothiils Wildlife Research
Facility (FWRF) during May-September 1998. Deer received natural forage, pelleted rations (high
energy supplement and "browser" diet), and alfalfa hay; water and mineralized salt were available ad
libitum. All deer were evaluated daily for clinical signs of CWO (and other health problems) in
conjunction with routine feeding and handling activities. Resident mule deer also represented the
source of infection (= "treatment") in an ongoing study of cattle susceptibility to CWO (see below).
Cattle susceptibility to CWO (Williams and Miller): We continued monitoring cattle for clinical
evidence of natural CWO transmission as part of a coordinated interagency effort to study cattle
susceptibility to CWO. Twelve 4-mo-old calves purchased from a private ranch located near Sheridan,
WY, were placed in paddocks at the FWRF with naturally-infected captive mule deer in July 1997 (see
above for description of resident deer herd). Twelve 4-mo-old mule deer fawns were captured at the
Rocky Mountain Arsenal National Wildlife Refuge (RMANWR) in late September and placed in the

�95

same paddocks as contact controls for natural transmission (extensive ongoing surveillance of
RMANWR deer has continued to confirm that this population is free of CWD).
CWD Pathogenesis in mule deer (Williams and Miller): In a separate but related study, 20 additional 6mo-old mule deer fawns were captured at the RMANWR in early December. Each fawn was given a
single oral dose of about 5 g of fresh brain tissue homogenate from captive mule deer with clinical
CWD. Fawns were then released into a separate paddock physically removed from the contact
transmission study. These experimentally-infected fawns serve two purposes: as controls for domestic
calves orally inoculated with a single oral dose of about 50 g of this same CWD brain homogenate
(Williams et al., 1998), and as subjects of a study on the pathogenesis of CWD in mule deer.
We have randomly sacrificed 2 experimentally-infected deer at 3,6,9, 12, and 16 mo after
inoculation; we also collected 2 age- and sex-matched control deer from RMANWR at each time step.
Complete necropsies were performed and samples collected as described in the original study plan. .
Select sections of brain tissue (obex) were examined after staining with hematoxylin and eosin (H&amp;E)
or anti-PrP immunostain (F89/160.1. 5; O'Rourke et al., 1998); examination of other tissues is pending.
Epidemic modeling (Gross and Miller): We developed a mechanistic model to simulate the dynamics
of chronic wasting disease in mule deer populations. The model projected age-specific disease
dynamics, changes in population size, and control strategies involving selective removal of infected
animals or changes in rates of disease transmission. Model parameters were estimated from
observations of infected and uninfected deer in Colorado and Monte Carlo techniques were used to
evaluate likely responses. Appendix A provides a more detailed description of our model.

CWD Monitoring and Management Plan
A statewide plan for monitoring and managing CWD in deer and elk was drafted.

RESULTS AND DISCUSSION
Surveillance
Targeted (= clinical disease) surveillance: Between June 1998 and May 1999, 8 chronic wasting
disease (CWD) cases were diagnosed among 25 "suspect" deer submitted from known endemic
.portions of northeastern Colorado; CWD was not diagnosed in any of 10 additional "suspect" deer
submitted from elsewhere in Colorado. All CWD cases confirmed in 1998-1999 were mule deer, and
all originated in game management units (GMUs) where the disease had been detected previously.
Harvest surveys: We sampled over 1800 harvested or road-killed deer to randomly survey for CWD in
select DADs. ruC-based prevalence in Larimer County (5%; 39/780) and South Platte River
bottom/plains (1.6%; 5/315) DADs were unchanged from previous years. We detected no evidence of
CWD in any of369 samples from Middle Park, or in any of over 300 samples from other GMUs
outside northeastern Colorado. Late doe hunts in Larimer County DADs provided an additional 212
samples for comparison of CWD prevalence between sexes; based on data compiled over the last 2
years, CWD prevalence does not differ between male and female mule deer (P = 0.72).

�96
Survey data gathered during 1996-1999 indicate that CWD is generally more prevalent and more
widely distributed in mule deer than in white-tailed deer in northeastern Colorado (Fig. 1). However,
limited data from white-tailed deer harvested near the mouth of the Big Thompson Canyon west of
Loveland suggest CWD could become quite prevalent among white-tailed deer (Fig. IB). In light of
this potential and the apparent spread of CWD eastward along the Big Thompson/South Platte River
corridor in both mule deer and white-tailed deer (Fig. 1), natural spread and eventual infection of more
densely populated white-tailed deer habitats in the midwestern and eastern US should be anticipated in
the coming decades unless management
interventions are successfully identified
and implemented.
A.Muledeer

Epizootiological Studies
Epidemiology of naturally-occurring
CWD in captive mule deer and whitetailed deer: Since June 1998, CWD
affected 8 of 29 adult (~ l-yr-old) mule
deer in the resident Foothills Wildlife
Research Facility herd (Fig. 2A).
Two other adult mule deer died between
June and May; enterotoxemia was
diagnosed in one, and pasteurellosis in
the other. Although neither showed
neuropathology consistent with CWD, 1
had IHC staining consistent with
preclinical CWD. Resident mule deer
also represented the source of infection
(treatment) in an ongoing 10-yr study of
cattle susceptibility to CWD (see
below).
One of 5 white-tailed deer
remaining in our resident FWRF herd
developed CWD and died in June 1999.
In all, CWD has claimed 7 of 11 captive
white-tailed deer held at FWRF since
1993 (Fig. 2B). One of the 4 remaining
individuals is showing early signs of
CWD.

I

B. White-tailed deer

Figure 1. Estimated CWD prevalence (%) among subpopulations of (A) mule deer and (B) white-tailed deer
in northeastern Colorado. Data were aggregated via
known deer movement patterns. Prevalence estimates
are based on IHC reactions only (IHC+ltotal).

Evaluation of tonsillar biopsies from captive deer are still pending. Lack of results has
precluded evaluation of tonsillar biopsy as a potential antemortem test for CWD in deer.
Cattle susceptibility to CWD (Williams and Miller): No signs of neurological disease were observed in
any of the II cattle (subjects) or II mule deer from the Rocky Mountain Arsenal National Wildlife
Refuge (RMANWR)(contact controls) housed with naturally-infected resident deer since July 1997.
Neither of2 contact control deer that died during October-June showed neuropathology consistent with
CWD, although both suffered from chronic weight loss; malnutrition probably contributed to at least I
of these deaths. Fifteen of the 36 &gt; l-yr-old naturally-exposed resident FWRF deer developed clinical

�97

CWD and died or were euthanized during the first 24 mo of this
study, thereby ensuring calves and control deer have received
considerable exposure to CWD.
Similarly, all 11 cattle exposed to a single 50 g oral dose
of brain tissue homogenate from CWD-infected deer remained
healthy 21 mo postinoculation (through 30 June 1999) (E. S.
Williams, pers. comm.), as did all cattle exposed to CWD
via intracerebral inoculation 22 mo ago (R. 1. Cutlip, pers.
commun.).

A.
lD

j
-

".dee,
,._.-.

:JJ

,-- •• :
:
::

o

~ 2l

i
10

::
::

r-':

:
:::

•

:: :::: :::: :::: ::: !---::
::

r'1i i~H:: ~~
~i ~~
:: :: ::

!_.-:: :: ::

! !; H ~~ ~. .: :. :
'III'

8. WlitR-t.Ied

dHr

lD

..,
i

Xl

o

t

2)

z
Pathogenesis of CWD in mule deer (Williams and Miller):
rcs
Using ruc, Prp was detected in brain tissue (medulla
oblongata at the obex) from 1 of2 muIe deer experimentally
inoculated with CWD 6 or 9 mo earlier. One of two deer
examined 16 mo after inocuIation (PI) had lesions of spongiform
Figure 2. Chronic wasting
encephalopathy, and both were ruC-positive. Two deer
disease continued to affect
both mule deer and whiteexamined 3 rno PI and 2 examined 12 mo PI were negative, as
tailed deer held at FWRF.
were all 10 uninoculated controls collected from RMANWR at
the same intervals. One of the 8 remaining deer inoculated in
December 1997 began showing early clinical signs of CWD ~ 15 mo PI; a second began showing early
signs 2-3 wks later, and subtle signs were noted in at least 4 of 8 inocuIated deer alive 18 mo PI.

ResuIts from examination of lymphoid tissues are pending.
Epidemic modeling (Gross and Miller): Simulations ofCWD dynamics that used a broad range of
parameter values resulted in projections in which either the disease or the deer population was
eliminated. We did not identify a set of realistic parameters that resulted in stable coexistence of
chronic wasting disease in deer populations. Population productivity (i.e., harvest) was reduced in
populations by very low rates of prevalence due to the combined effects of a reduction in per-capita
production and a decrease in population density. Spread of the disease was highly sensitive to the rate
of transmission, and a very small decreases in the efficiency of transmission resuIted in notable
decreases in rate of spread of the disease. Simulatedjest and slaughter programs revealed the
importance of initiating control activities while prevalence of the disease was low « 0.05). Low rates
of test and slaughter (e.g., &lt; 20% of the infected population) effectively eliminated wasting disease in
simulated populations if control measures were initiated while prevalence was low (i.e., 0.01), but the
likelihood of control diminished rapidly as disease prevalence increased. Test and slaughter programs
that examine will require an effort sustained over many decades to ensure elimination of chronic
wasting disease.
CWD Monitoring

and Management

Plan

The draft monitoring and management plan (Appendix B) has been distributed for internal and
limited external review, and will be finalized by 30 September 1999.
Surveillance activities for 1998-1999, as well as surveillance planned for 1999-2000, reflect
prioroties established in the monitoring portion of this plan.

�98

ACKNOWLEDGMENTS

.

The statewide CWD monitoring and surveillance program described here relies heavily on
efforts of dedicated field personnel throughout the Colorado Division of Wildlife, and truly represents a
division-wide effort to improve our understanding and management of this important disease problems.
In addition to those specifically listed, we collectively thank all of those regional and area biologists,
district and area wildlife managers, volunteers, deer hunters, and others who assisted by submitting
suspect cases, harvested animals, or road-killed animals throughout the year.

LITERATURE CITED
K. 1, T. V. Baszler, 1. M. Miller, T. R Spraker, 1 Sadler-Riggleman, and D. P. Knowles.
1998. Monoclonal antibody F89/160.1.5 defines a conserved epitope on the ruminant prion
protein. }. Clin. Microbiol. 36:1750-1755.
Williams, E. S., and S. Young. 1993. Neuropathology of chronic wasting disease in mule deer
(Odocoileus hemionus) and elk (Cervus elaphus nelsoni). Veterinary Pathology 30:36-45.
_--"
M. W. Miller, T. 1. Kreeger, H. Van Campen, and T. R Spraker. 1998. Susceptibility of cattle
O'Rourke,

to cervid spongiform encephalopathy. unpublished grant proposal, submitted to USDA,
CSREES, National Research Initiative Competitive Grants Program, 88 pp.

Prepared by

_
Michael W. Miller
Wildlife Research Veterinarian

�99
Appendix A

CWO:
Simulating Chronic Wasting Disease

User's Manual and Model Documentation
Version 1.0
June 1999

John E. Gross

Natural Resource Ecology Laboratory
Colorado State University
Ft. Collins, CO USA 80523-1499
Email: JohnG@NREL.ColoState.edu

�100

CWD: Simulating Chronic Wasting Disease
Summary
CWO is an individual-based model that represents the most important processes
determining the dynamics of animal populations over periods of decades or centuries. It
simulates reproduction, disease dynamics, and the interaction of the animals with
environmental characteristics that can change through time. Each animal in the population
is explicitly represented and individual characteristics including age, sex, and disease state
are tracked for the life of an individual. The model simulates 1 to 3 disease period, and
includes the capacity to model a wide variety of harvest scenarios. Files are written that
facilitate analyses of population responses to disease, harvest, or environmental variation,
including changes in disease prevalence, disease-caused mortality, harvest, and changes
in population age/sex structure.
CWO has a flexible structure and there are no inherent practical limitations to the
. number of individuals that can be simulated during a run. Practical limits to the number of
individuals are set only by the capabilities of the computer on which the model is run.
Introduction
To make informed decisions on management of large ungulates, biologists need to
evaluate the consequences of alternative management actions on population processes.
. Management' actions can include hunting by the public or agency personnel, vaccination,
selective harvest, habitat modification, or a combination of these actions. The
consequences of these decisions depend on a complex of factors, and it is thus difficult to
evaluate the relative merits of alternative management plans. CWO was designed to
simulate management actions that might be used in attempts to eliminate CWO or to inhibit
its spread. The model simulates each individual in the population and explicitly represents
reproduction, natural mortality, disease transmission, non-selective harvests (Le., hunting),
and selective harvests (e.g., test and slaughter). The use of an individual-based model is
particularly appropriate for CWO because stochastic effects are important in small
populations, or where a small number of individuals have a large effect on population
processes. This situation clearly applies to CWO, where the behavior of a small number of
infectious individuals can have a profound influence on long-term dynamics of a much .
larger population.

�101

An Overview of Model Structure and General Features
Animal populations are simulated within a landscape that potentially can consist of a
single or multiple patches. Each individual is simulated and has attributes including a sex,
age, disease state, and membership in a local population. Mortality and fecundity are stage
specific processes, and each individual is assigned to a specific stage based on its age.
Mortality is density-independent, and fecundity (recruitment) responds to density only when
density exceeds a threshold value. CWO differs from other population simulators by
.
incorporating disease, modeling both males and females, and by including functions that
permit age and sex-specific patterns of removal. Because the model is individual-based, it
is appropriate for representing the dynamics of small populations as well as large. In
general, the number of patches or individuals that can be simulated are limited only by
computer memory and processor speed. In reality, it is much easier to generate complex
model dynamics than It is to understand the output, and most practical limitations will result
from' an inability to analyze and understand output. It is essential to run many simple
simulations to ensure that you have a complete understanding of model behavior before
introducing spatial structure or other complexities.
i

Patch Attributes and Dynamics
A patch is an area of the landscape that can support a local population. A Patch has
the attributes of area, current quality (see below), maximum quality, mean environmental
quality (from 0-1), maximum environmental quality (0-1), deviation from mean quality, and
time since disturbance. Overall patch quality is quantified in a single variable ("forage")
calculated from a user-defined function that transforms current forage to quality multiplier'
(from 0-1; Fig. 2). This "forage" quality multiplier is used by the local population each year to
determine the ability of the patch to support a population of animals (see below).
Patch dynamics are simulated by predicting "forage" as a function of time since
disturbance. The function that determines "forage" is calculated from a linear interpolation
between forage and time values that are user-defined.
Patch attributes can dramatically affect population processes through densitydependent effects on recruitment. If you wish to remove density-dependent effects from the
model and control populations through harvest, set the patch size to a number much larger
than mean population size and set animal density (in the *.spc file) to a number greater than
one.
Recruitment and Death
The likelihood of recruitment changes with animal age and varies from year to year.
Yearly variation is represented by an "environmental quality" multiplier that modifies the
average recruitment rates. Each year, the model selects a random deviate from a Beta
distribution that represents the "environmental quality" for the current year. The distribution
of "environmental quality" is defined by the mean and standard deviation (entered by the
user), and if the standard deviation is set to 0 there is no annual variation in the overall rate
of recruitment. Each year the model loops through all females and compares the probability
that a female of that age recruits an offspring into the population to a uniform random
deviate. If the random deviate is less than the probability, recruitment occurs.
Animals are culled from the population at stage-specific rates once per year. Mortality
rates are independent of animal density and are subject only to stochasticity due to random
events and to acute catastrophes. Stage-specific mortality rates are input by the user, and

�102

for each individual, these rates are compared to a uniform random deviate to determine
whether that particular individual dies during the year.
Animal density dependent can effect population dynamics by reducing the probability
of recruiting into the population. There is no effect of density on survivorship. Population
density affects recruitment only when it exceeds a density threshold. Above the density
threshold, the probability of recruitment declines linearly to 0 at a user-defined upper
recruitment bound (Fig. ). In most situations this model is used to simulate, density plays
no role in population dynamics because populations are controlled primarily by harvest.
Under these conditions, its best to set the patch size sufficiently large to ensure that a
density function is never invoked.
Animal and Patch Aging
The age of both animals and patches are incremented at the end of summer, after
dispersal and prior to mating. At this stage, any patch manipulations are input and patch
disturbance occurs. New patch statistics are generated for each patch, to be used in the
following year's simulation.
Data Output
Model output is generated at the end of each year. The frequency of model output to
the screen is specific by the user, while file output is generated every year. Output files
formats are designed for analysis by statistical packages (e.g., SAS, SPSS) and are fixed
format. The year is incremented immediately before model output and before patch
dynamics are simulated. Thus year 0 output records are initial conditions.
Running a Simulation
To run a simulation, it is first necessary to build a set of input files that contain the variables
and parameters used in the simulation (Table 1). The overall model run (which may consist
of a large number separate Monte Carlo simulations) is controlled by a file with the
extension .run. This file contains the names of input files that define life history
characteristics, patch attributes, disease dynamics, and other run-time information
described in Table 1 and below. This section describes the input files necessary to conduct
a model run. The appendices to this manual include sample input file of each type.
Input Files
A simulation is controlled by variables and parameters specified in files that define the
characteristics of the. animal species and landscape, and by the a file that contains
information specific to a particular run (e.g., the number of years to simulate, names of input
files, and what information is to be written to output files). In general, lines in an input files
begin with an integer that tells the program what the rest of the line contains. This is
followed by a one word descriptor (e.g., a series of characters and/or numbers that contain
no spaces) of that line, followed by one or more parameters. It is essential that the one
word descriptor has no spaces, and that there is at lease one space between the descriptor
and the parameter(s). Input files are summarized in Table 1.
Summary of parameters contained in each input file.
1.

*.run Simulation run parameter file: Contains the names of files with parameters to
be used in a specific set of runs, the number of runs to be simulated, the length of

�103

each run, and which output files are to be written. It contains a variable for the
frequency of output to the screen and a delay interval so that screen output can be
more easily viewed. Screen output is slow; you can dramatically speed model
execution by increasing the interval at which output is printed to the screen. This is
the"master" file that and it deals with the highest level of model control.
Code: Inputs::ReadRUNFile
2. .. *.pch Patch attributes include the size of each patch, maximum quality of the patch
(0-1.0), a mean quality and the standard deviation of the mean patch quality, an initial
forage (which remains unchanged in the 'absence of disturbance). Specified changes
to patch quality and/or size in a given year can be used to simulate prescribed bums
or other management protocols.
Code: LandScape::ReadPCHFile
3.:''. *.spc Species characteristics:
sex ratio at birth (m:f), number of age/stage classes
for males and females, ages associated with each class, litter size, stage specific
mortality, birth schedule, adult male and female body size, maximum density. The
density threshold is estimated from the maximum density of animals, patch quality, and
patch area. This file also specifies a function that relates patch quality (summarized
into one variable, called "forage", for convenience) to a quality multiplier. Linear
interpolation is used to estimate quality for values intermediate to those entered.
Code: MammaIData::ReadSPCFile
4.

*.pop Population parameters: This file contains the initial 'size and composition (age,
sex) of populations.
Code: AnimaIPopulation::ReadPOPFileO

5.

*.hrv Harvest. File with parameters that determine the rules used to implement
harvests. This includes the frequency of harvest (every year, every other year, etc.),
threshold population sizes for determining the size of harvest, rules that govern the
number of animals harvested, and the age and sex composition of the harvested
population.

6.

*.dis Disease:. File with parameters that determine disease dynamics. Includes
parameters for transmission, and transition from incubating to infected and infected to
dead.
'

Model Functions and Details
This section describes the structure of specific model functions, the implementation
functions, and sources of data used to parameterize the model.

of model

Patch Dynamics
Patches are areas that potentially support a local population, and they are characterized by their
area (_area) and quality (_qualify, 0-1), constrained to a maximum for each patch (_maxQualify).
Patch
quality defines the ability of the patch to support animals relative to their maximum density. For
example, if the maximum density for a species is 10 and the quality of a particular patch 0.1, that patch

�104

Table 1. Input file extensions and the types of data they contain.
file name

type of data

example file parameters

*.pch

patch data

size, maximum quality, time since disturbance

*.spc

species attributes

sex ratio at birth, stage-specific fecundity and mortality, maximum

*.pop

local population data

number of local populations, age and sex of the members in each

*.run

simulation run control

# of years of the simulation, names of input and output files, output

*.hrv

harvest information

frequency, number harvested, and composition of harvest

*.dis

disease parameters

transmission and transition proabilities

I

will support 1 animal per unit of area (area is generally expressed in krrf). The quality of each patch can
be affected by environmental stochasticity, which is characterized by a normal random variate with a
specified mean LmeanEnvirQualify,
0:-1) and standard deviation LsdEnvirQualify).
The quality of a
patch during any given year is calculated from it's current forage (see Landscape, _forage), constrained
to a _maxForage level specific to each patch, and the quality associated with a given value of forage:
_qualify

= f(minLforage,_maxForage))

and the effects of environmental
_qualify = minLmaxQualify,

stochasticity (if any):

_qualify * norma/_randomLmeanEnvirQualify,

_sdEnvirQuality).

The function that calculates quality as a function of _forage is defined by the user. and linear
interpolation is used to evaluate points between those defined in the input file. If current forage is
greater than that defined by the user, the
_forage value at the maximum
_gTSinceDisfurb is used; e.g .• no values
are extrapolated beyond the data.
These are combined to determine the
population size at which reproduction is
inhibited, _densifyThresSize, as a function
of patch quality and the maximum density
of animals that the highest-quality patch
could support.
_densifyThresSize
_qualify.

= _maxDensify

*_area *

50

100

150

200

250

300

S50

••00

Forage

This design has been implemented to
Fig. 2. User-defined function relating quality to forage.
reflect the observation that population size
may be restricted by forage availability,
which changes over time. or other habitat features (perhaps escape terrain) that do not change. The
quality of any single patch is therefore constrained by both a "food" -type variable Lforage) and other
patch characteristics LmaxQualify).
Code: LocaIPop:SetDensThresSizeO;
LocalPop:DensThresSizeO

�105

Species Characteristics
Each species to be modeled must be described by life history characteristics including the number
of different stages for males and females LnMaleStages, _nFemaleStages), inclusive ages of each
stage LmStageMinAge, _'StageMinAge), maximum number of young LmaxYoung), the probability of
having O-_maxYoung (_pYoungm, stage-specific birth and death probabilities (_pRecruitj, _pMMortality;,
_pFMortality;. where I is stage).

Density Dependence
Density dependence influences the probability of dispersal and recruitment of new individuals into
the population. The probability of recruiting one or more young is stage-specific and is determined by
user-input values. This probability is then modified to reflect the effects of density and environmental
stochasticity,
To calculate density-dependent effects, it is necessary to specify. a species-specific maximum
density ·LmaxDensity, #/unit-area), the density a species achieves in optimal habitat.. The units of
patch size and ...;,maxDensity (e.g., ha) must be the same. The density at which recruitment falls to zero is
defined by _upperPopBound, a decimal value greater than 1 used to determine the population size at
which the probability of recruiting an individual falls to zero in the absence of environmental stochasticity
(Figure XX). When the population size in patch I is greater then _pop Ttuessize; the age-specific
probability of recruitment (_pRecruif) is modified to reflect the density-dependence:

_pRecruitj

.'

(

= _pRecruit

j

popSizej

l-----------------------------------~--(l+_upperPopBoundj)

)

_densThresSizej

Effects of Density on Recruitment

The probability of recruitment of a new individual can be
further influenced by environmental stochasticity, which is
constrained to the range of _envirQualMin andt:
environmental Quality =
maxL envirQualMin,
nonnalrandomLmeanEnvirQualify,_
_pRecruitj

11-----------------,.

l

sdEnvirQuality))

= _pRecruitj *environmental

Quality

Fig. 3. DensitY effects, where A

= _densThresSize

Taken together, these functions account for annual.stochastic
and B = _densThresSize • _upperPopBound
fluctuations in habitat quality that affect "carrying capacity",
and yearly fluctuations in recruitment that result from abiotic or biotic sources (weather, predation, etc.).

-.

Code: AnimaIPopulation::BreedAndRecruitO,
LocaIPop::SetDensThresSizeO;
LocaIPop::DensThresSizeO
Data: MammaIData._envirQuaIMean,
_envirQuaISD, _probRecruitD
Mortality
Natural mortality occurs once per year (Figure 1), and is a stage-specific function. Stage and sexspecific mortality rates are. user-specified parameters in the *.spc file. For each individual, a uniform
random deviate (0-1) is compared to the probability of death.
Code: AnimaIPopulation::CUII
Aging
At the end of each time loop, the age of each individuals is incremented by 1 and an appropriate
adjustment is made to _tSinceDisfurbance for each patch and local population.
Code: AnimaIPopulation::

AgeO; LocaIPop::SAgeO;

LandScape:: SetTimeO

�106

Model Output
Model output is written to standard ASCII text files that are created in the current directory, typically the
directory containing the input and executable files. By default, any existing files of with the same name are erased
upon opening, except for the error log file. Output file formats are described below. Any errors that occur during
the run are printed to the screen and error file, and the run will be aborted when a severe error is detected. Some
common errors in input parameter values are automatically corrected (e.g., an out-of-range parameter), in which
case a message is written to the error log file informing the user of any corrections. All simulation result files are
formatted to facilitate input to programs for further analysis in statistics, graphics, or spreadsheet programs.
Variables in output files are either space or comma delimited.
File output ceases when an entire population goes extinct, except for data written to the summary output file.
Thus if a population goes extinct in year 23 of a 50 year run, files will generally contain 24 years of data (year 0 +
23 years). The summary file will be filled with 0 values for the full length of the run (year 0 + 50 years).
All output file names begin with the same prefix, which can be specified in the *.run file or which will
default to "cwd". All output file names have an ".asc" extension except the error file.
Output Files Produced by Every Run
_pavg.as&lt;;: - 1 line for each year of run. Mean and standard deviation of the number of susceptibles, incubating,
infectious, and total population size.
_ sum.asc - 1 line for. each year of each run. Number of susceptibles, incubating, infectious, and harvested.
CWD _err. txt (if an error is detected).
Error information
Information about any errors detected during a run are printed to this file. Errors are assigned to categories
Warning, Error, and Fatal Error. Warning messages signal an error than can be automatically corrected within the
program or conditions that are unlikely to affect program results. Errors are more severe, and may be corrections
to parameters that are frequently entered incorrectly or a condition within the program that may be irregular.
Depending on the compilation, the program may abort upon detecting an error (this is a compiler switch, and
cannot be changed by the user). The program always aborts when a Fatal Error is detected. Fatal errors are
usually the result of an incorrect input file format, invalid parameter, or insufficient hard disk space or memory.
Table 2. Output file names and contents. Files in italics are always produced, others are produced only when
specified by a switching variable in the *.run file.
Files are comma-delimited.
File

Columns

Information

cwd err.txt

text

Produced or appended to if an error is reported.

_age

I-many

run, year, patch number, males by age (O-Age max), females by age (0Age max). Age max is specified in the *.spc file.

disfxhs

1-5

run, year, patch number, period, disease-caused deaths by sex and age
class

-hrv

l-many

run, year, patch, population size category, males by age (O-MaxAge),
females by age (O-MaxAge)

_pavg

l-many

year, mean and standard deviation of susceptible, incubating,
infectious, and total number of animals

_prevAge

l-many

run, year, patch number, susceptible males by age category, susceptible
females by age category, incubating by sex (m.f) and age category,
infectious by sex (m, f) and age category

sum

1-5

run, year, patch number, number of susceptible, incubating,
infectious, and harvested animals

ts

1-9

run, year, patch number, test&amp;slaughter index (O=off, I=on),
population size, prevalence before t&amp;s, prevalence after t&amp;s, males
removed, females removed

-

(produced only when
t&amp;s is on)

�107

Sample input files and formats
General File Format Used by CWD
The general format of CWD input files is to begin each line with an integer number that indicates
the content of one or more lines of the input file. "99" is always used to indicate a comment and the
program disregards all information on a line following the "99". In general, the integer is followed by
one word (i.e., a series of characters and/or numbers that contains no spaces) describing the following
parameter(s) or variable(s) .. The descriptive word can contain underscores, upper and lower case
letters, numbers, or any other characters except blank spaces or tabs. For situations where there are a:
variable number of input lines (e.g., the age structure of an initial population), lines may begin with a'
data value not preceded by an integer indicating the line content. Sections of input than can include a
variable number of lines always end with a delimiter, which is usually a number less than zero. It is
essential that these file formats be followed, and users are very strongly encouraged to modify existing
input files rather than create a new file. Virtually all errors in model runs can be traced to a mistake in
an input file. Many (but not all) common mistakes in input files will be detected by the program and
reported to the error file (CWD _err.txt).

Model Run Data (*.run)
"The *.run file is the first file read by CWD and it determines program operations at the highest levelwhich modules are used, the names of other input files, which files output files are to be written. _A
value of 1 or greater turns on optional functions or optional outputs and the value "0" turns these ','
function off. If Random = 0, the same random number seed is used at the beginning of all runs. nlls
option is used for debugging and Random should generally be set to "1". A delay can be used if you
wish to slow the program in order to more easily view screen output.
99 cwd.run
99 -2 PCHFileName: cwd_inpt.pch
3 SPCFile:
cwd_inpt.spc
4 POPFile:
cwdjnpt.pop
5 Harvest:
1 cwd_inpt.hrv
6 Disease:
1 cwd_inpt.dis
9 Test&amp;SI:
1 cwdjnpt.tst
99 -11 RunYears:
100
12 Runs:
250
14 ScreenOutputFreq: 50
99 - if random = 0 use same seed for all runs; if random = 1 use a different seed.
15 Random:
1
99 _ all output files will have the following "prefixed" to their names
99 _ E.g., the file beta_2_11_14_age.asc would be produced with this line. In addition,
99 _ any sensitivity variables are added to the file name (see below).
99 -16 OutputFilePrefix: beta_2_11_14
99 -21 PopAgeOut:
1
_age
22 PatchesOut:
o
_pch

�108

23 DoDisOutput:
1
dis
29 doHarvestOutput: 1
harv
9999 -- line 31: on/off prevalence level to begin output, prevalence level to end output
99 so the following results is output when the prevalence level is &gt;= 0.03 and &lt;= 0.50.
991 .01 .50
31 doPrevAgeOutput_startPrev_endPrev:
1
disDths
32 doDisDeathsByPeriodOutput
9999 101 = sensitivity analysis.
99 Variables are repeated for each variable, so the number of
99 values on the line MUST be divisible by 4.
99 var_number smallest_val largest_val step
99 -101 sens vars 123.4.8
.05
Lines 21 -31: Any integer of 1 or greater tufns output on.
31: These files can be very large, thus they are produced only when prevalence in a patch is equal to or
within the range of the starting and ending value.

Patch Parameters (*.pclz)
99 filename:
cwd_21 May.pch
10000
3 PatchArea:
4 MaxQuality:
1
5 MeanEnvQual:
1
6 sdEnvQual:
.0
7 maxForage:
100
100
8 initialForage:
PatchArea:

Area of patch used by the local population. Set to a large value unless you want
density.•.dependent population regulation to operate.
MaxQuality:
This value reflects the maximum density that a particular patch can support, relative to
the species-specific maximum density. The species-specific maximum density is
specified in the *.spc input file.
MeanEnvQual: Mean quality of the patch (must b~ less than MaxQuality).
sdEnvQuality: Standard deviation of the mean quality. If set to 0, there will be no annual variation in
the value of the density threshold due to differences in patch quality.
maxForage:
Maximum forage value that will ever be obtained on a specific patch.
initialForage: Forage value at start of the run

�109

Harvest
Populations are normally controlled by harvest of animals. The rate of harvest can vary
depending on population size, which can be categorized as small, normal, or large. Input
variables are used to determine threshold sizes between these categories. For each
population size category, input variables specify age-specific rates of harvest. There are no
limits to the number of age categories that can be specified, but if ages within a category
overlap, the last value in the input file will be used. If you want harvest to be independent ot
age, specify the same rate for all ages.
i.

Annual rates of harvest are determined each year by selecting the appropriate mean
harvest rate from the input file (lines 11-17) and then modifying this rate to account for
annual variation. Mean rates for all age groups are multiplied by a random deviate with
mean 1 and CV from line 10. Thus annual variation for all age groups are correlated.

99 CWD for mule deer
99 Rule 1 has proportion harvested for low, med, and high pop numbers, by sex and age
1 harv_rule
1
10 CV_on_percent_harv .2
99 _ FEMALES min_age max_age portion_harvested. Ages are inclusive
11 F_Iow
0 20
.0
12 F_med
0 0 .01
12 F_med
1 2 .02
12 F_med
3
20
.07
13 F_hgh
0 0 .03
13 F_hgh
1 2 .05
13 F_hgh
3
20
.10
99 - MALES
15 M low
0 20
.0
16 M med 0 0 .02
16 M med
1 1 .06
16 M_med 2
20
.20
17 M_hgh
0 0 _..03
17 M_hgh
1 1 .09
17 M_hgh
2
20
.27
99 -- repeat lines 21 &amp; 22 for each local population.
21 localPop
1
22 threshold numbers
500 1000

.

�110

Test and Slaughter
Test and slaughter is implemented by specifying the efficacy of the program for males and
females. Efficacy is the product of the portion of the population tested and the likelihood
that a positive animal will be detected. Variables in the input file determine whether the
program is implemented from the beginning of the program, or after other criteria are met.
A test and slaughter program can begin at a specific year of a model run, or after the
population has achieved a specified prevalence rate. Efficacy is the product of the
proportion of the population tested and ability to detect the disease.
The variable on line 3 (periods to detect) is the number of periods of incubation that must
elapse before a disease can be detected in an exposed individual. If there were 2 periods
per year and this parameter were set to 1, an exposed individual would not be detected until
they had incubated for a full period, equivalent to about 6 months. If you assume that rate
of exposure is constant, one could interpret this to suggest that the average incubation time
before detection would then be about 9 months, or one full period and (on average) half of
another period. However, since test and slaughter occurs only once per year (after harvest
and the second disease period), individuals infected during disease period 2 (falilwinter) will
not be detected until the following year unless periods of detection is set to O. Infectious
individuals are always detected.
99 cwd_test_ and_ slaughter.tst
99 3 periods_of_incubation_before_detection
4 local_pop_tested
1
5 Efficacy
.5
6 Start_year
10
7 Start_prevalence
.05

3

�III

Sensitivity Analysis
The model provides the user with very broad options to conduct sensitivity analysis. Todo
so, specify on line 1.01in the run file the variable number (from the table below), the initial
value, the maximum value, and the step (amount for the initial value to be incremented for
each set of runs). Some variables (will in the future) also require that a local population be
specified. When a sensitivity analysis is conducted, the names of all output files reflect this
by adding the number of the variable and the step (starting with 0) of variable value to the
file name. These values are added after the file name prefix specified on line 16 in the run
file and before the normal file suffix. For example:
lirie 16 in run file: 16 file_name: 24jan_larimer
line 101 in run file: 101 sens_vars 121 .01 .10 .01
Which means: do runs with maternal transmission rates from 0.01 to .1 by .01. Ten sets of
runswill be simulated, with 10 output files of each type (e.g., _pavg, _sum, etc.). The
summary output files, for example, would be:
24jan_larimer_:_121_0_sum.asc
24jan_larimer_121_1_sum.asc
24jan_larimer_121_9_sum.asc
If additional sensitivity variables are added, these are added to the file name in the general
format:
prefix_var#_step_var#_step ... suffix. There are no internal limits to the number of
sensitivity variables, but since all levels are fully crossed, you can easily generate hundreds
or even thousands of output files. The difficulties in analyzing such results are substantial.

�112

Sensitivit~variables available for anal~sis.

MammalData
MammalData
MammalData
MammalData
MammalData
MammalData
MammalData

Number Variable name
value or Mult # values
101
female survival
multiplier
3
102
male survival
multiplier
3
103
recruitment
multiplier
3
104
sex ratio at birth
value
3
105
mean environmental
value
3
quality
106
std environmental quality value
3
121
maternal transmission
value
3
122
prob. infected recruits
value
3
123
period 1 beta
value
3
124
period 2 beta
value
3
125
period 3 beta
value
3
beta for all periods
126
value
3

AnimalPop

21

periods for test detection value

3

LocalPopulation 51
LocalPopulation 61
LocalPoQulation 62

test efficacy mean - both value
harvest lower threshold value
harvest uQQerthreshold value

3
3
3

Class Affected
MammalData
MammalData
MammalData
MammalData
MammalData

�113

AppendixB

Chronic Wasting Disease in Deer and Elk:
DRAFT Colorado Statewide Monitoring and Experimental Management Plan
M. W. Miller and R.H. Kahn
Terrestrial Wildlife Resources, Colorado Division of Wildlife .

Background
Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) of native
deer (Odocoileus spp.) and elk (Cervus elaphus nelsoni) characterized by behavioral changes and
progressive loss of body condition that invariably lead to the death of affected animals (Williams and
Young 1992). Neither the causative agent nor its mode of transmission have been identified. There
are no tests currently available for diagnosing CWD in live animals, and extant postmortem tests
require microscopic examination of brain tissue. There are no known treatments for CWD. Previous
attempts to eradicate CWD from research facilities failed on at least 2 occasions (Williams and Young
1992; Miller et al. 1998). Although similar in some respects to other TSEs that affect domestic sheep
(scrapie) and cattle (bovine spongiform encephalopathy; BSE), existing data indicate CWD cannot be
naturally transmitted to domestic livestock, and that scrapie and BSE cannot be transmitted to native
cervids. Moreover, available data indicate that CWD does not present a threat to human health.
"Chronic wasting disease" was first recognized by biologists in the 1960's as a disease syndrome
of captive deer held in wildlife research facilities in Ft. Collins, CO. This disease was subsequently
recognized in captive deer, and later in captive elk, in wildlife research facilities near Ft. Collins,
Kremmling, and Meeker, CO and Wheatland, WY (Williams and Young 1980, 1982), as well as at in
least two zoological collections (Williams and Young, 1992). More recently, CWD has been
diagnosed in captive elk residing in one game ranch in Saskatchewan (Spinato, pers. comm.), two
ranches in South Dakota (Holland, 1997), one ranch in Nebraska (W. Cunningham, pers. comm.), and
one ranch in Oklahoma (L. Detwiler, pers. comm.). Since 1981, over 100 cases of clinical and
preclinical CWD also have been diagnosed in free-ranging mule deer (0. hemionus), white-tailed deer
(0. virginianus), and elk from northeastern Colorado; most of these diagnoses have been made since
1990 (Spraker et al. 1997; Miller, 1997). At present, the known world-wide distribution of CWD in
wild cervids appears to be limited to northeastern Colorado and southeastern Wyoming (Miller, 1997;
Williams et al., 1998). Although CWD was first diagnosed in captive cervids, the original source of
CWD in either captive cervids or free-ranging cervids is unknown; whether CWD in captive cervids
really preceded CWD in wild cervids, or vice versa, is equally uncertain (Spraker et al. 1997).
In Colorado, free-ranging CWD cases in deer and elk have originated from throughout the
northeastern portion of'the state. Game Management Units (GMUs) yielding infected deer or elk
include 7,8,9, 19, 191,20,29,91,93,94,95,951,
and 96. Although cases have come from 13
different GMUs, two Data Analysis Units (D4, DI0) have yielded over 85% of the documented cases.
Based on targeted surveillance data and select harvest surveys, wild deer or elk populations in other
parts of Colorado are probably not infected with CWD (Miller, 1997; 1998).
Both targeted and harvest surveys indicate GMUs 9, 191, 19, and 20 are the main foci ofCWD
in Colorado; estimated prevalence in all four GMUs is ~3% (Miller, 1997; 1998; M.W. Miller, unpubl.
data). Data from harvest surveys indicate that CWD is relatively rare in other parts of northeastern
Colorado, probably affecting ~2% of the deer in GMUs 7, 8, 29, 91, 93, 94, and 96 (Fig. 1). Similarly,
harvest surveys indicate &lt;1 % of the elk in DAUs E4 and E9 are infected with CWD (Miller, 1997;
1998; M. W. Miller, unpubl. data).
For deer populations in the four most heavily infected eastern Larimer County GMUs, no real
trend in prevalence (increasing or decreasing) can be discerned from data available to date. In the
absence of historical (20-30 years ago) prevalence data or reliable estimates of transmission rates, it is

�114

also unclear whether overall incidence ofCWD in northcentral Colorado DAUs is stable or increasing,
or whether short-term observations can accurately forecast long-term trends. Based on prevalence
estimates and preliminary results of simulation modeling to predict dynamics and impacts of CWD on
affected deer populations, it appears CWD was introduced into northern Larimer County over 30 yrs
ago (M.W. Miller and C.W. McCarty, unpubl. data).
Beyond Larimer County, the South Platte River corridor may be the single most predictable
avenue for spread of CWD. Kufeld and Bowden (1995) reported that a proportion of South Platte
River bottom deer were highly mobile; observed deer movements included some to and from eastern
Larimer County along the Cache la Poudre and South Platte Rivers. These movement patterns provide
a plausible mechanism for the apparent emergence of CWD in South Platte River GMUs detected
recently through targeted surveillance and harvest surveys. Other likely routes for deer emigrating
from Larimer County have not been identified, and may be less predictable. Altitudinal movements of
some elk subpopulations in the southern part of Larimer County are also somewhat predictable (Bear,
1982). Although there is potential for elk to cross the Continental Divide through Rocky Mountain
National Park, the relatively low prevalence of CWD among elk diminishes the likelihood of its spread
via their movements.
The significance of CWD and its impacts on native deer or elk populations have not been
determined. Preliminary results of simulation modeling suggest that, sustained at 5% prevalence as
observed in the four most heavily infected GMUs, CWD could impact wild deer herds and lead to
population declines (M.W. Miller and C.W. McCarty, unpubl. data). Data on CWD prevalence in .
female deer are particularly critical to predicting potential impacts of disease on long-term population
performance and assessing efficacy of management interventions. Preliminary comparisons made in
conjunction with 1997 and 1998 surveys showed no differences in CWD prevalence between male and .
female mule deer harvested in Larimer County GMUs (M.W. Miller, 1998; unpubl. data); these data
were comparable to results of simulation models where male and female deer were assumed to be
equally susceptible to CWD.
In the absence of data to the contrary, and considering the difficulties inherent in eliminating
CWD from captive or wild cervid populations once established, it seems most prudent to assume
CWD could adversely affect native deer or elk populations and manage to reduce its occurrence and
prevent its further spread in Colorado. Unfortunately, there is considerable uncertainty in how to
manage CWD in free-ranging wildlife, or whether such an endeavor could even be successful.
Because a more complete understanding of CWD is fundamental to developing comprehensive
management programs, the Colorado Division of Wildlife (CD OW) needs to further understanding
about CWD and its management through surveillance and experimental management. Data from
completed, ongoing, and proposed research, both basic and applied, will serve as the foundation of an
adaptive resource management plan for CWD in deer and elk. This plan will provide a mechanism for
incorporating new knowledge gained through surveys, modeling, research studies, and management
experiments into a continuously evolving management program for CWD.

STATEWIDE MONITORING

PROGRAM

Goals:
1.

Provide reliable estimates of CWD distribution and prevalence to serve as a basis for management
decisions and public information.

2.

Provide information to improve understanding of CWD epidemiology.

3.

Continue developing efficient and reliable techniques for detecting and monitoring CWD in freeranging populations.

�115

Strategy:
Reliable estimates of CWD prevalence in wild deer and elk populations are needed to guide
policy decisions and monitor efficacy of management efforts. We will continue to monitor deer and elk
populations throughout Colorado for occurrence of chronic wasting disease using a combination of
extensive and intensive approaches. These have been organized and conducted as follows:
Targeted (= clinical disease) surveillance: Ongoing statewide "targeted" surveillance (i.e., submissions
of "suspect" deer &amp; elk) will be used to determine &amp; monitor changes in CWD distribution. Based on·.
experiences in Colorado and elsewhere, this appears to be the most sensitive approach for determining
CWD distribution &amp; detecting range extensions (Miller, 1997).
A program for acquiring, examining, reporting on, and summarizing "suspect" CWD cases
occurring throughout Colorado has been in place since 1990 (Miller, 1997). This program has served
to increase ongoing surveillance efforts by field personnel statewide by encouraging submission of
carcasses from deer or elk showing clinical signs resembling CWD. A formalized process for
submitting cases has been developed; this process includes criteria for acceptable submissions,
submission forms, handling instructions, and a system for networking submissions within CDOW and
among the 3 Colorado State Veterinary Diagnostic Laboratories and the Wyoming State Veterinary
Laboratory.
Under this program, deer and elk showing clinical signs consistent with those seen in chronic
wasting disease are collected by field personnel statewide; a "suspect case" profile has been defined
(Table 1). Brain tissues are subsequently examined for evidence ofspongiform encephalopathy.
Where possible, whole carcasses will be submitted for complete necropsy; at minimum, heads
from suspect animals will be submitted for examination and sampling. Ancillary diagnostics, including
histopathology (Williams and Y oung,1993) and immunohistochemistry of brain tissue (Spraker et a1.,
1997), will be performed on all suspect cases; other ancillary tests may also be used to confirmor
support diagnoses. Preliminary examination and/or test results and final reports will be faxed to
CDOWs Wildlife Research Center. Pertinent data from preliminary and final reports will be entered
into a permanent database, and copies of reports will be filed as well as sent to appropriate field
personnel.
Results from targeted surveillance will be used to identify new potential foci of CWD infection
for further evaluation via harvest or road-kill surveys.
Harvest and road-kill surveys: Surveys of harvested or, in some areas, road-killed deer and elk will be
conducted in endemic and high-risk DAUs/GMUs to estimate and monitor CWD prevalence. We will
continue conducting annual surveys in DAUs or GMUs where CWD prevalence is &gt;2% ("endemic
foci") to obtain reliable-estimates of prevalence to use as a basis for monitoring natural trends, as well
as responses to management interventions. Annual surveys will be designed to provide an estimated
prevalence within ±2% at a 95% level of confidence for affected populations where true prevalence is
1%. In addition to annual surveys of endemic foci, we will also continue conducting a series of surveys
for CWD in other select deer and elk populations throughout Colorado over the next 5 yrs, with a goal
of determining statewide distribution of CWD.
Our surveillance strategy is as follows: Areas newly identified as infected via targeted
surveillance (e.g., GMU 29, South Platte River corridor GMUs) will be surveyed sufficiently to obtain
a reliable prevalence estimate. In areas where estimated prevalence is &lt;1 %, CWD will be regarded as
a sporadic disease and populations will be monitored at ~5-yr intervals to detect increases in
prevalence. Areas where estimated prevalence is &gt;2% will be regarded as new endemic foci, and will
be monitored annually to track changes in prevalence as described above. We also plan to continue
conducting surveys of at least 5 other select deer populations where CWD has not been reported

�116

previously. Target areas will include both high-risk (e.g., Middle Park, Piceance Basin) and low risk
(e.g., San Luis Valley, Gunnison, southern Front Range) populations. Surveys will be designed such
that the probability of failure to detect at least 1 case of CWD in an apparently-unaffected deer or elk
population will be ,::::0.01even if herd prevalence is 1%. Finally, we will attempt to gather a sufficient
number of random samples from DAUs statewide (n-l,OOO) to determine whether or not CWD should
be generally regarded as endemic in Colorado's deer populations. A tentative schedule for the
foregoing surveillance is outlined in Table 2.
Harvest surveys will be conducted using techniques developed in Colorado since 1991. Because
regulatory requirements for head submissions increase sample sizes &gt;4-fold, submissions will be
mandatory in most GMUs where surveys are being conducted. Limited licenses may also be used in
select GMUs to aid in increasing compliance. Unstaffed barrel sites appear to be the most efficient
method for sample collection, and will continue to be used as the primary method for conducting
harvest surveys. Brainstem (obex) from ~ I-yr-old deer and elk will be.collected for CWD testing, and
immunohistochemistry (IHC) using USDA monoclonal antibody F89/160.1.5 (O'Rourke et al., 1998)
will be used as the primary screening tool. Reported prevalence estimates will continue to be based on
numbers ofIHC:·positive cases; because IHC appears more sensitive than histopathology in detecting
preclinical CWD cases, IHC-based prevalence estimates should provide a relatively unbiased measure
of disease trends over time and allow more direct comparison between field data and simulation model
predictions.

EXPERIMENTAL MANAGEMENT
There is no precedent for attempting to manage a TSE in free-ranging wildlife. Moreover, the
biological need for such management is unclear at present. Programs for managing or eliminating
TSEs of domestic livestock have proven only marginally successful, and the lack of obvious success in
eradicating scrapie or BSE from endemic countries, compounded by epidemiological differences
between CWD and other TSEs, make such programs rather poor models for prospective CWD
management. Several fundainental features of CWD epidemiology are understood poorly, if at all; in
particular, the influences of host (e.g., population density, intraspecific vs. interspecific transmission,
genetics) and environmental factors (e.g., contamination, reservoirs, weather) on CWD dynamics
remain undescribed. In light of the uncertainties associated with its epidemiology and ecology, we
believe CWD management should be approached as an experiment, thereby allowing us to learn as we .
take actions intended to reduce prevalence and limit distribution.
The CDOW's initial approaches for attempting to control CWD in free-ranging deer and elk
were outlined in an action plan for CWD drafted in 1995 (Miller et al., 1995; Appendix A). In addition
to calling for a comprehensive public information campaign, this plan identified tactics for limiting
distribution and reducing prevalence of CWD based on contemporary knowledge of the problem.
Prompt removal of affected animals and enforcement of feeding prohibitions were recommended to
help reduce CWD prevalence and transmission. Policies and regulations were also recommended, and
subsequently instituted, to prevent wider distribution of CWD via human activities (e.g., trans locations,
rehabilitation, game ranching). The plan also identified a need for more extensive surveillance to
gather data on CWD distribution and prevalence.
As more data on CWD distribution and prevalence have been gathered over the last 2.5 yrs, it
has become apparent that CWD is more widely distributed and more prevalent in northeastern
Colorado (and elsewhere) than initially believed. It follows that policy, goals, and strategies for CWD
management in Colorado should be reevaluated in the context of new data, as well as changes in social
and political attitudes toward animal TSEs.

�117

Management policy:
At present, the CDOW has no stated policy related to the management of chronic wasting
disease in wild deer andelk. The lack ofa clear policy statement has led to internal confusion and
disagreement over how to resolve conflicts with other policies and Long Range Plan objectives (e.g.,
increase recreational opportunities for deer and elk hunters).

Recommendation: We recommend adoption of the following policy to guide decisions on deer and elk
population management. in DAUs where CWD is endemic:
Pl.

The Colorado Division of Wildlife is committed to minimizing the threat that chronic wasting
disease (CWD) poses to Colorado's native deer and elk resources. In DAUs where CWD is
endemic, goals of reducing the occurrence and the further spread of CWD will serve as the
primary basis for setting management objectives.

Prospective management goals:
We have. identified four overarching goals that could serve as a basis for decisions related to
managing CWD:
1. "natural regulation",
2. containment,
3. reduction,
4. eradication.
These goals represent a continuum of possible levels of intervention, ranging from benign. rs
neglect to aggressive action. There are clear advantages and disadvantages associated with each of ..
these prospective management goals. Although each progressive level offers more complete control of
the problem, better control is accompanied by ever-increasing technical, fiscal, and political challenges,
as outlined below:
l."Naturai regulation": Directing no specific management intervention toward CWD beyond
culling of reported clinical cases represents the status quo approach to both disease arid deer/elk
population management. It could be argued that the ongoing activities described above constitute
an attempt to manage CWD. Although the impacts of this approach on CWD prevalence in
endemic foci remain undetermined, prevalence in endemic foci appears to have remained stable
over at least the last J yrs. This approach offers the fewest technical challenges, may be regarded
by some as "safest'unlight
of the myriad of uncertainties in CWD epidemiology, and in the shortterm would be most sparing oflocal resources. Unfortunately, simulation models forecast that
problems with CWD will likely get worse in affected populations if left largely unmanaged, the
disease could become more widely distributed, and there are tangible potential impacts on wildlife
resources, recreational opportunities, and revenues. In addition, perceived "inaction" may be
unacceptable to some sportsmen's groups, agricultural interests, and perhaps the general public,
and could lead to the loss of management authority by CDOW. Finally, opting for "natural
regulation" seems biologically irresponsible.
2. Containment: Managing primarily to prevent spread of CWD from endemic foci would require
additional knowledge of the mechanisms and probable routes of CWD dissemination, but many of
the important strategic components needed to support this strategy are already in place. The
likelihood of trans locating infected animals from endemic areas to other areas in Colorado or

�118

elsewhere was significantly reduced by regulations adopted in 1996 (ch 14 ref). Between existing
data from previous movement studies (e.g., Kufeld et al., 1989; Kufeld and Bowden, 1995) and
data from studies initiated more recently, major natural emigration corridors from eastern Larimer
County could probably be identified and subsequently might be interrupted via intensive culling
operations. This approach, if successful, would limit the magnitude of the CWD problem while
largely sparing local resources. This alternative may be more acceptable to sportsmen's groups and
the general public than to agricultural interests, but is probably biologically justifiable. However,
such an approach would require an essentially infinite long-term commitment and yet will not
eliminate CWD entirely; prevalence could conceivably increase in endemic areas. There would
likely be some local impacts on resources and recreational opportunities, perhaps accompanied by
local public resistance.
3. Reduction: It may be possible to manage affected deer or elk populations to reduce CWD
prevalence in endemic foci. A goal of prevalence reduction clearly demonstrates intent to limit the
magnitude of the problem. It seems likely that this. approach would also provide for containment of
CWD. Attempting to reduce CWD prevalence might improve "consumer confidence" among
hunters in endemic GMUs. This alternative may be the most widely acceptable among sportsmen's
groups, agricultural interests, and the general public in terms of responsible disease and resource
management. It is probably biologically justifiable in view of projected long-term effects ofCWD
on infected populations and the potential for CWD to spread from endemic foci if left unmanaged.
As with the foregoing goal of disease containment, prevalence reduction will require a long-term
commitment and may not eliminate CWD from endemic areas; depending on specific tactics
employed, prevalence could even increase despite management efforts. This approach would likely
cause more severe impacts on local resources and recreational opportunities, and consequently
would be more likely to foster local public resistance to proposed management actions.
4. Eradication: Eradication is probably the most desirable goal of any attempt to manage CWD.
Whether it would be feasible to completely eliminate CWD from Colorado remains highly
questionable. Eradicating CWD would be the best means of restoring for "consumer confidence"
among northeastern Colorado deer and elk hunters, and would presumably nullify concerns of
traditional and alternative livestock interests about the potential for transmission to privately-owned
animals. Perhaps most importantly, eliminating CWD would be the most effective way to preempt
threats of its eventual spread to other native deer and elk populations in Colorado and elsewhere.
Although desirable in concept, CWD eradication is probably infeasible given the complexities and
uncertainties of its epidemiology. Eradication of CWD would require long-term commitment, and
probably would exaet catastrophic impacts on resources and recreational opportunities in affected
areas; broader ecological impacts (e.g., on predator-prey balances) could also be severe. Public
resistance is likely to emerge, at least locally, as details of such a management program emerge.
Finally, it is questionable whether the potential ecological costs of CWD eradication are biologically
justifiable in light of the uncertainty about long-term impacts of the disease itself.

Recommendations: Based on current understanding of CWD epidemiology, prevalence, and
distribution in free-ranging deer in northeastern Colorado, we believe eradication is an extreme and
unjustifiable management goal at this time. In light of the magnitude of prevalence and distribution
CWD has reached in Larimer County deer populations under historical management regimes, however,
continuing to rely on current management approaches seems equally unjustifiable. Consequently, we
recommend an intermediate approach with two goals for managing CWD in deer and elk:

�119

Gl.

limit distribution ofCWD
occurs.

to no more than the 5 deer DAUs and 2 elk DAUs where it already

G2. reduce average CWD prevalence among deer and elk to &lt;1 % in each endemic DAU and &lt;2% in
each endemic GMU; and
.

'~

We believe achieving the foregoing management goals will serve to protect Colorado's deer and
elk resources, restore confidence in the quality of deer and elk harvested in northeastern Colorado, and
ameliorate political pressures from agricultural constituencies concerned about potential for
transmission of CWD to domestic livestock or privately owned wildlife.

Prospective management strategies:
Effective strategies for managing CWD or any other TSE in free-ranging wildlife have never been
identified or evaluated. Many conventional disease management options are precluded from
consideration because vaccines, therapeutics, and live-animal tests for CWD are presently unavailable
(Table 3). Contrary to experiences with domestic sheep (Goldmann et al., 1994), available data
indicate relatively uniform genetic susceptibility to CWD among deer (K. I. O'Rourke and M. W.
Miller, unpulb. data); consequently, genetic selection would probably have no impact on prevalence
even if tools forits implementation were available. Similarly, controlling reproduction alone probably
would be ineffective even if practical tools were available because maternal transmission alone is
unlikely to be sustaining CWD prevalence at levels currently observed in some affected deer
.populations.
All remaining options we can identify to reduce CWD prevalence (Table 3) involve some form of
aggressive population control directed at diminishing or preempting-disease transmission -- themagnitude and duration of such control will be driven by management objectives and population
responses. Based on current understanding ofCWD epidemiology (Miller 1997, Miller et al., 1998,
M.W. Miller, unpubl. data), we believe that strategies capable of lowering CWD transmission rates by
reducing numbers of infected animals and point sources of environmental contamination (e.g., feeders)
should be most effective in lowering prevalence; although the precise mechanisms of transmission have
not been identified, those details will probably have little influence on the resolution of CWD
management at the population level. General models predict that random culling should be less
effective than selective culling in reducing disease prevalence (Barlow, 1996; McCarty and Miller,
1998). However, field data indicate that management strategies based on culling clinical suspects
probably will miss a large proportion of the infected (and potentially infectious) individuals in a
population; moreover, there is no practical way to apply "test and slaughter" regimes without an
antemortem diagnostic-test for preclinical CWD. Accelerated culling of early clinical cases, either by
humans or via predators, may help reduce CWD transmission and prevalence. Alternatively, if the
probability of CWD transmission is density-dependent, then reducing deer or elk densities in endemic
areas should lead to reduced CWD prevalence; to date, the hypothesis of density-dependent disease
transmission remains untested.
Obvious strategies for limiting CWD distribution remain equally elusive. The mechanisms driving
the spread of CWD among deer and elk populations are even less apparent than those driving disease
dynamics. It is possible that CWD distribution to date has been influenced by regular and/or random
movements of deer and, less commonly, elk. Previous studies (Kufeld et al., 1989; Kufeld and
Bowden, 1995; S. Steinert, pers. comm.; others?) have shown that proportions of both foothills and
river bottom deer populations in northeastern Colorado are either migratory or mobile; the movement
patterns documented in these studies provide at least a partial explanation for observed CWD
distribution. It is also possible that CWD influences its own distribution by changing behaviors, range

.....

�120

fidelity, and movement pattens of affected animals; observations of repetitive pacing in captive deer
and elk affected by CWD could be manifested as extensive wandering movements of free-ranging
individuals. Whether or not movement patterns or dispersal rates are density-dependent remains
unclear; either way, reducing population size should also reduce the probability of affected individuals
canying CWD to new areas. (However, we do recognize the possibility that at some lower threshold
reduced density may actually promote deer and elk movements, particularly during the breeding
season).

Recommendations: Based on current uncertainty about how to effectively disrupt the processes that
influence CWD epidemiology, prevalence, and distribution in free-ranging deer in northeastern
Colorado, we recommend initiating controlled management experiments directed toward testing one
(or both) of the following hypotheses:
HI. CWD transmission and prevalence infoothills and river bottom deer populations can be
diminished by
a) selective culling;
b) increasing natural mortality via mountain lion predation; OR
c) reducing deer density in affected populations.
H2. CWD distribution in foothills and river bottom habitats can be diminished by
a) selective culling;
.
b) increasing natural mortality via mountain lion predation; OR
c) reducing deer density in affected populations.
We further recommend that the experiment(s) be designed and conducted in a way that facilitates
achievement of two short-term management objectives:
MI. to stem dispersal ofCWD via deer movements along the South Platte River corridor (GMUs 94,
951,96,91,
and 92).
M2. to reduce CWD prevalence among deer inhabiting the four most severely affected GMUs (9, 191,
19,20).
Because CWD prevalence is low «1%) in elk, we recommend that populations in DAUs E4 and
E9 should be maintained at or below current densities and monitored via harvest surveys at least every
5 yrs to detect potential increases in prevalence that.might warrant more aggressive management
action. :.
Design of Management Experiment
We recommend using an adaptive resource management approach (Walters, 198_) to test candidate
strategies for reducing CWD prevalence and distribution. Based on initial evaluations of these
candidate strategies (Table 4), more detailed management experiments will be developed; as part of
that process, decisions will be made on which, if any, approaches to pursue and where CWD
management will be attempted. Tactics for accomplishing management approaches (e.g., harvest,
selective culling, ground/aerial gunning, changes in predator harvest, etc.) will follow from internal
consensus on which tactics are viable under the social and political constraints imposed by the area(s)
selected for study.

Prospective management tactics:
Tactics supporting selected management strategies:

�121

- harvest? (role of public hunting?)
- shift emphasis from recreational opportunity to population management
- modifications of GMU/ "management area" boundaries to focus mgt &amp; distribute pressure
- season structurellength &amp; bag limits- reg changes
- schedule
- culling?
- ground vs aerial vs capture &amp; kill options
- public vs agency c;
- private land issues
- fertility control? (probably not for reductions, but maybe to maintain)
- agent, delivery, cost?
- reduce predator quotas? (close seasons?)
- predator introductions?
- poisoning?
- other?
, ';

. &lt;"

Issues surrounding CWD management
- Should public hunting continue in endemic areas? - What are public desires/expectations related to CWD management?
- Can we impose intensive population management on private lands?
- What are reasonable expectations for funding and long-term agency/political/public
- Others?

commitment?

Outstanding tasks (partial list)
Human dimensions --

Public service -Funding (PBE)--

For both internal and external publics, seek consensus on: what direction to
take, which strategies are most viablelleast objectionable, etc., impacts on
recreational opportunity, trade-offs
Seek/gain cooperation, access, etc. (follows from lID issues above)
Estimate support required for evaluation of management activities, as well
as fiscal impacts of candidate management approaches

LITERATURE CITED
Goldmann, W., N. Hunter, G. Smith, 1. Foster, and 1. Hope. 1994. PrP genotype and agent effects in
scrapie: change in.allelic interaction with different isolates of agent in sheep, a natural host of
scrapie. 1. Gen. Virol. 75:989-995.
Miller, M. W. 1997. Monitoring and managing chronic wasting disease in Colorado. Pages _-_
in
Wildlife Research Report, Mammals Research, Federal Aid Projects, Job Progress Report,
Project W-153-R-I0, Work Plan 2, Job 17. Colorado Division of Wildlife; Fort Collins, Colorado,
USA. (in press)
Miller, M. W. 1998. Monitoring and managing chronic wasting disease in deer. Pages _-_
in
Wildlife Research Report, Mammals Research, Federal Aid Projects, Job Progress Report,
Project W-153-R-l1, Work Package 3001, Task 3. Colorado Division of Wildlife, Fort Collins,
Colorado, USA. (in press)
Miller, M. W. 1998. Monitoring and managing chronic wasting disease in elk. Pages _-_
in
Wildlife Research Report, Mammals Research, Federal Aid Projects, Job Progress Report,
Project W-153-R-ll,
Work Package 3002, Task 3. Colorado Division of Wildlife, Fort Collins,
Colorado, USA. (in press)

�122

Miller, M. W., M. A. Wild, and E. S. Williams. 1998. Epidemiology of chronic wasting disease in
captive Rocky Mountain elk. J. Wildl. Dis. 34:532-536.
Spraker, T. R., M. W. Miller, E. S. Williams, D. M. Getzy, W. J. Adrian, G. G. Schoonveld, R. A.
Spowart, K. 1. O'Rourke, J. M. Miller, and P. A. Merz. 1997. Spongiform encephalopathy in
free-ranging mule deer (Odocoileus hemionus), white-tailed deer (Odocoileus virginianus), and
Rocky Mountain elk (Cervus elaphus nelsoni) in northcentral Colorado. J. Wildl. Dis. 33:1-6.
Williams, E. S., and S. Young. 1980. Chronic Wasting disease of captive mule deer: A spongiform
encephalopathy. Journal of Wildlife Diseases 16:89-98.
and __
. 1982. Spongiform encephalopathy of Rocky Mountain elk. Journal of Wildlife
Diseases 18: 465-471.
and __
. 1992. Spongiform encephalopathies in Cervidae. Revue Scientifique et Technique
Office International des Epizooties 11:551-567.
---'
and __
. 1993. Neuropathology of chronic wasting disease in mule deer (Odocoileus
hemionus) and elk (Cervus elaphus nelsoni). Veterinary Pathology 30:36-45.
_-J

_-J

Table 1. Profiles used in chronic wasting disease targeted surveillance.
• Species:

• Age:

mule deer
white-tailed deer
elk

2:. 18 months

• Signs: emaciated and
abnormal behavior &amp;lor
indifference to human activity &amp;lor
increased salivation &amp;lor
tremor, stumbling, incoordination &amp;lor
difficulty or inefficiency in chewing/swallowing
increased drinking and urination

&amp;lor

�123

Table 2. Tentative schedule for systematic statewide chronic wasting disease surveys of deer
populations using harvest and/or road-kill samples.
.

CWD Status

GMUs

Years surveyed

Endemic foci
(:::::2%)

9, 19, 191,20

1996-2006

Endemic
(~1%)

.29
90,91,92,93
94
95,951,96

1997-2000
1997-1998;2004-2006
1997-2000
1996-1998,2004-2006

"High Risk"

87
:}8, 28, 37, 371
6, 16, 17, 161, 171
22

1997-2000
1998
1999-2001
1999

Other areas

. 104
66,67
83
"Uncompahgre"
"Southern Front Range"
Random Statewide

..r- -.

~·i ..

1996-2000
1997-1998
1994-1993, 1998-1999
2000
2001
2002-2003

[Note: Survey targets and schedules subject to changes influenced by new data and availability of
resources supporting CWD surveillance activities.]

Table 3. Prospective strategies for chronic wasting disease management.

Strategies for limiting distribution
- preclude human-caused translocations (mostly done)
- interrupt migration corridors (fencing?)
- change habitat (improve/degrade to influence animal distribution?)
- alter migratory behavior (how?)
- reduce density (relationship between density &amp; distribution untested)
- other?

Strategies for reducing prevalence
- vaccination (no vaccine available)
- treatment (no effective therapeutic drugs available)
- genetic selection (evidence of uniform susceptibility)
- fertility control (maternal transmission probably a minor contribution)
- eliminate clinical suspects (misses carriers; ineffective to date)
- test &amp; slaughter (no reliable, practical live animal test)
- selective culling (what criteria? mechanism?)
- foster natural mortality (e.g., predation) to promote selective culling
- reduce density (relationship between density &amp; transmission untested)
- other?

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Table 4. Initial CWD management tactics to be evaluated via field studies and/or simulation modeling.

Candidate tactic

Schedule

Selective culling via observation (± baiting)
Modified "test and slaughter"
(model/field)
Selective culling via predation (modeling)
Density reduction (modeling)
Fertility control (modeling)

2/99-4/99
5/99-4/00
5/99-9/99
5/99-9/99
5/99-9/99

EXPERMIENTAL
PLAN

MANAGEMENT

PROPOSAL

-- NOT CURRENTLY

INCLUDED

IN DRAFT

In all, eight management areas will be included in this before-and-after-controlled-intervention
(BACI)experiment (Fig._); management areas will be paired, with four areas targeted for density
reduction (50% reduction over a 2-yr period, then maintained at 50% of pretreatment density for 5 yr)'
and four held under status quo management regimes (i.e., discourage feeding, eliminate suspects, etc.)
as control areas (Table _). We will stagger the start of management treatments to minimize
confounding effects of temporal variation on CWD prevalence and distribution (Table _). Deer
density and CWD prevalence will be estimated annually in each management area, and mean CWD
prevalences before and after management intervention will be compared to test density-dependent
transmission hypotheses and assess the efficacy of treatment in reducing CWD prevalence. Similarly,
CWD prevalence and distribution in GMUs adjacent to treatment and control areas will be compared
to test hypotheses on density-dependent dispersal and assess the efficacy of treatment in stemming
CWD dispersal.

Table _. Treatment assignments and start dates for areas included in CWD management experiment.
Location

Treatment

Control

Start date

northern Larimer
County

GMU9

GMU 191

1999-2000

southern Larimer
County

GMU 1ge/20ea

GMU 19w120wb

2000-2001

South Platte River"
bottom/plains

GMU91

GMU92

1999-2000

South Platte River
bottom/plains

GMU96

GMU951

2000-2001

b

GMU 19e120e will be the portions ofGMUs 19 and 20 east of the Pingree Park Road and ???
GMU 19w/20w will be the portions of GMUs 19 and 20 west of the Pingree Park Road and ???

1 This

preliminary treatment regime is subject to modification guided by simulation modeling
exercises that will be completed later this year.

�181
-..:':,

\

"" Colorado Division of Wildlife
Wildlife Research Report
July 2000

/

\

JOB PROGRESS REPORT
State of

Colorado

Cost Center 3430

Project No.

W-153-R-13

Mammals Program

Work Package No. __

..:::.3.:::.;00~1~

Task No.

10

_

Deer Management
Monitoring and Managing Chronic Wasting
Disease in Deer

Period Covered: July 1, 1999 - June 30, 2000
Authors: M. W. Miller, C. T. Larsen, M. Conner, and R. Kahn
Personnel:

J. Gross, C. Krumm, M. Leslie, E. Myers, K. I. O'Rourke, T. R. Spraker, E. Wheeler, M. A.
Wild, and E. S. Williams

ABSTRACT
Deer from throughout Colorado were examined for occurrence of chronic wasting disease using a
combination of targeted surveys and harvest/road-kill surveys. Between June 1999 and May 2000, 11
chronic wasting disease(CWD)cases were diagnosed among 22 suspect deer submitted from known
endemic portions of northeastern Colorado. Thirteen additional suspect deer submitted from elsewhere in
Colorado were all CWD-negative. All confirmed CWD cases originated in game management units
(GMUs) where the disease had been detected previously.
We sampled about 1450 harvested or road-killed deer during October-December to randomly survey for
CWD in select data analysis units (DADs). Immunohistochemistry (llIC)-based prevalence in Larimer
County (6.4%) and South Platte River bottom/plains DADs (0%) were comparable to previous years'
estimates. All brain samples from deer harvested in North Park (n = 103), the Piceance Basin (n = 408),
and the Uncompahgre Plateau (11 = 209) tested negative. Overall, 1355 mule deer harvested or road-killed
outside northeastern Colorado have all tested negative for CWD; these data, combined with those from
targeted surveillance, support the contention that CWD is not distributed throughout the state.
Since June 1999, CWD affected 11 of 21 adult (;;.:l-yr-old) mule deer and 2 of 5 adult white-tailed deer in
the resident Foothills Wildlife Research Facility (FWRF) herds. No signs of neurological disease were
observed in any of the 11 cattle (subjects) housed with naturally-infected resident mule deer since July
1997, but 3 of 11 mule deer from the Rocky Mountain Arsenal National Wildlife Refuge
(RMANWR)(contact controls) held since October 1997 developed clinical CWD and were euthanized
between November 1999 and June 2000.

�182
Using ruc, Prl'?" was detected in brain tissue (medulla oblongata at the obex) from 2 mule deer
experimentally inoculated with a 5 g oral dose of brain tissue homogenate from CWO-infected deer 20 mo
earlier. One of the two deer examined 20 mo after inoculation (PI) also had gross lesions suggestive of
I
CWO and microscopic lesions of spongiform encephalopathy. Uninoculated controls collected from
RMANWR at the same time were negative. Five of the 6 remaining inoculated deer died of clinical CWO
or its sequelae 20-26 mo PI.
Movements of radiocollared deer appeared related to spatial patterns in CWD prevalence described
previously. Deer captured in GMU 9, where CWO prevalence is relatively high, moved north into areas of
Wyoming with equally high prevalence; deer from GMU 191, located west and adjacent to GMU 9 and
having relatively low levels of CWD prevalence, moved to the west into areas of even lower prevalence.
Despite their proximity, there was no overlap in winter range for deer in GMU 9 and deer in GMU 191,
and almost no overlap in summer range «1 %). Overall, deer movements appeared related to patterns of
prevalence in DAD D4. It follows that migration and dispersal patterns of mule deer may explain, at least
in part, spatial patterns of CWD prevalence in northcentral Colorado and southcentral Wyoming.
Western blotting appears to have potential application as a tool in studying CWD transmission
mechanisms. Preliminary evaluation revealed comparable sensitivity between Western blotting and ruc on
both brain and lymphoid tissues. Although PrPCWD was not detected in saliva or buffy coat samples from
infected deer, further development and evaluation of these and other potential media for CWD transmission
appear warranted.
Recommendations on a statewide approaches for monitoring and managing CWD in deer and elk, including
policy, goals, and management objectives, were reviewed and finalized in November 1999; specific plans
for CWD management will be included in individual DAU plans to be drafted in the next segment. Based
on these recommendations, 3 interim management actions were undertaken: First, deer and elk population
objectives for all DADs in the endemic area were reset to current (1999) levels regardless of previous longterm objectives established in DAD plans. Antlerless harvest levels were then set to hold populations at
1999 levels or, in cases where populations currently exceed DAU objectives, lower populations to objective
within 2 years. Second, a more aggressive program for culling clinical suspects was instituted; this
program enlists private landowners to assist in identifying and removing sick deer throughout the endemic
area. Third, a management experiment to test relationships between CWD prevalence and deer density was
planned and public information and regulation development processes supporting this experiment were
initiated; that experiment will probably begin during winter 2000-2001. Surveillance activities for 19992000, as well as surveillance planned for 2000-2001, reflect priorities established in the monitoring portion
of this plan.

.j

�183

MONITORING

AND MANAGING CHRONIC WASTING DISEASE IN DEER
M. W. Miller, C. T. Larsen, M. M. Conner, and R. Kahn

P. N. OBJECTIVES
( I) Design, conduct, and report results of:
(a) targeted surveillance to estimate and detect changes in distribution of chronic wasting disease
(CWD) in free-ranging deer populations; and
(b) harvest or road-kill surveys to estimate and detect changes in prevalence of CWD in endemic deer
populations.
(2) Design, conduct, and report results of experimental studies using captive deer naturally or
experimentally infected with CWD.

AGREEMENT OBJECTIVES
(1)

Conduct and report results of targeted surveillance to estimate and detect changes in distribution of
CWD in free-ranging deer populations statewide.

(2)

Conduct and report results of harvest surveys to estimate prevalence ofCWD in DAUs D3, D4,
D 10( +GMU 29), and D44 (+ GMUs 87 and 95), as well as select GMUs in the Piceance Basin
and Uncompahgre Plateau.

(3)

Continue an experiment evaluating cattle susceptibility to CWD via natural contact exposure.

(4)

Continue to study pathogenesis ofCWD in mule deer.

(5)

Conduct studies to determine factors contributing to occurrence and natural spread of CWD in
northeastern Colorado.

(6)

Evaluate select strategies for managing deer to limit distribution and occurrence of CWD .

MATERIALS AND METHODS
Surveillance
We monitored deer populations throughout Colorado for occurrence of CWD using a combination of
targeted surveillance and harvest or road-kill surveys. These were organized and conducted as follows:
Targeted (= clinical. disease) surveillance: Deer showing clinical signs consistent with those seen in chronic
wasting disease were collected by field personnel statewide and brain tissues examined for evidence of
spongiform encephalopathy. The "suspect case" profile was defined as follows:
• Species:
• Age:

mule deer
white-tailed deer
2: 18 months

�184
• Signs: emaciated and
abnormal behavior &amp;lor
indifference to human activity &amp;lor
increased salivation &amp;lor
tremor, stumbling, incoordination &amp;lor
difficulty or inefficiency in chewing/swallowing &amp;lor
increased drinking and urination
Where possible, submissions were subjected to complete necropsy; in some situations, only heads were
available for examination and sampling. In all cases, histopathology of brain tissue (Williams and Young
1993) was used to diagnose CWD; in some cases, immunohistochemistry (lliC) or other ancillary tests
were used to confirm or support diagnoses.
Harvest surveys: In order to obtain reliable estimates of CWD prevalence that will serve as a basis for
monitoring responses to management interventions, we continued conducting harvest surveys on select deer
populations. During the 1999-2000 hunting seasons, fresh brain and select lymphatic tissues were
collected from deer harvested in endemic game management units (GMUs). Deer harvested or culled in
other select data analysis units (DAUs) throughout Colorado were also sampled as negative controls; in
particular, deer populations in North Park (DAU D3), the Piceance Basin, and Uncompahgre Plateau were
foci of surveillance activities. Brain tissues were examined at the Colorado State University Diagnostic
Laboratory for anti-PrP inununostaining reactions (O'Rourke et at, 1998) and histopathological lesions
(Williams and Young, 1993) consistent with CWD infection.
Epidemiological Studies
Epidemiology of naturally-occurring CWD in captive mule deer and white-tailed deer: Naturally-occurring
CWD was a sporadic disease of resident FWRF mule deer prior to 1985 (Williams and Young, 1992), and
also has occurred sporadically since 1994; no cases had been observed in resident white-tailed deer since
their addition to FWRF in 1993. We maintained and observed 21 ~ l-yr-old mule deer and 5 ~ l-yr-old
white-tailed deer in paddocks at CDOW's Foothills Wildlife Research Facility (FWRF) during this
segment. Deer received natural forage, pelleted rations (high energy supplement and "browser" diet), and
alfalfa hay; water and mineralized salt were available ad libitum. All deer were evaluated daily for clinical
signs ofCWD (and other health problems) in conjunction with routine feeding and handling activities.
Resident mule deer also represented the source of infection (= "treatment") in an ongoing study of cattle
susceptibility to CWD (see below).
Cattle susceptibility to CWD (Williams and Miller): We continued monitoring cattle for clinical evidence of
natural CWD transmission as part of a coordinated interagency effort to study cattle susceptibility to
CWD. Twelve 4-mo-old calves purchased from a private ranch located near Sheridan, WY, were placed in
paddocks at the FWRF with naturally-infected captive mule deer in July 1997 (see above for description of
resident deer herd). Twelve 4-mo-old mule deer fawns were captured at the Rocky Mountain Arsenal
National Wildlife Refuge (RMANWR) in late September and placed in the same paddocks as contact
controls for natural transmission (extensive ongoing surveillance of RMANWR deer has continued to
confirm that this population is free of CWD).
CWD Pathogenesis in mule deer (Williams and Miller): In a separate but related study, 20 additional 6-moold mule deer fawns were captured at the RMANWR in early December 1997. Each fawn was given a
single oral dose of about 5 g of fresh brain tissue homogenate from captive mule deer with clinical CWD.
Fawns were then released into a separate paddock physically removed from the contact transmission study.
These experimentally-infected fawns serve two purposes: as controls for domestic calves orally inoculated
with a single oral dose of about 50 g of this same CWD brain homogenate (Williams et al., 1998), and as
subjects of a study on the pathogenesis of CWD in mule deer.

�185

We have randomly sacrificed 2 experimentally-infected deer at 3,6,9, 12, 16, and 20 mo after inoculation;
we also collected 2 age- and sex-matched control deer from RMANWR at each time step. Complete
necropsies were performed and samples collected as described in the original study plan. Select sections of
brain tissue (obex) were examined after staining with hematoxylin and eosin (H&amp;E) or anti-PrP
immunostain (F89/160 .1.5; O'Rourke et al., 1998); examination of other tissues is pending.
Spatial epidemiology of CWO in free-ranging mule deer (Conner and Miller): Dispersal and/or migration
movements could be related to the spatial distribution and spread of CWO. To determine whether mule
deer movements from areas of high CWO prevalence are related to levels of CWO prevalence in
surrounding areas and/or mule deer populations, we captured and radiocollared mule deer in 2 areas of high
CWO prevalence. On 9 December 1999 and 10 December
Number
1999,42 deer were captured in game management unit
Age
Radiocollared
Area
Sex
(GMU) 9 near Virginia Dale, and from 7 January 2000 to
Male
14
Fawn
29 February 2000, 22 deer were captured in GMU20 near GMU9
4
Yearling
Masonville (Table 1). Because mule deer typically
2
Adult
disperse between 12 and 30 months of age, we focused our
18
Female
Fawn
capture efforts on fawns and yearlings (6-30 months of
0
Yearling
age) in order to gather data on both dispersal and
4
Adult
42
Total
migration movements. We collected location data on deer
radiocollared from this study, as well as from deer
6
Male
Fawn
GMU20
radiocolIared for an ongoing survival study in DAU 4.
4
Yearling
Telemetered mule deer were located every 6-8 weeks.
1
Adult
From preliminary data, we developed graphical
6
Female
Fawn
Yearling
3
information system maps that included locations of
2
Adult
summer and winter range and migration movements. We
22
Total
also calculated overwinter survival rates in accordance
Table 1. Sex and age composition of mule deer
with protocols from an ongoing study of deer survival in
radiocollared during winter 1999-2000 in GMUs 9
DAU D4 as a basis for comparing vital rates for deer in
and
20.
areas of high and low CWO prevalence.
Utility of Western blotting in detection ofPrPCWD in excreta (Larsen and Miller): Mechanisms for
transmission of CWO remain undescribed. Circumstantial evidence suggests either direct or indirect
animal-to-animal transmission occurs, most likely via agent excreted in some combination of saliva, feces,
urine, or placental tissues (Miller et al., 2000). However, progress in understanding CWO transmission
routes has been hampered by lack of tools for detecting PrPCWD in non-tissue media. W~ conducted
preliminary evaluations of Western blotting as a technique for detecting PrPCWD in both tissue and excreta
samples. Details of Western blot methods are described in detail elsewhere (Larsen and Miller, 2000).

Monitoring and Management
Recommendations for statewide monitoring and management of CWO in deer and elk were finalized and
adopted.

RESULTS AND DISCUSSION
Surveillance
Targeted (= clinical disease) surveillance: Between June 1999 and May 2000, 11 chronic wasting disease
(CWO) cases were diagnosed among 22 «suspect" deer submitted from known endemic portions of
northeastern Colorado; CWO was not diagnosed in any of 13 additional «suspect" deer submitted from

�186
elsewhere in Colorado. All CWD cases confirmed in 1999-2000 were mule deer, and all originated in
game management units (GMUs) where the disease had been detected previously.
Harvest surveys: We sampled about 1450 harvested or road-killed deer to randomly survey for CWD in
select DAUs. ruC-based prevalence in Larimer County mule deer (6.4%; 311487) was similar to
prevalence observed in previous years. In contrast, no cases were detected among 60 mule deer harvested
from South Platte River bottom/plains DAUs. Improvements in ruc techniques that allow identification of
very early preclinical cases (based on strong staining in lymphoid tissue even in the absence of staining in
brain tissue) should aid in reducing the bias in our prevalence estimates; we anticipate that these techniques
will be validated prior to the 2000-2001 survey season. Based on preliminary results, estimated prevalence
will likely increase by about 25-35% when these very early cases are included; the latter will likely be much
closer to true prevalence rates in infected populatiuons.
We detected no evidence ofCWD in any of the brain samples from North Park (0/105), Piceance Basin
(0/423), or Uncompahgre Plateau (0/205) GMUs, or in any of the other 150 samples from GMUs outside
northeastern Colorado. Overall, 1355 mule deer harvested or road-killed outside northeastern Colorado
have all tested negative for CWD; these data, combined with those from targeted surveillance, support the
contention that CWD is not distributed throughout the state.
Epidemiological Studies
Epidemiology of naturally-occurring CWD in captive mule deer and white-tailed deer: Between June 1999
and May 2000, CWD affected 11 of21 adult (z l-yr-old) mule deer in the resident Foothills Wildlife
Research Facility herd. Resident mule deer also represented the source of infection (treatment) in an
ongoing 10-yr study of cattle susceptibility to CWO (see below).
Two of 5 white-tailed deer remaining in our resident FWRF herd developed CWD during June-August
1999. The 3 remaining white-tailed deer were euthanized in September 1999 - 2 of the 3 showed mildmoderate spongiform encephalopathy on histopathology. In all, CWD claimed 8 of 11 captive white-tailed
deer held at FWRF between 1993 and 1999 and, based on the findings in the deer euthanized in September,
would have probably eliminated the entire population by 2001.
Examinations of tonsillar biopsies from captive deer are still pending. Lack of results has precluded
evaluation of tonsillar biopsy as a potential antemortem test for CWD in deer.
Cattle susceptibility to CWD (Williams and Miller): No signs of neurological disease were observed in any
of the 11 cattle (subjects) housed withnaturally-infected resident deer since July 1997. However, 3 of9
mule deer from the Rocky Mountain Arsenal National Wildlife Refuge (RMANWR)(contact controls)
developed clinical CWD between July 1999 and June 2000. Twenty-three of the 44 &gt; l-yr-old naturallyexposed resident FWRF deer developed clinical CWO and diedor were euthanized during the first 36 mo
of this study, thereby ensuring calves and control deer have received considerable exposure to CWD.
All 11 cattle exposed to a single 50 g oral dose of brain tissue homogenate from CWD-infected deer
remained healthy 33 mo postinoculation (through 30 June 2000) (E. S. Williams, pers. comm.). However,
3 of 14 cattle exposed to CWD via intracerebral inoculation died or were euthanized 22-27 mo
postinoculation after showing varying combinations of neurological signs and weight loss; mc staining
and Western blot results were consistent with probable CWD infection, although it is unclear whether
infection with the CWD agent actually caused the clinical signs displayed by the 3 affected calves (R. J.
Cutlip and A. Hamir , pers. comm.).

�187
Pathogenesis of CWD in mule deer (Williams and Miller): Using IDC, Prpres was detected in brain tissue
(medulla oblongata at the obex) from 1 of 2 mule deer experimentally inoculated with CWD 6 or 9 mo
earlier. One of2 deer examined 16 or 20 mo after inoculation (PQ had lesions ofspongiform
encephalopathy, and both were IHC-positive at each sampling. Two deer examined 3 mo PI and 2
examined 12 mo PI were negative, as were all 10 uninoculated controls collected from RMANWR at the
same intervals. One of the 8 remaining deer inoculated in December 1997 began showing early clinical
signs of CWO ~15 mo PI and died ~6 mo later; a second began showing early signs 2-3 wks later, and
subtle signs were noted in at least 4 of 8 inoculated deer alive 18 mo PI. Of the 6 inoculated deer surviving
&gt;20 mo PI, 5 died or were euthanized in end-stage clinical CWD 20-26 mo PI; the remaining animal
showed no appreciable clinical signs or lesions, and only minimal IHC staining in brain tissue, when
euthanized 26 mo PI.
Spatial epidemiology of
CWO in free-ranging mule
deer (Conner and Miller): .
TIlls year served as a pilot
study in which movements
of mule deer were
described. Most (86%) of
the deer captured in GMU 9
and GMU 20 were fawns
and yearlings (Table 1).
From preliminary data, we
mapped and visually
compared locations of
summer and winter range
and migration movements
_
SJmmer Heme Ranges
SUmmer GMU20
in areas of high CWD
C]GMJ
aty
prevalence (GMU 9, GMU
N/l../Hiltl-y
20
20) to and areas oflower
prevalence (GMU 191,
10
0
10
20 Kilanelers
GMU 19) (Fig. 1).
Movements of deer showed
a remarkably clear
Figure 2. Sununer and winter home range and movement patterns from winter to
relationship to prevalence
sununer home range for mule deer radiocollared in GMUs 9,191, 19, and 20.
patterns. Deer in GMU 9,
.
where CWD prevalence is relatively high, moved north into areas of Wyoming with equally high
prevalence. Deer in GMU 191, located west and adjacent to GMU 9 and having relatively low levels of
CWO prevalence, moved to the west into areas of even lower prevalence. Despite their proximity, there
was no overlap in winter range for deer in GMU 9 and deer in GMU 191, and almost no overlap in summer
range
1%). Overall, deer movements appeared related to patterns of prevalence in DAU 4. It follows
that migration patterns of mule deer may explain, at least in part, spatial patterns of CWD prevalence in
northcentral Colorado and southcentral Wyoming.
~

WlnI ••• Home

Ranges

~~~-

«

Overwinter fawn and adult survival was .estimated for 1 December to 15 June (Table 2). Survival did not
differ betwee~ high prevalence (GMU 9) and lower prevalence GMUs in DAU D4 (GMUs 191 and 19);
that is, all confidence intervals almost fully overlapped. TIlls is not surprising, because clinical CWO is

�188
rare in the younger age classes that
dominated our sample. Unfortunately,
our sample sizes were insufficient to
accurately estimate age- and sex-specific
survival rates within GMUs, and thus
comparisons of adult survival rates
between high and low prevalence GMUs
was precluded. We anticipate that
cumulative data gathered over the next
several years will eventually allow for
such comparisons.

Suvival

Year
1900-00

Period
10 Dec-15 June

Wrtering

twa
06.U4
GMJ9
GMJ19
GMJ191
GMJ2)

Sample

Suvival

Size Estimate
0.823
137
45
0.764
2)
0.612
0.940
52
2)
0.850

g)%CI
0.748 0.899
0.630 0.00)
0.378 0.843
0.874 1.000
o.eso 1.000

Table 2. Kaplan-Meier survival estimates for mule deer wintering in
GMU 9, GMU 19, GMU 191, and GMU 20. Trap mortalities were
excluded from survival calculations. Three deer radiocollared prior
to 1999 were present in GMU 9, thus sample size was 45 rather than
the 42 captured this year.

Utility of Western blotting in detection ofPrPCWD in excreta (Larsen and Miller): Western blotting
successfully detected PrPCWD in both brain and tonsil tissues from CWD-infected deer (fable 3, Fig. 2); all
negative control samples tested negative. Sensitivity of Western blotting in these tissues appeared similar
to mc. In contrast, we failed to demonstrate PrPCWD in either saliva or buffy coat extracted from blood.
Whether PrPCWD does not occur in these media, or whether it is simply present at concentrations that fall
below assay detection limits remains unclear. Tissue- and media-specific modifications in sample
preparation procedures probably will be needed before Western blotting can be applied reliably to various
materials of interest. In particular, modifications should focus on ways of concentrating the relatively
small quantities of PrPCWD that may occur in excreta and environmental samples. Provided such obstacles
can be overcome, Western blotting could have a variety of applications in studying CWD epidemiology.
Monitoring and Management
Recommendations for statewide monitoring and management of CWD (Appendix A) were finalized and
adopted. Specific recommendations for policy, as well as management goals and objectives were as
follows:
Policy
The Colorado Division of Wildlife is committed to minimizing the threat that chronic wasting
disease (CWD) poses to Colorado's native deer and elk resources. In data analysis units (DAUs)
where CWD is endemic, goals of reducing the occurrence and preventing the further spread of
CWD will serve as the primary basis for setting management objectives.
Goals
The CDOW's goals for CWD management will be 1) to limit distribution ofCWD to no more than
the 5 deer data analysis units (DAUs) and 2 elk DAUs where it already occurs and 2) to reduce
average CWD prevalence among deer and elk to &lt;1% in each endemic DAU and &lt;2% in each
endemic game management unit (GMU).
Short-term objectives
1. Manage to prevent dispersal ofCWD beyond endemic DAUs via mule deer, white-tailed deer,
and elk movements.
2. Manage to reduce CWD prevalence among deer inhabiting the three most severely affected
GMUs (9,191,19) by ~50% within 10 years (by 2011).
.
3. Manage to reduce CWD prevalence among deer and elk inhabiting all endemic DAUs to 51%
within 20 years (by 2021).
Based on these recommendations, 3 interim management actions were undertaken: First, deer and elk
population objectives for all DAUs in the endemic area were reset to current (1999) levels regardless of
previous long-term objectives established in DAU plans. Antlerless harvest levels were set to hold

�189
populations at 1999 levels or, in cases where populations currently exceed DAU objectives, lower
populations to those objective levels within 2 years. Second, a more aggressive program for culling clinical
suspects was instituted; this program enlists private landowners to assist in identifying and removing sick
deer throughout the endemic area. Third, a management experiment to test relationships between CWD
prevalence and deer density was planned and public information and regulation development processes
supporting this experiment were initiated; that experiment will probably begin during winter 2000-2001
(see details in Appendix B). Surveillance activities for 1999-2000, as well as surveillance planned for
2000-2001, reflect priorities established in the monitoring portion of this plan.

ACKNOWLEDGMENTS
The statewide CWD monitoring and surveillance program described here relies heavily on efforts of
dedicated field personnel throughout the Colorado Division of Wildlife, and truly represents a division-wide
effort to improve our understanding and management of this important disease problems. In addition to
those specifically listed, we collectively thank all of those regional and area biologists, district and area
wildlife managers, volunteers, deer hunters, and others who assisted by submitting suspect cases, harvested
animals, or road-killed animals throughout the year.

LITERATURE CITED
Larsen, C. T., and M. W. Miller. 2000. Evaluation of Western blotting as an investigation tool for
chronic wasting disease in mule deer. Colorado division of Wildlife, unpublished report. '
Miller, M. W., E. S. Williams, C. W. McCarty, T. R. Spraker, T. 1. Kreeger, C. T. Larsen, and E. T.
Thome. 2000. Epizootiology of chr6nic wasting disease in free-ranging cervids in Colorado and
Wyoming. Journal of Wildlife Diseases 38: 676-690.
O'Rourke, K. I., T. V. Baszler, J. M. Miller, T. R. Spraker, I. Sadler-Riggleman, and D. P. Knowles.
1998. Monoclonal antibody F89/160.l.5 defines a conserved epitope on the ruminant prion protein. 1.
Clin. Microbiol. 36: 1750-1755.
Williams, E. S., and S. Young. 1993. Neuropathology of chronic wasting disease in mule deer
(Odocoileus hemionus) and elk (Cervus elaphus nelsoni). Veterinary Pathology 30: 36-45.
---'
M. W. Miller, T. 1. Kreeger, H. Van Campen, and T. R. Spraker. 1998. Susceptibility of cattle to
cervid spongiform encephalopathy. unpublished grant proposal, submitted to USDA, CSREES,
National Research Initiative Competitive Grants Program, 88 pp.

Prepared by
Michael W. Miller
Wildlife Research Veterinarian

_

��191

Appendix A
Chronic Wasting Disease in Colorado Deer and Elk:
Recommendations for Statewide Monitoring and Experimental Management Planning
M W. Miller and R. H Kahn
Terrestrial Wildlife Resources, Colorado Division of Wildlife

Executive Summary
Chronic wasting disease (CWO) is a transmissible spongiform encephalopathy (TSE) of native deer and elk
that is endemic throughout northeastern Colorado and southeastern Wyoming. Estimated infection rates
range from &lt;1-15% in deer and s 1% in elk residing in northeastern Colorado game management units
(GMUs). There is no precedent for attempting to manage a TSE in free-ranging wildlife, and the biological
imperative for such management is not entirely clear. However, it seems most biologically responsible to
assume that CWO adversely affects native deer and elk populations and consequently manage to prevent its
further spread and reduce its occurrence in Colorado.
The CDOW has been actively monitoring CWO distribution and prevalence for over 10 years. Ongoing
surveillance programs should be continued to provide data on responses to management and public
information on CWO. Future monitoring should focus on reconfirming the limited distribution of CWO in
Colorado and on measuring responses to prospective disease management programs.
At present, the CDOW has no stated po~cy on managing CWO in free-ranging deer and elk. Lack of clear
policy has led to internal confusion, disagreement, and conflicts with other policies and Long Range Plan
objectives (e.g., increase recreational opportunities for deer and elk hunters). Because CWO currently
affects &lt;5% of Colorado's deer and elk resources and recreational opportunities but threatens far more
substantial resources both within and outside Colorado, the following policy should be adopted to guide
decisions on deer and elk population management in data analysis units (DADs) where CWO is endemic:
The Colorado Division of Wildlife is committed to minimizing the threat that chronic wasting
disease (CWD) poses to Colorado's native deer and elk resources. In data analysis units (DAUs)
where CWD is endemic, goals of reducing the occurrence and preventing the further spread of
CWD will serve as the primary basis for setting management objectives.
Based on current understanding of CWO in free-ranging deer and elk, eradication seems an extreme and
unjustifiable management goal at this time. Considering the prevalence and distribution CWO has reached
under historical management regimes, however, continuing to rely on current management approaches
seems equally unjustifiable. Consequently, two intermediate goals for managing CWO in deer and elk
should be adopted:
The CDOW's goals for CWD management will be 1) to limit distribution ofCWD to no more than
the 5 deer data analysis units (DAUs) and 2 elk DAUs where it already occurs and 2) to reduce
average CWD prevalence among deer and elk to &lt;1% in each endemic_DAU and &lt;2% in each
endemic game management unit (GMU).
Achieving the foregoing management goals should protect Colorado's deer and elk resources, restore
confidence in the quality of deer and elk harvested in northeastern Colorado, and address agricultural
constituencies' concerns about risk of potential transmission to domestic livestock or privately-owned
wildlife. To reach these goals, changes in population management should be made via revision ofDAU

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plans for the 5 deer DADs and 2 elk DADs where CWD is endemic by 1 January 2001 in order to achieve
three short-term management objectives:
1. Manage to prevent dispersal ofCWD beyond endemic DAUs via mule deer, white-tailed deer,
and elk movements.
2. Manage to reduce CWD prevalence among deer inhabiting the three most severely affected
GMUs (9, 191, 19) by ~50% within 10 years (by 2011).
3. Manage to reduce CWD prevalence among deer and elk inhabiting all endemic DAUs to 51%
within 20 years (by 2021).
Developing these plans will necessarily involve broader public input than typical DAD planning processes
in order to properly balance statewide concerns over CWD and its management with local concerns about
the impacts of proposed management actions. In light of uncertainties about CWD epidemiology and
ecology, plans should be approached as experiments that provide a mechanism for learning while
attempting disease management. Because CWD management will be experimental, individual DAD plans
should be coordinated through CDOW's Terrestrial Resources Program to ensure that elements of
uniformity, design, control, and implementation are identified and achieved. Plans for CWD management
should be reviewed and, where necessary, revised every 5 years as part of an adaptive strategy for
achieving management objectives.
Specific strategies and tactics for accomplishing CWD management objectives should be identified in
individual DAD plans. Many conventional disease management options (most notably, vaccines,
therapeutics, and live-animal tests for CWD) are presently unavailable; all other prospective strategies
identified to reduce CWD prevalence involve some form of aggressive culling or population control. It is
likely that current season structure, bag limits, and/or administrative boundaries may be too inflexible to
achieve management objectives. Some candidate tactics for CWD management may require modification or
temporary suspension of Commission regulations, as well as considerable human dimensions efforts.
Managing CWD represents an unprecedented challenge to CDOW's biologists, field personnel, public
service representatives, and administrators. However, rising to meet this challenge is vastly preferable to a
legacy of inaction that allows CWD to become more widespread at the expense of valuable wildlife
resources in Colorado and elsewhere.

Background
Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) of native deer
(Odocoileus spp.) and elk (Cervus elaphus nelsoni) characterized by behavioral changes and progressive
loss of body condition that invariably leadto the death ofaffected animals (Williams and Young 1992).
Neither the causative agent nor its mode of transmission have been fully identified; however, CWD is
suspected to be caused by aunique strain ofprion transmitted from animal-to-animal via some combination
of saliva, feces, urine, or other tissues or fluids (Miller et al. 1998, 2000; Williams et al. 2000). Both sexes
and all age classes show relatively uniform susceptibility (Miller et al. 2000, Williams et al. 2000). There
are no valid tests currently available for diagnosing CWD in live animals, and extant postmortem tests
require microscopic examination of brain tissue. There are no known treatments for CWD. Previous
attempts to eradicate CWD from research facilities failed on at least 2 occasions (Williams and Young
1992, Miller et al. 1998). Although similar in some respects to other TSEs that affect domestic sheep
(scrapie) and cattle (bovine spongiform encephalopathy; BSE), existing and unpublished experimental data
indicate CWD cannot be naturally transmitted to domestic livestock, and that scrapie and BSE cannot be
naturally transmitted to native cervids. Moreover, available data indicate that CWD does not present a
threat to human health.

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"Chronic wasting disease" was first recognized by biologists in the 1960's as a disease syndrome of captive
deer held in wildlife research facilities in Ft. Collins, CO. This disease was subsequently recognized in
captive deer, and later in captive elk, in wildlife research facilities near Ft. Collins, Kremmling, and
Meeker, CO and Wheatland, WY (Williams and Young 1980, 1982), as well as at in least two zoological
collections (Williams and Young, 1992). Since 1996, CWD also has been diagnosed in captive elk residing
in two game ranches in Saskatchewan, Canada, as well as five ranches in South Dakota, two ranches in
Nebraska, and one ranch each in Oklahoma, Colorado, and Montana (Fig. 1). Over 100 cases of clinical
CWD also have been diagnosed in free-ranging mule deer (0. hemionus), white-tailed deer (0.
virginianusi, and elk from northeastern
Colorado and southeastern Wyoming since
1981 (Miller et al. 2000). At present, the
known world-wide distribution of CWD in
wild cervids appears to be limited to
northeastern Colorado and southeastern
Wyoming (Miller et al. 2000). Although
CWD was first diagnosed in captive cervids,
the original source of CWD in either captive
cervids or free-ranging cervids is unknown;
whether CWD in captive cervids really
preceded CWD in wild cervids, or vice
versa, is equally uncertain (Spraker et al.
1997). Moreover, the relationship (if any)
between CWD cases in privately-owned
Figure 1. Distribution of chronic wasting disease in captive and freeelk industry and cases in
ranging deer and elk (November 1999).
free-ranging and research
animals is unclear.
A.MuJec2er
In Colorado, free-ranging
CWD cases in deer and
elk have originated from
throughout the
northeastern portion of the
state. Game management
units (GMUs) yielding
infected deer or elk
include 7, 8,9, 19, 191,
20,29,91,93,94,95,
951, and 96. Although
B. White-tailed ~er
cases have come from 13
different GMUs, two data
analysis units (04, 010)
have yielded over 85% of
the documented cases.
Harvest surveys indicate
GMUs 9,191, and 19 are
the most extensively
infected GMUs in
Colorado; estimated
Figure 2. Estimated CWD prevalence (%) among subpopulations of (A) mule deer and (B)
prevalence ranges from
white-tailed deer in northeastern Colorado. Data were aggregated on the basis of deer
about 6-15% (Fig. 2)
movement patterns. Prevalence estimates are based on immunohistochemistry
reactions only
(lliC+/total).
(Miller et al. 2000).

I

�194
Data from harvest surveys indicate that CWD is less prevalent in GMUs surrounding this core area,
affecting about 1-4% of the deer in GMUs 7,8,20,29,91,93,94,95,951,
and 96 (Fig. 2). Similarly,
harvest surveys indicate &lt;1 % of the elk in DAUs E4 and E9 are infected with CWD (Miller et al. 2000).
Based on targeted surveillance data and select harvest surveys, wild deer or elk populations in other parts
of Colorado and Wyoming are probably not infected with CWD (Miller et al. 2000); similarly, surveillance
data gathered to date indicate CWO has not yet spread to South Dakota, Nebraska, or Kansas (A. Jenny,
USDAIAPHISNS/NVSL,
pers. comm.).
For infected deer populations northeastern Colorado, CWO prevalence appears to be stable; however,
because small increases would be difficult to detect over only a few years it is doubtful that our short-term
observations accurately reflect or forecast long-term trends. In the absence of historical (20-30 years ago)
prevalence data or reliable estimates of transmission rates, changes in overall incidence or distribution of
CWO in northcentral Colorado DAUs are probably best projected via modeling. Based on field data and
results of simulation modeling to predict dynamics and impacts of CWO on affected deer populations, it
appears CWO was introduced into northern Larimer County over 30 years ago (Miller et al. 2000, Gross
and Miller 2000) and has increased in both prevalence and distribution since that time.
Beyond the Larimer County foothills, the South Platte River bottom corridor appears to be the single most
important and predictable avenue for spread ofCWD (Fig. 2). Kufeld and Bowden (1995) reported that a
proportion of South Platte River bottom deer were highly mobile; observed deer movements included some
to and from eastern Larimer County along the Cache la Poudre and South Platte Rivers. These movement
patterns provide a plausible mechanism for the extent of CWD' s distribution across South Platte River
bottom GMUs (Fig. 2) (Miller et al. 2000). Other likely routes for deer emigrating from eastern Larimer
County have not been completely identified, and may be less predictable or less commonly used.
Altitudinal movements of some elk subpopulations in the southern part of Larimer County are also
somewhat predictable (Bear 1982). Although there is potential for elk to cross the Continental Divide
through Rocky Mountain National Park, the relatively low prevalence of CWO among elk may diminish the
likelihood of its spread via their movements.
The significance of CWO and its impacts on native deer or elk populations have not been determined .
. Preliminary results of simulation modeling suggest that, sustained at &gt;5% prevalence as observed in the
most heavily infected GMUs, CWO could impact wild deer herds and lead to population declines (Miller et
al. 2000, Gross and Miller 2000). Analyses of harvest and other population data have not detected
evidence of population depression attributable to CWD, but existing inventory data for deer in northeastern
Colorado are probably insufficient to detect such trends (M. Conner, pers. comm.). In the absence of data
to the contrary, and considering the difficulties inherent in eliminating CWO from captive or wild cervid
populations once established, it seems most prudent to assume that CWO adversely affects native deer or
elk populations and manage to prevent its further spread and reduce its OCcurrence in Colorado. .
Unfortunately, there is considerable uncertainty in how to manage CWO in free-ranging wildlife, or
whether such an endeavor could even be successful (Gross and Miller 2000). Because a more complete
understanding of CWO is fundamental to developing comprehensive management programs, the Colorado
Division of Wildlife (CDOW) needs to further understanding about CWO and its management through
surveillance and experimental management. Data from completed, ongoing, and proposed research, both
basic and applied, will serve as the foundation of a series of adaptive resource management plans for CWO
in deer and elk. These plans will provide mechanisms for incorporating new knowledge gained through
surveys, modeling, research studies, and management experiments into a continuously evolving
management program for CWO.

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STATEWIDE MONITORING PROGRAM
The CDOW has been actively monitoring CWD distribution and prevalence for over 10 years. Ongoing
surveillance programs should be continued in order to provide data on responses to management attempts,
as well as public information on CWD. The recommended goals and strategies for statewide monitoring are
as follows:
.
Goals:
1. Provide reliable estimates of CWD distribution and prevalence to serve as a basis for management
decisions and public information.
2. Provide information to improve understanding ofCWD epidemiology.
3. Continue developing efficient and reliable techniques for detecting and monitoring CWD in free-ranging
populations.
Strategy:
Reliable estimates of CWD prevalence in wild deer and elk populations are needed to guide policy decisions
and monitor efficacy of management efforts. The CDOW should continue to monitor deer and elk
populations throughout Colorado for occurrence of chronic wasting disease using a combination of
extensive and intensive approaches. These have been organized and conducted as follows:
Targeted (= clinical disease) surveillance: Ongoing statewide "targeted" surveillance (i.e., submissions of
"suspect" deer &amp; elk) will be used to determine &amp; monitor changes in CWD distribution. Based on
experiences in Colorado and elsewhere, this appears to be the most sensitive approach for determining
CWD distribution and detecting range extensions (Miller et al. 2000).
A program for acquiring, examining, reporting on, and summarizing "suspect" CWD cases occurring
throughout Colorado has been in place since 1990. This program has served to increase ongoing
surveillance efforts by field personnel statewide by encouraging submission of carcasses from deer or elk
showing clinical signs resembling CWD. A formalized process for submitting cases has been developed;
this process includes criteria for acceptable submissions, submission forms, handling instructions, and a
system for networking submissions within CDOW and among the 3 Colorado State Veterinary Diagnostic
Laboratories and the Wyoming State Veterinary Laboratory. Under this program, deer and elk showing
clinical signs consistent with those seen in chronic wasting disease are collected by field personnel
statewide; a "suspect case" profile has been defined (Table 1). Brain tissues are subsequently examined for
evidence of spongiform encephalopathy. Where possible, whole carcasses will continue to be submitted for
complete necropsy; at minimum, heads from suspect animals will be submitted for examination and
sampling. Histopathology (Williams and Young, 1993) and immunohistochemistry of brain tissue (Spraker
et al., 1997) will be performed on all suspect cases; other ancillary tests may also be used to confirm or
support diagnoses. Pertinent data from preliminary and final reports will be entered into a permanent
database, and copies of reports will be filed as well as sent to appropriate field personnel.
Results from targeted surveillance should be used to identify new potential foci of CWD infection for
further evaluation via harvest or road-kill surveys.
Harvest and road-kill surveys: Surveys of harvested or, in some areas, road-killed deer and elk should be
conducted in endemic, high-risk, and outlying DAUs/GMUs to estimate and monitor CWD prevalence. We
recommend that initial surveys be conducted in all DAUs/GMUs where CWO is detected via targeted
surveillance to estimate prevalence, as has been done to date. We also recommend continuing to conduct
regular surveys at 1- to 5-year intervals in DAUs or GMUs where CWD is endemic to obtain reliable

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estimates of prevalence to use as a basis for monitoring natural trends or responses to management
interventions. Prevalence should be monitored annually in DAUs/GMUs where experimental management
programs are implemented. Surveys should be designed to provide an estimated prevalence within ±2% at
a 95% level of confidence for affected populations where true prevalence is 1%; we recognize that it may
be necessary to pool data from successive years in order to achieve desired sample sizes. In addition to
surveying endemic foci, CDOW should also continue conducting a series of surveys for CWD in other
select deer and elk populations throughout Colorado over the next 2 years, with a goal of determining
whether CWD is more widespread than suggested by targeted surveillance data.
We recommend the following surveillance strategy: Areas newly identified as infected via targeted
surveillance will be surveyed sufficiently to obtain a reliable prevalence estimate. Those areas where CWD
is not being managed or where estimated prevalence is &lt; 1% will be regarded as endemic and populations
will be monitored at -5-year intervals to measure long-term trends in prevalence. Areas where
experimental CWD management strategies are being tested (both treatment and control areas) will be
monitored annually to track changes in prevalence and evaluate management efficacy. We also recommend
conducting surveys of at least 2 other select deer populations where CWD has not been reported
previously. Target areas remaining include one high-risk and one low risk population (fable 2). Surveys
will be designed such that the probability of failure to detect at least I case of CWD in an apparentlyunaffected deer or elk population will be :sO.0 I even if herd prevalence is 1%. Finally, we will attempt to
gather a sufficient number of random samples from DAUs statewide (n-l,OOO) to determine whether or not
CWD should be generally regarded as endemic in Colorado's deer populations.
Harvest surveys should continue to be conducted using techniques developed and evaluated in Colorado
since 1991. With the advent of limited licensing for deer hunting statewide, mandatory submission
requirements in GMUs where surveys are being conducted can be dropped after 1999. Limited licenses
may be sought in select GMUs to aid in increasing compliance where elk surveillance is needed. Unstaffed
barrel sites appear to be the most efficient method for sample collection, and should continue to be used as
the primary method for conducting harvest surveys. Brainstem (medulla oblongata at the obex) from &lt;!: 1year-old deer and elk will be collected for CWD testing, and immunohistochemistry (lliC) using USDA
monoclonal antibody F89/160.1.5 (O'Rourke et al., 1998) should be used as the primary screening tool.
Reported prevalence estimates will continue to be based on numbers of IRC-positive cases; because mc
appears more sensitive than histopathology in detecting preclinical CWD cases, mC-based prevalence
estimates should provide a relatively unbiased measure of disease trends over time and allow more direct
comparison between field data and simulation model predictions. We also recommend continuing to
evaluate lymphoid tissue (e.g., tonsil) IRC as a means of increasing survey sensitivity and as a tool for
staging disease progress and monitoring responses to management attempts.

EXPERIMENTAL MANAGEMENT
There is no precedent for attempting to manage a TSE in free-ranging wildlife. Moreover, the biological
imperative for such management is not entirely clear at present. Programs for managing or eliminating
TSEs of domestic livestock have proven only marginally successful, and the lack of obvious success in
eradicating scrapie or BSE from endemic countries, compounded by epidemiological differences between
CWD and other TSEs, make such programs rather poor models for prospective CWD management.
Several fundamental features of CWD epidemiology are understood poorly, if at all; in particular, the
influences of host (e.g., population density, intraspecific vs. interspecific transmission, genetics) and
environmental factors (e.g., contamination, reservoirs, weather) on CWD dynamics remain unclear. In
light of the uncertainties associated with its epidemiology and ecology, we believe CWD management
should be approached as an experiment, thereby allowing us to learn as we take actions intended to reduce
prevalence and limit distribution.

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.

.

The CDOW's initial approaches for attempting to control CWD in free-ranging deer and elk were outlined
in an action plan for CWD drafted in 1995 (Miller et al. 1995; Appendix A). In addition to calling for a
comprehensive public information campaign, this plan identified tactics for limiting distribution and
reducing prevalence of CWD based on contemporary knowledge of the problem. Prompt removal of
affected animals and enforcement of feeding prohibitions were recommended to help reduce CWD
prevalence and transmission. Policies and regulations were also recommended, and subsequently instituted,
to prevent wider distribution ofCWD via human activities (e.g., translocations, rehabilitation, game
ranching). The plan also identified a need for more extensive surveillance to gather data on CWD
distribution and prevalence.
As more data on CWD distribution and prevalence have been gathered over the last 4 years, it has become
apparent that CWD is more widely distributed and more prevalent in northeastern Colorado (and
elsewhere) than initially believed (Miller et al. 2000). It follows that policy, goals, and strategies for
experimental CWD management in Colorado should be reevaluated in the context of new data, as well as
changes in social and political attitudes toward animal TSEs.
Management policy:
At present, the CDOW has no stated policy related to the management of chronic wasting disease in wild
deer and elk. The lack of a clear policy statement has led to internal confusion and disagreement over how
to resolve conflicts with other policies and Long Range Plan objectives (e.g., increase recreational
opportunities for deer and elk hunters).
.
Recommendation: Because CWD currently affects a relatively small portion of Colorado's deer and elk
resources «5% of both statewide populations and statewide harvests) but shows the potential to spread and
thereby threaten more substantial resources both within and outside Colorado, we recommend adoption of
the following policy to guide decisions on deer and elk population management in DAUs where CWD is
endemic:
PI.

The Colorado Division of Wildlife is committed to minimizing the threat that chronic wasting
disease (CWD) poses to Colorado's native deer and elk resources. In DAUs where CWD is
endemic, goals of reducing the occurrence and preventing the further spread of CWD will
serve as the primary basis for setting management objectives.

The foregoing policy, if adopted, should provide clear direction and a solid foundation for developing goals,
objectives, and strategies managing CWD, as detailed below. In the absence of this or a similar policy,
CDOW's ability to develop and implement a comprehensive approach for managing CWD will be severely
compromised.
Prospective management goals and objectives:
We have identified four overarching goals that could serve as a basis for decisions related to managing
CWD:
1. modified "natural regulation",
2. containment,
3. reduction,
4. eradication.
These goals represent a continuum of possible levels of intervention, ranging from benign neglect to
aggressive action. There are clear advantages and disadvantages associated with each of these prospective
management goals. Although each progressive level offers more complete control of the problem, better
control is accompanied by ever-increasing technical, fiscal, and political challenges, as outlined below:

�198
1. Modified "natural regulation": Directing no specific management intervention toward CWD beyond
culling of reported clinical cases and enforcing feeding and rehabilitation regulations represents the
status quo approach to both disease and affected deer and elk population management. It could be
argued that the ongoing activities described above, combined with ongoing changes in habitats and
movement corridors effected by development, collectively constitute an attempt to manage CWD.
Although the impacts of this approach on CWD prevalence in endemic foci remain undetermined,
prevalence in endemic foci appears to have remained stable over at least the last 3 years. This approach
offers the fewest technical challenges, may be regarded by some as "safest" in light of the myriad of
uncertainties in CWD epidemiology, and in the short-term would be most sparing of local resources.
Based on current culling rates reflected by case submissions, &lt;10% of clinical CWD cases are being
detected and removed from affected populations annually in Larimer County (and fewer elsewhere).
Unfortunately, simulation models forecast that problems with CWD will likely get worse in affected
populations managed in this manner (Gross and Miller 2000). Continuing existing management
practices will likely allow CWD to become more prevalent and widely distributed, with tangible
potential impacts on wildlife resources, recreational opportunities, and revenues. In addition, perceived
"inaction" may be unacceptable to some sportsmen's groups, agricultural interests, and perhaps the
general public, and could lead to the loss of management authority by CDOW. Finally, opting for
"natural regulation" of an emerging disease problem seems biologically irresponsible.
2. Containment: Managing primarily to prevent spread of CWD from endemic foci would require
additional knowledge of the mechanisms and probable routes of CWD dissemination, but many of the
important strategic components needed to support this strategy are already in place. The likelihood of
translocating infected animals from endemic areas to other areas in Colorado or elsewhere was
significantly reduced by Commission'regulations adopted in 1996. Between existing data from previous
movement studies (e.g., Kufeld et al., 1989; Kufeld and Bowden, 1995) and data from studies initiated
more recently, major natural emigration corridors from eastern Larimer County could probably be
identified and subsequently might be interrupted via intensive culling operations. This approach, if
successful, would limit the magnitude of the CWD problem while largely sparing local resources. This
alternative may be more acceptable to sportsmen's groups and the general public than to agricultural
interests, but is probably biologically justifiable. However, such an approach would require an
essentially infinite long-term commitment and yet will not eliminate CWD entirely; prevalence could
conceivably increase in endemic areas. There would likely be some local impacts on resources and
recreational opportunities, perhaps accompanied by local public resistance.
3. Reduction: It may be possible to manage affected deer or elk populations to reduce CWD prevalence
in endemic foci (Gross and Miller 2000). A goal of prevalence reduction clearly demonstrates intent to
limit the magnitude of the problem. It seems likely that this approach would also provide for
containment ofCWD. Attempting to reduce CWD prevalence might improve "consumer confidence"
among hunters in endemic GMUs. This alternative may be the most widely acceptable among
sportsmen's groups, agricultural interests, and the general public in terms of responsible disease and
resource management. It is probably biologically justifiable in view of projected long-term effects of
CWD on infected populations and the potential for CWD to spread from endemic foci if left
unmanaged. As with the foregoing goal of disease containment, prevalence reduction will require a
long-term commitment and may not eliminate CWD from endemic areas; however, early, aggressive
intervention may increase the likelihood of management success (Gross and Miller 2000). Depending
on specific tactics employed, prevalence could increase despite management efforts. This approach
would likely cause more severe impacts on local resources and recreational opportunities, and
consequently would be more likely to foster local public resistance to proposed management actions.
4. Eradication: Eradication is probably the most desirable goal of any attempt to manage CWD.
Whether it would be feasible to completely eliminate CWD from Colorado remains highly questionable.

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Eradicating CWD would be the best means of restoring for "consumer confidence" among northeastern
Colorado deer and elk hunters, and would presumably nullify concerns of traditional and alternative
livestock interests about the potential for transmission to privately-owned animals. Perhaps most
importantly, eliminating CWD would be the most effective way to preempt threats of its eventual spread
to other native deer and elk populations in Colorado and elsewhere. Although desirable in concept,
CWD eradication is probably infeasible given the complexities and uncertainties of its epidemiology.
Eradication of CWD would require long-term commitment, and probably would exact catastrophic
impacts on resources and recreational opportunities in affected areas; broader ecological impacts (e.g.,
on predator-prey balances) also could be severe. Public resistance is likely to emerge, at least locally,
as details of such a management program emerge. Finally, it is questionable whether the potential
ecological costs of CWD eradication are biologically justifiable in light of the uncertainty about longterm impacts of the disease itself.
Recommendations: Based on current understanding of CWD epidemiology, prevalence, and distribution in
free-ranging deer and elk in northeastern Colorado, we believe eradication is an extreme and unjustifiable
management goal at this time. In light of the magnitude of prevalence and distribution CWD has reached in
Larimer County deer populations under historical management regimes, however, continuing to rely on
current management approaches seems equally unjustifiable. Consequently, we recommend an intermediate
approach with two goals for managing CWD in deer and elk:
Gl.

limit distribution
occurs; and

of CWD to no more than the 5 deer DAUs and 2 elk DAUs where it already

G2.

reduce average CWD prevalence among deer and elk to &lt;1% in each endemic DAU and &lt;2%
in each endemic GMU.

We believe achieving the foregoing management goals will serve to protect Colorado's deer and elk
resources, restore confidence in the quality of deer and elk harvested in northeastern Colorado, and
ameliorate political pressures from agricultural constituencies concerned about potential for transmission of
CWD to domestic livestock or privately-owned wildlife.
We further recommend DAU plans for the 5 deer DAUs (04, D5, DI0, D27, and D44) and 2 elk DAUs
(E4, E9) where CWD is endemic be revised by I January 2001 to reflect changes in population
management sufficient to achieve three short-term management objectives:
Ml.

to prevent further dispersal ofCWD beyond endemic DAUs via mule deer, white-tailed
deer, and elk movements; and

M2.

to reduce CWD prevalence among deer inhabiting the three most severely affected GMUs
(9, 191, 19) by ~50% within 10 years (by 2011); and

M3.

to reduce CWD prevalence among deer and elk inhabiting all endemic DAUs to ~1 % within
20 years (by 2021).

Strategies for accomplishing management objectives will be identified in individual DAU plans. Developing
these plans will necessarily involve broader public input than typical DAU planning processes in order to
properly represent statewide concerns over CWO and its management; their development will entail
collaborative efforts of Terrestrial Resources, Public Service, and Human Dimensions staffs. Because we
regard any attempt to manage chronic wasting disease as experimental, we also recommend coordination
through CDOW's Terrestrial Resources Program to ensure that elements of uniformity, design, and control
are sufficient to implement management strategies and evaluate their effects. These plans should be

�200
collectively reviewed, evaluated, and revised every 5 years as part of an adaptive process for achieving
management goals. Where applicable, regulation adoption processes for implementing these DAU plans
should be independent of the 5-year season structure process.

Prospective management strategies:
Prescribing specific management strategies is beyond the scope or intent of this document. However, we
believe a clear understanding prospective strategies and options (or lack thereof) is a necessary prerequisite
to adoption of the foregoing policy, goals, and objectives for managing CWD in northeastern Colorado.
Consequently, we offer the following overview as a context for the decisions on CWD management
recommended here.
Effective strategies for managing CWD or any other TSE in free-ranging wildlife have never been
identified or evaluated. Many conventional disease management options are precluded from consideration.
Most notably, vaccines, therapeutics, and live-animal tests for CWD are presently unavailable (Table 3).
Contrary to experiences with domestic sheep (Dawson et al. 1998), available data indicate relatively
uniform genetic susceptibility to CWD among deer (K. I. O'Rourke and M. W. Miller, unpubl. data);
consequently, genetic selection would probably have no impact on prevalence even if tools for its
implementation were available. Similarly, controlling reproduction alone probably would be ineffective
even if practical tools were available because maternal transmission alone is unlikely to be sustaining CWD
prevalence at levels currently observed in some affected deer populations (Miller et al. 2000, Gross and
Miller 2000).
All other prospective options for reducing CWD prevalence that have been identified to date (Table 3)
involve some form of aggressive culling br population control directed at diminishing or preempting disease
transmission - the magnitude and duration of such control will be driven by GMU- and DAU-specific
CWD prevalence, management objectives, and population responses. Based on current understanding of
CWD epidemiology (Miller et al. 1998,2000; Gross and Miller 2000), strategies capable oflowering
CWD transmission rates by reducing numbers of infected animals. and point sources of environmental
contamination (e.g., feeders) should be most effective in lowering prevalence; although the precise
mechanisms of transmission have not been identified, those details will probably have little influence on the
resolution of CWD management at the population level. General models predict that random culling should
be less effective than selective culling in reducing disease prevalence (Barlow 1996, McCarty and Miller
1998, Gross and Miller 2000). However, field data and pilot work indicate that management strategies
based on culling clinical suspects probably will miss a large proportion of the infected (and potentially
infectious) individuals in a population; moreover, there is no practical way to apply "test and slaughter"
regimes without an antemortem diagnostic test for preclinical CWD. Accelerated culling of early clinical
cases, either by humans or via predators, may help reduce CWD transmission and prevalence.
Alternatively, if the probability ofCWD transmission is density-dependent, then reducing deer or elk
densities in endemic areas should lead to reduced CWD prevalence; to date, .the hypothesis of densitydependent disease transmission remains untested.
Obvious strategies for limiting CWD distribution remain equally elusive. The mechanisms driving the
spread of CWO among deer and elk populations are even less apparent than those driving disease
dynamics. It is possible that CWD distribution to date has been influenced by regular and/or random
movements of deer and, less commonly, elk. Previous studies (Kufeld et al. 1989, Kufeld and Bowden
1995, S. Steinert pers. comm.) have shown that proportions of both foothills and river bottom deer
populations in northeastern Colorado are either migratory or mobile; the movement patterns documented in
these studies provide at least a partial explanation for observed CWO distribution. It is also possible that
CWD influences its own distribution by changing behaviors, range fidelity, and movement pattens of
affected animals; observations of repetitive pacing in captive deer and elk affected by CWO could be
manifested as extensive wandering movements of free-ranging individuals. Whether or not movement

�201
patterns or dispersal rates are density-dependent remains unclear; either way, reducing population size
should also reduce the probability of affected individuals carrying CWD to new areas. (However, we do
recognize the possibility that at some lower threshold reduced density may actually promote deer and elk
movements, particularly during the breeding season).

Experiments to Manage CWD:
Based on current uncertainty about how to effectively disrupt the processes that influence CWD
epidemiology, prevalence, and distribution in free-ranging deer in northeastern Colorado, we recommend
initiating controlled management experiments directed toward testing one hypotheses about how best to
manage CWD. Prospective testable hypotheses include:
HI.

CWD distribution in foothills and river bottom habitats can be diminished by
a) selective culling;
b) increasing natural mortality via mountain lion predation; OR
c) reducing deer density in affected populations.

H2.

CWD transmission and prevalence in foothills and river bottom deer populations can be
diminished by
a) selective culling;
b) increasing natural mortality via mountain lion predation; OR
c) reducing deer density in affected populations.
I

We recommend using an adaptive resource management approach (Holling ~978, Walters and Holling
1990) to test candidate strategies for reducing CWD prevalence and distribution. Based on initial
evaluations of these candidate strategies, more detailed management experiments can be developed in
conjunction with the DAU planing process; as part of that process, decisions will be made on which, ifany,
approaches to pursue and where CWD management will be attempted. Tactics for accomplishing
management approaches (e.g., harvest, selective culling, ground/aerial gunning, changes in predator
harvest, etc.) will follow from internal consensus on which tactics are viable under the social and political
constraints imposed by the area(s) selected for study. All proposals should be review and approved through
appropriate internal and public processes. However, because it is likely that conventional recreation-based
season structures, bag limits, and/or administrative boundaries may be insufficient to accommodate
experimental approaches for managing CWD, the processes for changing regulations supporting
management experiments should be independent of the 5-year season structure process in order to
maximize flexibility in this adaptive management approach.
Prospective management tactics:
Specific tactical recommendations employed in experimental CWD management should follow from the
DAU planning process. As a general consideration, however, it is likely that current season structure, bag
limits, and/or administrative boundaries may be too inflexible to accommodate experimental approaches for
managing CWD that may be proposed for evaluation. Many candidate tactics (Table 4) for such
management will require modification or temporary suspension of Commission regulations, as well as
considerable human dimensions efforts. Within the confines of the broad policy, goals, and objectives
provided, we believe specific tactics are best identified by a combination of Staff and field collaborators on
a local level in conjunction with the DAU planning process and adopted as a package along with specific
DAU plans for managing CWD.
Developing comprehensive, objective-oriented DAU plans to manage CWD represents an unprecedented
challenge to CDOW's biologists, field personnel, public service representatives, and administrators.

�202
However, we believe rising to meet this challenge is vastly preferable to a legacy of inaction that will allow
a potentially manageable wildlife health problem to become widespread at the expense of valuable wildlife
resources in Colorado and elsewhere.
LITERATURE CITED
Barlow, N.D. 1996. The ecology of wildlife diesase control: simple models revisited. 1. Appl. Ecol. 33:
303-314.
Bear, G. D. 1989. Seasonal distribution and population characteristics of elk in Estes Valley, Colorado.
Colorado Division of Wildlife, Fort Collins, Colorado. Special Report Number 65: 1- 14.
Dawson, M. L. 1. Hoinville, B. D. Hosie, and N. Hunter. 1998. Guidance on the use ofPrP genotyping as
an aid to the control of clinical scrapie. Vet. Rec. 142:623-625.
"
Gross, J. E., and M. W. Miller. 2000. Chronic wasting disease in mule deer: A model of disease dynamics,
control options, and population consequences. 1. Wildl. Manage. (in reView).
Holling, C. S. 1978. Adaptive environmental assessment and management. John Wiley and Sons, London,
England.
Kufeld, R. C. and D. C. Bowden. 1995. Mule deer and white-tailed deer inhabiting eastern Colorado plains
river bottoms. Colorado Division of Wildlife, Fort Collins, Colorado. Technical Publication Number 41:
1- 58.
Kufeld, R. C., D. C. Bowden, and D.L. Schrupp,. 1989. Distribution and movement of female mule deer in
the Rocky Mountain foothills. J. Wildl. Manage. 53: 871-877.
McCarty, C. W., and M. W. Miller 1998. A versatile model of disease transmission applied to forecasting
bovine tuberculosis dynamics in white-tailed deer populations. J. Wildl. Dis. 34: 722-730.
Miller, M. W. 1999. Monitoring and managing chronic wasting disease in deer. Pages _-_
in Wildlife
Research Report, Manunals Research, Federal Aid Projects, Job Progress Report, Project W-153-R-12,
Work Package 3001, Task 3. Colorado Division of Wildlife, Fort Collins, Colorado, USA. (in press)
Miller, M. W. 1999. Monitoring and managing chronic wasting disease in elk. Pages _-_
in Wildlife
Research Report, Manunals Research, Federal Aid Projects, Job Progress Report, Project W-153-R-12,
Work Package 3002, Task 3. Colorado Division of Wildlife, Fort Collins, Colorado, USA. (in press)
Miller, M. W., M. A. Wild, and E. S. Williams. 1998. Epidemiology of chronic wasting disease in captive
Rocky Mountain elk. J. Wildl. Dis. 34:532-536.
Miller, M. W., E. S. Williams, C. W. McCarty, T. R. Spraker, T. 1. Kreeger, and E. T. Thome. 2000.
Epidemiology of chronic wasting disease in free-ranging cervids. J. Wildl. Dis. (in review).
Spraker, T. R., M. W. Miller, E. S. Williams, D. M. Getzy, W. 1. Adrian, G. G. Schoonveld, R. A.
Spowart, K. I. O'Rourke, 1. M. Miller, and P. A. Merz. 1997. Spongiform encephalopathy in freeranging mule deer (Odocoileus hemionus), white-tailed deer (Odocoileus virginianus), and Rocky
Mountain elk (Cervus elaphus nelsoni) in northcentral Colorado. J. Wildl. Dis. 33:1-6.
Walters, C. J., and C. S. Holling. 1990. Large-scale management experiments and learning by doing.
Ecology 71: 2060-2068.
Williams, E. S., and S. Young. 1980. Chronic Wasting disease of captive mule deer: A spongiform
encephalopathy. Journal of Wildlife Diseases 16: 89-98.
~
and __
. 1982. Spongiform encephalopathy of Rocky Mountain elk. Journal of Wildlife
Diseases 18: 465-471.
~
and .; __ . 1992. Spongiform encephalopathies in Cervidae. Revue Scientifique et Technique
Office International des Epizooties 11: 551-567.
_~
and __
. 1993. Neuropathology of chronic wasting disease in mule deer (Odocoileus hemionus)
and elk (Cervus elaphus nelsoni). Veterinary Pathology 30: 36-45.

�203

Table 1. Profiles used in chronic wasting disease targeted surveillance.
• Species:

• Age:
• Signs:

mule deer
white-tailed deer
elk
::::18 months
emaciated and
abnormal behavior &amp;lor
indifference to human activity &amp;lor
increased salivation &amp;lor
tremor, stumbling, incoordination &amp;lor
difficulty or inefficiency in chewing/swallowing &amp;lor
increased drinking and urination

Table 2. Tentative schedule for systematic statewide chronic wasting disease surveys of deer populations
using harvest and/or road-kill samples.
.

CWD Status

GMUs

Years surveyed

Endemic

7,8,9, 19, 191,20
29,91,93,94,95,951,96

1996-1999
1997-1999

"High Risk"

87, 88, 89, 90, 92
104
18,28,37,371
6, 16, 17, 161, 171
22
97, 98, 99, 100, 101

1997-2000
1996-2000
1998
1999-2001
1999
2000-2001

Other areas

66,67
83

1997-1998
1993-1994, 1998
1999
2000-2001
2001-2003

"Uncompahgre"
"Southern Front Range"
Random Statewide

[Note: Survey targets and schedules subject to changes influenced by new data and availability of
resources supporting CWD surveillance activities.]

�204
Table 3. Prospective strategies for chronic wasting disease management, as well as real or potential
limitations of these strategies.
Strategies for limiting distribution
- vaccination (no vaccine available)
- preclude human-caused trans locations (mostly done)
- interrupt migration corridors (fencing, local population suppression?)
- change habitat (improve/degrade to influence animal distribution?)
- alter migratory behavior (selective culling?)
- reduce density (relationship between density &amp; distribution untested)
Strategies for reducing prevalence
- vaccination (no vaccine available)
- treatment (no effective therapeutic drugs available)
- genetic selection (evidence of uniform susceptibility)
- fertility control (maternal transmission probably a minor contribution; no practical tools)
- eliminate clinical suspects (ineffective to date; intensive effort necessary)
- test &amp; slaughter (no reliable, practical live animal test)
- selective culling (what criteria? mechanism?)
- foster natural mortality (e.g., predation) to promote selective culling
- reduce density (relationship between density &amp; transmission untested)

Table 4. Prospective management tactics that could be needed to support selected management strategies,
as well as potential issues or limitations ito specific tactics.
Harvest (role of public hunting in disease management?)
- separate species management for mule deer and white-tailed deer
- shift emphasis from recreational opportunity to population management
- modify GMU/ "management area" boundaries to focus management &amp; distribute pressure
- expand or modify season structure/length
- increase bag limits
- bounty/incentive programs
Culling (public acceptance, access, efficiency?)
- ground vs. aerial vs. capture &amp; kill options
- use of agency vs. public agents for culling operations
- private land issues
- bounty/incentive programs
Fertility control (probably not useful for reductions, but maybe to maintain)
- agent availability and environmental safety
- delivery, cost
Increase predation (livestock and public safety issues)
- reduce predator quotas (close seasons?)
- predator introductions
Poisoning (specificity, environmental impacts, public acceptance?)

�205
Appendix B
Chronic Wasting Disease in Colorado Deer and Elk:
Recommendations for Experimental Management in GMU 9
M W. Miller and R. H Kahn
Terrestrial Wildlife Resources, Colorado Division of Wildlife
Executive Summary
Chronic wasting disease (CWO) is a transmissible spongiform encephalopathy (TSE) of native deer and elk
that is endemic throughout northeastern Colorado and southeastern Wyoming. Estimated infection rates
range from &lt;1-15% in deer and 1% in elk residing in northeastern Colorado game management units
(GMUs). There is no precedent for attempting to manage a TSE in free-ranging wildlife, and the biological
imperative for such management is not entirely clear. However, it seems most biologically responsible to
assume that CWO adversely affects native deer and elk populations and consequently manage to prevent its
further spread and reduce its occurrence in Colorado.
The Colorado Division of Wildlife is committed to minimizing the threat that CWO poses to Colorado's
native deer and elk resources. In data analysis units (DAUs) where CWO is endemic, goals of reducing the
occurrence and preventing the further spread of CWO currently serve as the primary basis for setting
management objectives. Based on current understanding of CWO in free-ranging deer and elk, eradication
seems an extreme and unjustifiable management goal at this time. Considering the prevalence and ..
distribution CWO has reached under historical management regimes, however, continuing to rely on
current management approaches seems equally unjustifiable.
Specific strategies and tactics for accomplishing CWO management objectives need to be identified in
individual DAU plans. However, many conventional disease management options (most notably, vaccines,
therapeutics, and live-animal tests for CWO) are presently unavailable; all other prospective strategies
identified to reduce CWO prevalence involve some form of aggressive culling or population control. Here,
we propose a management experiment in GMU 9 to evaluate the efficacy of density reduction on CWO
prevalence over time. Because current season structure and bag limits are too inflexible to achieve
management objectives, we recommend draft language for modifying Commission regulations to support
achievement of experimental management objectives.
Managing CWO represents an unprecedented. challenge to CDOW's biologists, field personnel, public
service representatives, and administrators, as well as to sportsmen, landowners, and other affected publics.
However, rising to meet this challenge is vastly preferable to a legacy of inaction that allows CWO to
become more widespread at the expense of valuable wildlife resources in Colorado and elsewhere.

�206

Background
Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (fSE) of native deer
(Odocoileus spp.) and elk (Cervus elaphus nelsoni) characterized by behavioral changes and progressive
loss of body condition that invariably lead to the death of affected animals (Williams and Young 1992).
Neither the causative agent nor its mode of transmission have been fully identified; however, CWD is
suspected to be caused by a unique strain ofprion transmitted from animal-to-animal via some combination
of saliva, feces, urine, or other tissues or fluids (Miller et al. 1998, 2000; Williams et al. 2000). Both sexes
and all age classes show relatively uniform susceptibility (Miller et al. 2000, Williams et al. 2000). There
are no valid tests currently available for diagnosing CWD in live animals, and extant postmortem tests
require microscopic examination of brain tissue. There are no known treatments for CWD. Previous
attempts to eradicate CWD from research facilities failed on at least 2 occasions (Williams and Young
1992, Miller et al. 1998). Although similar in some respects to other TSEs that affect domestic sheep
(scrapie) and cattle (bovine spongiform encephalopathy; BSE), existing and unpublished experimental data
indicate CWO cannot be naturally transmitted to domestic livestock, and that scrapie and BSE cannot be
naturally transmitted to native cervids. Moreover, available data indicate that CWD does not present a
threat to human health.
"Chronic wasting disease" was first recognized by biologists in the 1960's as a disease syndrome of captive
deer held in wildlife research facilities in Ft. Collins, CO. This disease was subsequently recognized in
captive deer, and later in captive elk, in wildlife research facilities near Ft. Collins, Kremmling, and
Meeker, CO and Wheatland, WY (Williams and Young 1980, 1982), as well as at in least two zoological
collections (Williams and Young, 1992). Since 1996, CWD also has been diagnosed in captive elk residing
in two game ranches in Saskatchewan, Canada, as well as five ranches in South Dakota, two ranches in
Nebraska, two ranches in Colorado, and' one ranch each in Oklahoma and Montana. Over 100 cases of
clinical CWO also have been diagnosed in free-ranging mule deer (0. hemionus), white-tailed deer (0.
virginianus), and elk from northeastern Colorado and southeastern Wyoming since 1981 (Miller et al.
2000). At present, the known distribution of CWD in wild cervids appears to be limited to northeastern
Colorado and southeastern Wyoming (Miller et al. 2000). Although CWO was first diagnosed in captive
cervids, the original source of CWO in either captive cervids or free-ranging cervids is unknown; whether
CWO in captive cervids really preceded CWD in wild cervids, or vice versa, is equally uncertain (Spraker
et al. 1997). Moreover, the relationship (if any) between CWD cases in privately-owned elk industry and
cases in free-ranging and research animals is unclear.
In Colorado, free-ranging CWO cases in deer and elk have originated from throughout the northeastern
portion of the state. Game management units (GMUs) yielding infected deer or elk include 7,8,9, 19, 191,
20,29,91,93,94,95,951,
and 96. Although cases have come from 13 different GMUs~ two data analysis
units (04, DI0) have yielded over .85% of the documented cases. Harvest surveys indicate GMUs 9, 191,
and 19 are the most extensively infected GMUs in Colorado; estimated prevalence ranges from about 615% (Miller et al. 2000). Data from harvest surveys indicate that CWD is less prevalent in GMUs
surrounding this core area, affecting about 1-4% of the deer in GMUs 7, 8, 20, 29, 91, 93, 94, 95, 951, and
96. Similarly, harvest surveys indicate &lt;1 % of the elk in DAUs E4 and E9 are infected with CWO (Miller
et al. 2000). Based on targeted surveillance data and select harvest surveys, wild deer or elk populations in
other parts of Colorado and Wyoming are probably not infected with CWO (Miller et al. 2000). Similarly,
surveillance data gathered to date indicate CWO has not yet spread to South Dakota, Nebraska, or Kansas
(A. Jenny, USDA-APHIS-VS-NVSL, pers. comm.).
For infected deer populations northeastern Colorado, overall CWO prevalence appears to be stable;
however, because small increases would be difficult to detect over only a few years it is doubtful that our
short-term observations accurately reflect or forecast long-term trends. In the absence of historical (20-30
years ago) prevalence data or reliable estimates of transmission rates, changes in overall incidence or
distribution of CWO in northcentral Colorado DAUs are probably best projected via modeling. Based on

�207
field data and results of simulation modeling, it appears that CWD was introduced into northern Larimer
County over 30 years ago (Miller et al. 2000, Gross and Miller 2000) and has increased in both prevalence
and distribution since that time.
The significance of CWD and its impacts on native deer or elk populations have not been determined.
Preliminary results of simulation modeling suggest that, sustained at &gt;5% prevalence as observed in the
most heavily infected GMUs, CWD could impact wild deer herds and lead to population declines (Miller et
al. 2000, Gross and Miller 2000). Analyses of harvest and other population data have not detected
evidence of population depression attributable to CWD, but existing inventory data for deer in northeastern
Colorado are probably insufficient to detect such trends. In the absence of data to the contrary, it seems
most prudent to assume that CWD adversely affects native deer or elk populations and manage to prevent
its further spread and reduce its occurrence in Colorado.
Unfortunately, there is considerable uncertainty in how to manage CWD in free-ranging wildlife, or
whether such an endeavor could even be successful (Gross and Miller 2000). Because a more complete
understanding of CWD is fundamental to developing comprehensive management programs, the CDOW
needs to further understanding about CWD and its management through surveillance and experimental
management.

EXPERIMENTAL MANAGEMENT
There is no precedent for attempting to manage a TSE in free-ranging wildlife. Moreover, the biological
imperative for such management is not entirely clear at present. Programs for managing or eliminating
TSEs of domestic livestock have proven only marginally successful, and the lack of obvious success in
eradicating scrapie or BSE from endemic countries, compounded by epidemiological differences between
CWD and other TSEs, make such programs rather poor models for prospective CWD management.
Several fundamental features ofCWD epidemiology are understood poorly, if at all; in particular, the
influences of host (e.g., population density, intraspecific vs. interspecific transmission, genetics) and
environmental factors (e.g., contamination, reservoirs, weather) on CWD dynamics remain unclear. In
light of the uncertainties associated with its epidemiology and ecology, we believe CWD management
should be approached as an experiment, thereby allowing us to learn as we take actions intended to reduce
prevalence and limit distribution.
The CDOW's initial approaches for attempting to control CWD in free-ranging deer and elk were outlined
in an action plan for CWD drafted in 1995 (Miller et al. 1995). In addition to calling for a comprehensive
public information campaign, this plan identified tactics for limiting distribution and reducing prevalence of
CWD based on contemporary knowledge of the problem. Prompt removal of affected animals and
enforcement of feeding prohibitions were recommended to help reduce CWD prevalence and transmission.
Policies and regulations were also recommended, and subsequently instituted, to prevent wider distribution
ofCWD via human activities (e.g., translocations, rehabilitation, game ranching). The plan also identified
a need for more extensive surveillance to gather data on CWD distribution and prevalence.
As more data on CWD distribution and prevalence have been gathered over the last 4 years, it has become
apparent that CWD is more widely distributed and more prevalent in northeastern Colorado (and
elsewhere) than initially believed (Miller et al. 2000). It follows that policy, goals, and strategies for
experimental CWD management in Colorado should be reevaluated in the context of new data, as well as
changes in social and political attitudes toward animal TSEs.
The CDOW is committed to minimizing the threat CWD poses to Colorado's native deer and elk resources.
In data analysis units (DAUs) where CWD is endemic, goals of reducing the occurrence and preventing the
further spread of CWD currently serve as the primary basis for setting management objectives. Based on
current understanding of CWD in free-ranging deer and elk, eradication seems an extreme and unjustifiable

�208
management goal at this time. Considering the prevalence and distribution CWD has reached under
historical management regimes, however, continuing to rely on current management approaches seems
equally unjustifiable.
Prospective management strategies:
A clear understanding of prospective strategies and options (or lack thereof) is a necessary prerequisite to
adoption of policy, goals, and objectives for managing CWD in northeastern Colorado. Consequently, we
offer the following overview as a context for the recommendations on CWD. management described here.
Effective strategies for managing CWD or any other TSE in free-ranging wildlife have never been
identified or evaluated. Many conventional disease management options are precluded from consideration.
Most notably, vaccines, therapeutics, and live-animal tests for CWD are presently unavailable (Table 1).
Contrary to experiences with domestic sheep (Dawson et al. 1998), available data indicate relatively
uniform genetic susceptibility to CWD among deer (K. I. O'Rourke and M. W. Miller, unpubl. data);
consequently, genetic selection would probably have no impact on prevalence even if tools for its
implementation were available. Similarly, controlling reproduction alone probably would be ineffective
even if practical tools were available because maternal transmission alone is unlikely to be sustaining CWD
prevalence at levels currently observed in some affected deer populations (Miller et al. 2000, Gross and
Miller 2000).
All other prospective options for reducing CWD prevalence that have been identified to date (Table 1)
involve some form of aggressive culling or population control directed at diminishing or preempting disease
transmission. The magnitude and duration of such control will be driven by GMU- and DAU-specific
CWD prevalence, management objectives, and population responses. Based on current understanding of
CWD epidemiology (Miller et al. 1998,2000; Gross and Miller 2000), strategies that lower CWD
transmission rates by reducing numbers of infected animals and point sources of environmental
contamination (e.g., feeders) should be most effective in lowering prevalence. (Although the precise
mechanisms of transmission have not been identified, those details will probably have little influence on the
resolution ofCWD management at the population level.) General models predict that random culling
should be less effective than selective culling in reducing disease prevalence (Barlow 1996, McCarty and
Miller 1998, Gross and Miller 2000). However, field data and pilot work indicate that management
strategies based on culling clinical suspects probably will miss a large proportion of the infected (and
potentially infectious) individuals in a population. Moreover, there is no practical way to apply "test and
slaughter" regimes without an antemortem diagnostic test for preclinical CWD. Accelerated culling of
early clinical cases, either by humans or via predators, may help reduce CWD transmission and prevalence.
Alternatively, if the probability of CWD transmission is density-dependent, then reducing deer or elk
densities in endemic areas should lead to reduced CWD prevalence; to date, the hypothesis of density- .
dependent disease transmission remains untested.
Obvious strategies for limiting CWD distribution remain equally elusive. The mechanisms driving the
spread of CWD among deer and elk populations are even less apparent than those driving disease
dynamics. It is possible that CWD distribution to date has been influenced by regular and/or random
movements of deer and, less commonly, elk. Previous studies (Kufeld et al. 1989, Kufeld and Bowden
1995, S. Steinert pers. comm.) have shown that proportions of both foothills and river bottom deer
populations in northeastern Colorado are either migratory or mobile. The movement patterns documented
in these studies provide at least a partial explanation for observed CWD distribution. It is also possible that
CWD influences its own distribution by changing behaviors, range fidelity, and movement patterns of
affected animals; observations of repetitivepacing in captive deer and elk affected by CWD could be
manifested as extensive wandering movements of free-ranging individuals. Whether or not movement
patterns or dispersal rates are density-dependent remains unclear; either way, reducing population size
should also reduce the probability of affected individuals carrying CWD to new areas. (However, we do

�209
recognize the possibility that at some lower threshold reduced population density may actually promote
deer and elk movements, particularly during the breeding season).
Experiments to manage CWD:
Based on current uncertainty about how to effectively disrupt the processes that influence CWD
epidemiology, prevalence, and distribution in free-ranging deer in northeastern Colorado, we have
recommend initiating controlled management experiments directed toward testing one hypotheses about
how best to manage CWD. Prospective testable hypotheses include:
HI.

CWD distribution in foothills deer populations can be diminished by selective culling and by
reducing deer density in affected populations.

H2.

CWD transmission and prevalence in foothills deer populations can be diminished by selective
culling and by reducing deer density in affected populations.

We recommend using an adaptive resource management approach (Holling 1978, Walters and Holling
1990) to test candidate strategies for reducing CWD prevalence and distribution. Based on initial
evaluations of these candidate strategies, larger management experiments can be developed in conjunction
with the DAU planing process.
Prospective management tactics:
Specific tactical recommendations employed in experimental CWD management should follow from the
DAU planning process. As a general consideration, however, it is likely that current season structure, bag
limits, and/or administrative boundaries may be too inflexible to accommodate experimental approaches for
managing CWD that may be proposed for evaluation. Many candidate tactics (Table 2) for such
management will require modification or temporary suspension of Commission regulations, as well as
considerable human dimensions efforts. Within the confines of the broad policy, goals, and objectives
provided, we believe specific tactics are best identified by a combination of staff and field collaborators on
a local level in conjunction with the DAU planning process and adopted as a package along with specific
DAU plans for managing CWD.
Developing comprehensive, objective-oriented DAU plans to manage CWD represents an unprecedented
challenge to CDOW's biologists, field personnel, public service representatives, and administrators.
However, we believe rising to meet this challenge is vastly preferable to a legacy of inaction that will allow
a potentially manageable wildlife health problem to become widespread at the expense of valuable wildlife
resources in Colorado and elsewhere.
Experimental management of CWD in GMU 9:
Within endemic portions of northeastern Colorado, CWD prevalence is highest in GMU 9. Of 174
harvested deer from GMU 9 sampled during 1996-1999,29 (16.7%) tested positive for CWD (Miller et al.
2000); because diagnostic tests currently in use underestimate true CWD prevalence by a factor of about
0.8 (Miller et al. 2000), true prevalence in GMU 9 is likely closer to 20%. Highest densities of infected
deer and highest local prevalence rates occur primarily in the northwestern portion of GMU 9 and coincide
with areas of highest wintering deer densities in this GMU (Fig. 1). Although sample sizes for individual

�210
CWO Density (No. PoslKm2) and locations of CWO Positive Mule Deer
years are small and some year-to-year
Clinical Cases and Hunter Survey Samples 1997-1999
variation probably occurs, CWD prevalence
N
among bucks harvested in GMU 9 has shown
an increasing trend over the last 3 years
(15.8% in 1997, 12.2% in 1998,20% in
1999), Computer models parameterized to
reflect this observed 3-year trend forecast that
CWD prevalence in GMU 9 will double in the
""'NH""" ••.
next 10 years in the absence of some change in
Ntransmission or population dynamics (Fig. 2).
6atv~""'.o
Under modest assumptions of densityIIIRO.1.0.15
dependent CWD transmission, models predict
that dramatic (e.g., 50% of current levels)
reductions in deer density could prevent further
increases in prevalence (Fig. 2). If transmission
GMJ 9 KrigedON;) Pr8talenceEstinBtes:
is more strongly density-dependent than
2x2 Km ard 100 NeaJestNeigl"bors
assumed, then prevalence should actually
decrease in response to density reductions.
Conversely, if CWD transmission is not influenced by
deer density, then models forecast that prevalence will
continue to rise despite density reductions (Fig. 2).

A

l.ocII:lonsd~lcdPosiMs

tiIrttGt SUN6f
O-O 25
0.025·0.OS
o.oS.0.1

Po!:itiw5INo. PosMn2)

i

0.15002
0.2-0.25

•

Understanding the relationship (or lack thereof)
between deer density and CWD prevalence trends
is fundamentally important to future decisions on
CWD management throughout northeastern
Colorado. In order to further this understanding,
we recommend an experimental reduction in deer
Figure 1.Highest densities of infected deer (upper map)
densities in GMU 9 to assess the effects of such
and highest local prevalence rates (lower map) occur
management intervention on CWD prevalence.
primarily in the northwestern portion of GMU 9. These
We have selected GMU 9 as a study area
heavily infected areas coincide with areas of highest
primarily because CWD prevalence is high
wintering deer densities in GMU 9.
enough to allow reliable measurement and
detection of trends over time. In addition, the
resident deer population in GMU 9 is relatively small (about 1000 head) and insular. Our experimental
management plan calls for reducing deer density in GMU 9 by about 50% over the next 2-3 years (20002002) and holding 'deer density at this reduced level for at least 5 years (2003-2007). CWD prevalence will
be monitored via sampling of harvested deer; in addition; we will monitor radiocollared deer in GMU 9 and
adjacent GMUs to examine effects of lowered density on home ranges and movement patterns. Prevalence
trends will be compared to trends in surrounding GMUs. In cooperation with the Wyoming Game and Fish
Department, we will also compare data from GMU 9 to data from a Wyoming "hunt area" (HA 64) where
current CWO prevalence trends are very similar to those in GMU 9. Because density will not be reduced
in HA 64 over the next several years, this population will serve as a control for our management
experiment.
Virtually all deer ranges in GMU 9 are in private ownership. Consequently, we have enlisted local
landowners as partners in this proposed management experiment. Based on input from GMU 9 landowners,
we recommend that density reductions be accomplished primarily via extended, limited access hunting
seasons; in some cases, culling may be needed to augment removals via harvest. Draft language for
regulations to establish these landowner-controlled hunts follows:

�211
Draft regulation for experimental

chronic wasting disease management

in GMU 9

Chapter 2
Article VIII
#250 E. Experimental Seasons for Chronic Wasting Disease Management
a. All landowners with fee title or exclusive lease to more than (20 acres) of land located in GMU 9 are
eligible to receive unlimited numbers of vouchers that may be used to purchase either-sex deer licenses
validfor the time period 1 November 2000 through 28 February 2001. Licenses are valid only in GMU
9. All deer harvested under this experimental season shall have the heads submitted to the Division of
Wildlife for chronic wasting disease testing. All other regulations are in effect for this season, including
but not limited to method of take, tagging, hunting hours and care of game meat. Experimental season
licenses will be considered additional licenses.
Quotas or limits on geographic distribution of vouchers will be established by CDOW Terrestrial
Resources staff, in consultation with Area personnel, in order to achieve uniform density reduction
throughout GMU 9. Population trends will be monitored by both aerial inventory and modeling.

LITERATURE CITED
Barlow, N.D. 1996. The ecology of wildlife disease control: simple models revisited. J. Appl. Ecol. 33:
303-314.
Bear, G. D. 1989. Seasonal distribution and population characteristics of elk in Estes Valley, Colorado.
Colorado Division of Wildlife, Fort Collins, Colorado. Special Report Number 65: 1- 14.
Dawson, M. L. 1. Hoinville, B. D. Hosie, and N. Hunter. 1998. Guidance on the use ofPrP genotyping as
an aid to the control of clinical scrapie. Vet. Rec. 142:623-625.
Gross, J. E., and M. W. Miller. 2000. Chronic wasting disease in mule deer: A model of disease dynamics,
control options, and population consequences. J. Wildl. Manage. (in review).
Holling, C. S. 1978. Adaptive environmental assessment and management. John Wiley and Sons, London,
England.
Kufeld, R. C. and D. C. Bowden. 1995. Mule deer and white-tailed deer inhabiting eastern Colorado plains
river bottoms. Colorado Division of Wildlife, Fort Collins, Colorado. Technical Publication Number 41:
1- 58.
Kufeld, R. C., D. C. Bowden, and D.L. Schrupp,. 1989. Distribution and movement of female mule deer in
the Rocky Mountain foothills. 1. Wildl. Manage. 53: 871-877.
McCarty, C. W., and M. W. Miller 1998. Aversatile model of disease transmission applied to forecasting
bovine tuberculosis dynamics in white-tailed deer populations. J. Wildl. Dis. 34: 722-730.
Miller, M. W. 1999. Monitoring and managing chronic wasting disease in deer. Pages _-_
in Wildlife
Research Report, Mammals Research, Federal Aid Projects, Job Progress Report, Project W-153-R-12,
Work Package 3001, Task 3. Colorado Division of Wildlife, Fort Collins, Colorado, USA. (in press)
Miller, M. W. 1999. Monitoring and managing chronic wasting disease in elk. Pages _-_
in Wildlife
Research Report, Mammals Research, Federal Aid Projects, Job Progress Report, Project W-153-R-12,
Work Package 3002, Task 3. Colorado Division of Wildlife, Fort Collins, Colorado, USA. (in press)
Miller, M. W., G. G. Schoonveld, B. Smith, R. A. Spowart, and R. H. Kahn. 1995. Chronic wasting
disease - proposed action plan. Unpubished report, Colorado Division of Wildlife, Fort Collins,
Colorado, 16 pp.
Miller, M. W., M. A. Wild, and E. S. Williams. 1998. Epidemiology of chronic wasting disease in captive
Rocky Mountain elk. J. Wildl. Dis. 34:532-536.

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Miller, M. W., E. S. Williams, C. W. McCarty, T. R. Spraker, T. J. Kreeger, C. T. Larsen, and E. T.
Thome. 2000. Epizootiology of chronic wasting disease in free-ranging cervids in Colorado and
Wyoming. J. Wildl. Dis. 36: (in press).
Spraker, T. R., M. W. Miller, E. S. Williams, D. M. Getzy, W. 1. Adrian, G. G. Schoonveld, R. A.
Spowart, K. I. O'Rourke, 1. M. Miller, and P. A. Merz. 1997. Spongiform encephalopathy in freeranging mule deer (Odocoileus hemionus), white-tailed deer (Odocoileus virginianus), and Rocky
Mountain elk (Cervus elaphus nelson i) in northcentral Colorado. J. Wildl. Dis. 33:1-6.
Walters, C. 1., and C. S. Holling. 1990. Large-scale management experiments and learning by doing.
Ecology 71: 2060-2068.
Williams, E. S.; and S. Young. 1980. Chronic Wasting disease of captive mule deer: A spongiform
encephalopathy. Journal of Wildlife Diseases 16: 89-98.
____:&gt; and __
. 1982. Spongiform encephalopathy of Rocky Mountain elk. Journal of Wildlife
Diseases 18: 465-471.
____:&gt; and __
. 1992. Spongiform encephalopathies in Cervidae. Revue Scientifique et Technique
Office International des Epizooties 11: 551-567.
____:&gt; and __
. 1993. Neuropathology of chronic wasting disease in mule deer (Odocoileus hemionus)
and elk (Cervus elaphus nelsoni). Veterinary Pathology 30: 36-45.

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Table 1. Prospective strategies for chronic wasting disease management (and real or potential limitations of
these strategies).
Strategies for limiting distribution
- vaccination (no vaccine available)
- preclude human-caused translocations (mostly done)
- interrupt migration corridors (fencing, local population suppression?)
- change habitat (improve/degrade to influence animal distribution?)
- alter migratory behavior (selective culling?)
- reduce density (relationship between density &amp; distribution untested)
Strategies for reducing prevalence
- vaccination (no vaccine available)
- treatment (no effective therapeutic drugs available)
- genetic selection (evidence of uniform susceptibility)
- fertility control (maternal transmission probably a minor contribution; no practical tools)
- eliminate clinical suspects (ineffective to date; intensive effort necessary)
- test &amp; slaughter (no reliable, practical live animal test)
- selective culling (what criteria? mechanism?)
- foster natural mortality (e.g., predation) to promote selective culling
- reduce density (relationship between density &amp; transmission untested)

Table 2. Prospective management tactics that could be needed to support selected management strategies,
as well as potential issues or limitations
specific tactics.

to

Harvest (role of public hunting in disease management?)
- separate species management for mule deer and white-tailed deer
- shift emphasis from recreational opportunity to population management
modify GMU/ "management area" boundaries to focus management &amp; distribute pressure
- expand or modify season structurellength
- increase bag limits
- bounty/incentive programs
Culling (public acceptance, access, efficiency?)
- ground vs. aerial vs. capture &amp; kill options
- use of agency vs. public agents for culling operations
- private land issues
bounty/incentive programs
Fertilitv control (probably not useful for reductions, but maybe to maintain)
- agent availability and environmental safety
- delivery, cost
Increase predation (livestock and public safety issues)
- reduce predator quotas (close seasons?)
- predator introductions
Poisoning (specificity, environmental impacts, public acceptance

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\

Colorado Division of Wildlife
Wildlife Research Report
Ju1y
2000
I

"

JOB PROGRESS REPORT
State of

Colorado

Cost Center 3430

Project No.

W-153-R-13

Mammals Research Program
Deer Conservation

Work Package No. ---"3'"""0..;;..0-=-1_ _ _ __
Task No.

4

Effects of Habitat Enrichment on Mule
Deer Recruitment and Survival Rates

Period Covered: July 1, 1999 - June 30, 2000
Authors: C. J. Bishop and G. C. White
Personnel: L. H. Carpenter, D. Coven, D. J. Freddy, R. B. Gill, R. Harthan, J. SaZina, B. E. Watkins, and
B. Welch

)

ABSTRACT
A Program Narrative {Appendix A) was developed to test the effects of habitat enrichment on mule deer
recruitment and survival rates on the Uncompahgre Plateau in southwest Colorado. Post hoc analyses were
completed to evaluate the effects of buck harvest on age and sex ratios (Appendix B), and to roughly
estimate the total number of deer in Colorado (Appendix C).

)

�136

I

\

�137
EFFECTS OF HABITAT ENRICHMENT ON MULE DEER
RECRUITMENT AND SURVIVAL RA TES

C. J. Bishop and G. C. White

P. N. OBJECTIVES
1. To conduct a one-year pilot study to assess the logistical feasibility of the proposed study and to gather
preliminary data to improve the study's efficiency and experimental design.
2. To determine experimentally whether enhancing mule deer nutrition during winter and early spring by
supplemental feeding increases December fawn:doe ratios and overwinter fawn survival.
3. To determine experimentally to what extent habitat treatments replicate the effect of enhanced nutrition
from supplemental feeding.
SEGMENT OBJECTIVES
1. Prepare a Program Narrative.
2. Plan field logistics and purchase equipment and supplies in preparation for initial field work beginning in
FY 2000-01.
INTRODUCTION
Mule deer numbers apparently declined during the 1990 •s throughout much of the West, and have clearly
decreased since the peak population levels documented in the 1940's-60's (Gill et al. 1999, Unsworth et al.
1999). Biologists and sportsmen alike have concerns as to what factors may be responsible for declining
population trends. Although previous and current research indicates that multiple interacting factors are
responsible, habitat and predation have received the focus of attention. A number of studies have evaluated
whether predator control increases deer survival, yet results are highly variable (Connolly 1981, Ballard et
al. 1999). Together, predator control studies with adequate rigor indicate that predation effects on mule
deer are variable as a result of time-specific and site-specific factors. Studies which have demonstrated
deer population responses to predator control treatments have failed to determine whether predation is
ultimately more limiting than habitat. Numerous research studies have evaluted mule deer habitat quality,
but virtually no studies have documented population responses to habitat improvements. In many areas
where declining deer numbers are of concern, predation is common yet habitat quality appears to have
declined. The question remains as to whether predation or habitat is more limiting to mule deer in these
situations, and whether habitat quality can be improved for the benefit of deer.
We designed a field experiment to measure deer population responses to habitat enrichment treatments. We
will conduct the study on the Uncompahgre Plateau, where several predator species are present in abundant
numbers. Predator numbers will not be manipulated in any way. Habitat enrichment treatments will
consist of supplemental feed provided to deer during the winter. If December fawn:doe ratios and
overwinter fawn survival improve as a direct result o(the supplemental feed, then we can presume that deer
nutrition is ultimately more limiting than predation. The field experiment also incorporates habitat
manipulation treatments, which will consist of prescribed fire or mechanical techniques to set back
succession ofpinyon-juniper habitat in an effort to improve the vigor and quality of winter habitat for mule
deer. Deer population responses will be measured in relation to the habitat manipulations in the same
manner as the supplemental feed. Thus, the experiment allows us to detennine whether nutritional quality

�138
of habitat is ultimately more limiting than predation in a late-seral pinyon-juniper/sagebrush landscape, and
if so, whether habitat can be effectively improved for mule deer.
There have been several challenges to implementing this study. First, using supplemental feed in a field
study sends a contradictory message to the public given the Division of Wildlife's policy on winter feeding.
Second, the study is very expensive and therefore requires considerable Division support to implement.
Third, logistical concerns raise the issue of whether the study can be carried out appropriately, such that
response variables are representative of treatment differences and measured without bias yet with adequate
precision. Finally, some personnel have questioned the need for such a study, particularly given the
expense. In result, we gave a number of presentations explaining the study in detail to generate widespread
support throughout the Division. We also decided to conduct a pilot study in the first year to address
logistical concerns and to allow more time to generate necessary funding.
MATERIALS AND METHODS
Program Narrative Development

We developed a Program Narrative (Appendix A), which addresses both the I-year pilot study as well as
the complete 4-6 year study. The P. N. has not been peer-reviewed at this point, but will be peer-reviewed
in early FY 2000-01 prior to the pilot study. The P. N. will be modified as necessary using results from the
pilot study, and once again peer-reviewed assuming there are significant changes. We based the P. N. on
an initial study proposal submitted by Gary White and Len Carpenter. We conducted a thorough literature
review and discussed study methodologies with numerous Division personnel to refine field methods. We
spent time in the field with the local Area Biologist, Bruce Watkins, and District Wildlife Manager, Dale
Coven, assessing the Uncompahgre Plateau for potential treatment and control areas. We worked closely
with the Uncompahgre Ecosystem Restoration Project (UERP) committee to select treatment/control sites
in the context of proposed habitat manipulation areas.
Uncompahgre Ecosystem Restoration Project

The Uncompahgre Ecosystem Restoration Project (UERP) was initiated by the Division of Wildlife after
former Director John Mumma allocated $500,000 of capital construction funds to habitat improvements for
the benefit of mule deer. UERP is comprised of individuals from DOW, U.S. Forest Service, Bureau of
Land Management (BLM), and the Colorado West Public Lands Partnership (PLP). Since the initial
$500,000, more funds have been obtained for UERP by the other agencies and PLP. Mike McLain
(AWM) and Bruce Watkins (Area Biologist) have represented DOW's interests in UERP from the onset,
while Jim Gamer (Habitat Biologist) and I joined the effort this past winter. UERP's mission is to improve
ecosystem health on the Uncompahgre Plateau through an integrated effort of the various agencies and
groups involved. A primary goal is to increase species diversity, age diversity, and the quality of habitat
communities on the Plateau in order to improve the distribution and quality of mule deer winter range. To
accomplish this goal, UERP is using a landscape approach to treat habitat using various techniques,
primarily prescribed fire and mechanical treatments. All treatments will be re-seeded with shrub-forb-grass
mixtures in an attempt to prevent invasive weeds from establishing and to increase forage diversity for mule
deer. Deer population responses on one of these habitat treatment areas will be intensively monitored as
part of our study's experimental design. The various other habitat treatments will be implemented in a
pattern of treatment and control areas such that long-term deer responses can be monitored using the
current mule deer population monitoring system on the Uncompahgre Plateau.
UERP is currently in the process of hiring a technical coordinator and a policy/education coordinator to
facilitate project implementation. The technical coordinator will assist with project design, implementation,
and evaluation; provide technical expertise and budget oversight; assist with grant writing and production

�139
of project reports; and ensure that proposed projects comply with state and federal regulations. The
policy/education coordinator will provide information concerning the project and generate support from
government agencies, stakeholders, and the general public. In essence, the policy/education coordinator
will serve a classic "information and education" role for UERP. Once the coordinators are hired, we will
begin identifying specific treatment sites and proceed with actual habitat treatments. UERP's current
timeline should enable some habitat manipulations to be completed in 2-3 years as needed for our habitat
enrichment study.

NEPA Requirements
Since much of the field work for our habitat enrichment study will be conducted on BLM lands, we are
subject to the requirements of the National Environmental Policy Act (NEPA). There are 2 types of
experimental treatments in our study: (l) supplemental feeding and (2) habitat manipulations. We
submitted our P. N. along with a detailed description of the supplemental feeding protocols to the
Uncompahgre Field Office of the BLM. They determined that the feeding portion of our study meets the
Categorical Exclusion requirement of NEPA, thereby granting approval to proceed without further review.
As explained above, all habitat manipulations will be performed by UERP, which assumes the
responsibility for obtaining NEPA approval and any other regulatory clearances.

Presentations
We presented our habitat enrichment study to both Division personnel and other groups throughout the
year. For Division personnel, our goal was to explain the study and address a variety of concerns that had
been raised. It was our intention to gain support for the study from the various leaders in the Wildlife
Programs Branch, as well as managers and biologists in the West Region arid particularly those in Area 18 .
.. ·For non-Division groups, we discussed the various issues affecting mule deer populations, and described
the habitat enrichment study in light of how the Division of Wildlife is attempting to address mule deer
concerns. We gave presentations at the following meetings, workshops, etc.:
♦
DWM Training Session (for incoming DWMs) - 1/5/2000, Denver
• West Section Terrestrial Biologist Staff Meeting- 2/7/2000, Grand Junction
♦ CSU Students/Faculty, Wildlife Field Studies Class Trip - 3/11/2000, Uncompahgre Plateau
♦ Wildlife Programs Branch Meeting- 3/14/2000, Denver
• Hunter Education Instructors, Big Game Workshop-4/15/2000, Montrose
• Hunter Education Instructors, Masters Workshop- 5/6/2000, Winter Parle
♦ Colorado Elementary and Secondary Education Teachers, Teacher Education Program 6/23/2000, Ridgway State Park/Uncompahgre Plateau
♦ Area 18 Staff Meeting- 7/27/2000, Lone Cone Cabin
The following presentation was also given, but was unrelated to the habitat enrichment study:
♦ Large Mammal Capture Techniques and Radio-Telemetry, CSU Wildlife Management Short
Course - 3/29/2000, Fort Collins
Other Activities
Mule Deer Legislative Report
Along with Mammals Research Leader, Bruce Gill, and other members of the research staff, I assisted in
the writing, editing, and publication of "Declining Mule Deer Populations in Colorado: Reasons and
Responses". The report was written for and submitted to the Colorado Legislature at their request. The
report was distributed widely via hard copies and the internet. I was responsible for responding to a
number of comments the Division received concerning the report. I presented the infonnation contained in
the report in several of the presentations listed above.

�140
Mule Deer Analyses
I completed several analyses/data summaries of statewide mule deer population data. I evaluated the
effects of limited buck harvest on mule deer sex and age ratios using data from quality (limited-harvest)
Game Management Units (GMUs). I also developed a rough estimate of total deer numbers in Colorado by
extrapolating deer density estimates from quadrat surveys to the total amount of delineated winter range in
Colorado. In doing so, I summarized the square miles of delineated mule deer winter range by GMU and
DAU throughout the state. These reports were distributed widely within the Division as a resource for
management biologists. I also attempted to "back-model" statewide mule deer numbers to obtain an
approximate estimate of Colorado's deer population in the 1950's. This daunting task has not been
completed, although considerable effort was put forth. Different models were developed by changing
assumptions; however, considerable refinement would be necessary before releasing any of the models.
While completing this task, I compiled monthly weather data from approximately 80 Colorado weather
stations from 1940-1999. Data were obtained from the W estem Regional Climate Center
(www.wrcc.dri.edu/index.html). These spreadsheets, which contain various statewide summaries, are
available.
RESULTS AND DISCUSSION
Habitat Enrichment Study

The various presentations we gave were very effective in gaining greater support for the habitat enrichment
study, particularly with Western slope managers and biologists. By openly discussing the major concerns,
and deciding to pursue a pilot study in the first year, most DOW personnel are generally supportive of the
study. Various personnel in the Montrose area have offered their assistance, and we have developed a
good, cooperative working relationship with Bruce Watkins, the Area Biologist. Presentations given to
non-Division groups were received very well. The different groups were supportive and interested in our
proposed study as well as the Division's overall efforts to manage mule deer in light of declining numbers.
Our presentations and other "I&amp;E" efforts were necessary to create a favorable climate prior to initiating
the study. It is important to note, however, that no presentations were given to the more outspoken critics
of DOW. Budget concerns have subsided given that we have submitted requests for outside grants to fund
a portion of the study, and because additional dollars may become available.in the research section during
the next 2 or 3 years.
Largely as a result ofUERP, a good relationship has been developed with the Uncompahgre Field Office of
the BLM as well as Forest Service personnel. The BLM has offered to store the supplemental feed in their
compound, and have been very cooperative in making the field work possible. They reviewed our study
proposal to ensure compliance with NEPA, and spoke with grazing permitees in the area to inform them of
the proposed study. These proactive efforts should prevent or at least alleviate any problems when field
work begins.
We selected several tentative treatment/control sites (experimental units) to be used for the study. We
initially planned to identify a number of potential experimental units, and then randomly select which would
be used in the study and which would be treatments and controls. However, given the logistical challenges
of this study and the need to maintain some level of homogeneity among experimental units, random
allocation is not realistic. In particular, feed treatment areas must be selected carefully to avoid feeding
more deer than we can afford, and to avoid feeding significant numbers of elk. We are currently planning
on distributing supplemental feed in the following 2 areas:
(1) The Colona Tract of the Billy Creek State Wildlife Area
(2) BLM Land adjacent to Shavano Valley as defined by the following:

�141
Within Dry Creek Basin Quadrangle (USGS 7.5 Minute), will primarily include Section 6 in T. 48 N.R. 10 W. and Section 1 in T. 48 N.-R. 11 W. (38°26'00"-38°27'30" N Lat., 108°00'00"-108°02'30"
W Long.). However, may also include Section 7 in T. 48 N .-R. 10 W. and Sections 2, 10, 11, 12, 13,
14, 15 in T. 48 N.-R. 11 W., depending on deer distribution and movements. This overall area roughly
includes 38°25'00" - 38°27'30" Latitude and 108°00'00" - 108°04'30" Longitude.
We are currently planning to use one of the following areas as a control area throughout the study (they are
too close together to both be used):
(1) Sims Mesa as defined by the following:
Within Government Springs Quadrangle (USGS 7.5 Minute), will approximately include Sections 31,
32 in T. 48 N.-R. 9 W., and Sections 5, 6, 7, 8, 17, 18 in T. 47 N.-R. 9 W. (~38°19'30" - 38°22'30"
N Lat. and 107°52'30" - 107°54'00" W Long.)
(2) Government Springs as defined by the following:
Within Colona and Government Springs Quadrangles (USGS 7.5 Minute), will approximately include
Sections 9, 10, 15, 16, 17, 20, 21, 22 in T. 47 N.-R. 9 W. (~38°18'30" - 38°21 '00" N Lat. and
107°50'00" - 107°53'00" W Long.)
There is little else to report concerning the study, other than we are in the process of purchasing supplies
and equipment, and preparing for field work. We have purchased and received 65 radio-collars to be used
in the pilot study, along with 15 additional collars from the Uncompahgre population monitoring work that
will be used in conjunction with the study. We have purchased radio-telemetry equipment and are in the
process of planning storage for and purchasing the supplemental feed. We are also working on drop-nets
that will be used along with helicopter netguns to capture deer. Again, the Program Narrative explaining
our detailed study plan is in Appendix A.
Mule Deer Report

The legislative report, "Declining Mule Deer Populations in Colorado: Reasons and Responses", has
proven to be a beneficial document for explaining the complex array of factors currently affecting mule
deer populations. During our presentations at 2 Hunter Education Workshops this spring, we presented
and provided copies of the report to all instructors in attendance. We received feedback from these
instructors as well as various other constituents responding to the report via email. The report is
apparently upsetting to some individuals who strongly believe predator control is the only solution for
reversing declining deer numbers, but for most others the report has provided a heightened awareness of
issues surrounding mule deer management. Aside from predation, buck harvest is the other factor
generating considerable debate. It would appear that certain sportsmen evaluate the fitness of deer
populations in terms of trophy buck opportunities while hunting. This perception confuses objective
evaluations of the effects oflow buck:doe ratios on declining deer populations. Clearly, low buck numbers
impact hunter success rates, particularly for trophy bucks, yet existing data does not suggest that buck:doe
ratios have had a significant impact on fawn production and recruitment. Harvest regulations represent a
trade-off between quality hunting and hunting opportunity. However, currently there is no scientific basis
for restricting buck harvest solely for the purpose of increasing fawn:doe ratios. In fact, if habitat is
limiting many of our deer herds, it could have the opposite effect on fawn recruitment.
Mule Deer Data Analyses

Limited buck harvest in quality ,GMUs has resulted in modest increases in buck:doe ratios but has had no
effect on fawn:doe ratios. The analysis and results are included in Appendix B. By extrapolating observed
deer density estimates from quadrat surveys to the total amount of winter range in Colorado, I estimated
approximately 575,000 - 580,000 deer in Colorado, which is very similar to the current estimate of deer
numbers based on DAU population models. The analysis and results are located in Appendix C.

�142
LITERATURE CITED
Ballard, W. B, D. Lutz, T. W. Keegan, L. H. Carpenter, and J.C. deVos, Jr. 1999. Deer-predator
relationships: a review of recent North American studies with emphasis on mule and black-tailed
deer. Unpublished manuscript.
Connolly, G. E. 1981. Limiting factors and population regulation. -Pages 245-285 in 0. C. Wallmo,
editor. Mule and black-tailed deer of North America. University of Nebraska Press, Lincoln,
Nebraska, USA.
Gill, R. B., T. D. I. Beck, C. J. Bishop, D. J. Freddy, N. T. Hobbs, R.H. Kahn, M. W. Miller, T. M.
Pojar, and G. C. White. 1999. Declining mule deer populations in Colorado: reasons and
responses. A report to the Colorado Legislature. Colorado Division of Wildlife, Denver,
Colorado, USA.
Unsworth, J. W., D. F. Pac, G. C. White, and R. M. Bartmann. 1999. Mule deer survival in Colorado,
Idaho, and Montana. Journal of Wildlife Management 63:315-326.

Prepared by _ _ _ _ _ _ _ _ __
Chad Bishop
Mammals Researcher

�143
APPENDIX A
PROGRAM NARRATIVE
FY 2000-01 - 2006-07

State of -----=C_,._ol=o=rad=o_ _ _ __
Project No. _ _ _ _W-'-'--~15:;..:3a...-=R=--------Work Package No. ---"3-"0"""0-=--1_ _ _ __
Study No. _ _ _ _ _ _4 ~ - - - - -

Cost Center 3430
Mammals Research Program
Deer Conservation
Effects of Habitat Enrichment on Mule Deer
Recruitment and Survival Rates

A. NEED
Background
Mule deer (Odocoileus hemionus hemionus) are a popular wildlife species with the public throughout
their range. Sportsmen place high value on mule deer as a harvestable big game species, and outdoor
enthusiasts of all kinds enjoy watching and photographing deer. The Colorado Division of Wildlife,
along with other state wildlife agencies in the West, depend on revenue generated from mule deer
license sales. Given such popularity and economic importance, an objective of western wildlife
agencies has been to maintain healthy, productive deer populations. Unfortunately, mule deer numbers
fluctuate widely, primarily in response to climatic and habitat conditions (Gill et al. 1999). Wildlife
managers have had little success attempting to maintain stable populations over a long time period.
Mule deer numbers peaked in the middle part of the 20th century, which for better or worse, set the
standard that many people use to evaluate the status of current deer populations. Since the mid to late
1900's, deer numbers have generally declined to the present. In particular, two widespread declines
have been documented; one occurred during the 1960 's through mid-1970 's (Workman and Low
1976), and the second occurred during the 1990's (Unsworth et al. 1999).
The recent decline in mule deer populations has caused widespread concern as to the causative factors.
Although reasons for declining populations are not clear and have been intensely debated, research
indicates multiple interacting factors are responsible. These factors include habitat change, weather,
urban development, predation, disease, competition with elk, among others (Gill et al. 1999).
Ironically, many of these same factors were raised as reasons for the decline during the 1970's crisis.
Great strides have been made during the past several decades to better understand the various aspects
of mule deer ecology and population performance. The challenge facing managers is that there are no
simple management solutions for increasing deer populations. In particular, harvest manipulations
alone are rarely sufficient to direct population levels. By and large, sportsmen have suggested that
predation is the major cause of declining deer numbers while biologists have implicated decreasing
habitat quality as the primary cause. Management actions addressing either factor will be expensive;
thus, high quality data should be obtained before any such management program is initiated.
Predation
Predator control efforts have been conducted on numerous occasions to evaluate whether predators
may be limiting mule deer recruitment, and if so, whether predator control is a viable management
strategy. Coyotes have been the primary target of such studies. Connolly (1981) summarized 12
studies assessing whether coyotes negatively impacted deer populations, which when taken together,
did not provide a definitive answer as to whether coyotes are a major limiting factor of mule deer.
Some of these studies found no benefit to controlling coyotes, and suggested that habitat quality was
ultimately the limiting factor (Murie 1940, Leopold et al. 1951, Robinette et al. 1977). Other studies

�144
were largely inconclusive (Smith and LeCount 1976, Robinette et al. 1977). The remaining studies
found coyote control to be potentially beneficial (Hom 1941, Brown 1961, McMichael 1970, Knowles
1976, Schladweiler 1976, Austin et al. 1977, Robinette et al. 1977, Trainer et al. 1978, Lemos et al.
1978), but given lack of proper experimental controls in many cases, the results were largely
speculative. Further, coyotes were primarily controlled by poisoning, which is no longer a possible
management strategy for reducing coyote numbers. Trainer et al. (1978) and Lemos et al. (1978)
suggested that coyotes were responsible for poor fawn survival in Oregon, but questioned whether
aerial shooting of coyotes could effectively reduce coyote densities.
Since Connolly's (1981) review of predation studies, several more predator control studies have been
conducted. Hartmann et al. ( 1992) found no benefit to coyote control in a deer population in northwest
Colorado, and provided strong experimental evidence that coyote predation was almost entirely
compensatory. In response to the recent deer decline, several more predator control studies were
initiated in various western states. The Idaho Department of Fish and Game and Montana Fish,
Wildlife, and Parks each began independent predator control experiments in 1997 (Gill et al. 1999).
Preliminary results from both studies indicate very little benefit from predator control, which has been
primarily aimed at coyotes. To this point in each study, cost/benefit analyses render coyote control as
an ineffective strategy for improving fawn recruitment. The Utah Division of Wildlife Resources
implemented a coyote control management plan in 1997 (Gill et al. 1999). Coyotes were controlled at
varying intensities in 15 herd units during 1997 and 1998. Winter fawn:doe ratios were higher in 1997
and 1998 than in 1995 and 1996 when coyotes were not controlled. However, this increase could not
be attributed to the coyote control efforts. The experimental design was flawed, and fawn:doe ratios
increased in Utah regardless of whether coyotes were controlled. In New Mexico, biologists from the
Jicarilla Apache Reservation suggested that mule deer numbers increased from 1991 through 1999 as a
result of predator control (Gill et al. 1999). However, the experimental design was flawed as well as
the methods used to estimate deer numbers. Deer population counts were related only to number of
hours flown while counting deer, and winter fawn:doe ratios did not improve despite coyote control.
Connolly ( 1981) drew several conclusions regarding predator control management which are briefly
summarized here: 1) careful localized study is required to determine whether observed predation is
impacting deer numbers; 2) coyote and/or lion predation has not been documented as the principle
cause of a mule deer population decline; 3) many predation studies may not have effectively controlled
predators; 4) predator control is expensive yet cost/benefit analyses are lacking; 5) predator control
may benefit deer populations that are below carrying capacity, but will not reverse deer declines that
are a result of habitat deterioration. We drew several other reasonable conclusions from both past and
present predator control studies: 1) predator control studies must incorporate experimental rigor in
order to obtain useful results; 2) under circumstances when coyotes may be limiting deer populations, it
appears very difficult and potentially cost prohibitive to effectively lower coyote densities on a
management scale with currently available control techniques; 3) predator control will be ineffective in
mule deer populations that are at or near carrying capacity (limited by habitat quality), where fawn
survival is ultimately a function of density-dependence and not predation; 4) in predator control
experiments, we typically cannot determine with much certainty whether habitat quality is ultimately
limiting fawn recruitment, even when the predator control treatments are ineffective.
Habitat Quality
The importance of habitat quality and quantity for sustaining mule deer populations is well understood.
In fact, various studies have provided considerable information regarding the components of quality
habitat for deer; these studies include habitat selection (Ordway and Krausman 1986, Carson and Peek
1987, Kufeld et al. 1988, Bodurtha et al. 1989, Thomas and Irby 1991,"Armleder et al. 1994), diet
composition/selection (Wallmo et al. 1973, Deschamp et al. 1979, Hartmann 1983, Campbell and

�145
Johnson 1983, Gill et al. 1983, Kasworm et al. 1984, Sowell et al. 1985, Austin et al. 1994), nutrient
analyses of forage (Bissell and Strong 1955, Smith 1957, Trout and Thiessen 1973, Urness et al. 1977,
Tueller 1979, Bartmann 1983, Welch 1989, Austin et al. 1994), foraging preference theory (Nudds
1980, Hanley 1982, White 1983, Spalinger and Hobbs 1992, Parker et al. 1996, Hanley 1997), and
energetics (Freddy 1984, Parker et al. 1984, Wickstrom et al. 1984, Hobbs 1989). It is generally
accepted that most wildlife populations are limited by habitat in terms of carrying capacity, which
incorporates all of the above components. At least theoretically, a deer population at carrying capacity
cannot expand beyond its current siz.e, which makes carrying capacity a very useful parameter.
However, given the complex, non-static relationships among biotic, physical, and edaphic factors of the
environment, it can be very difficult and time consuming to quantify and track carrying capacity. In
fact, carrying capacity of winter range continually changes as a function of the duration and severity of
winter (Wallmo et al. 1977). Based on the concept of carrying capacity and its limiting factors,
Wallmo et al. (1977) provided a model for evaluating deer habitat by quantifying the quality and
quantity of forage in relation to mule deer requirements. Using our accumulated knowledge of deer
habitat to qualitatively evaluate current Colorado deer ranges, it appears that habitat quality, and thus
carrying capacity, has declined in some of these ranges as a result of habitat changes over time.
Succession and disturbance are the principle components of habitat change. Generally speaking, mule
deer are better adapted to earlier-seral habitats, particularly those that are part of a larger habitat
complex in various successional stages (Bailey 1984). Disturbance-free communities will eventually
succeed to later-seral or climax-type habitats, which have a lower carrying capacity for deer because of
declining forage diversity and vigor. Thus, periodic disturbance may often be necessary for
maintaining healthy deer populations. Fire suppression is believed to have fostered the expansion of
late-seral, decadent habitats throughout many areas in the West. A particular concern has been the
encroachment ofpinyon (Pinus spp.)-juniper (Juniperus spp.) into sagebrush (Artemisia spp.) habitats
(Blackbum and Tueller 1970, Burkhardt and Tisdale 1976, Miller et al. 1999). Controlled bums and
mechanical treatments have been used to restore various habitats to early-seral conditions (Bunting
1996, Riggs et al. 1996, Erskine and Goodrich 1999, Sorensen 1999, Stevens 1999). Following such
habitat disturbances, deer have been found to prefer the disturbed habitat over the undisturbed habitat
(Keay and Peek 1980, Farmer 1995). Prescribed fire in northern California improved black-tailed deer
reproduction, which was considerably higher than in untreated habitat (Taber 1956, Taber and
Dasmann 1958). Hobbs and Spowart (1984) increased the·nutrition in winter diets of mule deer
following a prescribed fire in Colorado, which enabled greater foraging selectivity by deer. However,
reintroducing fire into later-seral communities can potentially have negative impacts, given the
increasing presence of exotic weeds. Some rangeland fires have perpetuated invasive weeds and
substantially reduced browse species as a result (Loft and Menke 1990,"Clements and Young 1997,
Bishop 1998). Thus, habitat treatments must be carefully planned and followed with reseeding to
achieve desired objectives (Sheley et al. 1996, Goodrich and Rooks 1999, Svejcar 1999).
Qualitative evidence suggests that habitat has declined in overall quality and quantity at the same time
deer numbers have declined throughout the West. Clements and Young (1997) linked a declining deer
population to habitat changes associated with grazing management, fire frequency, and invasion of
exotic annual grasses. Similarly, Gill et al. (1999) discussed declining deer numbers in Colorado in
relation to residential development, fire suppression, excessive herbivory from livestock and ungulates,
and invasion of exotic plants. Various habitats have inevitably declined in productivity as a result of
these factors, yet the impacts on deer populations have not been quantified. To better understand the
implications of habitat quality and carrying capacity, we need to quantify how deer populations
respond to changes in habitat. For management purposes, we need to improve our ability to actively
manage habitat for the benefit of mule deer (Boyd et al. 1986).

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Habitat vs. Predation
There are two overwhelming problems in current deer management regarding predators and habitats.
First, state agencies are becoming increasingly focused on predator control as a management solution,
typically as a result of public and political pressure, without regard to site-specific factors affecting
various deer populations or feasibility of predator control. Second, given the focus on predator control,
research and management studies have not addressed whether improving habitat quality is a viable
management solution for increasing deer numbers. The first problem may lead to unjustified and
poorly planned predator control management at unrealistically large scales, as was done by the Utah
Division of Wildlife Resources, which failed to effectively reduce predator numbers and therefore
wasted valuable management dollars. Low fawn survival and declines in total deer numbers are not
justification for predator control unless the deer population(s) are below habitat carrying capacity and
predation has been identified as a major limiting factor (Connolly 1981, Ballard et al. 1999). If
predator control is justified, it will not be beneficial for deer unless predator densities are sufficiently
reduced, which has only been achieved with carefully planned control efforts over relatively small areas
(Ballard et al. 1999). The bottom line is that experimental predator control studies cast a shadow of
doubt on the utility of predator control as a large-scale management strategy for reversing declining
trends in deer numbers and fawn recruitment.
The question remains as to whether or not habitat quality is more of a limiting factor than predation in
many of our deer herds. This question has rarely been rigorously addressed in past research and needs
more attention given the current debate surrounding wildlife agencies across the West. The prevailing
political tide is focused on predation as the overriding factor, yet there is no evidence to support that
predators ar~ having an impact on Colorado's deer herds. We must determine whether habitat or
predation is the more limiting factor before initiating a large-scale deer management program. The
other question is whether fawn survival and recruitment can be increased by enhancing habitat quality
in areas where habitat is perceived to be limiting. Much attention has been focused on predator
control, which for numerous reasons previously discussed, appears to have limited applicability as a
large-scale management strategy. However, virtually no studies have adequately assessed whether we
can effectively improve habitat quality for deer to increase fawn recruitment and ultimately population
productivity. lbis question has significant management implications for mule deer. Many biologists
believe that the overall drop in deer numbers from the middle of the 20th century to the present is a
result of declines in both habitat quality and quantity. Although predation may have slowed population
recovery at various times and places, deer numbers are ultimately limited by habitat (Connolly 1981).
It follows that improvements to habitat quality will provide a much greater long-term benefit to mule
deer populations. Also, habitat improvements are self-sustaining for many years following treatment
whereas predator control must be continually applied on an annual basis to have a long-term effect.
Our proposed study will assess whether nutrition is ultimately more limiting than predation in a deer
population with currently low fawn recruitment, and whether habitats can be manipulated to increase
fawn survival and recruitment. The greatest management concern over mule deer is focused on herds
below population objectives with low fawn recruitment. It is therefore sensible to select one of these
herds to evaluate whether habitat/nutrition or predation is more limiting to the deer population. If
habitat quality is identified as the ultimate problem, we must then determine whether we can improve
the deer herd by manipulating habitat. Although various habitat complexes have been manipulated to
benefit wildlife, deer responses have not been appropriately measured to determine if the treated habitat
actually improved deer populations. Assessments of treated habitat have traditionally comprised
arialyses of pellet-group counts, habitat selection, or forage selection pre- and post-treatment or
between adjacent treated and untreated areas (Wallmo 1969, Wallmo et al. 1972, Keay and Peek 1980,
Hobbs and Spowart 1984, Farmer 1995). These studies establish that deer used the treated habitat
more than untreated habitat, or in some cases demonstrate that diet quality was greater in the treated

�147

habitat, but they do not determine whether fawn survival or recruitment actually increased. Given the
expense of treating habitat, we must ensure that such treatments will improve deer productivity to
justify the cost.
Mule deer management decisions with a biological basis incorporate knowledge as to what factors are
limiting a·deer herd. Management decisions with a political basis are typically made without regard to
biological considerations. The question is whether future deer management decisions will be based on
political desires or biological data. The former may or may not benefit deer populations whereas the
latter will provide a basis for increasing mule deer numbers as well as sport harvest. Although we
must incorporate political decisions into our management programs, the Division of Wildlife will
ultimately be held responsible for the future status of mule deer populations. Our only means of
accountability is to ensure that our management decisions have scientific merit. This study allows the
opportunity for the Division to obtain information necessary for making biologically justifiable
management decisions for mule deer.

B. OBJECTIVES
1. To conduct a one-year pilot study to assess the logistical feasibility of the proposed study herein
and to gather preliminary data to improve the study's efficiency and experimental design.
2. To determine experimentally whether enhancing mule deer nutrition during winter and early spring
by supplemental feeding increases December fawn:doe ratios and overwinter fawn survival.
3. To determine experimentally to what extent habitat treatments replicate the effect of enhanced
nutrition from supplemental feeding.
Null Hypotheses:
a.

December fawn:doe ratios of deer groups that receive supplemental feed are not different from
fawn:doe ratios of deer groups that do not receive supplemental-feed.
b. Overwinter survival of fawns that receive supplemental feed is not different from survival of
fawns that do not receive supplemental feed.
c. December fawn:doe ratios of deer groups that utiliz.e habitat treatment areas are not different
from fawn:doe ratios of deer groups that occupy untreated (control) areas.
d. Overwinter survival of fawns that utilize habitat treatment areas is not different from survival
of fawns that occupy untreated (control) areas.

E. EXPECTED RESULTS
There is an urgent need for information regarding the causative factors limiting mule deer populations
that are currently below DAU (data analysis unit) objectives. This study will evaluate whether habitat
or predation is the more limiting factor to fawn survival and recruitment on the Uncompahgre Plateau
(DAU D-19), where December fawn:doe ratios have declined over the past 15 years. We will
accomplish this by monitoring deer responses in relation to supplemental feed, which will be provided
as a nutrition enhancement. We know that predators are killing fawns on the Uncompahgre Plateau
(Pojar 2000, B. E. Watkins unpublished data). If this observed predation represents additive mortality,
then the supplemental feed should not improve December fawn recruitment or overwinter fawn
survival. In other words, it would suggest that predators are killing fawns regardless of their
nutritional state. On the other hand, if the supplemental feed causes a beneficial response in the deer
population, then predation is largely compensatory and not the main underlying problem. So if fawn
survival and recruitment increases as a result of enhanced nutrition, without any manipulation of
predator populations, we can assume that habitat is ultimately more limiting than predators.

�148
If nutrition is found to be a critical problem, we need to evaluate management approaches for
improving habitat quality. Given available information, we do not know whether habitat treatments
benefit mule deer populations, even when they're designed to do so. This study will provide an
experimental assessment of the effectiveness of habitat manipulations for improving deer populations.
Results from the study will provide a quantitative basis for deciding which habitats to treat and how to
treat them, by monitoring deer population parameters in response to various treatment techniques. The
Division of Wildlife needs this information to plan management strategies for improving population
productivity in Colorado deer herds.

F. APPROACH
1. Pilot Study
The primary purpose of the pilot study is to address a variety of logistical concerns that could
impede both the quality and intent of the proposed study. If the pilot study runs smoothly or with
only minor problems, then any necessary revisions will be made to the Program Narrative and we
will pursue the actual study in the following year. On the other hand, if the pilot study reveals
acute problems in proposed methodology that would prevent us from adequately testing our null
hypotheses, then we will reevaluate the full-scale study. If possible, the Program Narrative will be
modified to address these problems without compromising our experimental approach. Otherwise,
a new experimental approach will be developed to address the same objectives, in which case we
would not be able to pursue a full-scale study in the following fiscal year.
The one-year pilot study will be very similar to the first year of the complete study described
below, except that it will only comprise two experimental units and one response variable. The
two experimental units will consist of a supplemental feed treatment area and a control area (Fig.
1). The single response variable will be December fawn:doe ratios, which will be measured the
December following the pilot winter's treatments. We will capture and radio-collar 40 adult
female mule deer in both the feed treatment area and the control area. This Program Narrative
addresses the full-scale experiment, with specific references to the pilot study as necessary.
2. Experimental Approach
a.

Experimental Units
Four areas on the Uncompahgre Plateau will be selected to create 4 experimental units (A-D)
(Fig. 1). Treatments will be randomly assigned to the experimental units. The following
criteria will be used to select experimental units:
1.) Deer densities (~50-80 deer/mi2): areas will be selected where deer densities are
sufficient to meet sample size requirements within the experimental unit, while
simultaneously selecting areas that will only require feeding less than ~500 animals
during a normal winter
2.) Buffer zones: areas will be selected such that experimental units are separated by
several miles of non-treatment area (buffers) to prevent deer from occupying more
than one experimental unit
3.) Similarity: areas will be selected that comprise relatively similar habitat complexes
and deer densities that are representative of the overall area
4.) Elk populations: areas will be selected that will minimize the number of elk present
during normal winters
Units B and C will be used alone during the pilot study, with Unit B receiving the supplemental
feed treatment. In the full-scale study, Unit A will serve as a control area, that will not receive

�149
any type of treatment throughout the study. Units Band C will be used to create a cross-over
design with supplemental feeding. Deer will be fed on Unit B during the first 2 winters of the
study, but not fed during winters 3 and 4. Deer will not be fed on Unit C during winters 1 and
2, but will be fed during years 3 and 4. Unit D will receive a habitat manipulation, which will
consist of fire or mechanical treatment, or possibly a combination of both.

Figure 1. Schematic representation of experimental units and their associated treatments. The pilot
study will incorporate a supplemental feed treatment area and a control area. Supplemental feeding
cross-over design will end after 4 years (not including the pilot study); monitoring in the habitat
manipulation experimental unit and paired control area will likely continue for 2 additional years.
Experimental units will be similar sized when initially selected. The mean deer density is
approximately 50-80 deer/mi2 on the portion of the Uncompahgre Plateau where the study will
be conducted. On average, 5 mi2 should contain anywhere from 250 to 400 deer, which is
probably the minimum necessary to capture 40 does and 40 fawns from separate groups. Thus
we will attempt to select experimental units that are at least 5 mi2 in size.
The actual size of experimental units will ~ary, however, in relation to a particular treatment.
Experimental units receiving the supplemental feed will need to remain relatively small to
successfully feed all collared animals without feeding more than a total of ~500 deer.
Maintaining the collared deer in a relatively small experimental unit should not be a problem
because they will likely have smaller home ranges as a result of the feed. The habitat
manipulation experimental unit will need to be larger to successfully treat enough habitat in a
mosaic pattern where untreated habitat tracts remain within the unit. We will of course have to
carefully monitor deer to ensure that they spend considerable time in the treated habitat.
Assuming the manipulated habitat confers an advantage over adjacent untreated habitats, deer
will likely demonstrate strong treatment site fidelity to capitalize on the more nutritious forage.
Control areas can be even larger without impairing or biasing the experiment, and in the
absence of feed or nutritionally enhanced forage, deer will probably utilize larger home ranges.
Success of the study in terms of experimental unit size primarily depends on intervening space
(buffer zone) between units. Theoretically, a control unit could be several times larger than a
supplemental feed unit as long as the control animals do not enter any of the other experimental
units.
b. Response Variables
The primary response variable will be fawn:doe ratios measured during the December
following the previous winter's treatments. In other words, the fawns counted during
December age classification will have been born the summer following the winter treatments,

�150
and classified when they are 6 months of age. Fawn:doe ratios will be measured in Units B
and C during the pilot year, and measured in each experimental unit during the initial 5 years
of the full-scale study. That is, prior to the first winter treatment of feeding on Unit B in the
pilot study, adult females will be radio-collared during the last half of November, and fawn:doe
ratios will be estimated from the collared sample to test the procedure and to obtain initial pretreatment data. Ratios will then be measured in each of the following 5 Decembers to evaluate
treatments in both the pilot and full-scale studies. Measurements will be continued for more
than 5 years only on Units A and D to adequately evaluate the impact of the habitat
manipulation on fawn:doe ratios. The second response variable will be overwinter fawn
survival, measured directly from radio-collared fawns during the same winter as the
treatments. Survival will be measured in each experimental unit for the first 4 winters of the
full-scale study. Survival measurements will be continued for several more years in Units A
and D to document the long-term impacts of the treatment. Overwinter fawn survival will not
be measured during the pilot study.
3. Sample Size/Power Analysis
a.

Fawn:Doe Ratios
The sampling unit of the proposed study is the same as the experimental units .. The primary
response variable is the mean fawn:doe ratios of the radio-collared does wintering on the
experimental unit of interest. We desire to detect an effect size, i.e., an increase in fawn:doe
ratios in response to the treatments, in the range of 15 to 20 fawns per 100 does. These values
are based on simple population models with overwinter fawn survival of 0.444, adult female
survival of0.853, and December fawn:doe ratios of 66 fawns per 100 does to obtain a
stationary population (Unsworth et al. 1999). The fawn:doe ratio for the Uncompahgre
Plateau during the 1990's averaged approximately 40 fawns per 100 does (Fig. 2).

90
80
u,
Q)

70

0

60

0
0

50

u,

40

0

.....
C:

~

co 30
20

LL

10
0
1982

1984

1986

1988

1990

1992

1994

1996

Year
Figure 2. Post-season fawn:doe ratios for deer in DAU D-19, Uncompahgre Plateau, in
southwest Colorado.

1998

�151
Fawn:doe ratios of the deer groups containing radio-collared animals will be the main source of
variation in the study. Groups may contain non-reproductive females such as yearlings or
barren old-age animals, and productivity per reproducing female varies. Based on surveys of
DAU D-19 from 1992-96, the standard deviation of the fawn:doe ratio for groups with at least
one adult female was 57, with a mean of 41. (Recent classifcation data from D-19 was not
incorporated into the standard deviation estimate because fawn:doe ratios are now measured
using quadrat classification as opposed to group classification.) Using an expected standard
deviation of 57, the standard error of the mean fawn:doe ratio for 40 radio-collared does is
57/(40 1~ = 9.0, which is the expected standard deviation of measured fawn:doe ratios on each
of the experimental units. We assessed power of the proposed experiment using SAS
Analyst®. We used a two-sample I-test with a sample size of 4, representing the years of the
study where treatment effects will be measured. The power of the design to detect an increase
of20 fawns per 100 does is about 0.87 (Fig. 3). Another way to interpret this power estimate
is to consider that the confidence interval on the treatment effect, e.g., effect of feeding, would
not include zero 87% of the time for replications of the entire experiment.
One source of variation has been neglected: sampling variance of the mean fawn:doe ratio of
the 40 radio-collared does. This variance can be reduced by repeated helicopter surveys to
estimate the fawn:doe ratio of the deer groups containing radio-collared does. Spatial variation
between the 4 experimental units will also exist, but will be accounted for in the design and
removed with the unit effect. Likewise, the temporal variation across years was included in the
standard deviation of 57, but will be accounted for in the design by the year effect. Thus, we
feel the power estimated in Figure 3 is reasonable for the proposed study.

1
0.9
0.8
0.7
L.
Q)
0.6
~
0
a.. 0.5
0.4
0.3
0.2
0.1

-- -----... ---

Increase in
Fawns:100 Does:

--

·······10 ----15

.... -

- - - -20 -

- 25

--30 - 3 5

......

.....
-40

... -

2

3

4
Sample Size (years)

5

6

Figure 3. Expected power of detecting fill increase from 10 to 40 fawns per 100 does with 40 adult females
collared per experimental writ, 8Ild a stfilldard deviation of the age ratio of 57.

A power of 0.87 is slightly higher than the commonly accepted power of 0.80. A sample size
of 35 radio-collared does in each experimental unit would achieve a power of approximately
0.80 using the previously described power calculations. However, it is likely that some
fraction of the radio-collared does in December of one year will not be alive to be sampled in
December the following year. Additionally, a few of the radio-collared animals may not
remain on the experimental unit where they were initially radio-collared. Animals that switch
experimental units during mid-winter will be discarded from the study because they would not

�152
represent either of the treatment areas that they inhabited. Thus, 40 radio-collared does per
experimental unit provides a slight cushion for collared doe losses from one December to the
next.
The habitat manipulation experimental unit along with the control unit will be measured for
more than 4 years because it is likely that deer will respond more slowly and less dramatically
than with the supplemental feed treatment. Thus, given &gt;4 years of measurements, additional
power will be obtained in the evaluation of habitat manipulations.
b. Overwinter Fawn Survival
A sample size of 40 fawns per experimental unit per year will provide power of O.81 to detect
a difference of O.15 in survival between 2 experimental units if survival on the control unit is
0.40. We expect to see an increase in fawn survival (effect size) of approximately O.15,
because this is the difference measured in the density reduction experiment conducted by White
and Hartmann (1998).
4. Procedures
a.

Capture Methods
Deer will be captured using helicopter net guns (Barrett et al. 1982, van Reenen 1982) and
baited drop nets (Ramsey 1968, Schmidt et al. 1978). Deer in the experimental unit receiving
the supplemental feed will be captured primarily with drop nets, where the bait will be partially
composed of the supplemental feed. Deer receiving the supplemental feed treatments may also
be captured via anesthesia from a projected syringe (dart) using the following procedure.
Feeding will be initiated in the appropriate experimental unit. We will monitor feed sites from
a nearby blind, and use a dart gun/projectile syringe to anesthetize deer that accept the feed.
Deer will be anesthetiz.ed with tiletamine HCI and zolazepam (Telazol®, 5 mg/kg) and xylazine
HCI (2.5 mg/kg) delivered intramuscularly. There are two primary advantages of using baited
drop nets and dart gunning to capture deer in the supplemental feed treatment areas. First,
deer will have demonstrated a willingness to consume the feed prior to being captured, which
increases the likelihood that these animals will utilize the feed through the winter. Second, we
will be able to capture the desired number of deer over a smaller geographical area than with
net gunning. If the 40 does and 40 fawns are captured over too large of an area, it will be very
difficult to successfully feed all 80 animals on a daily basis while attempting to feed no more
than a total of ~500 animals.
Deer will be fitted with leather radio collars equipped with mortality sensors, which after
remaining motionless for 4 hours, increase the pulse rate of received signals. Permanent
collars will be placed on females, while temporary collars will be placed on fawns. To make
collars temporary, one end of the collar will be cut in half and r~ttached using rubber surgical
tubing; fawns will shed the collars after approximately 6 months. Fawn collars will be reused
annually, which will reduce costs after the initial year of the full-scale study. Doe collars will
be equipped with a rectangular piece of flexible plastic (Ritchey® neck band material) stitched
to the top-side of the collar. The piece of flexible plastic will be engraved with a unique
identifier than can be visually identified and interpreted from the air. The plastic identifier will
be used to ensure that each doe is accurately and individually identified during helicopter age
and sex classification each December. A uniquely numbered ear tag will be placed on both
does and fawns. We will record the weight of each fawn, and collect blood samples from both
does and fawns whenever feasible to evaluate disease prevalence.

�153
b. Measurement ofFawn:Doe Ratios
Approximately 40 adult females will be captured and radio-collared in Units B and C from late
November through mid December prior to the pilot study. The following winter, 40 adult
females will be radio-collared in Units A and D, and additional females will be captured in
Units B and C to maintain a sample size of 40 collared does in each experimental unit. This
will result in a total sample size of 160 does during the full-scale study. Radio-collared
animals will be monitored through the winter to determine survival and fidelity to a particular
experimental unit. Does receiving the supplemental feed will be monitored to ensure that they
actually consume the feed on a regular basis. The December following each winter, the group
of deer with each radio-collared doe will be located by radio-tracking from a helicopter. Each
deer group containing the collared doe will be counted and classified by age and sex. The
procedure may be repeated if necessary to reduce the sampling variance of the estimates of
fawn:doe ratios for each experimental unit. Since ratio estimates will be based on individual
deer groups, we will attempt to capture each of the 40 does from separate groups of deer
scattered throughout the experimental unit. Multiple collared does in the same group of deer
during December classification flights will reduce our functional sample size. Additional deer
will be radio-collared each December to maintain sample sizes at 40 collared does per
experimental unit.
c.

Overwinter Fawn Survival
Approximately 40 fawns (6 months old) will be captured and radio-collared during late
November through mid December ofeach winter on each experimental unit during the fullscale study. Fawns will not be monitored during the pilot study. We will avoid capturing
sibling fawns to ensure that independent samples are used to evaluate overwinter fawn
survival. Survival will be directly measured through the winter by radio-monitoring collared
fawns to determine fate (live/mortality). Fawns will also be mo_nitored to determine fidelity to
the experimental units and to ensure that animals receiving the supplemental feed actually
consume the feed.

d. Feeding
The supplemental feed provided to the deer will consist of pelleted rations developed by Baker
and Hobbs (1985). Feed will be periodically transported to the experimental unit receiving the
treatment, where the feed will be stored on site in a large steel bin. Pellets will be distributed
daily via snowmobiles or ATV's along established trails throughout the experimental unit to
provide a food source for the entire deer population in the treatment unit. This will prevent
dominant animals from restricting access to the food supply because of the large area over
which pellets will be distributed. Pellets will be supplied ad libitum such that a small residual
remains when the next distribution of food is provided. Collared deer will be carefully
monitored to ensure that treatment deer are consuming the feed whereas non-treatment deer are
not. Deer that do not regularly consume the feed will be withdrawn from the sample. Any
non-treatment deer that find and utilize the feed will likewise be removed from the sample.
Keeping the experimental units spatially separate should minimize the latter problem.
The pelleted ration will be commercially produced in the form of 2x lx0.5-cm wafers (Baker
and Hobbs 1985). Feed constituents (i.e. digestibility, protein, gross energy etc.) vastly exceed
those of typical winter range deer diets; exact constituent values are provided by Baker and
Hobbs (1985). When provided ad libitum, the feed should allow deer to meet or exceed

�154
nutritional requirements for growth and maintenance (Ullrey et al. 1967, Verme and illlrey
1972, Thompson et al. 1973, Smith et al. 1975, Baker et al. 1979, Holter et al. 1979). The
basis for feeding such high quality pellets is to ensure that the treatment (enhanced nutrition) is
effectively delivered to the deer. Our intent is not to determine the exact level of nutrition
necessary to increase fawn recruitment, but rather to determine if nutrition is a limiting factor
to recruitment. If nutrition is in fact limiting, we will rely on the habitat manipulation
treatment to evaluate what exactly can be done via management to increase fawn survival and
recruitment.
e.

Habitat Manipulations
Habitat will be manipulated in experimental unit D through collaboration with the
Uncompahgre Ecosystem Restoration Project (UERP) committee, which comprises personnel
from the Division of Wildlife, U.S. Forest Service, Bureau of ~d Management, and the
Colorado West Public Lands Partnership. The UERP committee is using an experimental
landscape approach to manipulate various habitats in a mosaic pattern throughout the
Uncompahgre Plateau. We will focus our intensive deer monitoring on one of these habitat
manipulations that will be conducted in experimental unit D. The vast majority of deer winter
range on the Uncompahgre Plateau comprises pinyon pine (Pinus edulis)-juniper (Juniperus
spp.) habitat. Considerations and techniques for manipulating pinyon-juniper habitats have
been evaluated in various areas throughout the West (Monsen and Stevens 1999), including
considerations for benefiting wildlife (Fairchild 1999, Miller 1999). We will treat habitat
primarily using fire (Erskine and Goodrich 1999, Goodrich and Barber 1999, Roberts 1999)
and mechanical treatments such as rollerchopping (Sorensen 1999). The type of treatment
used in the experimental unit will be based on several factors, which include topography, seral
stage of the habitat, soil type, moisture regime, and information from previous studies.
Regardless of the technique employed, treated area will be reseeded with a grass-forb-shrub
mixture that is beneficial for mule deer. Reseeding will also be used to prevent invasive weeds
from establishing in the newly disturbed areas (Sheley et al. 1996, Goodrich and Rooks 1999,
Svejcar 1999).
The proximate objective of the habitat manipulations is to raise the overall forage quality on
treated areas in order to accomplish the ultimate objective of increased fawn recruitment. In
order to meet minimum maintenance requirements, deer must consume diets containing
approximately 50% digestibility (Ammann et al. 1973) and 5-7% crude protein (Einarson
1946, Dietz 1965, Murphy and Coates 1966, Holter et al. 1979). Most winter range browse
ranges from 25-50% digestibility and 5-10% crude protein (Welch 1989), which is why deer
rely heavily on pre-winter fat and protein stores in order to survive the winter. However,
because the nutritional value of winter forage is on the borderline of satisfying minimum
maintenance requirements, relatively modest increases in digestibility and protein should be
beneficial for both fawn survival as well as doe productivity. The majority of forage currently
available to deer during winter on the Uncompahgre Plateau consists of older-aged pinyonjuniper and decadent sagebrush (Artemisia spp.), and oakbrush (Quercus gambelli) at the
higher winter range elevations. The pinyon-juniper overstory has eliminated most understory
forbs, grasses and shrubs. Thus, plant species diversity is very limited, plant communities
predominantly comprise older shrubs, and even after "spring green-up" occurs, the quantity of
green forage is lacking throughout much of the winter range. Given these field observations,
we expect to increase the nutritional quality of winter range habitat by achieving the following
objectives with habitat treatments:
1.) Return portions of late-seral pinyon-juniper habitats to earlier successional stages in a
mosaic pattern across the landscape

�155
2.) Restore vigor to decadent sagebrush communities
3.) Increase the quantity and diversity of other winter browse species (primarily through
reseeding): mountain mahogany (Cercocarpus montanus), serviceberry (Amelanchier
alnifolia), bitterbrush (Purshia tridentata), gray rabbitbrush (Chrysothamnus
nauseosus), green rabbitbrush (C. viscidiflorus) ...
4.) Increase the extent of younger-aged, mixed shrub communities (by accomplishing the
first 3 objectives)
5.) Create a productive understory by increasing the quantity and diversity of various
forbs and grasses (by freeing up nutrient resources and reseeding)
Radio-tracking will be used to monitor deer use of the newly treated areas during each winter
following the treatment. We do not necessarily expect manipulated habitats to receive
extensive deer use the first winter after treatment, particularly following fire treatment where
considerable biomass is removed from the site. Depending on snow conditions, responding
vegetation may or may not be available to the animals. In short, it may require 2 or 3 years
before treated habitat confers an advantage over untreated habitat for mule deer during winter.
However, if December fawn:doe ratios and overwinter fawn survival do not increase after
several years, and we verify that collared animals are using the treated habitat, we will
quantify the nutritional quality of various forage species sampled from both the treatment and
control units. Nutrition will be evaluated based on both in vitro dry matter digestibility (Tilley
and Terry 1963) and crude protein (A.O.A.C. 1984). If nutritional quality of forage is not
greater in tlie treatment unit than in the control unit, then we will reevaluate our techniques
used to manipulate habitats. Treatment techniques used by the UERP committee will then be
modified in an attempt to better manipulate habitat for mule deer. If, on the other hand,· the
nutritional quality of forage is significantly greater in the treatment area than in the control
area, then we can assume one of two things. First, the increase in nutrition was not of
sufficient magnitude to increase fawn survival or December recruitment. Or secondly, the deer
did not spend enough time feeding in the treated habitat to benefit from the increased nutrition.
This could occur if deer perceived an increased level of wlnerability from the changes in
habitat structure. We would attempt to differentiate between these two scenarios with
intensive radio-monitoring.

f

Statistical Methods
We will test for differences between experimental units and years using the following statistical
model:
Yi.Jc=µ+ t:;- +A+ af3J1c + eifJ7iJ,

whereyiJc= fawn:doe ratio for the ith deer group in treatment combinationjk; i = 1, 2, ... , nJ/c
(deer groups);/= 1, 2, 3, 4 experimental units (control, supplemental feed, habitat
manipulation); k= 1, 2, 3, 4 (6) years; a/Jic= interactions among experimental units and years;
and ei(Jk) = random error associated withyiJ1&lt;. As stated earlier, we will obtain baseline data on
each experimental unit by measuring fawn:doe ratios the December prior to implementing the
first treatments. By not implementing the habitat manipulation until the second year of the
study, two years of baseline data on Unit D will provide an estimate of the differences between
this unit and the others. Likewise, the cross-over design on the feeding treatment allows
estimation of the year effects on Units Band C, relative to the overall control Unit A (Fig. 1).
A similar model will be used to analyze overwinter fawn survival, but a logit-link :function will
be used in place of the identity link function in the above general linear model.

�156
We will test for differences in fawn weights using a similar mcxlel as above, except the
response variable will be fawn mass instead of fawn:doe ratios. Various studies have closely
linked December fawn mass to survival probability (Bartmann et al. 1992, Bishop 1998,
Unsworth et al. 1999). Fawn mass analyses may help us describe or better understand
observed changes (or lack thereof) in population parameters as a result of the treatments. At
the minimum, mean December fawn mass from each experimental unit will allow us to
evaluate whether fawns are entering the winter treatments with equal survival probability. At
least during the first year of the study, the mean mass of fawns collared in December should be
similar among the various experimental units, assuming fawns are randomly captured. It is
possible, however, that in successive years December fawn mass might vary among the
experimental units as a result of previous winter's treatment effects. Although we cannot
directly link 6 month old fawns to the previous winter's experimental units, it is certainly
possible that many of those fawns' mothers occupied the same treatment areas the winter
before given home range site fidelity. For example, fawns collared during the second winter in
Experimental Unit B (which received the feed the winter before) could be heavier than fawns in
Unit A (control). If so, it would suggest that not only has the probability of survival to
December increased, but given the overall greater early winter mass, probability of overwinter
survival has increased as well. In short, increased doe nutrition may not only increase
December fawn recruitment, but yearling recruitment as well.

G. LOCATION OF WORK
Research will be conducted on the Uncompahgre Plateau in southwest Colorado, which comprises
DAU D-19 and GMUs (game management units) 61 and 62.

H. WORK ASSIGNED TO:
1.
2.
3.
4.

Chad J. Bishop, Mammals Researcher, Colorado Division of Wildlife
Gary C. White, Professor of Wildlife Biology, Colorado State University
R. Bruce Gill, Mammals Research Leader, Colorado Division of Wildlife
Len H. Carpenter, Southwest Field Representative, Wildlife Management Institute

E. RESOURCE REQUIREMENTS

Fiscal
Year

Equipment
and
Sue12lies

Rental
Services

Service
Contracts

Vehicles

FfE Requirements
PFfE

TFfE

Total
Costs

2000-01

$28,300

$45,200

$50,000

$11,046

1.00

0.5

$201,548

2001-02

$87,850

$147,900

$50,000

$11,046

1.00

1.00

$374,408

2002-03

$57,850

$116,400

$50,000

$11,046

1.00

1.00

$312,908

2003-04

$57,850

$116,400

$50,000

$11,046

1.00

1.00

$312,908

2004-05

$57,850

$116,400

$50,000

$11,046

1.00

1.00

$312,908

2005-06

$37,600

$65,200

$50,000

$11,046

1.00

0.5

$230,848

2006-07

$17,600

$50,000

$50,000

$11,046

1.00

0.5

$195,648

�157

F. REPORT DUE DATES
FY2000-01 Pilot Results/Revised Program Narrative
FY2001-02 Progress Report
FY2002-03 Progress Report
FY2003-04 Progress _Report
*FY2004-05 Progress Report
FY2005-06 Progress Report
*FY2006-07 Completion Report

8/1/01
8/1/02
8/1/03
8/1/04
8/1/05
8/1/06
8/1/07

*Supplemental Feed portion of experiment will be completed in FY2004-05. Monitoring of habitat
manipulation experimental unit and control area will likely continue for 2 more years unless
corresponding hypotheses can be adequately tested beforehand. We estimate to finish the completion
report for the entire study following FY2006-07.

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Colorado. Journal ofWildlife Management 36:1025-1033.
Welch, B. L. 1989. Nutritive value of shrubs. Pages 405-424 in C. M. McKell, editor. The biology and
utilization of shrubs. Academic Press, San Diego, California, USA.
White, G. C., and R. M. Bartmann. 1998. Effect of density reduction on overwinter survival of freeranging mule deer fawns. Journal ofWildlife Management 62:214-225.
White, R. G. 1983. Foraging patterns and their multiplier effects on productivity of northern ungulates.
Oikos 40:377-384.
Wickstrom, M. L., C. T. Robbins, T. A. Hanley, D. E. Spalinger, and S. M. Parish. 1984. Food intake
and foraging energetics of elk and mule deer. Journal of Wildlife Management 48:1285-1301.
Workman, G. W., and J.B. Low, editors. 1976. Mule deer decline in the West: a symposium. Utah State
University and Utah Agricultural Experiment Station, Logan, Utah, USA.

�162

�163

APPENDIXB
DRAFT
EFFECTS OF LIMITED BUCK HARVEST ON MULE DEER
SEX AND AGE RATIOS
An A Posteriori Analysis
Chad Bishop, Mammals Researcher

Objective
Determine whether significant reductions in buck harvest have improved buck:doe ratios and/or fawn:doe
ratios in Colorado.

Data Set
lbis analysis focuses on mule deer populations occupying mountainous regions of Colorado, or those
populations west ofl-25. Over the past 10 years, buck harvest restrictions were implemented in a number
of Game Management Units (GMUs) within several deer Data Analysis Units (DAUs) in western
Colorado (Table 1).

Table 1. Deer DAUs and inclusive GMUs in western Colorado where buck harvest limitations were

1990

D-1

201

238

47

,❖:-:-.-: 'ttltfNz'·:'\@f#@(tji
1992

D-14

44

666

157

1995

D-1

1, 2

123

21

21, 30

1219

595

i;E ,-4~™1e1iF-@!1@M?l,:::::il
1995

D-11

I used these various units to look at buck:doe and fawn:doe ratios an equal number of years before and
after the harvest limitation was implemented. DAUs D-1 and D-11 were excluded from all analyses due
to insufficient age and sex ratio data. Thus, my analysis of the effects of limited buck harvest is based on
DAUs D-3, D-o, D-14, and D-19(GMU 61).
I also looked at buck:doe and fawn:doe ratios in units where harvest limitations were not implemented
prior to 1999. Again, I only used those DAUs with adequate sex and age ratio data available, which
include: D-2, D-4, D-7, D-8, D-9, D-12, D-13, D-18, D-19(GMU62), D-20, D-21, D-22, D-24, D-25, D29, D-30, D-39, D-40, D-42, D-43, and D-51.
I obtained nearly all harvest data and age and sex ratio data from the DEAMAN32 database. Data from
1997 and 1998 that was not available on my version ofDEAMAN was obtained from John Ellengberger.

�164

Analysis
Basic Methodology and Justification

As now apparent, my primary goal was to determine whether a set of sex or age ratios prior to a buck
harvest restriction differed from a set of corresponding ratios following the restriction. It seems logical,
then, to think of a harvest treatment with two groups, or two treatment levels: pre- and post-harvest
restriction (unlimited vs. limited buck harvest). I can see a couple ways to approach this analysis. One
approach is to treat each ratio estimate as a sample observation, and then calculate a standard mean and
variance of the ratios for each treatment category. In other words, follow standard analysis of variance
procedures using only the ratio estimates themselves. However, each sex or age ratio estimate for a GMU
or DAU has an associated standard error. Our confidence in the accuracy of any given ratio depends
largely on the effort put forth for that particular classification. If we ignore this, then each measured ratio
is assumed to be an equally accurate measure of the true value. Ideally, my analysis should incorporate
the associated variance of each ratio estimate used to avoid bias.
I therefore took two approaches: (1) I used Program CONTRAST to analyze age and sex ratio estimates
and associated standard errors prior to and after the harvest restriction and (2) I used PROC GLM in SAS
and did a standard analysis of variance using only the ratio estimates. Justification for these analyses
follows. Program CONTRAST (Sauer and Williams 1989, JWM 53:137-142) is a generalized program
designed to evaluate differences in survival based on survival rate estimates and associated standard
errors. It is applicable to any type of rate estimates. Similar to my analysis here, it is desirable when
estimates and associated standard errors derived from data are available, as opposed to having the raw
data. It allows testing various hypotheses without ignoring the variance of estimates. As I alluded to
above, the problem with analysis of variance is that the variances are ignored. I considered converting the
age and sex ratios to rates, or proportions, which would be more similar to how survival rates are
expressed. A typical buck:doe ratio (bucks/does) or fawn:doe ratio (fawns/does) can be expressed as a
proportion: bucks/(bucks + does) or fawns/(fawns + does). However, the standard error calculated for an
age or sex proportion, based on a binomial distribution, can be much more biased than the standard error
estimator for an age or sex ratio. lbis occurs because of behavioral patterns in deer group formation, and
resulting sampling schemes used to estimate age/sex ~tios where groups of deer are the sampling unit
(Bowden et al. 1984, JWM 48:500-509). Thus, I chose to use the ratios and associated SE's. The chisquare statistic used in CONTRAST appears to be equally valid for analyzing age and sex ratio data. The
same assumptions for survival or recovery rates within the confines of this statistic can be made for age
and sex ratios given that the associated variance estimates are known.
My second approach involved a standard analysis of variance, or multivariate analysis of variance, using
buck:doe and fawn:doe ratios as the dependent variables. Although this analysis ignores the variance of
each ratio estimate, it is not that different from many of the analyses we do. In many cases, samples
obtained from field measur~inents have an associated error that we do not quantify. In other words, it is
not uncommon for raw data values to only be an approximation of the true value. Quantifying the
digestibility of forage is an example. Our measured digestibility of a plant sample is only an estimate of
the true value, yet quantifying an appropriate variance for each individual sample is difficult to do. Based
on this line of reasoning, I felt it appropriate to do an analysis of variance using only the ratio estimates as
raw data points. It follows that some caution should be used in interpreting the data since we know
beforehand that the accuracy of ratio estimates vary, yet this variance is not being accounted for.
Program CONTRAST

In my analysis of sex and age ratios, I chose to use an equal number of years before and after
implementation of the harvest restriction. I began by analyzing each DAU individually because harvest
limitations were implemented at various times. I then incorporated each of the DAUs into one analysis by

�165

using buck:doe and fawn:doe ratios for 4 years prior to harvest limitation and 4 years following the
limitation. This was decided based on the DAU with the least number of years of post-treatment data, D3. Thus, for this analysis of combined data. the 4 years pre- and post-harvest treatment were not
necessarily the same (D-3: 1991-94/1995-98; D-6: 1987-90/1991-94; D-14 and D-19: 1988-91/1992-95).
Buck:doe ratios increased following limited harvest in each DAU except for D-19, where buck:doe ratios
declined (fable 2). Conversely, fawn:doe ratios declined following implementation of limited harvest in
each of the DAUs (fable 3).
Table 2. Results of analyses contrasting buck:doe ratios pre- and post-implementation of limited harvest
._

' •.

-

=---

CO,

=

Pm-.:m

.-

C

•

-

_z

••

,r.:

.&gt;:.

·:,

.....

·.•

D-3

1991-98

18.9

26.4

D-14

1985-98

18.7

23.0

6.22

.013

D-3, D-6, D-14,
D-19(GMU 61)

4yrsPre-&amp;
Post-Limit

15.8

18.3

6.10

.014

Table 3. Results of analyses contrasting fawn:doe ratios pre- and post-implementation oflimited harvest
in ~Vi;;;W DAL~ i l l ~ ~ 4 : a ( ' u~ Pi~~ CO~==nL.\ST (~:~ ~:f "WHJm~~ l~),

D-3

1991-98

D-14

1985-98

D-3, D-6, D-14,
D-19(GMU61)

4 yrs Pre-&amp;
Post-Limit

56.1

48.1

59.4

45.3

95.07

&lt;.001

(Multivariate) Analysis of Variance using PROC GLM in SAS

DAUs D-3, D-6, D-14, D-19(GMU 61)
I analyzed the same data using PROC GLM in SAS without incorporating the associated variance
estimates. Buck:doe and fawn:doe ratios were the dependent variables while buck harvest was the
independent variable. Buck harvest was treated as a categorical variable with two levels: (I) pre-harvest
limitation and (2) post-harvest limitation. Results are reported for buck:doe and fawn:doe ratios
separately based on the respective ANOVA's. However, each significant result reported from an AN OVA
is protected by a significant overall MANOVA test.
Failing to incorporate the standard error with each ratio estimate apparently resulted in a less efficient
analysis. The change in buck:doe ratios following the harvest treatment was only significant in DAU D-3
(P = 0.020). The other comparisons among buck:doe ratios pre- and post-harvest treatment were not

�166

significant (Table 4). Declines in fawn:doe ratios following the harvest restriction were significant in 3 of
the analyses while not significant in DAUs D-3 and D-14 (Table 5).
Table 4. Results of analyses contrasting buck:doe ratios pre- and post-implementation oflimited harvest
in ~e·,r~t"~ DAU:!l. in lilii"i;:;~te,m Ql)ki,radl;l! mii:ini ~, ooaly~.i!.I ofv,arian~ mSAS_

D-3

1991-98

1;;;:;:;:;sMEi~Bf§J!m;;;.;;~;£f~:;;:;:;:;;:;112;_
D-14

18.9

26.4

11.39

.020

=~;i;t:;:·:::-=::#1111-=-?:!J!!!;tt~·:::!~t~iJ:~r··m_Yim'..='._=:=1:;~i:~·=mi@====t=mt~}·tfi~;:=::-:-:---:-:tti@:i:w=·\\,·.=.:.~=:5:~:mmmm}t;:t;

1985-98

18.7

23.0

1.61

.237

;i-i·l·itllC, .:-,;;:;,:'.=;::.:1-::;:~J,l·:·1l·l·l:l·::1l·l1•gi1i,l;;!;;l~:-l·l·11;!-i!:•:-J-:-l-1i·l:·:·~1l-··!·11~w.:···l·l·l·l·:·l::::·ili l·l::·:·l·l····-11!1l::-:-:-:-:-:1J·il ~i-l•l-l-l-l-i:·J,·~:-~11il-1:-l-·-·_:.J.ili :·i·:·:·1:·:·11ii-i-l i-1l-l·J,·1~1l·l·l·li•l-i-i-it;llilil·li~l-i·l·l l ·l··-

D-3, D-6, D-14,
D-19(GMU 61)

4 yrs Pre- &amp;
Post-Limit

15.8

18.3

0.88

.357

Table 5. Results of analyses contrasting fawn:doe ratios pre- and post-implementation oflimited harvest
. i,~1 ~v~r.a.l DAU~ i,!11 W~i;)f"fl C'\cilo:r~uk, ttiii!l'!:g :1m ~rn:thi~i~ ofl,i'.,!!;fiii"...-ic.:~ :i,rn S.ASL

D-3

1991-98

56.1

48.1

3.42

.124

===
:·!:·l·!::l:l:!··:::::!!l:l:!j·:::·!·!··:!··:I!!!!'~~,-!-::!·!·ll!!!·l~!:l·1!!~1~J.1::!

D-14

1985-98

~iinaiiiiiijiiii~ii~mifo1: .,. .
D-3, D-6, D-14,
D-19(GMU 61)

4 yrs Pre- &amp;
Post-Limit'

59.1

51.6

2.46

.151

45.3

15.87

&lt;.001

::i1iijiil1l!1:~ff-ii!iii1:i·i:i:i:-;~:iii·t,~-5 9 _4

Results from the chi-square analysis (Program CONTRAS1) are probably more informative because
more infonnation was provided by incorporating the standard errors of ratio estimates. Nonetheless, both
analyses indicate that buck:doe ratios, overall, have modestly increased following restricted harvest; and
fawn:doe ratios have significantly declined despite the conservative buck harvest.
All DA Us west ofl-25 with sufficient age and sex ratio data available
Up to this point I have not included any data from units without harvest restrictions prior to 1999. My
goal here is to compare buck:doe and fawn:doe ratios from the units with restricted harvest to those where
harvest was not restricted. I once again used a multivariate analysis of variance with buck:doe and
fawn:doe ratios as the independent variables, and as before, I will only report the univariate statistics.
Since I combined all of the data into one analysis, I adopted the same procedure I used previously in
selecting what data should be used: 4 years prior to and 4 years following the harvest limitation (based on
the fact that D-3 only has 4 years of post-treatment data). Thus, the same data will be used for DA Us D3, D-6, D-14, and D-19(GMU 61) as used in the previous combined analyses. For all DAUs without
harvest limitations, I used age and sex ratio data from 1991-98. I used 2 independent variables. The first
is whether or not buck harvest was limited in each DAU prior to 1999: (1) yes or (2) no. The second

�167

variable is a categorical time variable: (I) 1991-94 (or 4 yrs pre-harvest treatment for DA Us D-6, 14, 19)
and (2) 1995-98 (or 4 yrs post-harvest treatment for DAUs D-6, 14, 19). Tp.us the model I used is:
YJ11c = M + QJ + flx + !dl;1c + .iiutcJ
where i = I,2, ... , n11 (replicates),j = I, 2 (DAU with, or without, harvest limitation), and k = I, 2 (199194/pre-harvest treatment or 1995-98/post-harvest treatment). My principal concern with this analysis is to
determine whether there is a significant interaction. If limited harvest had a significant effect on buck:doe
ratios, I would suspect ratios to increase from the first time category to the second time category for the
DA Us where limited harvest was implemented. Conversely, I would suspect ratios to remain constant or
decline from the first time category to the second time category for the DA Us where harvest was not
limited.
There were no significant differences among buck:doe ratios. Buck:doe ratios increased in the harvestrestricted DA Us after harvest was limited while ratios remained constant in the unlimited harvest DAUs,
but the interaction was not significant (P = 0.348) (Fig. I). Fawn:doe ratios declined significantly from
the pre-harvest treatment to the post-harvest treatment time period (P &lt; 0.001). The interaction was
significant (P = 0.006), with fawn:doe ratios declining much more dramatically in the limited harvest
DAUs than in the unlimited harvest DAUs (Fig. 2). This indicates that buck harvest is probably of little
concern in terms of fawn recruitment. Other factors are clearly affecting the deer populations in the
DAUs where limited harvest was implemented.

-

DAUs without Limited Harvest

• • • • • DAUs with Limited Harvest

20

18.3
••••••

0

~

18

0::
Cl)

0

0

~
0

:::,

m

16

17.3 - - - - -..-.~..:-:.....--··-- 17.5
•••••••
15.8

14
Interaction not significant (P = .348)

C:

ca

Cl)

~

••••••

12
10
1991-94

1995-98

(Pre-Harvest
Treatment}

(Post-Harvest
Treabnent}

Figure 1. Mean buck:doe ratios in DA Us with and without harvest restrictions implemented prior to
1999. 1991-94 represents pre-harvest treatment while 1995-98 represents post-harvest treatment.

�168

-

• • • • • DA Us with Limited Harvest

DAUs without Limited Harvest

70

.....ca0

Cl'.:'.

65
60

59.4

55

53.6

Q.)

0

0

C

~

ca

50

C

ca
Q.)

45

~

40

•• ••

-

•• ••

LL

•• ••

•• ••

••

.

.. ••

•• ••

-49.8
•• ••
••
45.3

Significant Interaction ( P = .006)

35
1991-94
(Pre-Harvest
Treatment)

1995-98
(Post-Harvest
Treatment)

Figure 2. Mean fawn:doe ratios in DA Us with and without harvest restrictions implemented prior to
I 999. 1991-94 represents pre-harvest treatment while 1995-98 represents post-harvest treatment.
Discussion and Conclusions

Limited harvest in DAUs D-3, D-6, D-14, and D-19(GMU 61) have resulted in modest increases in
buck:doe ratios overall. However, buck:doe ratios in D-19 (GMU 61) declined despite conservative
harvest. There are several reasons why this may have occurred. First of all, GMUs 61 and 62, which
together comprise DAU D-19, likely represent a single deer population, at least on summer range.
Managing only half of the DAU, or half of this deer population, for limited harvest may have lessened the
likelihood that buck:doe ratios would respond positively to the reduced harvest. Other scenarios could
also be presented as reasons why differential harvest management in D-19 could influence the observed
decline in buck:doe ratios in GMU 61. On a different note, declining buck:doe ratios in 61 could be
another indicator of a much larger problem affecting the Uncompahgre deer herd. This is especially true
when the declining fawn: doe ratio is taken into account. It is important to point out here that the 1999
buck:doe ratio estimate in GMU 61 was 21.3, which is much higher than has been observed over a
number of years. The 1999 buck:doe ratio in GMU 62 dramatically increased as well (27 bucks/100
does). Interestingly, this coincided with the 1999 harvest limitation in GMU 62, which is the first time
both GMUs in D-19 have been managed for conservative harvest. When I removed D-19- GMU 61
from the combined analysis of limited harvest units, there was of course a greater increase in buck:doe
ratios. With D-19-0-MU 61 removed from the analysis of all DAU data, the interaction between
lirnited/unlimi~ed harvest DAUs and pre/post harvest treatment was more pronounced, although not
significant (P = 0.106).
Limited buck harvest has had no effect on fu.wn:doe ratios. In fact, fu.wn:doe ratios have declined more
rapidly in DAUs with limited harvest than those with unlimited harvest. Clearly, other factors of much
more importance are affecting these populations. Based on this analysis, it-is very difficult to argue that

�169

declining buck:doe ratios are a primary cause for declining fawn recruitment and declining deer numbers.
If anything, low buck:doe ratios may be yet another indicator of declining herd productivity.

In conclusion, substantial limitations on buck harvest is likely an effective management strategy for
increasing the number of bucks in a population. However, buck:doe ratios have increased slowly in these
limited harvest units. The judgment as to the effectiveness of this strategy depends on how much hunter
opportunity is sacrificed. It seems logical to manage a segment of our DAUs for limited harvest, thereby
increasing success rates of those hunters that draw a license while also increasing their chances for
shooting a trophy animal. The remaining DAUs should then be managed for much more liberal buck
harvest to provide as much hunter opportunity as possible. In other words, a balance needs to be achieved
between providing quality hunting (in terms of success rates and trophy buck numbers) and hunting
opportunity (in terms of hunter days afield). This will become an increasingly difficult management
challenge in the future as Colorado's human population continues to grow along with further inevitable
development of habitat. Conversely, limited buck harvest does not appear to be an effective management
strategy for improving fawn recruitment or population productivity. For this objective, our management
and research efforts must focus on other variables.

Graphs presenting the basic data from limited harvest DAUs

DAU D-3, GMUs: 6 16 161 17 171
Age and Sex Ratios Before and After Limited Harvest, 1991-98
. . Buck Harvest

en

a,

~

lfll Fawns:100 Does la Bucks:100 Does

600
500

70

488 56.1
48.1

ca

::c
.:.:::
u
:s

m
'ii
:s
C
C

&lt;

ci&gt;

~

60

400

50

en

0

;

cu

~

)(

-&lt;
a,

40
300

u,

a,

C)

30

C

:s

200

20

::c

10

D..

en

100
0

Before Limited
Harvest (1991-94)

After Limited
Harvest (1995-98)

0

0

�170

DAU D-6, GMU 10
Age and Sex Ratios Before and After Limited Harvest, 1983-98

Ill Buck Harvest

-.,
CD

~

-

Fawns:100 Does

b~~,d Bucks:100 Does

600

80

522 68.5

70

500

60

C'CJ

:::c

.x

400

50

u

:::,

m
ci
:::,
C
C

&lt;(
Cl

&gt;

&lt;(

300

40
30

200

20

0

.::

;;_
,c

CD

u,

CD
Cl

-.,

&lt;(
C

:::,

:::c
0

100
0

.,

10
Before Limited
Harvest (1983-90)

After Limited
Harvest (1991-98)

a.

0

DAU D-14, GMU 44
Age and Sex Ratios Before and After Limited Harvest, 1985-98

Ill Buck Harvest

-.,

•-

Fawns:100 Does

Mffil'fl Bucks:100 Does
70

800
700

666 59.1

60

CD

~

C'CJ

600

.x

500

C
C

&lt;(
Cl

&gt;

&lt;(

50

a::

40

-

400
·30
300

,c

u,

CD
Cl

-....,
&lt;(
C

:::,

20

200

10

100
0

C'CJ

CD

:::,

m
ci
:::,

0

.::

:::c
u

.,

Before Limited
Harvest (1985-91)

After Limited
Harvest (1992-98)

0

:::c
0

a.

�171

DAU D-19, GMU 61
Age and Sex Ratios Before and After Limited Harvest, 1985-98
-

Buck Harvest

en

Cl&gt;

~

1200

-

Fawns:100 Does b::::::::::::d Bucks:100 Does

60

53.8

50

1000

C'CS

C'CS

:::c
~

40

800

33.3

u

:::,

m
'ii
:::,
C
C

&lt;(
CJ)

~

en

0

.:::
)(

Cl&gt;

en

600

30

400

20

200

10

0

0::

Cl&gt;

CJ)

&lt;(
C

:::,

:::c
en
0

a.

0
Before Limited
Harvest (1985-91)

After Limited
Harvest (1992-98)

DAU's: D-3, D-6, D-14, D-19(GMU 61)
Age and Sex Ratios 4 Years Before and 4 Years After Limited Harvest
1111 Buck Harvest Ill Fawns:100 Does EEi] Bucks:100 Does

en

Cl&gt;

~

C'CS

:::c

2800

70

2400

60

2000

50

0::

40

-

45.3

m
'ii
:::,
C
C

&lt;(

C'CS

)(

1600

en

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-

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&lt;(

800

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400

10

a.

1200

C

:::,

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en

Q

~

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0

Before Limited
Harvest

After Limited
Harvest

0

0

�172

�173

APPENDIXC

DRAFf
ESTIMATE OF COLORADO'S CURRENT MULE DEER NUMBERS
How Many Deer Are There?
Chad Bishop, Mammals Researcher

Objective

Estimate the current number of mule deer in the state of Colorado by extrapolating deer density estimates
from quadrat population counts to the estimated amount of winter range in Colorado.
Background

Our current estimate of the total number of mule deer in the state of Colorado is derived from population
models for each deer data analysis unit (DAU). The total number of deer is estimated by summing the
individual population projections for each DAU. This is a rough estimate given that a number of the
DAU models are built from insufficient data. We cannot appropriately measure all relevant population
parameters in each DAU due to budget and logistical constraints. Given this inherent limitation, our
current ( 1998) post-hunt population estimate of ~526,000 deer is based on the best information available.
However, a number of our constituents believe this figure is too high. In essence, I believe they question
our ability to predict total deer numbers from models. Population models can be complex and difficult to
understand, particularly to those who lack a statistical or quantitative background. So it comes as no
surprise that some sportsmen would doubt our model estimates, particularly when those estimates differ
from their own preconceived notions.
The purpose of this analysis was to estimate statewide mule deer numbers by extrapolating deer density
estimates from DAUs where we have post-hunt population counts to other similar deer winter ranges in
the state. Specifically, the number of deer per square mile measured in certain DAUs was applied to the
total square miles of deer winter range in Colorado to estimate a total number of deer. In this manner, no
models are used and the estimates are based on direct observations of deer/mi2. This procedure also
allows us to evaluate whether our current model estimate of deer numbers is reasonable.
There are definite weaknesses to this approach. First, estimates of deer density are absolutely relative to
the amount of area designated as winter range. In other words, the legitimacy of the analysis depends on
how accurately mule deer winter range has been delineated, and more so, whether the standards used to
designate winter range were consistent from one biologist to the next around the state. This is a
formidable task since the area used by a deer population during winter varies as a function of several
environmental variables. Fortunately, similar criteria were used by biologists throughout the state to
delineate mule deer winter range, which provided a degree of consistency from one DAU to the next.
Another concern is that there is no rigorous way to evaluate whether deer densities measured in one DAU
are representative of adjacent DAUs. As with the population modeling approach, this is an inherent
limitation since we cannot measure all population parameters in every DAU. The analysis presented here
is another approach to estimating the total number of deer in Colorado given the information we have
available. The primary benefit of this analysis is that the public should be able to easily understand how
the estimate was derived.

�174

Methods
Winter Range Area

The total area (mi 2) of winter range in Colorado was determined for each GMU and DAU from the
current mule deer winter range spatial data located on the Colorado Natural Diversity Information Source
(NDIS) internet site:
http://ndis.nrel.colostate.edu/ndis/ftp html site/statewide ftp.html (file: mule_deerst.tgz).
The spatial data layers contained in the file, corresponding to mule deer seasonal activity ranges, were
developed through a combined effort among DOW's WRIS (Wildlife Resource Information System)
Biologists and Area Terrestrial Biologists. The winter range layer was developed according to the
following criteria: 'lhat part of the overall range where 90% of the individuals are located during the
average 5 winters out of 10 from the first heavy snowfall to spring green-up, or during a site specific
period of winter as defined for each DAU". I used PC Arc/Info to combine the mule deer winter range
spatial layer with the GMU-DAU spatial data layer (also obtained from the NDIS website), and then used
the combined data layer in ArcView to estimate square miles of deer winter range by GMU and DAU
(Fig. 1, Table 1).

}o~,,

l_E.-,.,,,.__;.:,:_ir--,....,......_·
.. ~ ·

,:

gJ

·.,

~~t~:

D-47
D-46

D-28

Rm Winter Range
Figure 1. Spatial distribution and area of delineated mule deer winter range by deer DAU in Colorado.

�175

Table 1. Delineated mule deer winter range (W.R.) in square miles by GMU and DAU in Colorado.

Deer

Deer
DAU

GMU

W.R

DAU

GMU

(mi2)

1
2
201
Total
3
301
4
441
5

14
214
Total
6
16
161
17
171
Total
7
8
9
19
191
Total
87
88
89
90
93
95
97
98
99
100
101
102
Total
10
11
211
12
13
131
231
22
23
24
Total

32
1033
125
1190
533
334
156
64
32
1
2
1122
190
40
119
85
38
473
31
138
189
138
291
787
70
211
275
319
286
263
347
1038
741
298
522
373
4744
615
581
295
94
89
9
19
750
175
1
2014

15
35
36
45
Total
18
181
27
28
37
371
Total
20
21
30
Total
41
421
42
Total
43
47
471
Total
44
48
481
56
561
Total
49
57
58
581
59
Total
39
46
51
461
Total
40
61
62
Total

W.R

Deer
DAU

GMU

W.R

Deer
DAU

GMU

(mi2)

(mi2)

53
111
54
167
74 m@t».:t!HM 55
551
0
353
Total
60
85
70
96
71
69
711
83
83
Total
66
9
67
425
543
Total
68
608
397
681
1005
Total
118
29
38
104
317
Total
All
539
143
72
73
13
Total
0
75
156
751
128
77
33
771
91
78
126
51
Total
301
83
218
85
851
255
140
492
568
Total
All
278
2024
69
42
84
47
86
861
250
78
Total
80
459
81
488
626
Total
76
683
79
1308
Total

.124
280
114
500
185
501
299
Total
310
63
1012
64
7
65
329
Total
1347 it.w.Uti 31
205
32
228
Total
433
33
257
25
230
26
487
34
227
Total
198
91
425
92
0
94
951
0
248
96
248
Total
301
150
102
302 t88.N All
317
105
1171
277
106
930
Total
264
511
512
116
1309
Total
0 ,@I».5tm 411
52
171
521
921
153
Total
151 lOfStm 74
1589
741
231
Total
260
491
63
252
'315

W.R
(mi2)

11
219
490
230
81
185
266
261
126
387
187
77
62
31
170
63
72

92
87
234
547

37
227
212
658
96
28
124
62
107
63
232
33
467
499

�176

Mule Deer Density Estimates
Conceptually, it is simple to estimate the total number of deer statewide by extrapolating several deer
density estimates to the total amount of Colorado winter range: calculate a mean deer density and
multiply it by the total square miles of winter range. However, we can be fairly certain that deer density
varies across Colorado, and so using a single mean density may not be the best approach. Ideally, deer
DA Us should be grouped according to ecological similarities such that deer density is somewhat similar
across all winter range in the DAU grouping. Density estimates measured in one DAU would then be
representative of the other DA Us in the group. The inherent limitation is that density estimates are needed
for at least one of the group's DA Us. Thus, these DAU groupings are dependent on data availability.
Mule deer density estimates were obtained from the DEAMAN database (Table 2). These estimates are
not corrected for sightability bias, and therefore should represent conservative estimates of the true deer
density. I took a several tiered approach to estimate statewide deer numbers from the existing density
data. My first objective was to delineate groups of DA Us based on ecological similarities, where at least
one DAU in the group had some density estimates available over the past 15 years (Fig. 2). The 15-year
time limit was arbitrarily set based largely on available data. For each DAU with density estimates
available, I calculated a high, low, and overall mean for the 15-year period. The high mean was
calculated from the upper half of recorded density estimates while the low mean was calculated from the
lower half of density estimates. The overall mean was naturally calculated using all density estimates
recorded in the DAU during the 15 years. In several of these DA Us, only 2 density estimates were
available during the 15-year period (D-2, D-6, D-12, and D-42). D-2 and D-12 were the only source of
density data for their respective DAU groups, which is a limitation of this first objective analysis. DA Us
D-6 and D-42 were in the same DAU group as D-7, which had 6 density estimates available. Density
estimates from D-42, which were much higher than those from D-6 and D-7, were applied only to winter
range in D-42 and not incorporated into the mean for the DAU group. D-50, which incorporates the Air
Force Academy, had only one density estimate available. It was not grouped with any other DAUs,
though, because it typically has had higher deer densities than areas adjacent to it. Figure 2 depicts these
DAU groupings, and also shows which DA Us provided density data to estimate deer numbers. Table 2
lists the actual density data. This approach enabled me to keep DAU groupings small and more
ecologically meaningful, to maximize my use of density data available in DEAMAN, and to estimate a
minimum and maximum number of deer for the past 15-year period. The primary drawbacks of this
approach were twofold: 1) only limited data was available for some DA Us ·and 2) resulting estimates of
total deer numbers do not represent current numbers.
My second objective was to use density estimates from only those DA Us with recent data(~ 1995),
which primarily corresponded to the intensive deer population monitoring areas (D-4: Red Feather, D-9:
Middle Parle, D-16: Cripple Creek, and D-19: Uncompahgre Plateau) (Fig. 3). D-24 in southwest
. Colorado also had recent density data available. This required reducing the number of DAU groups, with
each group now containing more DA Us. Again, I attempted to group DA Us based on ecological
similarities given the obvious constraint that most DAUs do not have any recent data available. The
purpose of this analysis was to obtain a current estimate of total deer numbers using recent density
estimates while maintaining DAU groupings that are at least somewhat similar from a habitat and deer
ecology standpoint. My final objective was to apply a single mean deer density, calculated from recent
estimates only(~ 1995), to the total winter range west ofl-25 (Fig. 4). This approach also provides a
current estimate of deer numbers in Colorado, but removes any DAU groupings.
In all of these analyses, I have focused only on deer populations west ofl-25. There are no density
estimates from quadrat counts available for deer populations east ofl-25, yet we would anticipate deer
densities to be quite different in a plains landscape. Therefore, in DA Us east ofl-25 that have mule deer
winter range delineated, I applied density estimates from the current DAU population models. This was

�177
done only to complete my estimate of statewide deer numbers based on delineated winter range. I realize
that applying density estimates from biologists' population models directly biases my analysis as an
independent estimate. But again, it was only done east ofl-25, which represents a small portion of the
state's total mule deer numbers. Also, there is no winter range delineated in deer DAUs 28, 33, 45, 46,
47, and 48, although mule deer are present. I did not include these DA Us in any of my estimates of total
deer numbers.

Table 2. Mule deer density estimates (deer/mi2) measured during quadrat population counts in various
DAUs. Estimates were obtained from the DEAMAN 3.2 database.

Year
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999

D-2
13.88

Low Mean
High Mean
Overall Mean
Recent(:2: 1995)

13.88
73.46
43.67

D-4

D-6

28.35
32.14
31.17
28.53
46.73

Density Estimate bv DAU"
D-19b
D-9
D-12 D-16
7.55
25.83
21.51

D-24

D-42c

D-50&lt;1

22.78
9.89
35.73

47.64

37.97

25.18

70.09

30.82

10.86
19.16

27.07
17.02

73.46

D-7
32.67
32.57

32.23

149.16
71.96

12.57
8.33
6.96
3.45

46.83
17.58

24.40
14.21
5.19

22.36

24.66

22.28

33.48

19.02

3.5

25.38
35.57
30.47
22.32

17.02
27.07
22.05

6.25
34.40
20.33

20.34
31.29
26.49
29.07

34.17

46.83
47.64
47.24

4.35
9.43
7.40
4.35

19.45
34.17
22.39
34.17

18.30
26.80
22.55
19.02

71.96
149.16
110.56

70.09
70.09
70.09

8Density estimates from all DAUs included in the table were used in the first objective analysis. Only those DAUs
with recent (:2: 1995) density data were used in the second and third objective analyses.
1,n D-19, the delineated winter range was modified prior to the 1998 quadrat count to make it more representative of
observed wintering deer distribution, which decreased the size of the winter range by 446 mi2. Thus, the density
estimate measured in 1998 was based on a smaller winter range area than the densities measured prior to 1998.
"For the first objective analysis, I assigned D-42 to the same DAU group as D-6 and D-7 (Fig. 2). However, because
density estimates for D-42 were much higher than those for D-6 and D-7, they were applied only to winter range
in D-42. Density estimates from D-6 and D-7 were used to calculate a mean deer density for this particular DAU
group.
dFor the first objective analysis, D-50 was not grouped with any other DAUs (Fig. 2) because it typically has had
higher deer densities than areas adjacent to it. The single density estimate for D-50 was applied only to winter
range in D-50.

�178

Figure 2. First-level grouping of deer DAUs shown by like-patterned blocks. Density estimates based on quadrat
counts were obtained from the labeled DAUs to estimate the number of deer in each DAU block. Current
population models were used to derive density estimates east ofI-25.

Figure 3. Second-level grouping of deer DAUs shown by like-patterned blocks. Density estimates based on quadrat
counts were obtained from the labeled DAUs to estimate the number of deer in each DAU block. Current
population models were used to derive density estimates east ofI-25.

�179

j
~-iO M'U:li!!! ,Oe~r

:R,ii!in-0,,;---···

---~-..c:,.J
\
\

~~=•~
h:!r !
II

I

-~

~W7d
Figure 4. Third-level grouping of deer DAUs shown by like-colored blocks. Density estimates based on quadrat
counts were obtained from the labeled DAUs to estimate the total number of deer in all DAUs west of 1-25. Current
population models were used to derive density estimates east ofl-25.

Results
First Obiective

My first estimates of statewide deer numbers incorporated measured density estimates from the past 15
years. I used the low mean density estimates from each DAU to calculate a minimum mean estimate of
statewide deer numbers: 421,894 deer (408,486 west"ofl-25). I used the high mean density estimates
from each DAU to calculate a maximum mean estimate of statewide deer numbers during this 15-year
time period: 807,472 deer (794,065 west ofl-25). My final calculation incorporated the overall mean
density estimates from each DAU over the 15 years: 608,608 deer (595,200 west of 1-25).
Second and Third Obiectives

Using DAU groupings (Fig. 3) based on recent(:.!: 1995) density data, the estimate of total deer numbers
currently in Colorado is 575,912 deer (562,505 west of 1-25)). Applying a single mean density estimate
to all DAUs west ofl-25, the estimate of total deer numbers currently in Colorado is 581,331 deer
(567,923 west ofl-25).
Discussion

The purpose of this "analysis" was to develop an independent estimate of total deer numbers in the state
of Colorado that did not incorporate any modeling, but rather application of measured density estimates
obtained from direct observation during aerial quadrat counts. The analysis could certainly have been
done· differently, particularly in regards to how the DAUs were grouped together; but it appears that any
reasonable method using the available density estimates would have resulted in relatively similar figures.
First Obiective

I used this 15-year data set to incorporate density estimates from a greater number ofDAUs, and to place
upper and lower bounds on the possible deer numbers in the state. Using a mean of the lowest density

�180

estimates measured during the past 15 years in various DA Us, we would still estimate there to be at least
400,000 deer in Colorado. Conversely, using a mean of the highest density estimates measured, we
wouldn't expect the total population to have been much more than 800,000 deer in the recent past.
Second and Third Ob;ectives

The second and third objectives dealt with recent density estimates, which was my primary focus. I
estimated there to be approximately 575,000- 580,,000 deer currently in Colorado, and approximately
560,000- 570,000 deer west ofl-25. The 1998 estimate of total deer numbers based on summation of
individual DAU population models is approximately 525,000 deer (actual estimate: 526,406), and
approximately 495,000 deer west ofl-25 (actual estimate: 496,603). The estimates are surprisingly
similar given the large degree of error involved with either method of estimating Colorado's total deer
numbers. In my perspective, these 2 independent estimates provide the Division of Wildlife with greater
confidence that 500,000 to 600,000 deer is a reasonable estimate of the state's total mule deer population.
At the very least, this analysis suggests that our population models are not drastically overestimating deer
numbers, which is what some of our constituents have claimed.
As I stated in the methods section, I did not include several southeast Colorado DAUs (D-28, D-33, D-45,
D-46, D-4 7, D-48) in my statewide analysis because winter range had not been delineated. The total
number of deer from 1998 population models for these DA Us is 16,695 deer. To make the DAU model
estimates more comparable to my estimate, I subtracted these deer from the statewide total (526,406 16,695 = 509,711). Thus, with the southeast plains DAUs excluded, population models indicate
approximately 510,000 deer, as compared to my estimate of 575,000-580,000 deer. This further suggests
that we are not overestimating deer numbers using DAU population models.
I also used another approach to evaluate the legitimacy of our population models. I calculated a mean
deer density per square mile of winter range using the DAU model estimate of total deer numbers. This
provides another check on the accuracy of the DAU modeling approach because the resulting mean deer
density should be in the ball park of density estimates that have actually been measured from quadrat
counts. There are 32,230 square miles of deer winter range delineated in Colorado (which excludes the
southeast plains DA Us described above). The 1998 DAU model estimates would indicate a statewide
mean density of 16 deer per square mile (510,000 deer/32,230 m.i2). This is clearly a reasonable density
estimate, which lends further credence to the accuracy of the DAU population models. I also calculated
the mean deer density for DAUs west ofl-25 only. There are 26,070 square miles of deer winter range
delineated west ofl-25, and 1998 DAU population models indicate approximately 495,000 deer west ofl25. This gives a mean deer density of 19 deer per square mile for DAUs west ofl-25, which is also quite
reasonable. The mean deer density measured from recent(~ 1995) quadrat counts in several deer DA Us
west ofl-25 (D-4, 9, 16, 19, 24) is 22 deer/m.i2 .
Summary
Our current (1998) DAU population model estimate of statewide deer numbers is roughly 525,000 deer
(526,406). When the southeast plains deer DAUs are excluded (D-28, 33, 45, 46, 47, 48), this estimate
reduces to approximately 510,000 deer (509,711). My estimate, calculated by extrapolating measured
deer densities to the total amount of deer winter range, which also excludes these southeast plains DAUs,
is 575,000-580,000 deer. Considering only DAUs west ofl-25, our population models indicate there are
approximately 495,000 deer (496,603)~ while my estimate using measured deer densities in select DAUs
indicates there are approximately 560,000-570,000 deer west ofl-25. This latter comparison is more
appropriate because the estimates are completely independent of one another. The DAU population
models indicate that the mean deer density on winter range west ofl-25 is 19 deer/mi2. The mean deer
density measured from recent(~ 1995) quadrat counts in several deer DAUs west ofl-25 (D-4, 9, 16, 19,
24) is 22 deer/m.i2 . The Division's current estimate of deer numbers from DAU population models is
reasonable, if not conservative. It appears justifiable to assume there are roughly 500,000 to 600,000
mule deer in Colorado.

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                  <text>125

Colorado Division of Wildlife
Wildlife Research Report
July 1999

JOB PROGRESS REPORT

Smteof __ ~
~C~o~lo~r=ad~o~
_
Cost Center 3430
Mammals Program
Project No.
W..:...:..,_-1=5=3--=-R=-_",1=-2_,.....-_
Work Package No. ___,3::....:0=0~1
_
Deer Management
Task No.
-'4'-_
Regulation of Mule Deer and Elk Population
Growth by F ertilitv Control
Period Covered: July 1, 1998 - June 30, 1999
-Author: Dan L. Baker
Personnel: T. M. Nett, M. A. Wild

ABSTRACI'

We conducted preliminary investigations to evaluate the effectiveness and side effects of two
contraceptive agents in captive mule deer and elk. We treated female mule deer with a permanent
fertility control agent (GnRH-PAP) and female elk with a temporary, reversible contraceptive. In mule
deer, serum luteinizing hormone (LH) levels were reduced by 55-78% for at least 6 months following
treatment. For elk, serum LH concentrations were reduced to baseline levels for 90 days posttreatment.
Body weight dynamics, blood chemistry, hematology, and social behavior of female mule deer and elk
appeared normal compared to untreated animals.

�127

REGULATION

OF MULE DEER POPULATION

GROWTH

BY FERTILITY

CONTROL

. Dan L. Baker
P. N. OBJECTIVES

1. To develop a practical and acceptable technology to inhibit reproduction in mammalian species
which cause damage or constitute a significant public nuisance.
2.

To demonstrate the feasibility of such technology in a field application.

3.

To predict population impacts of alternative contraceptive regimens using simulation modeling.

SEGMENT

OBJECTIVES

1. To develop and test GnRH-toxin conjugate in captive mule deer and elk.
2.

To develop a si~ulation
populations.

model to evaluate the ability of contraceptives

to regulate large ungulate

INTRODUCTION
Segment

Objective

1: GnRH-ToxinlAgonist

Controlling the abundance of animals is fundamental to contemporary wildlife management.
This is particularly true for wild ungulates. The most compelling motivation for regulating ungulate
numbers is that overabundance causes problems that can be biological, economical, or political in
scope (Jewel and Holt, 1981). Resolving these problems requires controlling population growth.
Wild ungulate populations have traditionally been regulated by influencing death rates using
controlled harvest or CUlling. However, there are an increasing number of circumstances where these
traditional methods are not feasible. The use of fertility control to decrease birth rates is one of the most
promising approaches to the long-term control of overabundant wild ungulates. During the past
decade, research aimed at developing effective contraceptives for free-ranging wildlife populations has
accelerated. These efforts have resulted in development and testing of a wide variety of potential
contraceptive agents (Kirkpatrick and Turner 1985, Warren et aI. 1995).
One of the most promising new non-steroidal, non-vaccine, approaches to contraception
involves synthetic analogs of gonadotropin-releasing hormone (GnRH). GnRH is a molecule produced
in the hypothalamus of the brain. It directs specific cells in the pituitary gland to synthesize and secrete
two important reproductive hormones; follicle stimulating hormone (FSH) and luteinizing hormone
(LH). These latter two hormones, known as gonadotrophs, control the proper functioning of the
ovaries in the female and testes in the male.
Analogs of GnRH have the potential to either permanently or temporarily inhibit reproduction.
For most free-ranging wild ungulate applications, permanent sterilization or a combination of
permanent sterilization and culling have been proposed as the most efficacious approaches to
population management (Hone 1992, Garrot 1995, Hobbs et al. 1999, in press). For this application,

�128

superactive analogs ofGnRH are coupled to a cytotoxin. The GnRH-toxin conjugate specifically
targets the gonadotroph cells and permanently inhibits the ability of the cell to secrete FSH and LH.
This approach has several potential advantages over other methods of contraception. These include:
1) a single treatment should permanently sterilize an animal
2) the same treatment should be effective in both males and females and in different mammalian
species
3) GnRH-toxin conjugate will be metabolized from the body within a few days of treatment
4) the proteinaceous nature of GnRH-toxin conjugate eliminates the possibility of passage
through the food chain.
5) the small volume required for effective contraception would facilitate microencapsulation and
administration by syringe dart or biodegradable projectiles.
In other situations where wildlife managers need to maintain flexibility in the use of fertility
control, reversible contraception may be desirable. Examples of these situations include 1) wild
ungulate populations exposed to periodic, severe, unanticipated winter mortality, 2) populations with
low genetic variability, 3) populations that cannot be effectively monitored, 4) populations where public
attitudes are opposed to permanent contraception, or 5) populations where non-lethal hunting recreation
is a primary management objective.
In these situations, superactive analogs of GnRH without the toxin subunit would be more
appropriate. The inhibitory actions of long-term GnRH analog agonist on the ovulatory cycle of
humans and other mammals is well-established (Casper and Yen 1979, Fraser 1983, Fraser et al. 1987,
Concannon et al. 1991). Constant administration of high .doses of GnRH agonist results in down
regulation of the pituitary GnRH receptors and suppression ofsecretionofLH
andESH. Continued·
treatment suppresses LH secretion, preventing the maintenance of normal.luteal function, and thus
prevents viable pregnancy.
Inhibition of ovulation caused by chronic administration of GnRH agonist has been successful
in several species, including dogs (Vickery et al. 1989), cattle (Herschler and Vickery 1981), sheep
(McNeilly and Fraser 1987), white-tailed deer (Becker and Katz 1995), and elk (Baker and Nett,
1999). Evidence from studies on pituitary receptors and gonadotropin content in experimental animals
treated by long-term infusion ofGnRH agonist shows that sustained release is themost effective
approach for temporarily suppressing pituitary-gonadal function (Clayton 1982, Sandow 1982). The
practicality of this approach, however, is dependent upon development of a long-acting, slow-release
preparation of agonist that can be remotely delivered.
Recently, a practical mode of administration using subcutaneous implants has overcome the
need for constant mechanical infusion of the analog. Slow release formulations of superactive GnRH
agonist are now commercially available and have been shown to be effective in suppressing the
pituitary ovarian axis for up to 6 months in a variety of mammalian species (Fraser et al. 1987, Asch et
al. 1985).
To our knowledge, only limited investigations have been conducted with either of these fertility
control techniques on wild ungulates (Baker 1994, Baker et al. 1995, Becker and Katz 1995).
Thus the specific objectives of these investigations were:
1) To evaluate the effectiveness and duration ofa single dose application of GnRH-toxin conjugate and
GnRH - Agonist in preventing normal production of reproductive hormones in captive mule deer and
elk.
2) To evaluate the effects of these contraceptives on the general health, blood chemistry, and
hematology in mule deer and elk.

�129

Segment Objective 2: SimulationModeling
Using either culling or contraceptives to meet deer population objectives will require, wildlife
managers to choose specific tactics of treatment Choices must be made on the number and age to
treat, frequency of treatment, species, sex, etc, Decisions on the best tactics will depend on comparing
the effects of alternative management actions on population behavior. To assist in these decisions, we
developed an interactive simulation model of deer population dynamics to allow managers to evaluate
alternative treatment regimes on simulated populations before applying them to real animals. Critical
to model performance is knowledge of population demographics of the RMA deer herd and requires
information on sex and age composition, recruitment, pregnancy rates, fetal sex ratio, and estimates of
population density. This information together with knowledge of the habitat resources available to deer
will provide a sound biological basis for management of deer populations at the RMA.

METHODS AND MATERIALS
GnRH- Toxin! Agonist

Experiment 1: Evaluation of GnRH-PAP in mule. deer.
Previously, we conducted controlled experiments with captive mule deer to determine the most
effective dose of GnRH analog and the season of the year when treatments would be most effective in
preventing fertility (Baker 1997). Here, we evaluate the effectiveness of GnRH..,P AP in preventing
normal production of luteinizing hormone (LH) and the duration of effectiveness. We will evaluate
contraceptive effectiveness in 4 ovariectomized mule deer.
.

Protocol for Ovariectomy in Mule Deer
Tonic secretion of pituitary LH is the result of an interplay between a stimulatory input from
the brain and an inhibitory feedback from the gonads. In the intact female, estradiol secreted from the
gonads is a potent negative feedback hormone on LH secretion during anestrus (Goodman and Karsch
1980). Since measurement ofLH secretion is the primary indicator of GnRH-toxin conjugate
effectiveness, it is imperative that female mule deer in this experiment be ovariectomized.
Ovariectomies of mule deer were conducted at FWRF during the week of May 11, 1998. Deer
were isolated and fasted for about 24 hr prior to surgery to alleviate regurgitation and aspiration of
rumen contents. On the day of surgery, anesthesia was induced with intramuscular (IM) administration
of 100 mg xylazine w/o 500 mg ketamine depending on response of the animal. Deer were then
intubated and surgical anesthesia was maintained using a rebreathing circuit with isoflurane.
Anesthetized deer were prepared for surgery by clipping hair in the abdominal area. They were then
carried to a designated surgery area., placed in right lateral recumbency, and the surgical site prepared
using standard surgical scrub. The surgical area was prepared with sterile towels and a surgical drape.
Ovariectomy was performed via mid-ventral laparotomy and require 20 - 30 min per animal.
Surgeons were attired in a sterile gown, mask, cap, disposable shoe covers and sterile gloves. Surgical
assistants wore cap, mask, and disposable shoe covers. The ovarian artery was ligated prior to removal
of the ovary. The incision was closed using a continuous suture and the skin closed with interrupted
mattress stitches. We reversed anesthesia with yohimbine at a dose of 0.2 mg/kg (N). To minimize
infection, deer were given ceftiofur sodium (1.1 mg/kg IV) administered perioperatively.
Phenylbutazone (4 mglkg) was administered orally when deer were partially recovered from anesthesia

�130

and every 48 hr for up to one week, if needed. Animals were placed in isolation pens for 24 hr and
were observed every 5 min during recovery from anesthesia. This procedure followed ARBL Standard
Operating Procedure #1 - Protocol for OvariectomylLuteectomy
in Ewes and was modified for use in
mule deer at FWRF.

GnRH-toxin Conjugate Protocol
Approximately 6 weeks following ovariectomy, GnRH-toxin was administered. Four
ovariectomized deer were moved from 5 ha pastures to individual isolation pens, sedated with xylazine
(100 mg 1M), and administered IV an optimum dose of GnRH-toxin (3 J-lgl50 kgBW). Deer were then
placed in individual isolation pens and fitted nonsurgically with indwelling jugular catheters. Indwelling
catheters remained in deer for up to 6 weeks and were checked and flushed daily. Deer remained in
individual isolation pens for the first 6 weeks of the trial. This minimized tranquilization and general
handling of deer and allowed daily evaluation of intake and general health of experimental animals.
After 6 weeks, catheters were removed and deer were returned to 5 ha pastures. For subsequent
trials, deer were removed from 5 ha pastures one day prior to GnRH trials and fitted with indwelling
jugular catheters. Sampling was conducted the next day, catheters removed and deer returned to 5 ha
pastures.
One week after GnRH-toxin treatment, GnRH analog challenge trials were conducted.
Experimental animals were moved to individual isolation pens and 3 J-lgl50 kg BW GnRI:i analog
(Baker 1997) was administered through the indwelling cannula Blood samples (5ml) were collected at
0,30,60,90,
120, 180,240,300,
and 360 min postinjection. After collections, blood was held at 4 C
for 24 hours and serum obtained by centrifugation. Serum was stored at -20 C until analyzed. GnRH '
analog challenge trials were repeated each weekfor 6 weeks, then twice monthly for 3 months, then _'
once monthly for 1 year.
.
Serum concentrations ofLH were quantified by means of ovine LH RIA (Niswender et al.
1969). The limit of sensitivity of the assay is 0.4 nglml. Response of the pituitary to GnRH-toxin
conjugate was be assessed by 1) maximum LH response achieved postinjection, 2) total amount ofLH
secreted (nglml/min); estimated by calculating the area under the LH curve, and 3) an LH response of
&lt; 2.5 ng/ml following GnRH challenge was be considered sufficiently low to prevent ovulation.

Experiment 2: Evaluation of GnRH- Agonist (Lupron) in elk.
Here, we conducted a pilot experiment to evaluate the effectiveness of GnRH agonist analog in
suppressing ovarian function in elk. We determined the most effective dose and evaluated the duration
of effectiveness. We also used these studies to evaluate the safety and side effects (if any) of treatment
on a small number of animals before proceeding to a larger investigation. The information collected in
the pilot study was used to assess individual variation in treatment responses and to conduct statistical
power analysis to increase efficiency of future research efforts,
We conducted controlled experiments with adult, tame female elk at the Colorado Division of
Wildlife's Foothills Wildlife Research Facility, Fort Collins, Colorado during November 1998 to
March 1999,

Objective: To determine the amount of GnRH agonist analog that will induce half-maximal release of
LH in female elk during estrus and evaluate duration of effectiveness.

Design: We observed the LH response offemale elk to three levels ofGnRH agonist (0, 19,39, and
78 J-lglhour) in a completely randomized design with two animals per level. Based on results from
previous studies, we chose a range of doses that should include the biologically effective range for elk.

�131

We evaluated the effective duration of treatments by monitoring ovarian function throughout the
remainder of the breeding season (Nov - Apr).

Dosage Trial - This experiment was conducted during the breeding season to insure that the pituitary
gland was at its most active state when stimulated by the GnRH agonist. On Day 1 of the experiment,
9 female elk were moved from 5 ha pastures to individual isolation pens, sedated with xylazine
hydrochloride (50-100 mg/animal, IM), fitted nonsurgically with indwelling jugular catheters and
administered subcutaneously one of three experimental doses of GnRH agonist analog. The sampling
period began at 1000 h. Blood samples (5 ml) were collected at 0,60, 120, 180,240,300,360,480
min, 12,24,36,48,84,
and 240 h postinjection. Animals remained in isolation pens during the 10 day
trial. Elk were observed daily for side effects of treatments (if any) and catheters flushed with sterile
saline solution. Following the last blood collection, catheters were removed and animals returned to 5
ha paddocks. After collection, blood was held at 4 -c for 24 h until serum was obtained by
centrifugation. Serum was then stored at - 20°C until analyzed for LH. Serum concentrations ofLH
was quantified by means of ovine LH RIA (Niswender et al. 1969). The limit of sensitivity of the
assay was 0.4 ng/ml.

Analysis: Responsiveness

of the pituitary to GnRH agonist analog challenge was assessed in four
ways: 1) maximum LH response achieved postinjection minus baseline 2) time required to reach
maximum LH 3) total amount ofLH secreted (ng/mllmin) 4) the amount ofLH required to induce half
maximal release ofLH (EDso). Response to treatments was analyzed with a one way analysis of
variance for a completely random design with 3 levels of dose as treatments and 3 individual animals
as replications.

Simulation Model
We developed an interactive simulation model to allow RMA biologist to evaluate alternative
mule deer culling strategies. This model combines extant knowledge of mule deer population biology
with measured population parameters at the RMA to predict the proportion of male and female deer
that need to be removed each year to accomplish management objectives for this herd.

Table 1. Principal parameters in culling simulation model for mule deer at RMA.
Definition

Value

Measured

Adult/yearling female survival
Adult/yearling male survival
Fawn survival coefficient a
Fawn survival coefficient 13
Fetal sex ratio ('Yo males)
December recruitment

0.90
0.90
1.20
-0.053
0.47-0.62
0.59-0.72

No
No
No
No
Yes
Yes

Reference
Whittaker, 1992
Whittaker, 1992
Bartmann et aI., 1992
Bartmann et aI., 1992

�132

RESULTS AND DISCUSSION
GnRH Toxin/Agonist
Experiment 1: Evaluation of GnRH-PAP in mule deer.
Mean serum LH concentrations were reduced in all experimental animals compared to
pretreatment levels following treatment with GnRH-PAP (Fig 1). Mean levels ofLH (ng/ml) were
initially reduced 72% of pretreatment levels after 15 days, then increased to about 51% (se ± 0.75)
after 33 days and have remained relatively unchanged through 100 days posttreatment. Body weight
dynamics, blood chemistry, hematology and social behavior of treated deer appear normal compared to
non-treated female deer.
125

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Figure 1. Luteinizing hormone release in ovariectomized female mule deer treated with GnRH-PAP during the
breeding season.

Experiment 2: Evaluation of GnRH-Agonist in Rocky Mountain Elk.
Administration of GnRH-Agonist implants resulted in a prompt and expected increase in serum
LH levels in all female elk. We observed an average peak LH response of 15.52 ng/ml (se ± 0.94)
which occurred approximately 3.5 h posttreatment. Peak response (ng/ml) and time to peak (h) were
not different (p &gt; 0.01) among treatment levels. Serum LH levels returned to baseline after 12 hours
for all elk.
Subsequent challenge with an intravenous injection of 1 f.,l GnRHI50 kg BW at 35,75,110, and
130 days posttreatment resulted in a significant (p &lt; 0.02) increase in LH levels of control elk
compared to elk treated with GnRH-Agonist implants (Fig. 2). We did not observe a significant (p &lt;
0.001) treatment difference among doses of GnRH-Agonist. Lack of treatment effect was not due to
high variation among animals but instead to small differences among treatments responses. Serum LH
levels of treated elk remained at baseline (0.34 ng/ml) for the duration of the experiment (130 days).
These findings are consistent with other evidence for desensitization of the pituitary gonadotrophs due

�133
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Figure 2. Effects of subcutaneous administration otGnRH-Agonist on serum LH concentrations in elk. Doses
were: control = 0, low = 32.5 mg, medium = 65 mg, and high = 130 mg.

to prolonged and sustained stimulation. The results of this study demonstrate that one subcutaneous
implant containing at least 32.5 mg of GnRH-Agonist can suppress pituitary-ovarian function for at
least 90 days in elk.
Simulation

Model

. Professional culling of adult mule deer at the RMA was implemented on a prescribed basis
beginning in November 1994. Prior to 1994, the mule deer population was increasing at a rate of
approximately 20 % per year. Since 1994, annual culling has reduced the population growth rate to
4% per year and allowed resource managers to meet deer management objectives for this herd. To
meet these objectives has required that resource managers remove approximately 10- 15% of the adult
females and 6-10% of the young males from the population each year. These estimates vary each year
depending on productivity of the population, changes in sex and age ratios, and deer habitat resources.
The mathematical model used to estimate the number of animals that must be culled annually
to maintain a target, steady state population appears to provide a reasonably accurate representation of
mule deer population dynamics at the RMA.· The efficacy of this model, however, is dependent on
intensive monitoring of the population and adapting management actions to a changing environment.

LITERATURE

CITED

Asch, R H, F. J. Rojas, T. R Tice, and A. V. Schally. 1985. Studies of a controlled - release
microcapsule formulation of an LH-RH agonist in the rhesus monkey menstrual cycle.
International J. Fertility 56:78-81.
Baker, D. L. 1997. Regulation of mule deer population growth by fertility control: laboratory, field,
and simulation experiments. Pages 81- 87 in Wildlife Research Report, Mammals Research,

�134

Federal Aid Projects, Job Progress Report, Project W-153-R-4, SP1, Jl. Colorado Division of
Wildlife, Fort Collins, Colorado, USA.
Baker, D. L., and N. T. Hobbs. 1996. Regulation of mule deer population growth by fertility control:
laboratory, field, and simulation experiments. Pages 113 -148 in Wildlife Research Report,
Mammals Research, Federal Aid Projects, Job Progress Report, Project W-153-R-4, SPl, J1.
Colorado Division of Wildlife, Fort Collins, Colorado, USA.
Baker, D. L, M. W. Miller, and T. M. Nett. 1995. Gonadotropin-releasing hormone analog-induced
patterns of luteinizing hormone secretion in female wapiti (Cervus elaphus nelson i) during the
breeding season, anestrus, and pregnancy. Bio. Reprod. 52: 1193-1197.
Becker, S. E., Katz, L. S. 1995. Effects of gonadotropin - releasing hormone agonist on serum LH
concentrations in female white-tailed deer. Small Ruminant Research 18: 145-150.
Casper, R. F., and S. S. C. Yen. 1979. Induction of luteolysis in the human with a long-acting analog
of luteinizing hormone-releasing factor. Science 205 :408-41 O.
Clayton, R. N. 1982. GnRH modulation of its own pituitary receptors: evidence ofbiphasic
regulation. Endocrinology 111: 152-161.
Concannon, P. W., and V. N. Meyers-Wallen,
1991. Current and proposed methods for
contraception and termination of pregnancy in dogs and cats. 1. Am. Vet. Med. Assoc.
198:1214-1225.
Fraser, H. M. 1983. Effect of treatment for one year with a luteinizing hormone-releasing hormone
agonist on ovarian, thyroidal, and adrenal function and menstruation in the stump tailed monkey
(Macaca arctoides). Endocrinology 112:245-253.
__
, M., 1. Sandow, H. Seidel, and W. von Rechenberg. 1987. An implant of a gonadotropin
releasing hormone agonist (burserelin) which suppresses ovarian function in the macaque for 3-5
months. Acta Endocrinological 15: 521-427.
Garrot, R. A. 1995. Effective management of free-ranging ungulate populations using contraception.
Wildlife Society Bulletin 23:445-452.
Goodman, R. L., and F. 1. Karsch. 1980. Pulsatile secretion of luteinizing hormone: differential
suppression by ovarian steroids. Endocrinology 107:1286-1290.
Herschler, R. C., and B. H. Vickery. 1981. The effects ofLHRH ethylamide on the estrous cycle,
weight gain, and feed efficiency in feedlot heifer. Amer. 1. of Vet. Res. 42: 1405-1408.
Hobbs, N. T., D. L. Baker, and R. B. Gill. 1999. A general theory describing effects offertility
control on populations of ungulates. Journal of Wildlife Management (in press).
Hone, 1. 1992. Rate of increase and fertility control. 1. Applied Ecology 29:695-698.
Jewell, P. A., and S. Holt. 1981. Problems in management oflocally abundant wild animals.
Academic Press. 321pp.
Kirkpatrick, 1. F., and 1. W. Turner, Jr. 1985. Chemical fertility control and wildlife management.
Bioscience 35:485-491.
McNeilly, A. S., and H. M. Fraser. 1987. Effect of gonadotropin-releasing hormone agonist-induced
suppression ofLH and FSH on follicle growth and corpus luteum function in the ewe. 1.
Endocrinology 115:273-282.
Niswender, G. D., L. E. Reichert, Jr., A. R. Midgley, Jr., and A. V. Nalbandov. 1969.
Radioimmunoassay for bovine and ovine luteinizing hormone. Endocrinology 84: 1166-1173.
___
. 1973. Influence of the site of conjugation on the specificity of antibodies to progesterone.
Steroids 22:413-424.
Sandow,1. 1982. Inhibition of pituitary and testicular function by LHRH analogs. Pages 19-39 in
Jeffcoate S. L. and Sandlier (eds). Progress towards a male contraceptive. Wiley and Sons,
Chichester.
Warren, R. 1., L. M. White, W. R. Lance. 1995. Management of urban deer populations with
contraceptives: practicality and agency concerns. Wildlife Society Bulletin 23: 441-444.

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                  <text>135

Colorado Division of Wildlife
Wildlife Research Report
July 1999

JOB PROGRESS REPORT

Smteof
~C~o~lo~r~ad~o~ _
,Project No.
W.!.!--1~5~3~-R~-..!..12~
__
Work Package No. __ ~3~0:..:::0..!..1
_
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Task No.'

Cost Center 3430
Mammals Program
Deer Conservation
Investigating Factors Contributing to Declining
Mule Deer Numbers

Period Covered: July 1 1998 - June 30, 1999
Authors: T. M. Pojar and W. F. Andelt
'"

Personnel.. R Arant, D. L. Baker, B. Banulis, D. Hartmann, G. Bock, D. C. Bowden, M. Caddy, D.
Coven, B. Devries, B. Diamond, B. Dreher, 1. Ellenberger, V. Graham, D. Gustine, P.
Hayden, G. Hust, C. Krumm, A Larsen, K. Larsen, S. Larsen, D. Masden, D. Matiatos,
M W. Miller, C. Oliver. J. Olterman, M. Potter, E. Scott, L. Spicer, D. Steele, C.
Wagner,:a. Watkins, M. Wild, M. Zeeman, S. Znamenacek.

ABSTRACT
Long-term data indicate that fawn:doe ratios have shown a significant and consistent decline
over the past 20 years in most deer management units in Colorado as well as in most of the western
states, This has resulted in a general decline in mule deer (Odocoileus hemionus) density and
diminished recreational potential from this major resource. It is important for the Division of Wildlife
to elucidate the factors contributing to the reduced doe:fawn radios and the declining deer populations.
Reproduction and neonatal survival are 2 important components of population recruitment. Therefore,
2 studies were initiated during this segment to investigate pregnancy and fetal rates of adult does and
the survival of neonatal fawns. Both of these studies were done on the Uncompahgre Plateau and, in
addition, a supplemental neonate fawn survival study was done in Middle park. Thirty-seven of 40
(93%) adult does on the Uncompahgre Plateau were detected pregnant with transrectal ultrasound.
The proportion of does detected pregnant with ultrasound did not differ (P = 0.817) from the
proportion of does pregnant (91.4% of303 does) in previous Colorado studies. The average number of
fetuses/doe, 1.70, (n=40) for adult does on the Uncompahgre Plateau was not less (Z = 0.340, P =
0.367) than the fetal rate of 1.74 (n=276) in previous Colorado studies. We therefore conclude that
does are getting bred and producing fetuses at normal rates for the species and that this component of
, the reproductive cycle is most likely not responsible for declining December fawn:doe ratios and,
'consequently, declining deer populations. The field operation was done during February 5-8, 1999; a
draft of the manuscript to be submitted to a peer reviewed publication is in Appendix I. The objective
of the fawn survival investigation was to put radios on 60 neonatal fawns on the Uncompahgre and 20
neonatal fawns in Middle Park. By June 30, 1999, we had put out 50 and 14 radios on fawns on the

�136

Uncompahgre and in Middle Park, respectively for a total of 64 radioed fawns. First fawns were
captured on June 9 in both areas and fawn capture peaked during June 13-24 with 76% of the total
captured during this time; 19 fawns (30%) were captured during June 22-24. The first mortality was
recorded on June 13 with the peak of mortality (50% of total) during June 28-July 12. Causes of
mortality when divided between predation, sickness/starvation, and unknown was 47%, 47%, and 6%,
respectively. As of this date (August 18, 1999) 30 of64 fawns have died for a mortality rate of 46.9%,
Fawns were monitored every day (except weekends) from capture with the exception of the period of
July 5-27 when they were monitored twice a day. After July 27 they were again monitored daily
except on weekends. Eleven of the 14 fawns that died of causes other that predation (or unknown
causes) have been necropsied thus far; all had in common severe thymic atrophy indicating a
compromised immune system and chronic stress. It is difficult to discern if the stressor(s) predisposed
them to the variety of other pathogens that appeared to be factors in their deaths. Some of the disease
agents identified were: Cryptosporidia, Pasteurella, E. Coli, BVD, and a hemorrhagic disease (Blue
Tongue or EHD). It should be noted that mortality attributed to predation is probably liberal because
the fawn's sickness (including diarrhea in many cases) and weakened condition probably predisposed
them to olfactory or visual location by a predator. Positively identifying scavenging vs. predation was
difficult even when they were monitored once or twice a day because dense vegetation precluded
tracking for evidence of pursuit and kill sites as can be done with snow cover.

�137

MULE DEER PREGNANCY AND FETAL RATES
William F. Andelt and Thomas M. Pojar

P. N. OBJECTNES
1. Estimate pregnancy and fetal rates of adult mule deer does on the Uncompahgre Plateau during the
1998-1999 reproductive cycle.
2. Publish results in a peer-reviewed scientific journal (Appendix I).

SEGMENT OBJECTNES
1. Estimate accuracy of an ultrasound system for detecting' pregnancy and number of fetuses in mule
deer does maintained at the Colorado Division of Wildlife's Foothills Research Facility in
Northwest Fort Collins and in mule deer does collected on the USFWS Rocky Mountain Arsenal.
2. Estimate pregnancy and fetal rates of adult mule deer in DAU D-19 (Uncompahgre).
3. Compare pregnancy and fetal rates of adult mule deer to historic rates in Colorado.
4. Analyze data and prepare an annual Federal Aid Job Progress report.
RESULTS
See Appendix I for the Research Program Narrative and a draft of the manuscript to be submitted to a
peer reviewed publication.

�138

�139

lMPACT OF PREDATION AND VEGETATIVE COVER ON MULE DEER FAWN SURVIVAL
Thomas M. Pojar and William F. Andelt

P. N. OBJECTIVES
1. Identify agents of neonatal mule deer fawn mortality from birth to 6 months of age.
SEGMENT OBJECTIVES
1. Capture and radio collar 30-35 neonatal fawns each on the Uncompahgre Plateau (D-19), Middle
Park (D-9), and Red Feathers (D-4).
2. Measure vegetative density and height at fawn bed sites.
3. Measure distance between successive bed sites for individual fawns.
4. Compare fawn survival and causes of mortality among 3 vegetatively and ecologically different
study areas.
5. Correlate height and density of vegetation at fawn birth sites and bed sites with percent of fawns
killed by predators.
6. Compare height and density of vegetation at fawn bed sites and random sites.
INTRODUCTION
The Research Program Narrative is in Appendix II. Because of budget redirection to
accomplish the estimation of pregnancy and fetal rates via ultrasound the objectives outlined in the PN
were modified to fit within budget, personnel, and logistic constraints. Major changes include:
1. Limit the fawn collaring effort to the Uncompahgre and Middle Park rather than attempt to do
it on 3 study areas. Because of the size and diversity of vegetative communities on the
Uncompahgre and because of intense political interest in this area, the target sampling intensity
was increased to 60 fawns. The target sample in Middle park was reduced to 20 fawns due to
the redirection of resources.
2. Abandon the idea of measuring vegetation at bed sites because of evidence that persistent
disturbance of bed sites reduces survival of young ungulates (Philips 1998).
3. The logistics of placing an adequate crew in remote fawning areas and the unknown of whether
or not fawns could be captured in sufficient numbers given deer density, terrain, and vegetative
cover encountered negated many of the objectives in the PN.
In essence, this investigation was reduced to placing emphasis on determining if fawns can be captured
under these conditions and, if so, monitor their survival and causes of mortality. Summer fawn
survival and causes of mortality are 2 important factors impacting deer population performance.
STUDY AREAS
There are 2 study areas involved in this investigation, the Uncompahgre Plateau and Middle
Park. The Uncompahgre Plateau includes Game Management Units 61 and 62. It is a high elevation
plateau, oriented northwest-southeast, formed by a structural uplift that is characterized by steep
canyons in both directions from the divide ridge that runs the length of the plateau. The soils are
primarily shallow with areas of rich deeper soils that support aspen (Populus tremuloides)
communities at intermediate to higher elevations. High elevations have extensive stands of spruce-fir

�140

(Picea-Abies) and fir-aspen (Abies-Populus tremuloides). The crest of the plateau peaks at about
9,500 ft (2,898 m) and declines in both directions through oakbrush (Quercus gambellii), pinyonjuniper (Pinus edulis-Juniperus osteosperma), and large sagebrush (Artemisia tridentata) parks as the
elevation decreases. A thorough description of the physiography, geography, climate, and vegetation
can be found in Anderson et. aI (1992) and Kufeld (1979).
Middle Park is a high mountain park with similar plant communities as the Uncompahgre
Plateau at similar elevations. A description of the area can be found in Tiedeman et. aI (1987).

MElHODS
Radio collared does were used to locate fawning areas although no special effort was made to
capture the fawns of radioed does. The strategy for capturing fawns involved observing does for
behavioral and physical signs, such as udder development, of having fawned. If it was determined that
these indicators suggested that the doe had fawned, the area was searched for the fawn(s). Once
located, the fawn was approached from behind (out of direct eyesight) and restrained for weighing,
measuring, and putting on the radio collar. ·The collars used were expandable with elastic and loops
sewed with cotton thread to accommodate growth and to drop off at about 6 months; they weighed
about 65 g.
RESULTS
A total of 64 fawns were captured and radio collared; 50 on the Uncomphagre Plateau and 14
in Middle Park. The first fawns were captured on June 9 with 76% of the total captures made during
June 13-24; the peak 3-day period of capture was June 22-24 when 30% of the captures were made
(Figure 1).
Total fawn mortality as of this writing (August 18) is 30 with 14 from a condition that is
generally described as sickness/starvation (S/S), 14 from predation, and 2 from unknown causes where
only the collar was found (Table 1). The 14 that died from SIS were all collected, frozen or stored on
ice, and later necropsied at the Colorado State University Veterinary Teaching Hospital in Fort Collins.
Results thus far are preliminary with some of the lab tests still pending and that is the reason for
categorizing these deaths as general SIS. Some disease agents have been identified but it is not known
if these were the cause of the fawns deaths. A common condition in all of the fawns is that they had
atrophied thymus glands indicating chronic stress and probable immunodeficiency which could have
predisposed them to succumbing to the pathogens that they encountered. Some of the pathogens

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Figure 1. Dates of fawn capture combined
Uncompahgre Plateau and Middle Park.

from 2 areas in Colorado.

1999-

�141

identified are: the parasite Crhyptosporidia, Pasterrella, E. Coli, Bovine Virus Diarrhea (BVD), and a
hemorrhagic disease (Blue Tongue or Epizootic Hemorrhagic Disease (EHD». In addition to the 30
dead radioed fawns, we found 2 stillborns, 2 other intact fawn carcasses, and one adult doe carcass.
One of the stillborns was fresh enough to necropsy and was small {1.5 kg) and also had an atrophied
thymus. The lab results on the adult doe are not complete but she showed some signs of a hemorrhagic
condition; the other carcases were in stages of decomposition that precluded materials collection.
Determining if a fawn died from some other cause or was killed by a predator is difficult.
Because the fawns were monitored on a daily or twice daily schedule, all carcasses that were found
partially eaten were attributed to predation; some errors were undoubtedly made by doing this which
would inflate the deaths attributed to predation. Vegetation was too thick to discern tracks of a chase
and capture as is possible during winter with snow cover, so unless the predation was actually
witnessed, there will always be doubt as to the whether or not predation was the cause of death. In 2
instances, only the collar was found with no other tracks or supporting evidence of predation. These
are categorized as "unknown" but are likely predator kills. It is unlikely that the collars were slipped
because they fit snugly around the neck. One of these collars had a triangular rip that could have been
caused by a predator tooth (or barbed wire), the other was without marks or blood so it's categorization
is even less certain.
With nearly half of the fawns dying of SIS it is probable that some portion of the fawns eaten
by a predator were in some stage of "sic knessl starvation" resulting in them being more susceptible to
discovery by a predator ~ Several of the fawns that died had diarrhea which would have broken their
.shield of scentlessness that protects them from predators early in life. Other fawns that were in a
diseased or weaken state may have lacked normal hiding or escape behavior that would have
predisposed them to either visual or olfactory location by a predator in the vicinity. The classical
evidence that an animal was alive when bitten (i.e. predated) by a predator is subcutaneous
hemorrhage; this, however, does not establish that the prey was in a healthy state when preyed upon.
The peak of mortalities from all causes was during June 28-July 11 with 16 of30 (53%) dying
during this 14-day period (Figure 2); 5 from SIS and 11 from predation. One fawn died on the 2nd day
after capture and was judged to be a day old at capture. It was found to have no milk in it's abomasum
and had a small amount of forage in it's rumen both of which indicate that it had not nursed and was
starving. It is not possible to determine if this fawn was abandoned because of handling or if the dam
was not providing milk; a doe was in the area (and acting maternal) during capture and 2 days later
when the fawn carcass was recovered. If the fawn was truly a day old when captured and had not
nursed by that time it is possible that there was a bonding or lactation problem on the part of the doe.
5
CI)
Q)

E

(ij

4

t

0

~

c:

3

3:

-.8
&lt;IS

u..

2

0

E

1

::s

z

0

.•....

N

0
.•...
CD

00
.•....
fb
.•....

C{i

CD

~

g
ch
C:!
&lt;0

.•...

N

~
,..._

0
.•...

00
.•....
fb
.•...
-..
,..._

j::::
Dates

..,.

.

~
~
,..._

g,
00

~

It)

£2
00

.•...
.•....
,
~
00

Figure 2. Neonatal fawn mortality from all causes for the Uncompahgre
and Middle Park, Colorado, 1999.

,..._

.•...

&amp;b
.•....

-..
00

Plateau

�142

All of the other SIS occurred on the 3rd, or later, day after capture. Six fawns died between the 3ni and
5th day after capture and the rest of them (77%) died after the 6th day of capture (Figure 3).
It is interesting to note that there were 2 somewhat long time spans where there were no mortalities
from any cause - 6 days, July 14-19, and 17 days, July 26- August 13. It seems that if there were
constant predator pressure on neonatal fawns as a food source and that sickness were not a factor in
predator location of fawns, then there would not be these long spans of no mortality on the marked
fawns. However, it is possible that just by chance alone, predators did not encounter a marked fawn
during these time periods.
One radio was verified to have failed and It is believed that 2 other radios ceased to work
because extensive ground and aerial searches failed to make signal contact. A set of twins that were
radioed recently disappeared after domestic sheep were herded into the area they were inhabiting; no
signal was obtained with a ground search of the area so an aerial search will be made.

12,-------------

-,

10
CI.I

~
tIS
u..
'0

8
6

~

g

:z:

4
2

&lt;0 r= 1

Days From Capture
Figure 3. Days from capture that fawns died from any cause. Total for fawns
captured on the Uncompahgre Plateau and Middle Par1&lt;.Colorado. 1999.

CONCLUSIONS
The following conclusions can be made from this investigation.
1. It is possible to capture neonatal fawns under the conditions found on the Uncompahgre Plateau and
in Middle Park. Success in capturing fawns is dependent mostly on doe density which dictates the
number of does that the capture crew can encounter during a search. Road network is also
important because of the greater mobility of the capture crew and, therefore, a greater probability
of encountering does .. And finally, experience of the capture crew is a major factor in the success
of finding fawns. Dense vegetative cover and roadless areas make sighting of does and capture of
fawns unproductive for reasonable sample sizes.
2. There is evidence that there are stress factors impacting the 2 mule deer populations that were
sampled. Atrophied thymus glands of all the intact carcasses recovered along with a variety of
pathogenic agents identified suggests that the stressor(s) resulted in a suppressed immune response
in the fawns making them susceptible to encountered pathogens. It has been demonstrated that
thymus gland size in mule deer is seasonally cyclic with the peak during summer (good nutrition)
and the trough during winter (limited resources) (Anderson et aI. 1974). Ozoga and Verme
(1978:794) have demonstrated the relation between thymus size and dietary plane in white-tailed
deer (0. Virginianus) fawns in controlled tests. They also noted that the thymus glands offawns
dying of disease or malnutrition within a month of birth were "extremely small" compared to fawns
dying of other causes (accidents).

�143

LITERATORE CITED
Anderson, A E., D. C. Bowden, and D. M. Kattner. 1992. The puma on Uncompahgre Plateau,
Colorado. Technical Publication No. 40, Colorado Division of Wildlife.
Anderson, A E., D. E. Medin, and D. C. Bowden. 1974. Growth and morphometry of the carcass,
selected bones, organs, and glands of mule deer. Wildlife Monographs, No. 39.
Kufeld, R C. 1979. History and current status of the mule deer population of the east side of the
Uncompahgre Plateau. Division Report No. 11, Colorado Division of Wildlife.
Ozoga, J. J. and L. J. Verme. 1978. The thymus gland as a nutritional status indicator in deer. Journal
of Wildlife Management, 42:791-798.
Philips, G. E. 1998. Effects of human-induced disturbance during calving season on reproductive
success of elk in the upper Eagle River valley. Ph. D. Dissertation, Colorado State University, Fort
Collins.
.Tiedeman, J. A, R E. Francis, C. Terwilliger, Jr., and L. H. Carpenter. 1987. Shrub-steppe habitat
types of Middle Park, Colorado. USDA Forest Service Research Paper RM-273, Rocky Mountain
Forest and Range Experiment Station, Fort Collins.

Table 1. Neonatal fawns captured and radio collared on the Uncompahgre Plateau and Middle Park,
Colorado, 1999. Radio frequencies in the 149-150 KHz band are Uncompahgre fawns and 173 KHz
radios are Middle Park fawns.
ID

Date

Sex

Weight (kg)

Hindfoot

Date

Probable

149.410/99

06/1611999

M

3.5

24.4

07/0111999

Predation

150.010/99

0611511999

F

0.0

24.9

150.020/99

06/0911999

F

0.0

24.7

150.030/99

06114/1999

F

0.0

27.3

06/2911999

Sick/Starve

150.040/99

06114/1999

F

0.0

27.6

07/0611999

Sick/Starve

150.050/99

06/1511999

F

0.0

27.9

150.070/99

0611711999

M

3.8

26.0

08/1811999

Predation

150.080/99

06/2211999

F

4.4

27.0

06118/1999

Sick/Starve

06/29/1999

Predation

150.090/99

06/2111999

F

5.9

27.6

150.100/99

06/2111999

M

5.2

26.4

150.110/99

06114/1999

U

2.3

0.0

150.120/99

06/1711999

F

5.0

26.0

150.130/99

0611411999

F

2.5

24.8

150.140/99

06110/1999

F

3.3

24.4

150.150/99

06/1711999

M

5.3

26.7

07/2011999

Predation

150.160/99

06/2211999

F

0.0

26.0

06/3011999

Predation

150.170/99

0611511999

F

3.7

26.0

150.180/99

06/2111999

F

6.1

29.2

07/2511999

Sick/Starve

07/0711999

Sick/Starve

150.190/99

0611511999

M

4.0

26.0

150.200/99

06/2211999

M

3.3

24.1

150.210/99

06/2411999

F

4.4

26.4

150.220/99

06/1611999

M

3.8

24.4

150.230/99

06/2211999

F

5.3

28.6

150.270/99

06/23/1999

M

5.6

26.4

�144

Weight (kg)

Hindfoot

Date

Probable

M

3.1

25.0

06118/1999

Sick/Starve

M

4.6

26.0

0611611999

M

0.0

26.7

150.310/99

06/2811999

F

5.6

28.6

150.320/99

06123/1999

M

6.0

27.9

150.340/99

06/2311999

F

5.6

27.6

06/30/1999

Sick/Starve

150.350/99

0611711999

M

0.0

28.7

06/22/1999

Sick/Starve

150.360/99

06/2411999

M

6.0

26.7

150.370/99

06/2311999

M

6.0

27.3

150.380/99

0612411999

M

2.4

23.2

07/1111999

Predation

150.390/99

06/2411999

F

3.8

26.7

07/0111999

Predation

150.400/99

06/2211999

M

5.0

27.3

150.420/99

06128/1999

F

4.2

26.2

150.430/99

06124/1999

M

5.3

26.7

0711111999

Unknown

0811611999

Predation

ID

Date

Sex

150.280al99

06/15/1999

150.280b/99

06/28/1999

150.290/99

150.440/99

06/2511999

M

6.0

29.2

150.45Q/99

06115/1999

F

3.5

25.7

150.460/99

06124/1999

M

3.1

23.5

150.480/99

06/3011999

F

4.2

24.8

08/16/1999

Sick/Starve

150.510/99

0611611999

F

3.6

24.1

07/0111999

Predation

150.520/99

06116/1999

F

3.5

24.8

07/0811999

Predation

150.530/99

06114/1999

M

3.6

25.4

150.540/99

06/29/1999

M

4.5

26.0

150.570199

06/24/1999

F

2.5

21.9

0711311999

Sick/Starve

150.600/99

06/2911999

M

6.0

28.9

150.610/99

06/18/1999

M

3.6

25.4

07/23/1999

Sick/Starve

150.620/99

06/30/1999

M

4.5

24.4

07/0511999

Predation

173.510/99

06/0911999

M

4.5

26.7

0611311999

Sick/Starve

173.540/99

0611111999

F

3.8

26.0

07/2211999

Predation

173.550/99

0612411999

F

4.7

27.3

173.560/99

06/2111999

F

4.1

26.0

173.590/99

06/2211999

M

5.5

28.6

173.600/99

06/2111999

F

4.1

26.0

173.610/99

06/2111999

M

5.1

28.6

06/25/1999

Sick/Starve

07/0811999

Predation

-.

173.630/99

06/2111999

F

3.8

25.4

173.640al99

06/22/1999

M

4.5

26.7

06/2511999

Sick/Starve

173.640b/99

06/30/1999

M

4.2

25.4

08/16/1999

Predation

173.660/99

06/29/1999

M

6.5

27.9

173.670/99

06/2511999

F

6.0

29.2

173.690/99

06/19/1999

U

0.0

0.0

07/0511999

Unknown

173.700/99

06/1811999

M

4.7

27.0

'Due to the preliminary nature of this report, the causes of death have been put into only 3 categories, sick/starve, predation,
and unknown. The unknown category includes 2 radios that were found that had no other evidence present. It is suspected that
these were actually predator kills because the collars fit snug enough that slipping the collar was unlikely, in addition, one of
the collars had a small triangular rip in it that could be consistent with a predator tooth tear.

�145

APPENDIX I

Research Program Narrative
and
Draft Manuscript

MULE DEER PREGNANCY AND FETAL RATES ON THE

UNCOMPAHGRE PLATEAU

January 12, 1999

Principal Investigators:

WILLIAM F. ANDELT
Department of Fishery and Wildlife Biology
Colorado State University
Fort Collins, CO 80523
970-491-7093

mOMAS M. POJAR
Colorado Division of Wildlife
317 W. Prospect
Fort Collins, CO 80526
970-472-4308

�146

�147

PROGRAM NARRATIVE

State of.
___;C::::;o::::..:l~or:..::a:::::d~o_
Project No ..
W..!.!._-~15~3::....-.:!:.::R,__
_
Work Package No. ---,3~0~0~1,-_
Task No.
-=5'--_

Cost Center 3430
Mammals Program
Deer Conservation
Mule Deer Pregnancy and Fetal Rates on the
Uncompahgre Plateau

NEED
Fawn:doe (f:d) ratios obtained in December on the Uncompahgre Plateau (Game Management
Units 61 and 62, Data Analysis Unit (DAU) D-19) have declined (t = -3.39, P = 0.004) by an average
of 1.8 fawns: 100 does per year from 1982-1998. December ratios ranged from a high of79f:l00d in
1982 to a low of 32f: 1OOdin 1996 and 34f: 100d in 1997; there were 51.9f: 1OOdin 1998. Besides low
December f:d ratios, over-winter (December - May) fawn survival on the Uncompahgre Plateau was
49% during the winter of 1997-1998 (Bartmann and Pojar 1998a). The low December f:d ratios and
poor over-winter survival of fawns for the Uncompahgre deer herd is of concern to the public and
game managers. It is unknown if the low December ratios are due to a failure to breed, reduced fetal
production, resorption/abortion offetuses, or low summer and fall fawn survival (Bartmann 1998).
Pregnancy and Fetal Rates
Pregnancy rates are key information to determine if does are breeding. Recent data show that the
pregnancy rate during January 1998 of93.0% for 29 does ~ 1 year old in the Red Feather DAU
(Bartmann and Pojar 1998b) was similar to 92.0% of 163 does ~ 2 years old in the same area during
1961-1964 (Medin and Anderson 1979). A 94.8% pregnancy rate for does ~ 2 years old (n = 114)
and a 94.0% pregnancy rate for does&gt; 1 year old (n = 134) in Middle Park (DAU D-9) was reported
by Gill (1971) during 1969-197l.
Other pregnancy rates and locations reported in the literature are as
follows: 100% for does ~ 2 years old (n = 18) on the Forbes-Trinchera Ranch, Colorado (Freddy
1988), 89% (n = 47) during 1973 and 82% (n = 83) during 1978 in the Piceance Basin, Colorado
(Bartmann 1998), and 94% of mule deer does&gt; 1 year old in a California study (Salwasser et al.
1978). The 1998 data collected in Colorado appears to be normal and does not indicate that pregnancy
rate is a contributing factor to the low f:d ratios, however these data were not collected in the
Uncompahgre DAU where December f:d ratios were lowest.
Fetal rates, the number of fetuses per pregnant doe, that are in a normal range for the species
would indicate that nutritional and other needs of breeding does are being met. The fetal rate for does
&gt; 2 years old was 1.83 (n = 41) in the Cache la Poudre River drainage from 1961-1965 (Medin and
Anderson 1979), 1.82 (n = 114) in Middle Park (Gill 1971), 1.89 (n = 18) on the Forbes-Trinchera
Ranch (Freddy 1988), and l.46 (n = 61) and 1.65 (n = 37) in the Piceance Basin (G. C. White,
Colorado State University, personal communication). Salwasser et al. (1978) reported a fetal rate of
l.62 for 2 and 3 year old mule deer does (n = 47) and a rate of l.85 for does&gt; 4 years old (n = 34) in
California
To help ascertain the cause of low fawn:doe ratios on the Uncompahgre Plateau of Colorado, an
investigation to estimate: a) the proportion of ~ 2 year old does that become pregnant and b) the
number of fetuses produced is needed. Estimates of pregnancy and fetal rates will indicate if these
critical reproductive parameters are within the normal range for the species and will contribute to the
understanding of the causes of the observed low f.d ratios and low recruitment into the Uncompahgre
mule deer population.

�148

OBJECTIVES
We propose to estimate pregnancy and fetal rates of adult mule deer does on the Uncompahgre
Plateau during the 1998-1999 reproductive cycle.

HYPOTHESES
H"l:

H,,2:

Pregnancy rates of adult mule deer does on the Uncompahgre Plateau during the
1998-1999 reproductive cycle do not differ from historic pregnancy rates (93%) in
Colorado.
Fetal rates of adult mule deer does on the Uncompahgre Plateau during the 1998-1999
reproductive cycle do not differ from historic fetal rates (1.74 fawns per adult doe) in
Colorado.

EXPECTED RESULTS OR BENEFITS
This research will help ascertain if pregnancy and fetal rates are outside the normal range
expected for mule deer in Colorado and if they are contributing factors to the observed low December
fawn:doe ratios. Knowledge of fetal rates is essential for determining what factors might be causing
the low fawn:doe ratios observed in Colorado. Recruitment into a mule deer population is dependent
on adequate pregnancy and fetal rates, and young survival through breeding age. This investigation
will provide information on the early stages of the recruitment process, i.e. whether or not does are
becoming pregnant and producing normal litters. These data are imperative before research and
management experiments are conducted to estimate the effect of various experimental manipulations
on fawn:doe ratios.

APPROACH
Capture and Handling of Does
Forty mature does C:::. 2 years old) will be captured using a helicopter and netgun on the
Uncompahgre Plateau during February 1999. The deer usually will be pursued for &lt; 2 minutes. We
expect &lt; 2% of the captured does to sustain injuries or mortalities (R. M. Bartmann, Colorado Division
of Wildlife and A. W. Alldredge, Colorado State University, personal communications). Captured
does will be hobbled, blindfolded, and transported via helicopterto a base station, usually &lt; 5 miles
from the capture site to.minimize stress, where they will be processed. Does captured &lt; 2 miles from
the processing station will be released at the station, whereas does captured&gt; 2 miles from the station
will be released at the capture site. We anticipate that does will not be held for more than 30 minutes.
Pregnancy and Fetal Detection
The does will be manually restrained without the use of a tranquilizer to allow quick release at
the processing site, unless we find sedation is necessary. If necessary, does will be sedated with
ketamine and xylazine and reversed with yohimbine. The does will be placed in lateral or sternal
recumbency, depending on location of the fetuses. We will use trans rectal ultrasonography, pioneered
by Lindahl (1971) and applied in field situations by Barrett (1981), Smith and Lindzey (1982). White
et al. (1989), and Stephenson et al. (1995), to estimate pregnancy and fetal rate. A portable ultrasound
unit available from the Colorado State University Veterinary Teaching Hospital will be used; the

�149

equipment will be transported in a mobile processing station to within 5 miles of capture sites to
minimize transport time and stress on the does. Blood will be collected by carotid venipuncture and
serum pregnancy-specific protein-B (PSPB) (Sasser et al, 1986) will be used to provide a second
estimate of pregnancy rates (Stephenson et al. 1995).
The use of ultrasonography to detect pregnancy is a well tested method and provides accurate
estimates of pregnancy rates in elk (Cervus elephus) (Bingham et al. 1990, Revol and Wilson 1991,
Willard et al, 1994). Transrectal ultrasonography was found to accurately detect pregnancy in
domestic sheep (Schrick and Inskeep 1993) and fallow deer (Dama dama; Lenz et al. 1993). Because
the method is not as well tested to detect the number of fetuses carried by pregnant female mule deer,
we will have controls in our study to document the accuracy of the method and make adjustment in the
observed fetal rate if necessary.
Ten potentially pregnant does that are held in captivity in the Colorado Division of Wildlife Big
Game Research Facility on the Foothills Campus, Fort Collins will be untrasounded for pregnancy and
fetal rates as a control on the methodology and to test the proposed handling and restraint methods to
be used on does during the field operation. These does will be under close surveillance throughout
pregnancy and during fawning to verify the ultrasound results. In addition, we will have access to ~ 10
deer to be collected in January or February on the Rocky Mountain Arsenal. These does will be
ultrasounded and then necropsied for immediate verification of the effectiveness of detecting the
number of fetuses.
Ninety-five percent of Colorado mule deer conception dates, based on back-dating from fetal
forehead-rump measurements, over a 3 year span (n=135) were reported to be between November 18
and December 12 (Gill 1972). Ultrasounding for fetal rate is most successful on small ungulates
during 30-60 days into pregnancy (LaRue Johnson, CSU Veterinary Teaching Hospital, personal
communication). We will target the time period ofJanuary 20 through February 10 to do the.
ultrasounding. Dr. LaRue Johnson will perform the ultrasounding procedures.
Animal Care and Use
All capture and handling of animals will comply with the standards of the Colorado State
University and Colorado Division of Wildlife Animal Care and Use committees.
We will secure
trespass permission from study site owners prior to the study.
Sample Sizes and Power of Tests
The following power analysis (Table 1) was developed to estimate sample sizes necessary to
detect various mean departures of fetal rates from historic levels for adult does. For the historic data,
we used the weighted mean of fetal rates for adult does from the Poudre River drainage (n = 41, =
1.83, SD = 0.44; Medin and Anderson 1979), Middle park (n = 119, x = 1.86, SD = 0.57; Gill 1971),
the Forbes-Trinchera Ranch (n = 18, x = 1.89, SD = 0.47; Freddy 1988), and the Piceance Basin
([1973: n = 61, x= 1.46, SD = 0.77][1978: n = 37, x = 1.65, SD = 0.72]; G. C. White, Colorado State
University, personal communication) to estimate the historic mean (1.74) and standard deviation
(0.64). We used an expected 1999 standard deviation equal to the historic standard deviation (0.64; G.
C. White, personal communication). An alpha of 0.05 was used in our estimates of power. Power of
0.8 or higher is desired.

x

�150

Table 1. One-tailed power to estimate if 1999 fetal rates differ from historic rate of 1.74 fawns per
mature doe (;:: 2 years old).
Sample size
(n)

Fetal
rate

Power

Sample size
(n)

Fetal
rate

Power

20
20
20
20
30
30
30
30
40
40
40
40

1.3
1.4
1.5
1.6
1.3
1.4
1.5
1.6
1.3
1.4
1.5
1.6

0.91
0.74
0.49
0.24
0.97
0.87
0.62
0.31
0.99
0.93
0.72
0.36

50
50
50
50
60
60
60
60
80
80
80
80

1.3
1.4
1.5
1.6
1.3
1.4
1.5
1.6
1.3
1.4
1.5
1.6

1.00
0.97
0.79
0.41
1.00
0.98
0.84
0.46
1.00
0.99
0.91
0.53

Regarding sample sizes, the desired differential in fetal rate that we wish to detect is somewhat
problematic. We are primarily interested in ascertaining if pregnancy rates and fetal rates are a major
contributor to the observed low December fawn:doe ratio (0.36 fawns/doe predicted by the regression
equation in 1998) on the Uncompahgre Plateau. Considering historic fetal rates of L 74 fetuses/doe,
there apparently is a major failure to breed, inadequate fetal production, a major loss of fetuses, high
neonatal fawn mortality, or a combination of these factors which result in only 0.36 fawns/doe
(predicted by regression) remaining in December 1998. On average, fawn:doe ratios in Colorado have
declined by about 0.015 fawns/doe/year during the last 20 years which results in a decline of about 0.3
fawns/doe over the 20 years. Fawn:doe ratios on the Uncompahgre Plateau have declined by 0.018
fawns/doe/year during the last 17 years (1982-1998), resulting in a decline of 0.30 fawns/doe over the
17 years. Thus, to determine if fetal rates contribute to the observed changes, we will attempt to detect
a change of 0.30 fawns/doe. A change of 0.30 fawns/doe represents 21 % of the 1.4 (1.74 - 0.36
[predicted by the regression equation for 1998] = 1.4) reduction in the fawn:doe ratio from fetal counts
to December age-ratio counts. Thus, we believe that detecting 21% (±) of the overall loss of
fetuses/fawns from the fetal stage of reproduction to December will provide strong evidence that fetal
production is or is not a major contributing factor to low fawn:doe ratios. To detect a change of 0.30
fawns/doe, about 40 does will be necessary for our evaluation.
Data Analyses
Fetal rates obtained during 1999 on the Uncompahgre Plateau will be compared to historic rates
with a Z test. Significance level to reject the null hypothesis will be at P &lt; 0.05.

LOCATION
This study will be conducted on the Uncompahgre

62 (D-19).

Plateau, Big Game Management

Units 61 and

�151

WORK SCHEDULE
Jan-Feb 1999
Mar-Jun 1999

Capture and ultrasound does
Data analysis and write report

PERSONNEL
Thomas M. Pojar
F. Andelt
LaRue W. Johnson
David C. Bowden
Kenneth P. Burnham

Co-Principal Investigator, Colorado Division of WildlifeWilliam
Co-Principal Investigator, Department of Fishery and Wildlife
Biology, Colorado State University
Co-Principal Investigator, College of Veterinary Medicine and
Biomedical Sciences, Colorado State University
Statistical Consultant, Department of Statistics, Colorado State
University
Colorado Cooperative Fish and Wildlife Research Unit,
Department of Fishery and Wildlife Biology, Colorado State
University

ESTIMATED COST
Item
Helicopter capture
Veterinary consulting
Ultrasound rental
Travel expenses
Vehicle
Mileage
TOTAL
10% contingency
GRAND TOTAL

Number
40 does
1
1
15 days
1 month
2,000 miles

CostlItem
$ 400
$1,000
$ 600
$ 95
$ 400
$
0.15

Total
$16,000
$ 1,000
$ 600
$ 1,425
$ 400
$ 300
$19,725
1,972
$21,697

s

LITERA TURE CITED
Barrett, R H. 1981. Pregnancy diagnosis with doppler ultrasonic fetal pulse detectors. Wildlife
Society Bulletin 9:60-62.
Bartmann, R M. 1998. A prospectus on mule deer in Colorado. Colorado Division of Wildlife, Fort
Collins, Colorado, Unpublished report.
Bartmann, R M., and T. M. Pojar 1998a Experimental deer inventory. Colorado Division of
Wildlife, FederalAid in Wildlife Restoration Job Progress Report, Project W-153-R-ll, July.
_, and _. 1998b. Deer reproduction assessment. Colorado Division of Wildlife, Federal Aid in
Wildlife Restoration Job Progress Report, Project W-153-R-11, July.
Bingham, C. M., P. R. Wilson, and A S. Davies. 1990. Real-time ultrasonography for pregnancy
diagnosis and estimation of fetal age in farmed red deer. Veterinary Record 126:102-106.
Freddy, D. 1. 1988. Effect of elk harvest systems on elk breeding biology. Colorado Division of
Wildlife, Federal Aid in Wildlife Restoration Job Progress Report, Project W-153-R-2, July.
Gill, R B. 1971. Middle Park deer study - productivity and mortality. Colorado Division of Wildlife,
Federal Aid in Wildlife Restoration Job Progress Report, Project W-38-R-25. July:189-207.
_. 1972. Productivity studies of mule deer in Middle Park, Colorado: Second Annual Mule Deer
Workshop, Elko, Nevada, January 12. Xerox.
Lenz, M. F., A W. English, and A Dradjat. 1993. Real-time ultrasonography for pregnancy
diagnosis and foetal ageing in fallow deer. Australian Veterinary Journal 70:373-375.

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Lindahl, I. L. 1971. Pregnancy diagnosis in the ewe by intrarectal doppler. Journal of Animal Science

32:922-925.
Medin, D. E., and A. E. Anderson. 1979. Modeling the dynamics of a Colorado mule deer population.
Wildlife Monographs 68:1-77.
Revel, B., and P. R Wilson. 1991. Ultrasonography of the reproductive tract and early pregnancy in
red .deer. Veterinary Record 128:229-233.
Salwasser, H., S. A. Holl, G. A. Ashcraft. 1978. Fawn production and survival in the North Kings
River deer herd. California Fish and Game 64:38-52.
Sasser, R G., C. A. Ruder, and K. A. Ivani. 1986. Pregnancy detection in farm animals by
radioimmunoassay of a pregnancy-specific protein in serum. in 1. Hau, ed., Pregnancy proteins
in animals. Walter de Gruyer &amp; Co. Berlin.
Schrick, F. N., and E. K. Inskeep. 1993. Determination of early pregnancy in ewes utilizing
transrectal ultrasonography. Theriogenology 40:295-306.
Smith, R B., and F. G. Lindzey. 1982. Use of ultrasound for detecting pregnancy in mule deer.
Journal of Wildlife Management 46:1089-1092.
Stephenson, T. R, 1. W. Testa. G. P. Adams, R G. Sasser, C. C. Schwartz, and K. 1. Hundertmark.
1995. Diagnosis of pregnancy and twinning in moose by ultrasonography and serum assay.
Alces 31:167-172.
Welker, H. 1. 1986. Fawn mortality in the Lake Hollow deer herd, Tehama County, California
California Fish and Game 72:99-102.
White, I. R, W. A. C. KcKelvy, S. Busby, A. Sneddon, and W. 1. Hamilton. 1989. Diagnosis of
pregnancy and prediction of fetal age in red deer by real-time untrasonic scanning. The
Veterinary Record 124:395-397.
Willard, S. T., R G. Sasser, J. C. Gillespie, J. T. Jaques, T. H. Welsh, Jr., and RD. Randel. 1994.
Methods for pregnancy determination and the effects of body condition on pregnancy status in
Rocky Mountain elk (Cervus elephus nelsonii. Theriogenology 42:1095-1102.

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DRAFT MANUSCRIPT
ESTIMATION

OF MULE DEER PREGNANCY AND FETAL RATES ON THE

UNCOMPAHGRE

PLATEAU, COLORADO USING TRANSRECTAL

ULTRASOUND

William F. Andelt, Thomas M. Pojar, and LaRue W. Johnson

Abstract
Mule deer (Odocoileus hemionus) populations apparently have declined in several western states
during the 1990's. In Colorado, mule deer fawn:doe ratios in December have declined by 0.15
fawns/doe/year from 1972 through 1995. Significant declines in the fawn:doe ratio have especially
occurred on the Uncompahgre Plateau near Montrose, Colorado. Thus, we estimated adult mule deer
pregnancy and fetal rates on the Uncompahgre Plateau during the 1998-1999 reproductive cycle to
determine if lower pregnancy or fetal production was the cause of the deer decline. Thirty-seven of 40
(93%) adult does on the Uncompahgre Plateau were detected pregnant with ultrasound, and 36 of the
40 does were detected pregnant with pregnancy-specific protein-B (PSPB). The proportion of does
detected pregnant with ultrasound does not differ (Xl) = 0.053, P = 0.817) from the proportion of does
pregnant (91.4% of303 does) in previous studies in Colorado. The average number of fetuses/doe for
all adult does (pregnant and non-pregnant) on the Uncompahgre Plateau (n = 40, '! = 1.70, SE = 0.109)
was not less (Z = 0.340, P = 0.367) than in previous studies (n = 276, '! = 1.74, SE = 0.038). The
average number of fetuses/doe for pregnant adult does on the Uncompahgre Plateau (n = 37, '!= 1.84,
SE = 0.082) also was not less (Z = 0.260, P = 0.397) than in previous studies (n=258, '! = 1.86, SE =
0.028).

INTRODUCTION
Mule deer (Odocoileus hemionus) populations apparently have declined in several western states
of the United States during the 1990's (Unsworth et al. 1999). In Colorado, mule deer fawn:doe ratios
in December have declined by 0.15 fawns/doe/year from 1972 through 1995 (G. C. White, Colorado
State University, unpublished data). In particular, fawn:doe ratios on the Uncompahgre Plateau of
Colorado have declined (I = -3.39, P = 0.004) by an average of 0.18 fawns/doe/year from 1982-1998,
and have ranged from a high of 79 fawns/100 does in 1982 to a low of 32 fawns/l00 does in 1996 and
34 fawns/100 does in 1997 (Colorado Division of Wildlife, unpublished data). In addition to low
December fawn:doe ratios, over-winter (December - May) fawn survival on the Uncompahgre Plateau
was 49% during the winter of 1997-1998 (Bartmann and Pojar 1998a). The low December fawn:doe
ratios are a concern to the public and game managers.
Pregnancy rates of collected adult (2:2years old) female mule deer have ranged from 97 to 100%
during the 1960's, 1970's, and 1980's in Colorado (Gill 1971, 1972; Medin and Anderson 1979;
Freddy 1987, 1988). The average numbers offetuses per adult doe (fetal rate) have ranged from an
average of 1.83 to 1.91 (Medin and Anderson 1979; Gill 1971, 1972; Freddy 1987, 1988) during the
same period in various areas of Colorado.
Several hypotheses exist to explain the decline in December mule deer fawn:doe ratios including
a failure to breed, reduced fetal production, resorption/abortion of fetuses, or low summer and fall fawn
survival (R. M. Bartmann, Colorado Division of Wildlife, personal communication) mediated by low

�154

buck doe ratios and a protracted fawning period, poor habitat quality and reduced nutrition or hiding
cover, more predators and increased predation, competition with elk (Cervus elaphus), disease,
poisonous plants; drought, or perhaps a combination of these factors. Our objectives in this study were
to determine adult mule deer pregnancy and fetal rates on the Uncompahgre Plateau, Colorado during
the 1998-1999 reproductive cycle. We hypothesized that pregnancy and fetal rates did not differ from
rates obtained during the 1960's, 1970's, and 1980's in Colorado.
Transrectal ultrasonography has been used to accurately detect pregnancy in domestic sheep
(Schrick and Inskeep 1993), fallow deer (Dama dama; Lenz et aI. 1993), red deer (Cervus elaphus;
Bingham et aI. 1990, Wilson and Bingham 1990, Revol and Wilson 1991), and elk (Willard et aI.
1994). Pregnancy-specific protein-B has been used to reliably detect pregnancy in mule deer and
white-tailed deer (Odocoi/eus virginianus; Wood et aI. 1986), muskoxen (Ovibos moschatus; Rowell
et aI. 1989), fallow deer (Wilker et aI. 1993), moose (Alces alces; Haigh et aI. 1993, Stephenson et aI.
1995), and elk (Willard et aI. 1994, Noyes et aI. 1997). Because neither technique has been used
extensively in mule deer, with the exception of Smith and Lindzey (1982) and Wood et aI. (1986), we
also verified the accuracy of both techniques.

STIJDY AREAS
To assess accuracy in determining pregnancy and number of fetuses per mule deer doe, we
investigated captive does at the Colorado Division of Wildlife's Foothills Research Facility in
Northwest Fort Collins,and wild does that were culled on the USFWS Rocky Mountain Arsenal,
Commerce City, Colorado. In our main study, we ultrasounded does on the Uncompahgre Plateau
(Game Management Units 61 and 62, Data Analysis Unit (DAU) D-19) in southwestern Colorado.
The plateau is about 100 km long and 29-40 km wide, and is bounded by the San Miguel and Dolores
rivers on the southwest and west, the Uncompahgre and Gunnison rivers on the east, the Colorado river
on the North, and an escarpment of Dakota sandstone above Pleasant Valley and Dallas creeks on the
southeast (Anderson et aI. 1992). Topography ranges from gently rolling to steep canyons. Deer were
captured on winter range consisting of Pinyon pine (Pinus edulis)-Utahjuniper (Juniperus
osteospenna)-sagebrush
interspersed with open sagebrush parks. The climate is semi-arid, with warm
summers and cold winter.

METHODS
We evaluated 10__
captive and 15 wild mule deer does to ascertain the accuracy of ultrasound and
PSPB for detecting pregnancy and fetal rates. We restrained 6 (5 or 6 years old) of the 10 captive does
in a capture pen and immobilized them with an intramuscular injection of 420-500 mg ofketamine and
80-100 mg ofxylazine (a 5:1 mixture) on 25 January 1999. We also immobilized 4 yearling (about
1.6 years old) captive does with a dart gun using 250 mg oftelazol and 125 mg ofxylazine. After
processing, tranquilization was reversed with 10 mg of yohimbine. We evaluated the 15 wild does (2
yearling and 13 adults), which were culled for herd management purposes by the U.S. Fish and
Wildlife Service, on 31 January 1999. We captured 40 adult mule deer does on the Uncompahgre
Plateau with a netgun fired from a Hughes 500C helicopter (Helicopter Capture Services, Marysvale,
Utah, USA; Barrett et aI. 1982). The does were captured on deer winter range in proportion to their
density within 8 strata located around the edge of the plateau. The deer were manually restrained,
hobbled, blindfolded, and transported by helicopter to a base station, usually &lt;6 km from the capture
site, where they were processed on 5-8 February 1999. We aged each doe as ajuvenile, yearling, or
adult by tooth replacement and wear, weighed each doe, and injected the first 32 does subcutaneously

�155

with 5 ml of vitamins A (500,000 iu's), D3 (50,000 iu's), and E (1,500,000 iu's). We attached a 148
MHz telemetry collar, and, after processing, released all except 1 doe at the processing sites; the 1 doe
was transported by helicopter to the capture site and released there because a steep canyon separated
the capture and processing sites. In addition, 1 juvenile female, 2 yearling females, and 2 males were
captured. The juvenile was immediately released at the processing site, the 2 yearlings were processed
similar to the adult does and released at the processing site, and the 2 males were immediately released
at the capture site. We processed and released does within about 30 minutes of capture.
We placed the 25 does used for accuracy evaluation and the 40 study does in dorsal recumbency
and used a portable ultrasound unit (Aloka 500V, Aloka, Wallingford, Connecticut, USA) with a 5
MHZ linear-array probe, powered by a portable generator in the field, to ascertain pregnancy and
number of fetuses/doe via trans rectal ultrasonography (Smith and Lindzey 1982, Bingham et al. 1990,
Stephenson et al. 1995). We also collected about 10 ml of blood viajugular venipuncture to assess
levels ofPSPB and ascertain pregnancy status. The blood was allowed to clot, centrifuged, and, the
serum was decanted and stored on ice and then frozen. The serum was submitted to BioTracking
(Moscow, Idaho, USA) to assess levels ofPSPB (Stephenson et al. 1995, Noyes et al. 1997).
We ascertained accuracy of the ultrasound and PSPB procedures by performing necropsies and
counting the number of fetuses in 1 captive doe that died from chronic wasting disease and 3 other
does that were euthanized because of chronic wasting disease (M. A. Wild, Colorado Division of
Wildlife, personal communication). We also ascertained accuracy of the ultrasound and PSPB by
counting the number of fawns born during May-June 1999 for the other 6 captive does, whereas we
necropsied the does collected on the Rocky Mountain Arsenal to determine the number of fetuses. One
of us (L WJ) had extensive experience using ultrasound techniques and conducted all ultrasound
procedures.
Apriori, we conducted a power analysis to estimated the sample size necessary to detect a
departure in fetal rates from previous studies of fetal rates in Colorado. For the previous studies, we
used the weighted mean of fetal rates for adult does from .the Poudre River drainage (n = 41, x = 1.83,
SD = 0.44; Medin and Anderson 1979), Middle Park (n = 119, x= 1.86, SD = 0.57; Gill 1971), the
Forbes-Trinchera Ranch (n = 33, x = 1.91, SD = 0.46; Freddy 1987, 1988), and the Piceance Basin
([1973: n = 61, x= 1.46, SD = 0.77][1978: n = 37, x= 1.65, SD = 0.72]; G. C. White, Colorado State
University, personal communication) to estimate a historic mean (1.74) and standard deviation (0.64).
We used an expected 1999 standard deviation equal to the historic standard deviation (0.64; G. C.
White, personal communication) in our analysis.
We were primarily interested in ascertaining if pregnancy rates and fetal rates were a major
contributor to the observed low December fawn:doe ratio (0.36 fawns/doe predicted by the regression
equation for 1998 using data on fawn:doe ratios from 1982-1998) on the Uncompahgre Plateau.
Considering historic fetal rates of 1.74 fetuses/doe, and a predicted fawn:doe ratio of 0.36 remaining on
the Uncompahgre Plateau in December 1998, there is considerable loss of fetuses or fawns. On
average, fawn:doe ratios in Colorado have declined by about 0.015 fawns/doe/year from 1972 to 1995
which results in a decline of about 0.3 fawns/doe over the 23 years. Fawn:doe ratios on the
Uncompahgre Plateau have declined by 0.018 fawns/doe/year during the last 17 years (1982-1998),
resulting in a decline of 0.30 fawns/doe over the 17 years. Thus, we attempted to determine if fetal
rates contributed to the observed change of 0.30 fawns/doe which represents only 21% of the observed
reduction in the fawn:doe ratio of 1.4 (1.74 - 0.36 [predicted by the regression equation for 1998] =
1.4). Thus, our sample size of 40 does was aprior estimated to have power of 80% for detecting a
change of 0.3 fawns/doe at an alpha of 0.05.
The proportion of adult does pregnant during 1999 was compared to historic data with a chisquare test (proc Freq, SAS Institute 1988). Fetal rates obtained during 1999 were compared to
historic rates with a Z-test. An alpha level 0[0.05 was considered significant.

�156

RESULTS
Via necropsy or observing newborn fawns, we ascertained that 1 of the 10 captive does did not
have a fetus, 3 does produced 1 fetus or fawn, and 6 does produced twin fetuses or fawns. Via
ultrasound, we estimated that 3 captive does had single fetuses, 6 does had twins, and 1 doe had
triplets. Thus, for each of 3 does, we estimated 1 more fetus via ultrasound compared to necropsies or
observation of newborn fawns. All does were detected pregnant via PSPB levels.
We necropsied the 15 culled mule deer does (2 yearlings and 13 adults) and found 5 does (2
yearlings and 3 adults) were barren, 3 does each contained 1 fetus, 6 does contained twins, and 1 doe
contained triplets. Using ultrasound, we accurately detected all 15 does as pregnant or not pregnant.
We also detected the correct number of fetuses per doe for 12 of the 15 does. We incorrectly detected
3 fetuses via ultrasound in 1 doe but she had only 2 fetuses, and we detected only 1 of 2 fetuses in 2
other does. PSPB levels indicated that 12 of the 15 does were pregnant; two of the 12 does were not
detected-pregnant via both ultrasound and necropsy ..
Thirty-seven of the 40 (93%) adult does on the Uncompahgre Plateau were detected pregnant
with ultrasound. This proportion does not differ (XZJ = 0.053, P = 0.817) from the proportion of does
pregnant (91.4% of303 does) in previous studies in Colorado (Gill 1971, 1972; Medin and Anderson
1979; Freddy 1987, 1988; R M. Bartmann, Colorado Division of Wildlife, unpublished data). The
average number of fetuses/doe for all adult does (pregnant and non-pregnant) on the Uncompahgre
Plateau (n = 40, ~= 1.70, SE = 0.109) was not less (Z= 0.340, P = 0.367) than in previous studies (n
= 276, ~= 1.74, SE = 0.038; Gill 1971, 1972; Medin and Anderson 1979; Freddy 1987, 1988; R M.
Bartmann, Colorado Division of Wildlife, unpublished data). The average number of fetuses/doe for
pregnant adult does on the Uncompahgre Plateau (n = 37, ~ = 1.84, SE = 0.082) also was not less (Z =
0.260, P = 0.397) than in previous studies (n = 258, ~ = 1.86, SE = 0.028). PSPB levels concurred
with ultrasound in ascertaining pregnancy in 39 of the 40 does; PSPB levels indicated 1 doe was not
pregnant whereas 2 fetuses were visually detected via ultrasound.

DISCUSSION
We failed to detect a difference in pregnancy and fetal rates of adult female mule deer between
our and previous studies in Colorado. Bartmann and Pojar (1998b) also found a relative high
pregnancy rate of93.0% for 29 does ~1 year old near Red Feather, Colorado during January 1998.
Thus, a failure to breed or maintain pregnancy thru at least early February can be discounted as the
cause of the low fawn:doe ratios observed on the Uncompahgre Plateau.
We restricted our. analyses of pregnancy and fetal rates to adult (~2 years old) mule deer does.
We did not include yearlings in our sample because a lower proportion of yearlings become pregnant
and they have lower fetal rates which would have biased our comparisons to historic rates unless the
proportions of yearlings in both samples were equal.

�157

LITERATIJRECITED
Anderson, A. E., D. C. Bowden, and D. M. Kattner. 1992. The puma on Uncompahgre Plateau,
Colorado. Colorado Division of Wildlife Technical Publication No. 40. Fort Collins, Colorado,
USA.
Barrett, M. W., J. W. Nolan, and L. D. Roy. 1982. Evaluation of a hand-held net-gun to capture large
mammals. Wildlife Society Bulletin 10:108-114.
Bartmann, R M. 1998. A prospectus on mule deer in Colorado. Colorado Division of Wildlife, Fort
Collins, Colorado, USA. Unpublished report.
_, and T. M. Pojar 1998a. Experimental deer inventory. Colorado Division of Wildlife, Federal Aid
in Wildlife Restoration, Project W-153-R-11, Progress Report .
._, and _. 1998b. Deer reproduction assessment. Colorado Division of Wildlife, Federal Aid in
Wildlife Restoration, Project W-153-R-11, Progress Report.
Bingham, C. M., P. R Wilson, and A. S. Davies. 1990. Real-time ultrasonography for pregnancy
diagnosis and estimation of fetal age in farmed red deer. The Veterinary Record 126:102-106.
Freddy, D. J. 1987. Effect of elk harvest systems on elk breeding biology. Colorado Division of
Wildlife, Federal Aid in Wildlife Restoration, Project 01-03-047, Progress Report.
Freddy, D. J. 1988. Effect of elk harvest systems on elk breeding biology. Colorado Division of
Wildlife, Federal Aid in Wildlife Restoration, Project W-153-R-2, Progress Report.
Gill, R B. 1971. Middle Park deer study - productivity and mortality. Colorado Division of Wildlife,
Federal Aid in Wildlife Restoration, Project W-38-R-25, Progress Report.
_. 1972. Productivity studies of mule deer in Middle Park, Colorado. Second Annual Mule Deer
Workshop, Elko, Nevada
Haigh, J. C., W. J. Dalton, C. A. Ruder, and R G. Sasser. 1993. Diagnosis of pregnancy in moose
using a bovine assay for pregnancy-specific protein B. Theriogenology 40:905-911.
Lenz, M. F., A. W. English, and A. Dradjat. 1993. Real-time ultrasonography for pregnancy
diagnosis and foetal ageing in fallow deer. Australian Veterinary Journal 70:373-375.
Medin, D. E., and A. E. Anderson. 1979. Modeling the dynamics of a Colorado mule deer population.
Wildlife Monographs 68: 1-77.
Noyes, J. H., R G. Sasser, B. K. Johnson, L. D. Bryant, and B. Alexander. 1997. Accuracy of
pregnancy detection by serum protein (PSPB) in elk. Wildlife Society Bulletin 25:695-698.
Revol, B., and P. R Wilson. 1991. Ultrasonography of the reproductive tract and early pregnancy in
red deer. The Veterinary Record 128:229-233.
Rowell, J. E., P. F. Flood, C. A. Ruder, and R G. Sasser. 1989. Pregnancy-specific protein in the
plasma of captive muskoxen. Journal of Wildlife Management 53:899-901. .
Salwasser, H., S. A. Hell, G. A. Ashcraft. 1978. Fawn production and survival in the North Kings
River deer herd. California Fish and Game 64:38-52.
SAS Institute Inc. 1988. SAS/STAT User's guide, release 6.03 edition, SAS Institute Inc., Cary,
North Carolina, USA.
Schrick, F. N., and E. K. Inskeep. 1993. Determination of early pregnancy in ewes utilizing
transrectal ultrasonography. Theriogenology 40:295-306.
Smith, R B., and F. G. Lindzey. 1982. Use of ultrasound for detecting pregnancy in mule deer.
Journal of Wildlife Management 46:1089-1092.
Stephenson, T. R, J. W. Testa G. P. Adams, R. G. Sasser, C. C. Schwartz, and K. J. Hundertmark.
1995. Diagnosis of pregnancy and twinning in moose by ultrasonography and serum assay.
Alces 31:167-172.
Unsworth, J. W., D. F. Pac, G. C. White, R. M. Bartmann. 1999. Mule deer survival in Colorado,
Idaho, and Montana. Journal of Wildlife Management 63:315-326.

�158

Wilker, c., B. Ball, T. Reimers, G. Sasser, M. Brunner, B. Alexander, and M. Giaquinto. 1993. Use
of pregnancy-specific protein-B and estrone sulfate for determination of pregnancy on day 49 in
fallow deer (Dama dama).
Willard, S. T., R G. Sasser, J. C. Gillespie, J. T. Jaques, T. H. Welsh, Jr., and RD. Randel. 1994.
Methods for pregnancy determination and the effects of body condition on pregnancy status in
Rocky Mountain elk (Cervus elephus nelsoni). Theriogenology 42:1095-1102.
Wilson, P. R, and C. M. Bingham. 1990. Accuracy of pregnancy diagnosis and prediction of calving
date in red deer using real-time ultrasound scanning. The Veterinary Record 126:133-135.
Wood, A. K., R E. Short, A. Darling, G. L. Dusek, R G. Sasser, and C. A. Ruder. 1986. Serum
assays for detecting pregnancy in mule and white-tailed deer. Journal of Wildlife Management

50:684--687.

�159

APPENDIX II

Research Program Narrative

IMPACT OF PREDATION AND VEGETATIVE COVER ON
NEONATAL MULE DEER FAWN SURVIVAL

21 October 1998

Principal Investigators:

THOMAS M. POJAR
Colorado Division of Wildlife
317 W. Prospect
Fort Collins, CO 80526
970-472-4308

WILLIAM F. ANDELT
Department of Fishery and Wildlife Biology
Colorado State University
Fort Collins, CO 80523
970-491- 7093

�160

�161

PROGRAM NARRATIVE
State of
--"C=o=lo=r=ad=o~
_
Project No.
W!..!.--.:..:15::..::3:....-R~ _
Work Package No. _;3:::..;0:&lt;...:0'-"1
_
Task No.
----:.4
_

Cost Center 3430
Mammals Program
Deer Conservation
Impact of Predation and Vegetative Cover on
Mule Deer Fawn Survival

NEED
There is evidence that the mule deer (Odocoileus hemionus) population in Colorado has
declined during recent years due mostly to low fawn survival and subsequent low population
recruitment (Bartmann 1997). Colorado Division of Wildlife quadrat surveys to estimate population
size suggest that some mule deer herds have declined by 31 % since 1992 while some have not shown
much change during this time (Bartmann 1997). On 2 areas where recent over-winter (1997-98) survival
was estimated, rates of fawn and adult doe survival was 74% (n = 38) and 100% (n = 30) for the Red
Feather herd (D-4) and 49% (n = 39) and 84% (n =31) for the Uncompahgre herd (D-19), respectively
(Bartmann and Pojar 1998a). This supports the contention that some of the purported population
declines may be influenced by over-winter fawn survival. However, some herds have low December
fawn:doe ratios indicating possible deficiencies in 2 major population growth mechanisms - initial fawn
production (pregnancy rates) and neonatal fawn survival (Bartmann 1998).
Pregnancy rates during January 1998 were 93% for 29 does &gt;1 year old in the Red Feather
DAU (Bartmann and Pojar 1998b) which was similar to 92.0% ofl63 does (&gt;2 years old) pregnant in
the same area during 1961-1964 (Medin and Anderson 1979), a 94.8% pregnancy rate for adult does
(n = 114) and a 94.0% pregnancy rate for adult and yearling does (n = 134) in Middle Park (Gill 1971),
and rates of 89% (n = 47) during 1973 and 82% (n = 83) during 1978 in the Piceance Basin (Bartmann
1998). The 1998 data indicate that the proportion of does becoming pregnant probably was not
contributing to the low fawn:doe ratios, however these data were not collected in the Uncompahgre
DAU where ratios were lowest. Pregnancy rates will be obtained in the Uncompahgre DAU during
January 1999 to ascertain if these rates are contributing to the low fawn:doe ratios.
Fetal rates for does older than yearlings were 1.83 (n = 41) in the Cache la Poudre River
drainage from 1961-1965 (Medin and Anderson 1979) and 1.82 (n = 114) in Middle Park (Gill 1971).
If fetal rates are currently as high as they were in the 1960's, then high rates of fawn mortality are likely
responsible for the low. and declining fawn:doe ratios. Thus, determining the causes and magnitude of
fawn mortality from birth through December will be extremely important for understanding mule deer
population trends in Colorado.
Low neonatal fawn survival is probably the most sensitive indicator that the environmental needs
of populations are not being met (Gaillard et al. 1998). Fawn:doe ratios obtained in December have
declined by an average of 1.5 fawns per 100 does per year from 1972-1995 (Bartmann 1997, G. C.
White, Dept. Fishery and Wildlife Biology, Colorado State University, pers. commun.). December
1997 fawn:doe ratios were 34.2 in the Uncompahgre DAU and 58.8 in the Red Feather DAU
(Bartmann and Pojar 1998a). The December fawn:doe ratios and over-winter survival rates indicate
that the status of the Uncompahgre deer herd is of greatest concern.
Gruell (1986) hypothesizes that historic (1880-1930) domestic livestock grazing and fire
suppression caused successional changes in rangeland communities favoring shrubby species resulting
in optimal mule deer habitat during the period 1930-1960. These conditions resulted in the irruption
and overpopulation of deer herds and may have reduced present day carrying capacity which may be

�162

mediated by lower nutrition andlor greater susceptibility to predation (see also Salwasser et al. 1978).
Fire suppression and removal of herbaceous species by grazing can foster conditions that favor woody
species invasion (Skovlin 1991) and decadent/senescent stands of shrubby species (Clements and
Young 1996) thereby reducing the canying capacity for deer. Once the stable state of a particular
vegetation type has been disrupted, especially in arid or semi-arid rangeland types, the vegetative
community may stabilize at a lower successional state that is highly resistant to change without drastic
perturbations (Laycock 1991). It is possible this situation is in process on the Uncompahgre Plateau
(and other areas of the West) with the constant expansion of the pinon-juniper vegetative community
into sagebrush and grassland communities.
A low fawn:doe ratio on the Uncompahgre DAU could result from several causes including
malnutrition and predation. Competition with elk (Cervus elaphus) for food or space on wintering
grounds, or for fawning sites on summer range may cause poor neonate survival through decreased
nutrition or increased susceptibility to predation. Livestock grazing can reduce forbs and fawn hiding
cover (Loft et al. 1987) which can influence nutrition and predation (Smith and LeCount 1979, Bowyer
and Bleich 1984), but there likely is less livestock grazing now thanwhen deer were more abundant
indicating recent grazing may not be the cause of the decline. A short-term drought may have reduced
forage for lactating does, may have protracted the fawning period making fawns more susceptible to
predators as in white-tailed deer (Odocoi/eus virginianus, Andelt et al. 1987), or reduced alternate
prey for predators which may be exacerbating the low fawn:doe ratios. Smith and LeCount (1979)
reported that survival of mule deer fawns was associated with winter forb yield and October-April
rainfall of the winter-spring period preceding the fawning period.
Coyotes (Canis latrans) and other predators kill and eat mule deer fawns and adults, however
the population impact of this predation is variable. Connolly (1978) cited 31 studies which reported
predation as a limiting or regulating influence on ungulate populations in North America Connolly
(1978) also cited 27 studies which indicated that predators did not limit or control the size of ungulate
populations. Filonov (1980) provides evidence that the total loss to natural mortality for ungulates is
relatively stable and that it is maintained by a complex system of compensating mechanisms, one of which
is predation. Because of functional substitution of mortality factors, the various reasons for natural
mortality are independent of the total mortality and the range of mortality rates remains somewhat constant.
An example of compensatory mortality was demonstrated in the Piceance Basin of Colorado where
predator control reduced overwinter mule deer mortality to predators, but the effect was compensated
for by additional mortality due to starvation (Bartrnann et al. 1992). We need to determine the causes
of neonatal fawn mortality in areas with low fawn:doe ratios, such as Uncompahgre Plateau, so that we
know where to focus experimental research and management.
Predator density is one factor that may have a significant impact on fawn survival independent of
vegetational or nutritional components of the habitat (Smith et al. 1986). Coyotes, black bears (Ursus
americanus), mountain lions (Felis concolor), and bobcats (Felis rufus) are found on the
Uncompahgre Plateau and in other areas of Colorado, and may have a limiting effect on mule deer.
Coyotes have been responsible for high neonatal white-tailed deer fawn (Cook et al. 1971, Garner et al.
1976, Litvaitis and Bartush 1980, Stout 1982), high neonatal mule deer fawn (Steigers and Flinders
1980, Steigers 1981), and high overwinter mule deer fawn (White et al. 1987) mortality. Beck (1995)
reported a density of O. 93 black bears/mf on the Uncompahgre Plateau, and black bears can prey on
mule deer fawns (Smith 1983), white-tailed deer fawns (Ozoga and Verme 1982, 1986; Mathews and
Porter 1988), and elk calves (Schlegel 1976). Anderson et al. (1992) estimated that a minimum
population of34 mountain lions on 3,120 km2 of the Uncompahgre Plateau may have killed 1,885 to
2,060 mule deer or about 8 to 12% of the estimated wintering deer population during 1987. Welker
(1986) reported that mountain lions killed 2 or 3 of 16 radioed mule deer fawns; Bleich and Taylor
(1998) found that mountain lion predation on adult does was the primary source of mortality in
northeastem California herds. Bobcats also kill deer (Litvaitis et al. 1986) and pronghorn fawns

�163

(Antilocapra americana) (Autenrieth 1982, 1984). Although these predators kill deer, their impact on
mule deer fawn:doe ratios in Colorado is unknown. If predators are responsible for the low fawn:doe
ratios, we need to determine which predator is the major contributor, and if some factors, such as low
hiding cover, less alternate prey (Horejsi 1982, Andelt et al. 1987), a protracted fawning season,
predator abundance, and possibly a high predator:deer ratio are making fawns more vulnerable to
predation.
Height of vegetation apparently plays an important role in the survival of neonate ungulates.
Riley and Dood (1984) and Boyer et al. (1998) reported that mule deer fawns and (Decker 1991)
reported that white-tailed deer fawns selected habitat types with dense vegetative cover. Horejsi
(1982) reported that in years of drought, mule deer fawn survival was lower in areas oflivestock
grazing and attributed this to decreased ground cover. Benzon (1996) reported that white-tailed deer
fawns in the Black Hills, South Dakota, selected an understory of grasses for diurnal bed sites; height
and density of vegetation was higher at bed sites than what was randomly available. Tucker and
Garner (1983) reported that bed sites of pronghorn &lt;4 weeks old were found in cover taller than that in
surrounding areas. Autenrieth (1982, 1984) suggested that taller cover was important for reducing
pronghorn fawn mortality to predators. Rothchild (1993) reported that vegetation was taller at the bed
sites of pronghorn fawns than at random sites and the vegetation also was taller at bed sites of
surviving pronghorn fawns compared to fawns that did not survive. Rothchild et al. (1984) suggested
that pronghorn fawns with larger home ranges may sustain higher coyote predation in tall grass prairie
of east central Kansas.
Fawns have an infinite number of potential bed site locations within their home ranges.
Measurement of random sites that are possible bed sites should be within a typical home range of a
fawn. Home ranges of mule deer fawns in northern Colorado were variable and estimated at 130 ha
from 10 June through August (Geduldig 1981). Average summer home range size offawns was 185
ha in the Missouri River Breaks, Montana and home range size decreased with increased population
size (Riley and Dood 1984). Home range size of fawns increased with age in south-central
Washington and averaged 257 ha for fawns 60 days or older (Steigers and Flinders 1980). Mule deer
fawns traveled variable distances each day, and these distances more than doubled when fawns were
61-90 days old (640 m) compared to when 1-30 days old (319 m) (Steigers and Flinders 1980).
OBJECTIVES
We propose to identify the agents of mortality and quantify the extent of depredations on neonatal
mule deer fawns. We also propose to correlate height, density, and composition of vegetation at fawn
birth and bed sites with fawn survival.

HYPOTHESES
Our hypotheses are divided under two research areas, predation and vegetative cover.
1.
What is the contribution of coyotes and other predators to neonatal mule deer fawn mortality?
Hoi: The proportions of fawns killed by coyotes, black bears, mountain lions, and bobcats do not
differ from one another.
H.,2: Predation on fawns is not related to sex or activity of fawns; activity as measured by the
distance between successive bed sites.
Ho3: Predation on fawns to 8 weeks of age is not related to the average distance between a fawn
and its mother.
H04: Survival offawns and causes of mortality do not differ among 3 vegetatively and
ecologically different study areas.
Hos: Fawn birth weights and measurements do not differ among study areas.
Roo: Distances between fawn bed sites do not differ among study areas.

�164

2.

Do height and density, and/or composition of vegetation at fawn birth and bed sites correlate with
the percent of fawns killed by predators?
H"I: Predation rates on fawns is not related to height and density (visual obstruction readings),
and/or composition of vegetation at birth and bed sites.
Ho2: Height and density (visual obstruction readings, VOR), and/or composition of vegetation
do not differ between fawn bed sites and random sites.
Ho3: Height and density (VOR), and/or composition of vegetation at fawn bed sites and random
sites do not vary among study areas.

EXPECTED RESULTS OR BENEFITS
This research will quantify the amount and causes of neonatal fawn mortality and contribution of
various predators to this mortality. The influence of vegetative characteristics at birth and bed sites on
subsequent fawn survival will be estimated. Knowledge of these factors will assist in evaluating the
causes of low December fawn:doe ratios and will guide future research to determine the effect of
various experimental manipulations on neonatal fawn survival. For political, social, and economic
reasons, we need to have knowledge about the causes of low fawn:doe ratios before corrective action is
taken.

APPROACH
Animal Care and Use: All capture and handling of animals will comply with the standards of the
Colorado Division of Wildlife and Colorado State University Animal Care and Use Committees. We
will obtain a collectors permit from the Colorado Division of Wildlife and secure trespass permission
from study site owners prior to the study.
Fawn Capture: In a related study, 40 radioed mature does will be monitored on each study area to
determine adult doe survival (Federal Aid Project W-153-R); fawns will be located primarily by
monitoring these does and capturing their fawns. Our objective will be to capture and radio 25-35
fawns on each of 3 study areas. Three study areas will be selected based on : a) contrasting
vegetative/ecological characteristics, b) a range in fawn:doe ratios indicating contrasting fawn survival
rates, and c) availability of radio collared does to minimize fawn capture costs and ensure randomness
in fawn capture. Three candidate areas which meet all 3 characteristics are: The Uncompahgre, Middle
Park, and Red Feathers DAUs.
Fawns &lt;10 days old will be captured and fitted with expandable, drop-off radio collars. Fawns
younger than 24 hr will not be captured to allow dam-newborn fawn bonding (White et al. 1972).
Precautions will be taken to minimize injury or abandonment by the dam from the capture operation
based on recommendations of Beale and Smith (1973) and Livezey (1990). The radio collars and all
handling equipment will be stored in containers with native shrub/tree (sagebrush or juniper) material to
help mask "unnatural" odors. Plastic gloves will be worn by the handlers.
Fawn Processing: Captured fawns will be blindfolded, weighed, and the right hind foot will be
measured as an index of skeletal size. If age is not known from observed parturition, it will be
estimated by hoof condition and length, umbilical condition, and general body size, activity, and hair
coat condition will be subjective measures of age. Each fawn will be individually marked with a plastic
ear tag in the right ear; the ear tag will have engraved numbers which contrast to the color of the tag.
An expandable radio transmitter (with mortality sensor) collar will be fitted; the collar will be designed
to drop off after about 6 months. Before release, the fawn will be examined for injuries and it's general
health and condition will be noted and recorded. Each fawn will be carefully observed after release and,
. if possible, observed until it is rejoined by it's mother.

�165

Fawn and Doe Monitoring: Each fawn and doe will be radio located daily for the first 6 weeks of the
fawn's life, every 3rd day for the next month, and then once weekly through the end of November.
Precautions will be taken to avoid disturbance of the fawn or dam during radio relocation except when
prescribed bed site measurements are taken (see below). Radios on mortality signal will be located and
the carcass (if available) will be examined for cause of death using criteria outlined in White (1973),
Wade and Bowns (1984), Acorn and Dorrance (1990), and Andelt et al. (1998). If the carcass is
missing, the general area will be surveyed for signs of predation and our best judgement of cause of
death will be made or the cause will be recorded as "unknown".
Birth and Bed Site Measurements:
Vegetative cover will be measured at birth sites when they can be
positively identified. Measurements will be taken at bed sites every 5th day to minimize disturbance of
individual fawns. If a bedded fawn is found and does not flush, the point of observation will be flagged
and GPS coordinates will be recorded. Distance to the bed sitewill be measured with a laser range
finding scope (e.g. Bushnell "yardage Pro") and the direction to the site will be measured with a hand
held compass. Marked bed sites will be measured the next day to minimize any changes in vegetation
from time of use. The objective will be to obtain lObed site measurements for each fawn during their
first 8 weeks of life.
Micro habitat vegetational measurements of birth and bed sites will be a modification of those
taken by Benzon (1996). Cover of shrubs by species, grass, and forbs will be estimated using 4 0.1 m2
(20 x 50 em) quadrants (Daubenmire 1959) 'placed in the 4 cardinal directions length-wise from the bed
center; the 20 em end of the frame will be centered on and touching the bed site center stake. Visual
obstruction from the birthlbed site will be estimated from the 4 cardinal directions using a robel pole
viewed from a distance of 4 m and height of 0.5 m from the site (Robel et al. 1970). No adjustments
will be made for relief in the terrain.
For every birth or bed site measured, we will take identical measurements on IO.random sites
within aBO ha square area centered on the bed site. The random sites will be located using random
coordinates.
Sample Sizes and Power of Tests: Estimates of the means and variances of2 or more treatments are
necessary before conducting power analyses. Estimates of these parameters are not known for the
proportions of fawns killed by various predators, and the effect of vegetation height on susceptibility of
fawns to predation. However, some educated guesses about the magnitude of these parameters will
help determine sample sizes. We calculated power for our hypotheses of primary management interest
including: 1) proportions of fawns killed by various predators, and 2) the effect of vegetation height on
susceptibility of fawns to predation. We calculated for vegetation height vs. susceptibility to predation
by using 2 height categories, whereas the actual analysis' will consist of regression using a continuum of
vegetation heights. Thus, the power of the actual experiment likely will be somewhat less than
presented below. We did not calculate power for our hypothesis of differences in vegetation height at
fawn bed sites and random sites because sample sizes will be inherently larger that number 2 above.
An alpha of 0.05 was used in all estimates of power. Power of 0.8 or higher is desired.
Data Analyses: The proportions of fawns killed and the proportions killed by various causes of
mortality (predation, disease, malnutrition) will be compared among study areas with chi-square (proc
Freq, SAS Institute, Inc. 1988). The proportion of fawns killed by various predators and the proportions
of male and female fawns killed by predators will be compared with chi-square. The effect of distance
between bed sites and the distance between fawns and their mothers on fawn survival will be estimated
with logistic regression (Proc Genmod, SAS Institute Inc. 1993) by blocking on study areas. Fawn birth
weights and measurements, and distances between consecutive bed sites will be compared among study
areas with analysis of variance. The effect of vegetation height and density (VOR) on survival of fawns
will be estimated with logistic regression (proc Genmod, SAS Institute Inc. 1993) by blocking on study

�166

Power for Evaluating if the Expected Relative Proportions of Fawns Killed by Coyotes, Black Bears,
and Mountain Lions Varies from Equality (i.e. 0.33 killed by each predator):
Fawns
killed en)
10
20
30
50
75
100
10
20
30
50
75
100

Coyotes
0.5
0.5
0.5
0.5
0.5
0.5
0.7
0.7
0.7
0.7
0.7
0.7

Proportion killed by various predators
Black Bears
Mountain Lions
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15

Power
0.16
0.27
0.39
0.60
0.79
0.90
0.59
0.89
0.98
1.00
1.00
1.00

I-Sided Power for the Effect of Vegetation Height on Survival of Fawns to 2 Months:
Sample sizes
Short
20
40
40
80
40
40
40

Tall
20
40
40
80
40
40
40

ProPQrtion surviving
Short
Tall
0.7
0.8
0.7
0.8
0.7
0.9
0.7
0.9
0.5
0.64
0.5.
0.7
0.5
0.8

Power
0.11
0.18
0.61
0.88
0.27
0.73
0.80

areas (Appendix 1). The height and density of vegetation at fawn bed sites and random sites will be
compared with analysis of variance by blocking on study areas. The proportion of vegetation that is
composed of forbs, grass, and shrubs will be compared between bed sites and random sites and among
study areas with analysis of variance. Significance level to reject the null hypothesis will be at P &lt; 0.05.

LOCATION
This study will be done on 3 areas, Uncompahgre Plateau (D-19), Middle Park (D-9), and Red
Feathers (D-4).

WORK SCHEDULE
Oct-Dec 1998
Jan-May 1999
Jun-Dec 1999
Jan-Jun 2000

Complete Program Narrative and confirm study area selection
Procure and test field equipment and hire summer crew
Capture, radio collar, and track fawns
Data analysis and report writing

PERSONNEL
Thomas M. Pojar

Co-Principal Investigator, CDOW

William F. Andelt

Co-Principal Investigator, Department of
Fishery and Wildlife Biology, Colorado State
University

�167

David C. Bowden

Statistical Consultant, Department of
Statistics, Colorado State University

Gary C. White

Analytical Consultant, Department of Fishery
and Wildlife Biology, Colorado State
University

ESTIMATED COST

Personal Services
PFTE costs
Andelt
Pojar
TFTE costs
Operating
Vehicle (4x4)
Radios
Field equipment
Travel Expenses
Capitol
TOTAL
5% contingency
GRAND TOTAL

FY 98-99·

FY 99-00b

Totalc

$ 56,250
$ 45,000
$ 18,216

$ 75,000
$ 60,000
$ 26,717

$131,250
$105,000
$ 44,933

$ 18,306
$ 22,000
$ 13,500
$ 1,800

$ 33,900
na
na
$ 2,250
0
$197,867
$ 9,893
$207,760

$ 52,206
$ 22,000
$ 13,500
$ 4,050
0
$372,939
$ 18,647
$391,586

o
$175,072
$ 8,754
$183,826

"Cost for FY 1998-99, representing field operations during May-June, 1999.
"Cost for completion of the 1999 field operation during FY 1999-00, July-December 1999.
"Total cost for 1 complete field season spanning 2 fiscal years.
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�168

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_
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Prepared by

_
Thomas M. Pojar
Wildlife Researcher
Colorado Division of Wildlife

William F. Andelt
Associate Professor
Department of Fishery and Wildlife Biology
Colorado State University

Appendix 1. Logistic regression table for the effect of vegetation height on survival offawns. The
analyses will be conducted with SAS using Proc Genmod.
Numerator
Source
Height
Areas

DF
1
2

M.S.
height
area

Denominator
DF
M.S.
Fawns -5
Error (Model)
Fawns -5
Error (Model)

�127
Colorado Division of Wildlife
Wildlife Research Report
July 2000

JOB PROGRESS

State of
Project No.

Colorado

Cost Center 3430

W-153-R-13

Mammals Program

Work Package No. _---'3:;...;:0'-"'0..:...1
Task No.

1

Period Covered:

REPORT

Deer Conservation

_

Investigating Factors Contributing to Declining
Mule Deer Numbers

July 1 1999 June 30, 2000

Author: T. M. Pojar
Personnel:
_)
.-- /

T. Baker, T. Beck, C. Bishop, G. Bock, D. Coven, L. Dehart, B. Diamond, B. Dreher, J.
Ellenberger, V. Graham, J. Griggs, D. Gustine, B. Hoffner, B. Lamont, M. King, K. Larsen,
M. Mclain, H. McNally, K. Miller, M. W. Miller, E. Myers, J. Olterman, D .
Schweitzer, T. Spraker, B. Watkins, S. Znamenacek.

ABSTRACT
Long-term data indicate that fawn:doe ratios have shown a significant and consistent decline over the past
20 years in most deer management units in Colorado as well as in most of the western states. This has
resulted in a general decline in mule deer (Odocoileus hemionus) density and diminished recreational
potential from this major resource. It is important for the Division of Wildlife to understand the factors
contributing to the reduced fawn:doe ratios and the declining deer populations. Neonatal survival (birth to
6 months of age) is an important component of population recruitment. This is the second year of
monitoring cause-specific neonatal fawn mortality on the Uncompahgre Plateau. In 1999, a sample of 50
fawns was radioed and during the 2000 fawning season 88 fawns were captured. Fawns were captured as
. near birth as possible and are monitored to about 6 months of age. A new design radio collar that weighed
1109 was used on the 2000 season fawns. The collar was expandable and used latex tubing to facilitate
drop-off in about 6 months. Neonatal fawn survival for 1999 was 38%. Of the 50 fawns collared, 30%
died of sickness/starvation, 26% from predators (12% coyote, 8% feline, and 6% bear), 4% from unknown
causes, and 2% from poaching. Thirty-one of 50 fawns died with 58% dying from causes other than
predation. Monitoring is in progress for the 2000 season fawns. Early season 2000 mortality is less than it
was in 1999. Deaths from sickness/starvation are half (10% vs. 20%) what they were in 1999 (as of .
August 1) and predation is about three-fourths (15% vs. 20% that of 1999 (Figure 1). June 2000 was
warm and dry, which may have affected early fawn survival. On the Uncompahgre, December fawn:doe
),
ratios are negatively correlated (r = -0.8183) with the preceding June precipitation (R~.6697,
P=0.0038).
/i:
d
However, mean temperature for June had a weak positive correlation (r = 0.2756) and was not significant
(R2 =.0.0760, P = 0.4409). The peak offawning was between June 14thand June 26th when 93% of the
-,

�128
fawns were caught (Figure 2). Year 2000 fawns were slightly larger than the 1999 fawns in terms of body
weight and hindfoot length. Neither the difference in weight, 4.4692 (2000)vs. 4.3714 kg (1999), nor the
difference in hing foot length, 10.474 (2000) vs. 10.297 (1999) inches, was statistically different, P =
0.5845 and P = 0.1309, respectively.

�129
IMPACT

OF PREDATION

AND VEGETATIVE

COVER ON MULE DEER FAWN SURVIVAL

Thomas M. Pojar

P. N. OBJECTIVES
1. Identify agents of neonatal mule deer fawn mortality from birth to 6 months of age.
SEGMENT

OBJECTIVES

1. Capture and radio collar 30-35 neonatal fawns each on the Uncompahgre Plateau (D-19), Middle Park
(D-9), and Red Feathers (D-4).
2. Measure vegetative density and height at fawn bed sites.
3. Measure distance between successive bed sites for individual fawns.
4. Compare fawn survival and causes of mortality among 3 vegetational and ecologically different study
areas.
5. Correlate height and density of vegetation at fawn birth sites and bed sites with percent of fawns killed
by predators.
6. Compare height and density of vegetation at fawn bed sites and random sites.
INTRODUCTION
Major changes in the original Program Narrative include:
1.
Limit the fawn collaring effort to the Uncompahgre Plateau (D-19). Because of the size
of the area and diversity of vegetative communities on the Uncompahgre and because of
intense political interest in this area, all resources were concentrated on the Uncompahgre
during this segment. The target sampling intensity was increased to 80 fawns with
emphasis placed on getting the sample widely distributed over the entire 2,300 square mile
area.
2.
Abandon the idea of measuring vegetation at bed sites because of evidence that persistent
disturbance of bed sites reduces survival of young ungulates (Philips 1998).
3.
The logistics of placing an adequate crew in remote fawning areas and the unknown of
whether or not fawns could be captured in sufficient numbers given deer density, terrain,
and vegetative cover encountered negated many of the objectives in the PN.
In essence, this investigation was reduced to placing emphasis on capturing fawns on the Uncompahgre and
monitoring their survival and causes of mortality. Summer fawn survival and causes of mortality are 2
important factors impacting deer population performance.
STUDY AREA
The study area is described in Pojar and Andelt (1999).
METHODS
Radio collared does were used to locate fawning areas although no special effort was made to
capture the fawns of radioed does. The strategy for capturing fawns involved observing does for
behavioral and physical signs, such as udder development, of having fawned. If it was determined that
these indicators suggested that the doe had fawned, the area was searched for the fawn(s). Once located,

�130
the fawn was approached from behind (out of direct eyesight) and restrained for weighing, measuring, and
putting on the radio collar. Processing usually took less than 5 minutes.
The collars used were made of 1.5-inch elastic with an expansion ratio of 1.5:1 and equipped with
surgical tubing to allow the collar to drop off after about 6 months. Each collar weighed 110 g. The
circumference of the collar was 10 inches, 6 of that was elastic. The 6 inches of elastic has the ability to
expand to 9 inches. A l-inch loop was sewn in the elastic reducing the collar circumference to 9 inches.
The loop was sewn with 4 stitches of cotton thread with the intent that these would rip out within 2-3 weeks
after the collar was put on a fawn. When the collar was put on a fawn it was 9 inches in circumference and
fit quite loosely. When the loop was released the circumference increased to 10 inches and as the elastic
relaxed the collar could expand another 3 inches giving a totally expanded circumference of 13 inches.
Collars were hung outside in the shade for several days before use to help dissipate any fabric and
human scents associated with manufacture. When taken to the field in workers backpacks, the collars were
sealed in zip loc bags.
If a collar was to be recycled, i.e. removed from a dead fawn and reused, it was washed in tap
water (no soap), hung out to dry, then placed in aplastic bag with native forage.

RESULTS
By recycling some of the collars, 88 fawns were radioed. The sample was roughly distributed
according to deer density on the summer range. The sample of radioed fawns were distributed across the
Uncompahgre Plateau as follows: North (Cold Springs) 29, central (25 Mesa) 16, south (Celesca) 33, and
far south (10).
Thus far, the collars are expanding as expected. From recovered collars, it appears the cotton
stitching rips out in about 4 weeks or less. There was only one instance of suspected slippage of a collar
and it is possible the fawn was killed or scavenged and the collar carried away from the carcass. Of the
fawns recovered, there was no sign of the collar causing abrasions on the skin, however, there was slight
hair loss in some cases from the collar being loose enough to rotate or move on the neck.
The fawns captured during 2000 had a mean weight of 4.47 kg compared to 4.37 kg in 1999; this
difference was not significant (P=0.5845). The hind foot length of 10.48 inches in 2000 was not different
from that of 1999, 10.30 inches (P=0.1309).
There was a noticeable difference in the weather, both precipitation and temperature, during the
fawning period between 1999 and 2000 with the most recent year being warmer and dryer. Early
sickness/starvation deaths (through August 1) in 2000 were half (10% vs. 20%) what they were in 1999
(Figure 1). It was theorized that the warmer, dryer June weather was a key factor in neonate fawn survival.
Weather data for the Montrose area was tabulated for the past 10 years. I tested the hypothesis that June
temperature and precipitation are related to the subsequent early winter (December) fawn:doe ratios
collected during helicopter classification surveys done by management personnel. The correlation with
precipitation was highly significant and negatively correlated (r = -0.8183) with subsequent fawn:doe
ratios, R2 = 0.67, P = 0.0038; temperature had a slight positive correlation (r = 0.2756) with fawn:doe
ratios but it was not significant, R2 = 0.0760, P = 0.4432.
Although the search for newborn fawns began in early June, the first fawns were not caught until
June 14thin 2000. In the 13-day period between June 14thand June 26th, 93% of the fawns were caught.
The last fawn was caught on July 9th (Figure 2). In 1999, the 17-day period from June 13 to June 30,96%
of the fawns were captured; the first fawns were captured on June 9th. From this data there is no evidence
that a double fawning peak is occurring on the Uncompahgre Plateau.
Data on captured fawns is in Table 1. Although the information for 2000 regarding mortalities
only goes through August Pt, Figure 3 shows a comparison of total cause-specific mortality for 1999
(total) and 2000 (through August 1~.

�131
LITERATURE

CITED

Philips, G. E. 1998. Effects of human-induced disturbance during calving season on reproductive success
of elk in the upper Eagle River valley. Ph. D. Dissertation, Colorado State University, Ft. Collins.
Pojar, T. M. and W. F. Andelt. 1999. Investigation offactors contributing to declining mule deer
numbers. Wildlife Research Report, Mammals Research, Federal Aid Projects, Job Progress
Report, Project W-153-R-12, Colorado Division of Wildlife, Fort Collins, Colorado, USA.

Table l. Neonatal mule deer fawns captured and radio collared on the Uncompahgre Plateau, Colorado
2000. The mortality data is very preliminary and represents only deaths through August 1,2000.
Probable Cause
Radio I.D. Date of
Capture location UTM
Hindfoot
Date
Sex Wt
Recovered
of Death
Capture Coordinates
(kg)
(inches)
East
North
150.023 6-15
703980
4268055 F
10.75
4.4
150.033 6-18
700954
4278742 F
10.25
4.7
150.044 6-16
702309
4280011 F
11.125
5.3
150.054 6-24
703446
4267697 F
11.25
5.1
150.064 6-18
700353
10.625
4274667 M
5.0
150.074 6-24
703050
4267256 M
11.00
4.4
150.084 6-24
703442
4267726 M
6.1
11.00
150.094 6-18
704622
4274176 M
11.00
5.0
150.104 6-22
700255
10.625
4282798 F
5.5
150.114 6-19
697815
5.3
11.375
4283738 M
150.134 6-20
6+
11.875
703390
4279744 M
Sick/starve
150.146 6-19
7-9
701207
4279027 M
9.75
3.9
150.155 6-20
702179
10.125
4275357 F
4.1
150.163 6-18
700357
10.50
4283325 M
4.2
7-19
Sick/starve
150.184 6-22
703468
10.00
4279642 M
4.0
150.192 6-20
702293
4.5
10.125
4281859 M
150.204 6-22
'4.7
700428
4283374 M
10.25
150.214 6-26
704463
10.50
4272215 F
4.7
Coyote
150.223 6-21
751358
6-23
4236752 M
3.6
10.50
150.234 6-20
727652
10.125
4252092 F
3.5
723136
150.244 6-26
4257872 F
10.625
5.7
150.254 6-22
730938
4264027 M
3.9
9.625
150.263 6-19
750827
4230756 M
4.0
10.25
150.272 6-25
700728
10.25
4284815 M
3.75
150.283 6-25
703475
10.50
4279355 F
5.0
10.00
150.294 6-26
241593
4235614 M
4.2
Sick/starve
150.303 6-21
760162
11.25
7-31
4237065 M
5.2
7-3
Bear
150.314 6-23
732743
4251998 M
11.125
5.0
150.324 6-26
241806
9.50
4236255 M
2.9
721362
10.00
8-1
Coyote
150.334 6-22
4264368 M
4.6
150.344 6-20
720095
4265861 F
5.2
11.00
Coyote
150.353 6-24
730048
9.75
7-27
4263042 F
3.4
150.362 6-20
748878
4231358 M
10.625
4.6
150.374 6-21
756526
10.75
4248692 M
5.1
150.383 6-26
728565
4254798 M
3.4
9.875
Coyote
150.393 6-21
10.125
7-5
743115
4255001 F
3.8
150.423 6-25
10.25
730831
4263910 M
4.0
150.434 6-18
757228
4232141 F
5.3
11.25
7-17
_~LcJcl~L ___
6-20
4.~~!~2~_
__I4.~~I~ ___
J':____4.]___ J.9.:~Q_____ -----------__ l_?.9A4.4. --------

�132
Table 1 Continued
Radio I.D.
Date of
Capture
150.455
150.464
150.473
150.484
150.495
150.504
150.514
150.524
150.545
150.553
150.564
150.573
150.584
150.593
150.604
151.114
151.123
151.144
151.153
151.164
151.173
151.195
151.203
151.233
151.245
151.254
151.263
151.274
151.284
151.294
151.314
151.324
151.333
150.013A
150.013B
150. 124A
150. 124B
150.172A
150.172B
150.403A
150.403B
150.415A
150.415B
150.533A
150.533B
151.134A
151.134B
151.183A
151.l83B

6-19
6-16
6-19
6-14
6-17
6-19
6-16
6-19
6-19
6-23
6-17
6-15
6-17
6-14
6-20
6-15
6-16
6-18
6-18
6-18
6-18
6-18
6-26
6-17
6-17
6-14
6-14
6-22
6-22
6-22
6-19
6-22
6-15
6-26
7-6
6-24
6-27
6-20
6-26
6-26
7-9
6-18
6-26
6-21
6-29
6-16
6-30
6-18
7-5

Capture location UTM
Coordinates
North
East
762275
4233303
755233
4247651
760381
4232242
754488
4235165
756570
4233083
762275
4233303
4247828
754392
727428
4251901
749686
4229850
755706
4231637
4246702
757702
752002
4249457
754295
4247567
4249079
752525
754867
4231692
756942
4231730
754848
4331643
751910
4249670
751910
4249670
4249165
752547
752639
4248689
742905
4240385
731972
4251646
4251207
750332
754406
4248275
248077
4233576
248077
4233576
762261
4224531
761180
4220892
761688
4221672
761310
4220980
761688
4221672
761539
4223050
703376
4267562
704293
4269378
705226
4269426
4274463
704284
702297
4280730
730004
4261815
728978
4254395
702133
4280026
730056
4262079
730074
4261926
751358
4236752
707752
4270072
755167
4231731
707752
4270072
746380
4247269
701385
4279114

Sex

Wt
(kg)

Hindfoot
(inches)

M
M
M
F
M
M
M
F
M
M
F
M
M
M
F
M
F
F
F
F
F
M
F
M
M
F
M
F
F
F
F
F
F
F
F
F
F
M
M
M
M
F
F
M
F
F
F
F
M

5.7
3.1
5.3
3.8
4.1
5.2
4.5
3.6
5.1
3.8
3.0
4.7
4.8
3.6
4.8
4.3
3.6
3.8
3.6
5.0
4.1
4.7
5.7
4.7
5.2
4.3
4.6
4.8
6.1
3.4
3.1
3.6
3.5
6.0
5.8
3.4
4.0
4.9
5.0'
4.3
6.7
3.5
3.0
3.7
6.1
4.4
5.0
4.0
6+

11.50
9.625
10.50
10.50
10.25
10.75
10.625
10.25
10.25
10.50
9.625
11.00
11.125
10.125
10.25
10.50
9.875
10.25
9.75
10.50
10.625
10.75
11.125
10.25
11.375
10.83
10.25
10.43
12.20
10.16
8.86
10.00
9.76
11.00
11.00
8.00
10.25
11.00
10.875
10.625
11.50
9.875
8.875
10.50
10.625
10.75
11.50
10.125
11.75

Date
Recovered

Probable Cause
of Death

7-8

Sick/starve

6-30
7-31
6-25

Coyote
Bear?·
Sick/starve

6-23

Sick/starve

7-3

Bear

6-24
. 7-5
6-23
7-31
6-21

Sick/starve
Bear
Coyote
Sick/starve
Coyote

6-26
7-6

Coyote
Coyote

�133
YEAR 2000 - Through
Number of fawns radioed
Number of fawn deaths
Cause
Predation
Sick/starve
Total Alive

% of morts

Number
13
9
66

August

1

88

% of Total Sample

22

Predation
'lb

% of total

59%
41%

15%
10%
75%

Sick/starve
10%

Total Alive
75%

YEAR 1999 - Through

Number of fawns radioed
Number of fawn deaths
Cause
Predation
Sick/starve
Total Alive

Number
10
10
30

August

1

50
20

% ofTo~1

% of morts
% of total
50%
20%
50%
20%
60%

Sample

Predation
20%

Figure 1. Comparison of cause-specific mule deer fawn mortality, Uncompahgre Plateau, Colorado.
represents mortality from collaring through August 1st.

14
"'C
Cl)

12

•...

.aa. 10
C'O

()

8

-

-

6

I--

o
c

~

u.
o
o

Z

4

f-

f-

2

o

lLU

.IL_I_

Jul8
Jun 14 Jun 18 Jun 22 Jun 26 Jun 30 Jul4
Jun 16 Jun 20 Jun 24 Jun 28 Jut 2
Jut6

Figure 2. Capture dates for year 2000 fawns from the Uncompahgre Plateau, Colorado.

Data

�CAUSE-SPECIFIC FAWN MORTALITY - UNCOMPAHGRE 2000 (Through Aug 1)
Number of fawns radloe
88
Num ber of fawn deaths
22
Cause
Number % of mort % of total
8
36%
9%
Coyote
4
18%
5%
Bear
Unk Pred
1
5%
1%
Sick/starve
9
41%
10%
66
75%
Total Alive

•....•
w
.j::o.

r----------------------------,
% of Total Sample
Bear
5%
Unk Pred
1%
Sick/starve
10%

% or Mortalltl ••

'"

,...

CAUSE-SPECIFIC FAWN MORTALITY - UNCOMPAHGRE 1999 (Total for year)
Number of fawns radloe
50
...--'---------------------------,
Number of fawn deaths
·31
Number
%
of mort % of total
Cause
Coyote
6
19%
12%
4
13%
8%
Feline
Bear
3
10%
6%
Sick/starve
15
48%
30%
Totalilive
Unknown
2
6%
4%
38%
Poached
1
3%
2%
Total alive
19
38%

./. of Total Sample
Coyote
12%
Bear
6%

% or Mortalltl.s

•..".

Unknown
4%

Sick/starve
30%

''''

Figure 3. Comparison of cause-specific mortality for 1999 and 2000, Uncompahgre Plateau, Colorado. The tabulation of 1999 includes the entire
period from fawn capture to approximately 6 months of age. The data for 2000 only goes through August 1, 2000 (the date of this writing).

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                  <text>83

Colorado Division of Wildlife
Wildlife Research Report
July 1993
JOB PROGRESS REPORT
State of ______..!C~o~l~o~r~a~d~o~---Project No.

W-153-R-6

Mammals Research

Work Plan No. -~3_ _ _ _ _ _ __

Elk Investigations

Job No. ---~9_________

Estimating Survival Rates
of Elk and Developing
Techniques to Estimate
Population Size

Period Covered:;
Author:

July 1, 1992 - June 30, 1993

D. J. Freddy

Personnel: R. Bartmann, and C. McCarty, CDOW;
White, CSU.

C. Vardeman, D. Bowden and G.

Abstract
A detailed study plan for this project was completed and approved through the
required peer-review system. The study area selected was that portion of Game
Management Unit 42 south of Newcastle and Rifle, Colorado . Two elk corral traps
were refurbished for use in December 1993 and arrangements made to contract
trapping of 100 elk using a helicopter . Radio-collars for adult cows and male
and female calves were designed and purchased.

�85

JOB PROGRESS REPORT
ESTIMATING SURVIVAL RATES OF ELK AND DEVELOPING TECHNIQUES TO
ESTIMATE POPULATION SIZE
David J. Freddy
P. N. OBJECTIVE
Estimate survival rates of adult female and calf elk and develop techniques to
estimate population size.

SEGMENT OBJECTIVES
1.

Complete detailed and approved study plan and select study area.

2.

Refurbish elk traps and identify potential trap-site locations within the
selected study area.

3.

Design expandable radio-collars for calves and purchase and assemble collar
materials transmitter units.

A complete copy of the approved study plan presented.

�86

STUDY PLAN FOR RESEARCH
FOR 'FY 1992-93 - 1996-97

V

State of ___c~o~l~o~r~a~d~o:.-_ _
Project No.

4400

Work Plan No.
Job No.

Hunt
3

9

0715

Mammals I Research
Elk Investigations
Estimating Survival Rates of
Elk and Developing
Techniques to Estimate
Population Size

ESTIMATING SURVIVAL RATES OF ELK AND DEVELOPING TECHNIQUES TO
ESTIMATE POPULATION SIZE
Principal Investigators
David J. Freddy, Wildlife Researcher, Mammals Research
R. Bruce Gill, Wildlife Research Leader, Mammals Research
Cooperators
John E. Ellenberger, Wildlife Biologist, Northwest Region
James H. Olterman, Wildlife Biologist, Southwest Region
David C. Bowden, Professor Statistics, Colo. St. Univ.
Gary C. lJltite, Professor Wildlife Biology, Colo. St. Univ.
STUDY PLAN APPROVAL
Prepared by: _____________Date : _ _ _ __
Submitted by: ____________Date : _ _ _ __
Reviewed by: _____________Date : _________
_____________Date: _ _ _ __
_____________ Date: _ _ _ __
_____________ Date: _ _ _ __
Approved by: _____________ Date : _ _ _ __
Biometrician
_____________Date: _ _ _ __

V

�87

FREDDY STUDY PLAN
PROGRAM NARRATIVE
State of ---~C~o~l_o~r~a~d~o____
Project No.

4400

Work Plan No.
Job No.

I.

\....,,._/

Hunt
3

9

0715

Mammals I Research
Elk Investigations
Estimating Survival Rates of
Elk and Developing
Techniques to Estimate
Population Size

NEED

Elk (Cervus elaphus nelsoni) are a high-profile wildlife resource
throughout much of Colorado because they provide recreation for persons who
hunt, watch, and photograph wildlife (Freddy et al. 1993). The popularity of
elk with the public is undoubtedly related to the expanding geographic
distribution and increasing size of the State's elk population. This
burgeoning elk resource has many benefits but frequent social, political, and
economic conflicts suggest elk, to some degree, have reached a "social"
carrying capacity. Balancing these uses and conflicts by maintaining
acceptable numbers of elk is a challenge for future management of this species
in Colorado.
The positive and negative economic impacts of elk are often the most
influential forces directing management of elk. In 1990 and 1991, 193-194,000
hunters harvested 46-51,000 elk in Colorado (CDOW 1990, 1991). In doing so,
hunters generated at least $20 million in yearly license revenue to the
Colorado Division of Wildlife (CDOW) and contributed about $250 million in
direct and secondary expenditures to the yearly economy of Colorado (Freddy et
al. 1993). Revenues derived from elk hunting provide the financial resources
for many wildlife programs of the CDOW and for many private businesses in the
State. However, rising numbers of elk and attendant harvests have also
brought about conflicts with agricultural interests. Demands to reduce elk
populations and expand payments for damage by elk to cultivated and native
forage on private lands have resulted in the CDOW altering statewide
objectives for elk from increasing to decreasing the total population and
creating a Habitat Partnership Program with private land owners. This
partnership to cooperatively manage elk that impact private lands may reach
expenditures of $1 million annually.
The core of the conflict in elk management, in part, stems from
inadequate estimates of population size resulting in an inability to establish
management objectives for specific populations that are agreeable to competing
interests. Even when objectives are established, we can not readily quantify
impacts of management decisions because current methodology for monitoring
populations is neither precise nor accurate.

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FREDDY STUDY PLAN

The CDOW has relied on computer modeling, rather than direct
measurements, to generate estimates of population size. This approach has
been inadequate because model outputs have not been validated with independent
estimates of population size. Estimates of population size and subsequent
proposed harvest levels have, therefore, been subjected to endless debate.
Computer models based on POP-II (Bartholow 1992) or POPMOD ('White 1992)
function best when natural rates of survival or mortality, hunter harvests,
and population size are reliably measured. In the current modeling process,
survival of calves from June 1 until September 1 is implicitly estimated by
measured post-hunting season calf:cow ratios, which along with bull:cow
ratios, are used to estimate composition of the pre-hunting season population.
However, the size of the preseason population is not measured. From this
preseason population, hunter harvests, which are adequately measured, are
subtracted resulting in a prewinter population. The prewinter population is
multiplied by rates of survival, which are not measured, to estimate a postwinter population and subsequently the next preseason population. Obvious
missing links in this modeling process are measured estimates of survival for
calves and adult females during winter (Nelson and Peek 1982) and population
size at some time during the annual cycle. Importantly, estimates of
population size independent of the modeling process could be used to align
models on measured values. The current modeling process is prone to many
subjective estimates regarding population size and survival rates which has
resulted in diminished confidence in using models to guide management of elk
populations (Freddy 1987).
The CDOW recognized the need to improve monitoring status of ungulate
populations during 3 planning efforts. First, the statewide Long Range Plan
(LRP), approved in 1988 and updated in 1991 (CDOW 1991b), highlighted the need
for improved population data to accommodate increasing recreational demands
and reduce conflicts among competing interests. The LRP targeted 25% of the
revenues generated from increasing hunting license fees towards improving and
expanding efforts to monitor ungulate populations. In 1991, increased fees
associated with elk licenses generated approximately $4.5 millon in new
revenue potentially resulting in $1.1 millon towards expanded population
monitoring. Second, CDOW terrestrial biologists at a statewide meeting held
in July 1991 stated that obtaining quantified estimates of survival rates and
population size were their priority needs for developing more reliable models
of elk populations. Third, the CDOW Deer and Elk Management Analysis Guide,
approved in November 1991, identified as priority issues the need to obtain
reliable estimates of population size and survival rates of calves and adult
female elk (Freddy et al. 1993).
Estimating both survival rates and population size are fundamental to
developing systems for monitoring and predicting changes in elk populations.
We believe estimating calf and adult female survival rates during winter and
annual survival rates of adult females are a higher priority than estimating
adult male survival rates primarily because most males are harvested when they
reach legal age and contribute little to problems of either population growth
or decline. Models having valid estimates of survival rates for calves and
adult females along with currently obtained estimates of harvests and
population composition will provide more defensible estimates of population

.

V

�89

FREDDY STUDY PLAN

size and trend than similar estimates derived from current models. However,
an independent estimate of population size generated from a sampling system
designed to enumerate elk would provide the opportunity to validate population
estimates derived from models. Ideally, estimates of both survival and size
would be obtained simultaneously.
Changes in either calf or adult female survival have pronounced effects
on population growth and greater effects than changes in fecundity (Nelson and
Peek 1982). Sensitivity analyses indicated population growth is more affected
by changes in survival rates of adult females than to equivalent changes in
calf survival. A 15% increase in adult female survival resulted in a
population increase 7x that of the increase from a 15% change in calf survival
(Table 1). Although small changes in adult female survival can have major
effects on population growth if compounded for 10-20 years, we expect calf
survival to be more variable among years and our ability to detect changes in
calf survival should be greater than detecting smaller, but important changes
in adult female survival (White et al. 1987, Bear 1989, Bartmann et al. 1992).
Because there are few estimates of either calf or adult female survival rates,
we need to measure both simultaneously to document the relative differences in
survival rates and patterns of mortality in order to develop more reliable
population models.

\.-,I'

An example of how measurements of survival can alter our perception and
modeling of populations involves the Piceance deer population in northwest
Colorado. Measured overwinter survival of fawns (0.22) was much lower than
perceived, and survival of adult females (0.82) was more stable among years
than anticipated (White et al. 1987). Using measured rates of survival in
existing models of this deer population resulted in radical changes in
estimated population size, and served to focus wildlife managers on probable
causes of low fawn recruitment and solutions to improve recruitment (Bartmann
and White 1991, Bartmann et al. 1992).

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FREDDY STUDY PLAN

Table 1. Sensitivity analysis for 3, 10, and 15% increases in survival rates
of calves and adult females for a beginning population of 1000 elk simulated
for 20 years. Initial survival rates for calves (0.705) and adult cows
(0.800) essentially stabilized population growth for 20 years. Growth rate
increase equals the percent increase in yearly average growth rate compared to
stabilized average growth rate,
Change in Calf Survival Rate

Calf Survival
Ad. Female Survival 8
Ad. Male Survival
Avg. Yrly. Growth Rate
Growth Rate Increase
End 20 Yr. Pop. Size

0%

+3%

+10%

+15%

0.705
0.800
0.650
0.82%
0.00%
990

0.726
0.800
0.650
1.49%
82.5%
1109

0. 775
0.800
0.650
3.21%
293.0%
1441

0.811
0.800
0.650
4.61%
465.0%
1742

Change in Adult Cow Survival Rate
+15%
0%
+3%
+10%
Calf Survival
Ad. Female Survival
Ad. Male Survival
Avg. Yrly. Growth Rate
Growth Rate Increase
End 20 Yr. Pop. Size
a Ad.-adult ~

0.705
0.800
0.650
0.82%
0.00%
990

0.705
0.824
0.650
3.35%
310%
1531

0.705
0.880
0.650
12.1%
1378%
4093

0.705
0.920
0.650
22.1%
2609%
8038

V

1 year old.

Our lack of adequate population data on elk is not without just cause as
known methodologies are limited and expensive. As resource.managers, we have
likely reached a threshold where we must expand our investment in monitoring
the processes that affect the growth or decline of the elk resource to
accommodate the rising and often conflicting demands for managing elk.
II .

OBJECTIVES

Our objectives are to provide reliable estimates of survival rates for
calves and adult females overwinter and adult females throughout the year, and
develop and test a system for estimating population size. Our efforts will
focus on elk inhabiting winter ranges south of NewCastle and Rifle, Colorado.
Our specific objectives are:
1) Estimate survival rates of calves from 1 December - 31 May within±
15% of the true survival rate at the 95% confidence interval and
identify sources of mortality using adequate numbers of radio-collared
calves.
2) Estimate winter (1 December - 31 May) and yearly (1 December - 30
November) survival rates of adult females within± 10% of the true

V

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FREDDY STUDY PLAN

survival rate at the 95% confidence interval and identify sources of
mortality using adequate numbers of radio-collared adults.
3) Monitor the fate of yearling bull elk radio-collared as calves in
relation to antler-point restrictions designed to protect yearling bulls
from harvest.
4) Develop and test a system to estimate population size during winter
within± 20% of the true population size -at the 90% confidence interval
using radio-collared elk to evaluate sighting bias and to provide
population estimates based on random plot searches and mark-resight
theory.
5) Provide data on general movements, distribution, and dispersal of
radio-collared elk within the study area. Establish cooperative studies
with universities and land management agencies to investigate specific
aspects of habitats used by elk and to relate genetic characteristics of
elk to their survival.
III.

EXPECTED RESULTS OR BENEFITS

This investigation will provide estimates of survival rates for calf and
adult female elk in a selected elk population during 4 consecutive years.
These estimates will immediately assist CDOW biologists not only in refining
population models for this specific population but also in providing estimates
of survival that may be applicable to modeling other elk populations
inhabiting similar habitats. Quantified estimates of survival will allow
objective assessment of whether major restructuring of current population
models is necessary. In the process of estimating survival rates, we will
document sources of mortality.
Our efforts to estimate population size are inherently more difficult
than estimating survival rates. If we obtain relatively precise and unbiased
estimates of true population size, the CDOW will have a method to obtain valid
independent estimates of population size to compare with estimates derived
from modeling, and therefore, provide another objective basis for assessing
the current modeling process. If our efforts provide less than satisfactory
results, we will have an objective basis for either continuing with
refinements or discontinuing efforts to estimate population size and invest in
measuring other population parameters.
IV.

APPROACH

A. Survival
General Approach
We will estimate survival rates for calves (6 mos old) and adult females
(~ 1 yr old) during winter, 1 December - 31 May, and for adult females
annually, 1 December - 30 November, by using radio-telemetry collars that emit
a mortality pulse code when animals remain motionless for 4-6 hours (White
1983, Bear 1989, White et al. 1987). Radios provide the ability to know the
fate of individual animals (alive or dead) over discrete periods of time
unlike marking animals with other types of tags that are seldom recovered upon
the animal's death (White and Garrott 1990). Improved longevity of batteries

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FREDDY STUDY PLAN

for radio collars will allow us to monitor status of individual animals for up
to 4+ years. Survival will be monitored from 1993-94 through 1996-97.

V

We assume that radio-collaring calf and adult female elk does not bias
estimates of survival rates by jeopardizing or enhancing the welfare of
individuals. This assumption can be violated in studies involving birds when
transmitter packages exceed critical weight/body size ratios (Burger et al.
1991, Foster et al. 1992) but does not appear to be a detectable bias with
ungulates when radio collars weigh about 0.8% of an animal's body weight
(Garrott et al. 1985, White et al. 1987). Although some level of bias may
occur, radio collars will likely provide much less positively biased estimates
of survival compared to other indirect methods (Bartmann 1984, Zager and
Leptich 1991). Radio collars used in this project will weigh about 1.1 kg and
represent about 0.8% of calf and 0.5% of adult female body weights. Collars
for adult females will be of fixed circumference and fitted for each
individual. Collars for male and female calves will allow for expansion to
adult size (Bear 1986, White et al. 1987, Appendix I).
We assume that survival of those animals captured unbiasedly represents
survival of individuals in the population. Individual behavior, social
behavior, trapping method, and distribution of trapping effort all potentially
bias those individuals trapped and marked (White el al. 1982, Garrott and
White 1982). Recognizing these problems, we will capture elk with the
objectives of marking animals throughout the distribution of the population
and reducing influences of social hierarchies. The study area will be divided
into several zones each having multiple capture sites to assure that marked
elk represent the population. Capture quotas for calves and adult females
will be established for each zone. A Hughes 500 helicopter and a net-gun will
be used to capture individuals from groups of elk in more remote areas where
portable corral traps would be inefficient to use. In those areas inhabited
by people or having agricultural activities, we will use portable corral traps
to capture groups of elk. Elk caught in corral traps are likely less affected
by social dominance hierarchies than elk captured with single animal Clover
traps (Garrott and White 1982, Bear et al. 1989). For groups of elk captured
in traps, only a fraction of each group will be randomly selected and radio
collared. We will attempt to collar equal numbers of adult females and calves
within each capture method. Trapping will occur from approximately 29
November-20 December each year. While handling animals we will minimize
capture stress and follow guidelines for animal welfare (Appendix II).

V

Each collared animal will be individually recognizable based on radio
collar frequency, an external symbol/number on the top surface of the collar,
and a numbered metal ear-tag placed in each ear. Radio collars will be white
with a black symbol/number (Appendix III). Additionally, male and female
calves or yearlings captured but not collared will be ear-tagged to provide
additional data on dispersal when and if recovered as harvested animals during
hunting seasons.
Collared calves, and when possible, yearling females, will be weighed to
nearest 0.5 kg. Additionally, hind foot lengths and total body lengths will
be measured for calves. Blood samples will be obtained via venepuncture to
assess pregnancy status of adult females using progesterone assays (Freddy

u

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FREDDY STUDY PLAN

1991) and from calves for potential genetic analyses related to measured
survival rates (Pemberton et al. 1988). All collared elk will be aged as
calves, yearlings, or young (2-3 yrs), prime·(4-10 yrs), and old(~ 10 yrs)
adults based on visual inspection of tooth replacement and wear (Quimby and
Gaab 1957).
We will use periodic and systematic aerial and ground searches
throughout areas inhabited by collared elk to determine.their life or death
status based on pulse rates of collars (Gilmer et al. 1981).
Animals will be
monitored daily from the ground during winter with aerial searches done twice
per month depending upon frequency of mortalities and relative ability to
monitor all animals from the ground. During spring, summer, and fall we will
conduct monthly or bi-monthly aerial searches. During fall hunting seasons,
aerial searches may be conducted weekly in conjunction with intensified ground
searches.
Mortalities coarsely located during aerial surveys will be found from
ground searches using hand-held antennas. Criteria for assigning probable
cause of death (primarily during winter) will include body position, presence
of bite or claw marks and subdermal hemorrhaging, tracks, drag marks, and when
necessary rumen or tissue samples (Wade and Browns 1982). Potential causes of
death include starvation, accidental trauma, plant poisoning, predation by
black bears, mountain lions, coyotes, and domestic dogs, and legal and illegal
hunter harvest (Bear 1989, Schlegel 1977).
Analyses
Number of animals collared depends on expected survival rates, desired
precision, and degree of statistical power desired for comparative tests. The
few studies that have estimated survival rates for elk used either age
structure analyses or radio collars. Annual survival rates estimated from age
structure analyses were: 64% for all calves (overwinter only) in Yellowstone
National Park (Houston 1982); 61% for female and 26% for male calves in
Jackson Hole, Wyoming (Boyce 1989); 90% for all calves in Colorado's White
River population (Laake 1992): and for adult females, 97% (Houston 1982), 68%
(Boyce 1989), and 79% (Laake 1992). Annual survival rates based on radio
telemetry were: 93% for male and female calves pooled with adult females
(nonhunted segments of the population) in northern New Mexico (White 1983);
75-94% for calves through their first 9 months in Rocky Mountain National
Park, Colorado (Bear 1989); 100% for calves from shortly after birth through
their first winter in central Colorado (de Vergie 1989); 88% for adult females
in northern Idaho where all mortality was attributed to hunting (Leptich and
Zager 1991); and nearly 100% for adult females in northern Colorado
(overwinter only, G.D. Bear pers. comm.). These results suggest that
survival may be&gt; 70% for calves and&gt; 85% for adult females·overwinter with
annual survival rates for adult females varying due to intensity of hunting.
We will radio-collar 75 calves (38 female, 37 male) yearly and initially
collar 75 adult females and maintain at least 75 adults(~ 1 year old)
collared in the population yearly to estimate rates of survival for these 2
age classes of animals. Assuming 75 collars remain functioning and survival
is~ 0.7 or~ 0.9, 95% confidence intervals will be S ± 15% or S ± 8% of the

�94

FREDDY STUDY PLAN

mean survival rate, respectively. If survival for either calves or adults
approaches 0.5 then considerably more collars must be deployed to maintain
high precision (Appendix IV). These confidence intervals are calculated as
1.96 ± vVAR(S) where survival (S) is a binomial with a variance, VAR(S) - S(lS)/n, and n is number of collars deployed (White et al. 1982). Power (1-beta)
to detect differences in survival rates~ 0.20 among years or age/sex classes
will be~ 0.70 but power will be S 0.25 for differences in survival S 0.10
when survival rate is 0.7 and alpha - 0.05. If survival is 0.9, power will be
~ 0.80 for differences in survival~ 0.20 and 0.40 for differences S 0.10
(Appendix IV, White and Garrott 1990:32). Reliably detecting differences of
0.05 in survival rates would require deployment of about 1,000 collars yearly
for each age class.
Analyses of survival rates assumes that individual animals are known to
be either alive or dead during specific time intervals of interest and that
their individual life status is independent among animals. This binomial
approach is most correct if all animals of interest enter and leave the
population simultaneously and there are no animals of unknown status
(censored) due to emigration or failure of radio collars (White and Garrott
1990). Typically, animals are trapped and marked over varying time periods
and some animals emigrate or radio collars fail. To account for these
problems, we will use a staggered entry Kaplan-Meier analysis, which is a
modification of the binomial estimator, to estimate survival rates (Pollock et
al. 1989, White and Garrott 1990, Bartmann et al. 1992). If no censoring
occurs, the Kaplan-Meier approach will provide an estimate identical to the
binomial estimator. We believe the binomial approach and attendant
assumptions provides a more realistic basis for estimating survival rates than
alternative approaches that assume constant survival rates for specified time
intervals (Heisy and Fuller 1985). Staggered entry Kaplan-Meier analyses are
readily available in programs written for SAS (SAS 1988, White and Garrott
1990, G. C. White, pers. comm.). The PC database program RADIOS (G. C. White
pers. comm) will be used to store data on each collared animal.
We will test the following generalized hypotheses:

Ho:

Survival Rate - S
Scalves - Sadult females during winter

Ho:

Smale calves - Sfamale calves

H0 :

Sadult females

H0 :

Scalves

during winter

is equal among years

is equal among years

We anticipate the following comparative analyses of survival rates using
data from animals of known fate. We will conduct pair-wise comparisons using
log-rank tests (Pollock et al. 1989, Bartmann et al. 1992) to compare survival
functions for: calves and adult females during winter and for male and female
calves during winter. Program SURVIV (White and Garrott 1990) will be used to
test for differences in survival rates among and between age classes and years
(Table 2). For example, to compare survival rates of adult females among

V

V

�95

FREDDY STUDY PLAN
years, constraints for program SURVIV would be S1 - S2 , S1 - S3, S1 - S4, and
to compare survival of adult females and calves within years, constraints
would be S1 - S5, S2 - S61 S3 - S7 , S4 - S8 • Similar constraint pairings would
occur for comparisons between male and female calves. These reduced models of
survival would be tested against a generalized model that estimates all
survival parameters individually, using log-likelihood ratio and goodness-offit tests in program SURVIV. Tests will be significant at PS 0.05.
Table 2.
SURVIV.
Age/Sex
Class

~

Generalized structure for analyzing survival rates with program

Year

Radios
Deployed

Proportions
Lived
Died

Adult
Females

93-94
94-95
95-96
96-97

75
75+
75+
75+

S1
S2
S3
S4

(l-S1)
(l-S 2 )
(l-S3)
(l-S4)

Calves

93-94
94-95
95-96
94-95

75
75
75
75

Ss

(1-Ss)
(1-S6)
(l-S7)
(1-Sa)

s6

S1
Sa

-----------------------------------------------------------------------------93-94
37
(l-Sg)

Male
Calves

Female
Calves

S9

94-95
95-96
94-95

37
37
37

S10
Su
S12

(l-S10)
(l-S 11 )
(l-S12)

93-94
94-95
95-96
94-95

38
38
38
38

S13
S14
S15

(l-S 13 )
(l-S14)
(l-S15)
(l-S 16 )

s16

We will assess whether calf survival can be predicted from body weight,
hind foot length, or total body length at time of trapping (continuous
variable) and sex, year, and trapping zone(s) (categorical variables) using
logistic regression. We will also assess whether calf and/or adult survival
can be predicted from weather variables such as mean monthly snow depth and
temperature using logistic regression (PROC LOGISTIC, PROC CATMOD, SAS 1988;
Bartmann et al. 1992). Tests will be significant at PS 0.05. We will use
NOAA weather data from Rifle, Collbran, and Bonham Reservoir, Colorado, USDASCS snow depth coarses at Overland and Park Reservoirs on the Grand Mesa, and
establish our own snow measurement coarse and weather station on the Garfield
Creek State Wildlife Area deer/elk winter range.
We will monitor fate of yearling bulls collared as calves immediately
before and during hunting seasons to ascertain whether yearling bulls are
illegally taken by hunters in areas where these bulls are protected from

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FREDDY STUDY PLAN
harvest by antler-point restrictions. Our selected study area is subject to
antler-point restrictions during all hunting seasons but is adjacent to
management areas where antler restrictions are not in effect during all
seasons. Some yearling bulls may disperse into areas where they will be legal
as yearlings, some will undoubtedly reside along the border where combinations
of restrictions apply, and some will remain within the antler-point
restriction area. We must assume hunters would select against yearling bulls
having white radio collars compared to yearling bulls without collars
resulting in negatively biased estimates of illegal harvest. However, if
several collared bulls are taken illegally, we have evidence that a problem
exists and the basis for designing a study specifically to test hypotheses
regarding harvests of yearling bulls. If no bulls are illegally taken we
cannot conclude that illegal harvest does not exist because the collars may
effectively cause hunters to avoid taking marked bulls.

u

B. Population Size
General Approach
Counting all animals in a specific area is the intuitive approach to
determining population size. Unfortunately, total counts over large areas are
prohibitively costly in time and money and generally highly inaccurate because
many animals present are not seen and counted (Caughley 1977).
Efforts to
improve population counts have followed 2 basic paths: designing sampling
systems with statistical rigor to obtain precise estimates that often
underestimate true population size (Siniff and Skoog 1964, Kufeld et. al.
1980), and developing procedures to correct for missed animals to improve
accuracy of estimates (Bartmann et al. 1986, Samuel et al. 1987).
Efforts to minimize numbers of animals missed during aerial counts often
focused on variables that affect actual counting conditions such as experience
of observers, height and speed of aircraft, type of aircraft, search time,
weather conditions, and extent of snow background (Erickson and Siniff 1963,
Caughley 1974, Gasaway et al. 1986). Although standardizing procedures may
reduce variability between sampled counts, animals are stili missed, often in
percentages exceeding 30% (Bartmann et al. 1986). Other efforts at improving
accuracy attempted to model the probability of detecting animals. This
probability function depends on group size, animal behavior, vegetation type
and density, and age and sex class of individual (Floyd et al. 1979, Burnham
et al. 1980, Samuel and Pollock 1981, Pollock and Kendall 1987, Samuel et al.
1987, Unsworth et al. 1990, Samuel et al. 1992). One solution to correcting
for bias therefore lies in calculating probabilities of detection and
correcting observed counts.
We propose a multiple-step approach to developing a system to estimate
elk densities: 1) estimate degree of sighting or counting bias on sample
quadrats and develop an equation for predicting sightability using radiocollared elk as a known subpopulation, 2) apply predictive sighting bias
correction factors to adjust counts of elk on sampled quadrats used to
estimate density of elk over a large area and use mark-resight estimators
based on radio-collared elk to provide an additional estimate of elk density
from counts of marked and unmarked elk on the same quadrats, and 3) conduct
multiple counts of elk on quadrats to test the repeatability of estimates
based on the predictive sighting equation and mark-resight estimators. Elk
radio-collared to estimate rates of survival will be used in developing
methods to estimate population size.

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FREDDY STUDY PLAN
Fundamentally, we believe a sampling system using quadrats instead of
transects will be most appropriate for estimating densities of elk. Although
line transect theory accounts for missing animals (negative sighting bias)
(White et al. 1989), our experience with line transects to estimate densities
of elk in portions of Middle Park, Colorado indicates too few groups of elk
will likely be detected to provide reasonable precision, even with intensive
repeated flights of transects (Freddy 1991). Additionally, quadrats are
easier to fly than transects in rough terrain inhabited by elk. Initially, we
will use a 2.59 km.2 quadrat.
Developing a Sightability Model
Given the premise of using a 2.59 km.2 quadrat as a sampling unit, we
will estimate the probability, or degree of bias, of detecting elk on this
size of quadrat using radio-collared elk (Samuel et al. 1987, Ackerman 1988).
These authors used logistic regression to develop sighting models to predict
the probability of detecting elk and mule deer (Odocoileus hemionus). Samuel
et al. (1987) found group size and percent vegetation canopy coverage were the
most useful variables to predict the probability of detecting elk in forested
terrain of northern Idaho (n - 111 trials) while Ackerman (1988) found group
size, animal activity, and vegetation type most useful for predicting
detection of mule deer in brush-dominated habitats in southeastern Idaho (n 277 trials). Probability of sighting elk has been 0.35-0.95 in dense or .. open
vegetation, respectively (Samuel et al. 1987) and 0.6-0.7 in mixed conifersagebrush (Artemisia tridentata) habitats (Bear et al. 1989).
The logistic regression for predicting sightability is
p..
exp(u)
1 + exp(u)
where p - the sighting probability, (exp) - 2.718 1 and u - b 0 + b 1x 1 +b 2x 2 +
... bn'Xn, the multiple linear regression equation of (n) variables affecting
sightability. Correction factors for each group of elk detected are obtained
by inverting the estimated sighting probability (Samuel et al. 1987). The
primary advantage of this sighting bias model approach is .that marked animals
are not needed in the elk population once the model has been developed unlike
traditional mark-resight models that require marking animals before every
survey.
The primary assumptions of this approach are:
1) Behavior of elk is not altered by the radio collar,
2) Visual detection of elk is not enhanced by the presence of the radio
collar as concluded by Bartmann et al. 1987 1 Samuel et al. 1987,
Ackerman 1988, and Bear et al. 1989 1
3) Selected radio-collared elk can be located to within a quadrat,
4) Collared elk can be individually identified either by radio frequency
or collar symbol/numbers when detected,
5) Observers attempting to visually detect collared elk do not know the
locations of marked elk,
6) The dependent variable, sighting probability, is asymptotic between
values of O and 1,

�98

FREDDY STUDY PLAN
7) The independent variables, whether numeric or categorical, are
measured accurately,
8) Selected elk represent heterogenous habitats typically frequented by
elk.

V

Major hypotheses to be tested are:
1) Logistic regression improves precision of sighting probability
compared to a simple binomial sighting probability model, and
2) Predictive sighting models are repeatable among periods of time
(years).
The entire winter range within the study area will be divided into 2.59
lan2 units having boundaries based on topographic features instead of cadastral

surveys.

These irregularly shaped units will be approximately equal in size.

Sightability tests will be conducted during 2 5-day periods in Januaryearly February 1994 and during 3 5-day periods in December, January, and
February 1994-95. Our objective is to complete 80 test trials (16/day) on
marked animals (seen or missed) during each 5-day period. We anticipate
searching 16 quadrats/day at a rate of 15 min/quadrat resulting in 4-5 hours
of helicopter use per day. During the 5 days, we will systematically cover
the study area. During the first year, up to 150 different collared elk will
be available which should reduce our need to repeat trials on individual elk
during any 5-day period. We will conduct tests during the morning and
afternoon and avoid mid-day to approximate traditional time periods when elk
counts are conducted. Because sighting bias is largely associated with small
groups of elk, we will attempt to fly when elk are widely distributed in small
groups (Appendix VI).

V

A primary observer in a Cessna 185 will locate selected radio-collared
elk (Gilmer et al. 1981) and assign each elk to a quadrat or quadrats if
animals are near a quadrat boundary. Within 2 hours of locating an elk, 2
observers along with the pilot in a Bell-Soloy helicopter will search assigned
quadrat(s) and enumerate all groups of elk and identify all radio-collared elk
on the quadrat. Radio-collared elk will be identified either by the
symbol/number on the collar and/or radio frequency using a receiver-scanner in
the helicopter (Appendix I). When observers have completed their search of
each quadrat they will check via radio with the primary observer to determine
if they found the assigned elk. If the elk was found they will proceed to the
next quadrat, but if the elk was missed the helicopter crew will immediately
find the marked elk using telemetry and document its location as on or off the
assigned quadrat. If more than 1 assigned elk occurs in a group only one
animal will be used because observations may not be independent. If an
assigned elk is missed and then found off the quadrat, the trial will be
voided. To maintain vigilant observers, the helicopter crew will be assigned
quadrats where there are no known radio-collared elk to serve as controls.
For each group detected on a quadrat, observers will assign
classification variables to describe conditions potentially affecting
detection of each group whether or not the group contained a marked elk.
These independent variables will be group size, activity of animal first
detected in the group, vegetation type, percent vegetation canopy density, and

V

�99

FREDDY STUDY PLAN
percent snow cover. These variables must also be noted for those groups
containing assigned marked elk that are missed during the initial search of
the quadrat. Additional independent variables assigned to all groups observed
during a flight will be year, flight, pilot, observer, search time per
quadrat, and age/sex of marked animals detected (Appendix V).
During the first year we will attempt to use only one experienced
observer, navigator, and pilot in the helicopter with the intent of
controlling these variables. The helicopter crew will be trained prior to
collecting data.
We anticipate group size, activity, vegetation type, and percent
vegetation canopy cover may significantly influence sighting probability
(Samuel et al. 1987 and Ackerman 1988). We also anticipate that percent
vegetation canopy cover may be difficult to judge. Samuel et al. (1987)
worked primarily in habitats having tall conifers. They considered vertical
canopy cover to be any vegetation obstructing the observer's view of an elk
group for up to 30 m around the group (Unsworth et al. 1991). Ackerman (1988)
correctly noted that animals are seldom viewed from vertical but rather from
oblique angles. Confounding this perception of visual obstruction are
• deciduous habitats, such as oakbrush (Quercus gambelii) and aspen (Populus
tremuloides), that can be seen through during winter and only partially
obscure one's view of elk even when canopy coverage may approach 100%. A
similar problem involves sagebrush which can effectively hide a bedded animal
with little distinguishable vertical canopy. We will follow suggestions by
Unsworth et al. (1991) but anticipate this to be a difficult variable to
estimate.
Using stepwise logistic regression (SAS 1988), independent variables
will be evaluated as to their significance in predicting the probability of
sighting elk (groups seen or missed) to develop a predictive sightability
model. Model fit will be assessed using AIC and log-likelihood values. We
anticipate transforming some independent numeric variables .to improve
conformity of data to model assumptions.
We will compare simple binomial and complex sightability models using
computer simulations to assess whether independent variables meaningfully
improve precision of the sighting probability estimator and also compare the
mean and variance of estimates of elk density derived from corrected and
uncorrected counts of elk on quadrats. Sightability models among flight
periods will be compared to assess the repeatability of the sighting model
when pilot and observers remain constant. If we achieve a sample of 80
trials/flight period, power (1-beta) at alpha - 0.05 to detect a difference
between sighting models will be about 0.57 (SE~0.016) (sighting models from
Samuel et al. 1987 for sighting functions at 20 and 40% vegetation cover).
Power improves to about 0.87 (SE=0.006) when n &gt; 160 trials. These power
calculations assume surveys will encounter groups of elk at frequencies of
group sizes similar to those observed during preliminary sampling flights
(Appendix VI, Table 2). If observed sizes of groups shift towards large
groups then power of tests would be less because differences in sighting
probabilities between models is most pronounced for small groups (Appendix
VI).

�100

FREDDY STUDY PLAN

Comparing Population Estimators
We will estimate total population size within the study area during
winter using 3 approaches based on a random quadrat sampling system. This
effort will begin in 1994-95 with one flight of quadrats to evaluate
logistics, adequacy of sampling, and initial estimates of population size and
then continue in 1995-96 and 1996-97 with 3 repeated flights each year if
quality of results justifies the effort.
We will randomly select about 15% of the potential quadrats and search
these quadrats each flight following procedures suggested by Kufeld et
al.(1980). Sampling may be stratified according to expected animal density
based on distribution of radio-collared elk in 1993-94.
For quadrats, we will use 3 estimators to calculate density
of elk and all 3 estimators will use the same counts of elk generated from
each flight: 1) uncorrected counts of elk on quadrats, 2) counts of elk on
quadrats corrected for sighting bias based on the appropriate sighting bias
model, and 3) counts of elk on quadrats corrected for sighting bias based on
Lincoln-Petersen mark-resight estimator combined for repeated flights using
the joint hypergeometric maximum likelihood estimator (JHE) (White and Garrott
1990). The Lincoln-Petersen estimator for each individual flight is:
A

N1 -

-11!1 + 1} Cn 1 + 1)

-1

V

(m1 + 1)

with an estimated variance of
A

A

Var CN1) -

....!n1

+ 1) Cn1 + 1) Cn~1lln1-=-m1l
(m1 + 1) 2 (m1 + 2)
A

A

A

and a nominal 95% confidence interval of N1 ± 1.96 vVar(N1 )
where n 1 is number of radio-collared elk, n 1 is number of elk observed on each
aerial survey, and m1 is number of marked elk observed on.each survey.
We will compare means and variances of estimates derived from each
method.
Assumptions for each estimator are:
Uncorrected Counts: a) All elk on the quadrats are counted and b) only
elk on quadrats are counted (no boundary errors). Assumption a) is
likely violated and is the reason for developing a sighting bias model
to correct counts.
Corrected Counts: c) assumptions are listed in the previous section.
We will apply sighting bias corrections to each observed group of elk
according to the sighting bias model.
Lincoln-Petersen Mark-Resight: d) probability of sighting marked and
unmarked elk is the same, e) marked and unmarked elk are correctly
classified (marks are discernible), f) marked elk are randomly selected
and distributed throughout the population or at least resighting effort
is randomly distributed throughout the population, g) each animal has an

V

�101

FREDDY STUDY PLAN

identical but independent probability of being resighted, h) number of
marked elk (radio collars) in the population is known at the time of the
survey which implies that marks are not lost or unaccounted for, and i)
the population is geographically and demographically closed; i.e., there
is no immigration or emigration, recruitment or death during the survey
in a geographically defined area (Otis et al. 1978, Bear et al. 1989).
Assumptions for Lincoln-Petersen mark-resight estimates may be the most
difficult to achieve and evaluate. To achieve adequate numbers of marked
animals in the population, elk marked each year must accumulate and be used
during the years of population surveys. We implicitly assume that detection
of white radio collars from year 8 is equal to detection of white collars from
yearb when surveys are flown in yearc, otherwise there will be different
sighting probabilities for each cohort of marked elk. We also must assume
there will be some (1-5%) nonoperative radio collars on live elk which would
create an error in knowing how many elk are marked within the area surveyed
(fixed-winged flights will be conducted prior to population surveys to
determine number of functioning radios in the sampled area using and observer
independent of counters). This type of error would cause positive bias in
population estimates.
Bear et al. (1989) identified marker visibility, random sampling of the
population, and heterogeneous sighting probabilities due to group size or
vegetation type as problems associated with applying mark-resight estimators
to elk populations. We have attempted to address these concerns by using
high-contrast white collars not prone to color bias, helicopters to capture
elk throughout the distribution of the population, use of random sampling to
survey the population, and use of multiple independent aerial resight
(recapture) surveys to reduce recapture bias associated with other recapture
techniques and to improve precision of estimates (Otis et al. 1978, Bartmann
et al. 1987, Bear et al. 1989, Neal et al. 1993). Effects of group size and
vegetation type are sources of sighting heterogeneity which can bias the
variance of the estimate and may negatively bias the estimate (Bear et al.
1989, Neal et al. 1993). Comparing variances of estimates derived from markresight and the sighting probability model may provide some insight into the
severity of heterogenous sighting probabilities.
Population estimates based on the JHE mark-resight approach will be
calculated using the program NOREMARK (G. White, pers. comm.). We also used
NOREMARK to simulate expected quality of population estimates for the JHE
estimator given the following constraints. If the real population consists of
2,000 elk, 200 elk are marked with radio collars, about 10% of all elk are
observed on each flight ([sighting probability - 0.60) x [proportion of area
sampled - 0.15)), and 3 replicate flights are completed, we should achieve a
90% confidence interval about the true population of± 20% with a 1%
positively biased estimate of population size. Confidence interval coverage
would be 89% (n - 500 Monte Carlo simulations). During the second year of the
project when mark-resight surveys will be initiated on quadrats, there could
be about 200 marked elk in the population. Precision of JHE estimates would
improve to± 15% if 300 marked elk were available or 5 replicate flights were
completed. These would be potential design options if marked elk continued to
accumulate in the third or fourth year of the project or helicopter hours were

�102

FREDDY STUDY PLAN

V

reallocated among uses or increased.
The JHE estimator does not require that marked elk are individually
identified, only that marked and unmarked elk are discerned. If we can
consistently identify individual elk by collar numbers or radio frequency, the
Minta-Mangel mark-resight model can be used to estimate population size and
associated variance (Minta and Mangel 1989) using program N0REMARX. Variance
of this estimator can be calculated as described by Minta-Mangel (1989) or in
a new approach developed by Bowden (1993, unpubl. ms.). Complete capture
histories on each marked elk would also allow an assessment of bias associated
with the estimate of N due to unequal individual capture probabilities.
Unequal capture probabilities can be caused by individual animal behavior,
time intervals between initial capture and resight surveys, and heterogeneity
of capture probabilities due to factors of age, sex, social dominance, or
habitat. Program CAPTURE will be usedAto evaluate the most appropriate
capture probability model to estimate N (Rexstad and Burnham 1991).
C. Distribution and Movements of Elk
General Approach
All visual sightings of live and dead collared elk will be assigned UTM
coordinates as determined from USGS topographic maps. Visual sightings of
collared elk during winter will occur during ground surveys to determine
life/death status of elk and during aerial surveys to estimate population
density. These locations will provide a general perspective of the
distribution of elk on their winter range.

V

Seasonal patterns of movement will be obtained primarily from aerial
surveys. Accurate seasonal locations on all collared elk would be cost
prohibitive and not commensurate with the main objectives of the project.
Therefore we plan to randomly select 20% of the calves (8 M, 8 F) and 20% of
the adult females (15) and monitor their locations periodically to reveal
patterns of seasonal movement. Yearling males marked as calves will be located
prior to hunting seasons to monitor their fates in relation to antler-point
restrictions. Distribution and movement data will be plotted following
suggestions of White and Garrott (1990).
V.

SCHEDULE

Activity

Approximate Date

Phase !--Complete detailed study plan,
July 1992-June 1993
select study location, refurbish
elk traps, purchase radio collars for
calves and design expandable collars
for calves.
Phase !!--Complete initial purchase of
July 1993-June 1994
radio collars; trap and radio-collar
Trapping 12/93
elk to estimate survival; begin surveys
Sighting bias
to design sighting bias estimator. 1 &amp; 2/94

V

�103

FREDDY STUDY PLAN

July 1994-June 1995
Phase III--Continue radio-collaring
Trapping 12/94
elk for estimating survival,
Sighting bias 12/94,
continue testing sighting
bias estimator, estimate population 1/95, 2/95; Pop.
Est. 1 &amp; 2/95
size using quadrats and mark-resight.
Phase IV-- Estimate pop. size
July 1995-June 1997
size using sighting bias correction,
Trapping 12/95 &amp; quadrats,
and mark-resight. Continue
12/96; Pop. Est.
trapping to estimate
survival.
1/96 &amp;1/97
VI.

PERSONNEL
PROGRAM RESPONSIBILITIES

David J. Freddy: Principal Investigator responsible for final project design,
organizing field personnel, obtaining and organizing data, financial
control, coordinating publications.
R. Bruce Gill: Provide administrative support, input for study design, and
liaison with other administrative sections within the Division of
Wildlife or other natural resource agencies.
\,_,_,/

John H. Ellenberger and James H. Olterman: Provide input for study design and
location, coordinate study with Regional activities, and logistical
support.
David C. Bowden and Gary C. White: Provide input for study design and
statistical protocol, conduct data analyses, and provide software
support.

�104

FREDDY STUDY PLAN

VII.

V

BUDGET-SUMMARY

ACTIVITY

FY92-93

Personal
Operating
Travel
Capital
Total

55,773
26,800
1,200
4,700
88,473

W/ 4% inflation
BUDGET-ITEMIZED

FY94-95

FY95-96

FY96-97

70,706
72,236
70,706
72,236
66,370
93,045
66,020
72,270
4,940
4,940
4,680
5,590
0
5,700
0
0
141,666
154,886
142,016
170.871
161,081
FY92-93

PERSONAL SERVICES
$49,841
A. D.J. FREDDY 12 MOS
$2,509
8. MAMMALS SECR. 1 MOS
$0
C. UTILITY I 6 MOS OCT-MAR
$2,723
D. UTILITY 1, TRAPPING
E. WORK STUDY STUDENT, 1 YEAR $700
$0
F. VOLUNTEER FOR 20 DAYS
$55,773
SUB-TOTAL
OPERATING
G. VEHICLES MILEAGE, 4X4, 3
$2,200
H. VEHICLES, SNOWMOBILES, ATV $0
I. NEW RADIO COLLARS
$19,500
J. REFURBISHED RADIO COLLARS $0
$3,000
J. TRAPPING, BAIT, SUPPLIES
$1,500
K. MISC. SUPPLIES, SERVICES
L. FIXEDWINGED, MORT. SURV.
$600
M. FIXEDWINGED, SIGHT. SURV.
$0
N. HELICOPTER, SIGHT. SURVEYS $0
0. HELICOPTER, QUAD. SURVEYS $0
P. HELICOPTER, NONRANDOM SURV. $0
Q. HELICOPTER TRAPPING
$0
SUB-TOTAL
$26,800
TRAVEL
R. DJF 10 DAYS, STANDARD
$650
S. DJF DAYS TRAPPING
$550
$0
T. VOLUNTEER, TRAPPING
U. REGION PERSONS, TRAPPING
$0
$0
V. REGION PERSONS, SURVEYS
$1,200
SUB-TOTAL
CAPITAL EXPENSES
$3,200
W. RADIO TELEMETRY RECEIVER
X. PACK-SETS/LAPTOP COMPUTER $1,500
$4,700
SUB-TOTAL
PROJECT YEARLY TOTAL
WITH 4X INFLATION

FY93-94

$88,473

177,706

147,333

FY93-94

FY94-95

FY95-96

$56,796

$56,796
$2,500
$9,180
$3,060
$700
$0
$72,236

$56,796

$56,796

$2,500
$9,180
$3,060
$700
$0
$72,236

$2,500
$9,180
$1,530
$700
$0
$70,706

$2,500
$9,180
$1,530
$700
$0
$70,706

$5,720
$350
$8,600
$0
$2,500
$2,500
$3,150
$2,700
$21,750
$0
$0
$25,000
$72,270

$5,720
$350
$15,000
$4,050
$2,500
$2,500
$3,150
$4,050
$32,625
$4,350
$0
$18,750
$93,045

$5,720
$5,720
$350
$350
$6,000
$5,000
$6,750
$5,400
$2,500
$2,500
$2,500
$2,500
$3,150
$3,150
$1,800
$1,800
$0
$0
$21,750 $21,750
$4,350
$4,350
$12,500 $12,500
$66,020 ,$66,370

$650
$1,365
$0
$1,365
$1,300
$4,680

$650
$1,365
$0
$1,365 .
$2,210
$5,590

$650
$1,365
$0
$1,365
$1,560
$4,940

$650
$1,365
$0
$1,3~5
$1,560
$4,940

$3,700
$2,000
$5,700

$0
$0
$0

$0
$0
$0

$0
$0
$0

147,697

FY96-97

$154,886 $170,871 $141,666 $142,016
$161,081 $177,706 $147,333 $147,697

"""**************************************"""1Tt*"""1Tt*****"""*************************************

0
REGION TRAPPING MDAYS
65
REGION PILOT, HRS
20
REGION BIOL.,FLYING MDAYS
REGION PICKUP(S)+TRAP TRAILER(S) TRAP
A/N
REGION SKIDOO ALPINE AND ATV
3
REGION PROP. TECH. MDAYS

21
65
20
TRAP
A/N
3

21
80
34
TRAP
A/N
3

21
55
24
TRAP
A/N
3

21
55
24
TRAP
A/N
3

--

V

..

�105

FREDDY STUDY PLAN
VIII. LOCATION
We selected the eastern portion of GMU 42 within the Grand Mesa DAU (E14) for conducting this project (Appendix VII). This area encompasses about
1,028 km2 (397 mi 2 ) in the Divide Creek drainages located south of the towns
of Newcastle and Rifle in west-central Colorado. We estimate that 1500-3000
elk inhabit about 642 km2 (248 mi 2 ) of winter range within this area. This
area meets the following necessary criteria: 1) the elk population is
relatively "closed" during the winter, that is, subject to minimal emigration
or immigration, and assumes a somewhat static distribution during winter; 2)
the winter range generally has reliable snow cover to facilitate detecting elk
during population surveys and mixed vegetation types consisting of oakbrush,
aspen, sagebrush, juniper-pinyon woodland (Juniperus osteosperma-Pinus
edulis), mixed conifers (Picea sp., Abies sp.) and agricultural fields typical
of many elk winter ranges in western Colorado; 3) there is dependable access
for research purposes to both private and public lands and dependable public
access to public lands for hunting; 4) there is minimal large-scale land-use
conflict problems such as agricultural damage; 5) there is local, area, and
regional CDOW support for conducting the project in this area; and 6) the
airport at Rifle will provide readily accessible support services.
IX.

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.,

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Quimby, D. C., and J. E. Gaab. 1957. Mandibular dentition as an age
indicator in Rocky Mountain elk. J. Wildl. Manage. 21:134-153.
Rexstad, E., and K. Burnham. 1991. User's guide for interactive program
CAPTURE. Coop. Fish &amp; Wildl. Res. Unit, Colorado St. Univ., Fort
Collins. 29pp.
Samuel, M. D. and K. H. Pollock. 1981. Correction of visibility bias in
aerial surveys where animals occur in groups. J. Wildl. Manage. 45:993997.
_ _ , E. O. Garton, M. W. Schlegel, and R. G. Carson. 1987. Visibility bias
during aerial surveys of elk in northcentral Idaho. J. Wildl. Manage.
51:622-630.
___ , R. K. Steinhorst, E. 0. Garton, and J. W. Unsworth. 1992. Estimation
of wildlife population ratios incorporating survey ~esign and visibility
bias. J. Wildl. Manage. 56:718-725.
SAS Institute, Inc. 1988. SAS Language guide for personal computers. SAS
Institute Inc., Cary, NC. 1028pp.
Sauer, J. R., and M. S. Boyce. 1983. Density dependence and survival of elk
in northwestern Wyoming. J. Wildl. Manage. 47:31-37.
Schlegel, M. W. 1977. Factors affecting calf elk survival on Coolwater Ridge
in north central Idaho. Pages 35-37 in Proc. Western States Elk
Workshop, Estes Park, Colo.
Siniff, D. B., and R. 0. Skoog. 1964. Aerial censusing of caribou using
stratified random sampling. J. Wildl. Manage. 28:391-401.
Unsworth, J. W., L. Kuck, and E. 0. Garton. 1990. Elk sightability model
validation at the National Bison Range, Montana. Wildl. Soc. Bull.
18:113-115.
___ , F. A. Leban, G. A. Sargeant, E. 0. Garton, M.A. Hurley, J. R. Pope,
and D. J. Leptich. 1991. Aerial survey: user's manual with practical
tips for designing and conducting aerial big game surveys. Idaho Dep.

�108

FREDDY STUDY PLAN

Game &amp; Fish, Boise. 54pp.
Wade, D. A., and J. E. Browns. 1982. Procedures for evaluating predation on
livestock and wildlife. Texas Agric. Expt. Sta. Publ. B-1429. 42pp.

u

White, G. C. 1983. Numerical estimation of survival rates from band recovery
and biotelemetry data. J. Wildl. Manage. 47:716-728.
_ _ . 1992. DEAMAN database manager and population modeling procedures;
Colorado Division of Wildlife User's manual and reference. Colorado St.
Univ., Fort Collins. 109pp.
___ ,D.R. Anderson, K. P. Burnham, and D. L. Otis. 1982. Capturerecapture and removal methods for sampling closed populations. Los
Alamos Natl. Lab. IA-8787-NERP. 235pp.
___ , R. M. Bartmann, L. H. Carpenter, and R. A. Garrott. 1989. Evaluation
of aerial line transects for estimting mule deer densities. J. Wildl.
Manage. 53:625-635.
___ , and R. A. Garrott. 1990. Analysis of wildlife radio-tracking data.
Academic Press, Inc., San Diego. 383pp.
___ , R. M. Bartmann, L. H. Carpenter, and A. W. Alldrege. 1987.
Survival of mule deer in northwest Colorado. J. Wildl. Manage. 51:852859.
Zager, P., and D. J. Leptich. 1991. Comparing two methods of calculating elk
survival rates. Pages 106-109 in A.G. Christensen, L. J. Lyon, and T.
N. Lonner, comps., Proc. Elk Vulnerability Symp. Montana St. Univ.,
Bozeman.
APPENDIX I
Specifications for Radio Collars
Pulse Rate Normal: 60-65 ppm
Pulse Rate Mortality: 120-130 ppm
Motion Sensor Delay: 4-6 hrs
Batteries: 4+ year life, 2 lithium D-cells adults, 1 lithium D-cell calves
Antenna: External whip, pvc coated
Collar Material: 7.6 cm (3") wide white colored smooth surfaced conveyor
belting, 2 layers sewn together, 0.64 cm (1/4") total thickness
Additional Material: Bright white with black core Ritchie All-Flex rubber
material for identifcation symbol/number placed as a sleeve over top
portion of collar
Collar Size: 61-81 cm (24-32") adult females, individually fitted 61-81 cm
(24-32") expandable for female calves 61-97 cm (24-38") expandable for
male calves
Collar Weight: About 1.1 kg

V

�109

FREDDY STUDY PLAN

APPENDIX II
Animal Welfare Concerns
There are 3 potential issues regarding animal welfare: use of ear-tags, use of
radio collars, and capture techniques.
Ear-tags: To permanently mark radio-collared animals and some non-collared
animals, an aluminum, numbered and colored ear-tag will be placed in each ear.
Tags are self-piercing using special pliers and have been used for many years
on elk. To reduce potential problems of tag loss, tags will be placed on
front edge of the ear about 1/3 to 1/2-way above the base of the ear and the
edge of the tag will be flush with the edge of the ear.
Radio collars: Fitted size of radio collars is based on measurements from
hunter-killed elk and captive research elk and testing of actual collars on
captive elk. The basic expandable design for calves has been extensively
field tested on deer and moose.
Capture Techniques: We will capture elk in traditional corral traps capable
of holding several elk at one time and by net-gunning individual elk from a
helicopter. We expect a 1-2% serious injury/mortality rate with either
technique. Animals having a broken leg, neck, or pelvis will be euthanized
with a gunshot to the head following euthanasia procedures in our Animal
Welfare guide. All persons involved in capture will be trained to properly
euthanize appropriate animals. Capture techniques will be constantly
monitored and changed if necessary to insure that minor injuries to animals do
not chronically occur.
Animals captured with a helicopter will be hobbled and blindfolded and
slung under the helicopter to a nearby field processing point where they will
be collared, weighed, etc. and then released at that site. We aniticapte 1-5
minutes to capture the elk, 1-2 minutes to ferry the elk to .processing point,
and 3-4 minutes to process the elk before release. This technique has been
successfully used to capture and radio-collar elk in Arizona, Colorado, Idaho,
Montana, Oregon, and Washington. Because of short handling times, mortalities
due to capture have been rare.
Animals captured in corral traps will be blindfolded as they are
processed in the chutes. Calves may be hobbled or walked into a holding box
for weighing. We prefer to trigger traps manually using a solenoid system so
we can be selective about animals captured and reduce the time animals are in
traps. However, traps may be triggered by animals entering and in such cases
animals may be in the trap overnight. Food will be provided via alfalfa used
as bait. We will use the minimum number of persons to process elk to reduce
capture stress.

�110

FREDDY STUDY PLAN

.

APPENDIX III
Visual Identification System for Radio Collars
Numbers, symbols, and letters will be used in ordered combinations to identify
individual elk primarily during mark-resight aerial surveys. No more than 3
characters will be used to identify an individual and there will always be a
2-digit number.
Numbers Used ( 8) : •0 , 1, 2 , 3 , 4 , 5 , 6 , and 7
Symbols Used (5): ., ■, ♦, ◄, +
Letters Used (11): A, C, F, H, K, N, P, T, V, X, y
10, 20,
11, 21,
12, 22,
13, 23,
14, 24,
15, 25,
16, 26,
17, 27,

Number Matrix
30, 40, 50, 60,
31, 41, 51, 61,
32, 42, 52, 62,
33, 43, 53, 63,
34, 44, 54, 64,
35, 45, 55, 65,
36, 46, 56, 66,
37, 47, 57, 67,

70
71

72
73
74
75
76
77

Each Symbol with each number represents 56 identification codes; all
symbols with each number equals 280 codes or animals.
Each letter with each number represents 56 codes; all letters with each
number equals 616 codes or animals.
Therefore, 896 different animals can be individually marked using this
system.

V

�.L.L.L

FREDDY STUDY PLAN

APPENDIX IV

,.

Precision and Power of Survival Estimates and Tests

30

ii

25

S•0.50

! ..
I

...

120

0

115

~

!,

10

S •0.80

..

S •0.80

•

S • 0.70

■

•

*
5

50

100

75

RADlO COLLARS DEPLOYED
1

=.
0

I

I

DETECT DIFFERENCES IN SURVIVAL OF:
DIFF•O.25
DIFF•0.2
DIFF•0.1
DIFF•0.05

o.a
... --------·······

0.8

@

.. -....

ffi 0.4

··········••••••••••••

~

I

..----·

---

---------······

................................... ......................

···-·••"

.....

0.2

a.

0
20

40

60

75

80

100

RADIOCOUARS DEPLOYED
1.2

!
I

I
@

DETECT DIFFERENCES IN SURVIVAL OF:
DIFF•O.25
DIFF•0.2
DIFF•0.1
DIFF•0.05

1

---------~------------------------------

o.a
············•••••••••••••••
0.8

Ii
~

~

·~

I

-

.-···············

................................................. ...

0.4
0.2
0
20

40

60
75
RADIO COLLARS DEPLOYED

80

100

�112

FREDDY STUDY PLAN

V

APPENDIX V
Classification variables for elk groups and flight conditions for sightability
trials,
Group Size
1
2
3

Vegatation Type

Activity Level

Oakbrush-dense/continuous
Oakbrush-scattered/clumped
Aspen
Sagebrush
Pinyon-Juniper
Tall Conifer
Agri. Fields/Clearings
Riparian

Bedded
Standing
Moving

4
5
6
7
8
9

10-14
15-19
20-24
~25
% Vegetation Canopy
Vertical Cover
0-15
16-25
26-35
36-45
46-55
56-65
66-75
76-85
86-100

%Snow Cover

Snow Type

0

Fresh New Snow
Old snow with old tracks

1-25
26-50
51-75
76-99
100

Lighting Conditions

Age/Sex Marked Elk

Bright Sun/High Contrast
Male Calf
Female Calf
Hazy Sun
Adult Female
Overcast, dull light
Yearling Male
Adult Male
Search Rate

Year/Period Pilot Observer
1993-94-I
1993-94-II
1994-95-I
1994-95-II
1994-95-III

1993

1993

1994

1994

km2 /

min

�113

FREDDY STUDY PLAN
APPENDIX VI
Power Considerations for Sightability Models
Dr. David C. Bowden
Consider the logistic model (1) below which describes the probability of
observing elk groups for a given set of observational conditions. Assume that
the same model also describes the probability of observing elk groups for a
different set of conditions but with a different value for the parameter Po•
Suppose data is obtained under both sets of conditions. This section describes
the results of a simulation study which investigates the power of a test of
the hypothesis that the parameter value for Po is the same for both sets of
conditions.
In the simulation study, observations were generated as if two sets of
conditions applied. Then a test of equality of the 2 Po values was performed.
This process was repeated 1000 times. The proportion of times that the null
hypothesis was rejected estimates the power of the given test.
Following Samuel et al. (1987), it is assumed that the probability of
sighting elk groups in uniform habitat relative to percent vegetation cover
can be adequately modeled as
P = 1/ (1 + exp (- ((3 0 +P 1 ln (g)) )

(1)

where pis the probability of sighting a group of size gin the specified
habitat, Po and P1 are parameters and ln(g) is the natural logarithm of g.
Those authors estimated the parameter values to be .22 and 1.55, respectively
for

habitat locations with 20 % vegetation cover and -0.78 and 1.55 with 40%
vegetation cover. These sets of estimates were used to specify the parameter
values for the simulation study. Table 1 gives values of p for the 2 sets of
parameter values and a few choices of group sizes. Thus the problem of
interest is, "What is the chance that a change in sighting probabilities as
given in Table 1 will be detected if the conditions of the simulation study
apply?"

�114

FREDDY STUDY PLAN

V
Table 1. Probability of sighting given 2 sets of parameter values at
different group sizes (g). Sample 1 uses Po = . 22 and P1 = 1, 55 in function
(1) and Sample 2 uses Po m - • 78 and p1 = 1. 55.
Group size(g)

PROBABILITY
SAMPLE 1
SAMPLE 2

1

.555

.314

2

.785

.573

3

.872

.716

4

.914

.797

5

.938

.847

6

.952

.881

10

.978

.942

15

.988

.968

20

.992

.979

30

.996

.989

Generation of observations for a single iteration in the simulation
study is described next. A set of n elk groups were used to generate 2 samples
of elk group observational data. Sample 1 was generated by taking an
observation from a Bernoulli random variable for each group where the
probability of success is given by probability function (1) with Po = .22 and
p1 = 1. 55 , that is, a random uniform number on the interval [O, 1), say u, was
selected, if u~p then the group was said to be sighted otherwise it was not
sighted. The second sample of n observations was independently generated with
the same group sizes using parameter values Po c - • 7 8 and p1 = 1. 55 and
function (1) to obtain the needed probability of success. ·The 2 samples of
sighting data were pooled and then analyzed using the SAS logistic regression
procedure. The following model was fit to the pooled data set:
p = 1 / ( 1 + exp ( - ( PO + P1 ln ( g &gt; + P2 z ) ) )

(2)

where z is an indicator variable which is equal to O if the observation came
from sample 1 and is equal to 1 if the observation came from sample 2. The
question of interest is, "What is the power of a «-.05 test of the hypothesis
that p2 O versus an alternative hypothesis 11 2 .. O when actually p2 = -1 ?"
This null hypothesis is equivalent to stating that the 2 samples were
generated from the same logistic function. Of course the power of the test
depends on the distribution of group sizes and the number of groups in each
sample. It should also be clear from Table 1 that groups of sizes 1-10 are
needed to obtain reasonable power unless very large numbers of groups are
observed in both samples.
Group sizes used in the study are those obtained from a sample survey
i.:

V

�115

FREDDY STUDY PLAN

of a winter elk population. This sample survey was a stratified random quadrat
count in game management unit 23, 24 on January 18-19, 1989 by C. Reichert,
J.Ellenberger, and D. Freddy. During the sample survey, 84 elk groups were
observed and group size recorded (Table 2).
Table 2. Frequency distribution of the 84 elk group sizes.
Group size

1

2

3

4

5

6

7

8

9

Frequency

9

12

10

9

10

5

4

4

6

Group size

10

11

12

13

16

18

19

20

39

Frequency

1

3

2

3

1

1

1

2

1

Two independent simulation studies were performed using the frequency
distribution ·of group sizes from Table 2 in the data generation step. Each
study consisted in 1000 replications of pairs of samples generated as
described above. In the first study, for each of the 84 listed group sizes, a
determination of sighting or not was made, independently, using the 2
probability sighting functions. In the second study the frequency of groups of
a given size·in Table 2 was doubled to give 2 samples of size 168, replicated
1000 times. For each replication the 2 samples were pooled and model (2)
fitted. Then the null hypothesis that 11 2 = O was tested. The number of
rejections of this null hypothesis is shown for the 1000 replications in Table
3 as 10 sets of 100 tests each. The standard error of the estimated power was
calculated using variation among the 10 sets.
Thus given 2 independent samples of observations each based on 84 groups
with frequency distribution listed in Table 2, a 5% significance level test
has an estimated power of . 57 ( se-.016) of rejecting H0 : 11 2 = O when P2 = -1.
The estimated power when the number of groups is doubled (n-168 each) is
estimated to be .873 ( se-.006).

�116

FREDDY STUDY PLAN

V
Table 3. Proportion of rejections of the null hypothesis
H0 : p2 = O vs HA: P2 ~ O when P2 = -1 , for 10 sets of 100 replications each,
Cl

= . 05.

Set

Sample I

Sample II

1

.58

.89

2

.59

.89

3

.62

.88

4

.66

.86

5

.57

.91

6

.58

.88

7

.52

.85

8

.51

.88

9

.57

.86

10

.50

.90

Mean

.57

.88

SE

.016

.006

u

Reference
Samuel, M., E. Garton, M. Schlegel, and R. Carson. 1987. Visibility bias
during aerial surveys of elk in northcentral Idaho. J. Wildl. Manage.
51: 622-630.

V

�.&amp;..&amp;.,

FREDDY STUDY PLAN

APPENDIX VII

Location of the study area in the eastern portion of Game Management Unit 42
within the Grand Mesa Data Analysis Unit E-14.

50 MILES

NEWCASTLE

GRAND MESA DAU
E-14 UNIT B
DARY

GRAND JUNCTION

�27
Colorado Division of Wildlife
Wildlife Research Report
July 1994

~~

JOB PROGRESS REPORT
State of

Colorado

Project No.

W-153-R-7

Mammals Research

Work Plan No.

3

Elk Investigations

Job No.

9

Estimating Survival Rates of Elk
and Developing Techniques to
Estimate Population Size

Period Covered:
Author:

July 1, 1993 - June 30, 1994

D. J. Freddy

Personnel:

F. Barnes, J. Broderick, G. Byrne, D. Crane, J. Ellenberger, J.
Frothingham, V. Graham, J . Gray, R. Hays, c. Kolus, G. Loucks, J.
Pelletier, S. Rivera, P. Will, CDOW; D. Bowden, C. Vardeman, G.
White, CSU; M. Miller, C. McCarty, R. Witt, Volunteers; USFS
Rifle, BLM Glenwood Springs, Cooperating.

Abstract
We radio-collared 73 calf elk (Cervus elaphus nelsoni) (6 mos old) and 68
adult female elk(~ 1 year old) in December 1993 to estimate survival rates
during winter and used these same elk in 110 aerial sighting bias trials to
develop models for estimating degree of negative sighting bias when counting
elk with a helicopter on sample quadrats. Elk were captured using portable
corral traps and helicopter net-gunning. Survival rates(± 95% CI) from
December 1993 to June 1994 were 0 . 918 + 0.063 for calves and 0.956 + 0.049 for
adult females. Suspected causes of death were primarily malnutrition and
predation for calves and shooting and predation for adult females. Calves
suspected of dying from malnutrition had marrow fat values&lt; 13% at death and
body weights&lt; 102 kg at capture . Blood tests for brucellosis were negative
in all 43 adult females sampled while progesterone assays indicated 74-80% of
the adult females were pregnant. Observers did not count 15.4% of the elk
during sighting trials resulting in a simple binomial correction factor of
0.846 ± 0.071 (± 95% CI). Univariate tests, however, indicated elk age,
log(ln)initial group size, log(ln) total group size, elk behavior, vegetation
type, percent occlusion cover, percent snow cover, and wind conditions
affected sightability of elk (P ~ 0.05). Step-down regression analyses
produced a complex 12 parameter sighting model inclusive of elk age, elk
behavior, vegetation type, log total group size, and percent snow cover.
Simpler models inclusive of log total group size or log total group size and
percent occlusion cover may be more utilitarian and provide acceptably precise
correction factors. The simple binomial correction model provided
unacceptably inflated and imprecise correction factors which supported
incorporating the variable total group size into sighting bias models.

�29

JOB PROGRESS REPORT
ESTIMATING SURVIVAL RATES OF ELK AND DEVELOPING TECHNIQUES TO
ESTIMATE POPULATION SIZE

David J. Freddy
P.H. OBJECTIVE

Estimate survival rates of adult female and calf elk and develop techniques to
estimate population size.
SEGMEw.l? OBJECTIVES

1.

Radio-collar 75 adult female and 75 calf elk during December 1993 in Game
Management Unit 42 south of Rifle, Colorado.

2.

Estimate winter and annual survival rates of calf and adult female elk
from known fates of radioed elk.

3.

Estimate probability of sighting and counting elk during helicopter
surveys using radioed elk as a known population.

4.

Analyze survival and sightability data and summarize annually in Federal
Aid Job Progress reports
IRTRODUCTIOH

Elk (Cervus elaphus nelsoni) are a high-profile and burgeoning wildlife
resource throughout much of Colorado. This burgeoning resource has many
benefits but frequent social, political, and economic conflicts suggest elk,
to some degree, have reached a "social" carrying capacity.
Many conflicts arise, in part, from an inadequate ability to predict the
dynamics of elk populations. Key population parameters such as survival rates
of calves and adult females and total population size are seldom measured
resulting in computer models of elk population dynamics that are based on
minimal data. Such models can be of little predictive value and, as such,
diminish confidence in using models to guide management of elk populations.
our objectives are to provide reliable estimates of survival rates for calves
and adult females during winter and for adult females throughout the year for
the period 1993-94 through 1997-98. Additionally, we will develop and test a
system for estimating population size that will incorporate estimates of
sighting bias in conjunction with a random sampling system using search
quadrats as sample units. our winter study area encompasses about 839 Jan2
(324 mi2) in the eastern half of Game Management Unit 42 south and east of
Rifle, Colorado~ Elk winter range vegetation types include juniper-pinyon
woodland (Juniperus ost;eosperma-Pinus edulis), oakbrush-mountain shrub
(Quercus gambelii-Amelanchier alnirolia), aspen (Populus t;remuloides),
sagebrush µrt;emisia t;rident;at;a), and agricultural fields ·(Freddy 1993).

�30

METHODS

Marking

V

We placed radio collars (l72-176MHz) having mortality sensors on 73 calves (6
mos old), of which 36 were males and 37 were females, and 68 adult females(~
l year old). Of these, 54 calves and 46 adults were trapped from 2-6 December
1993 using helicopter net-gunning and 19 calves and 22 adults were trapped
from 10-20 December using portable corral traps. Helicopter capture occurred
at 17 remote sites located primarily on public lands while corral-trapping
occurred at 3 sites primarily on private lands.
Trapping effort was allocated among 8 geographic trap zones to assure that
radioed elk were representative of most if not all segments of the population
(Table 1). Number of elk to be captured in each zone was established prior to
trapping based on distribution and relative numbers of elk observed during sex
and age ratio classification flights completed annually in January from 1989
to 1993.
Collars for adults were fixed in c·ircumference while those for both male and
female calves were expandable to accommodate growth when animals became
adults. Additionally, all radio collars had a 2 character visual
identification code on the dorsal surface of the collar consisting of letters,
numbers, or-symbols.
Collars were white with black symbols.
Calves captured by net-gunning were ferried by helicopter to processing points
usually within 1.6 km of capture sites. At processing points, body weight,
total body length, and hind foot length were measured and calves were then
radio-collared and released. Similar measurements were also made on calves
that were corral-trapped and then released at the trap site. Body
measurements for calves were compared between sexes using Proc FREQ and Proc
GLM (SAS 1988).

Physiological Assays
Serum samples were obtained from adult females captured by net-gunning for
brucellosis tests (USDA Lab, Denver) and progesterone assays (Physiology Lab,
Colo. St. Univ.). Fat content (percent dry matter) of femur marrow or lower
jawbone marrow obtained from dead radioed elk was determined (Colo. Div.
Wildl. Lab, Ft. Collins).
Survival
We monitored life or death .status of radioed elk during daily ground surveys
and aerial surveys conducted at 2-4 week intervals from December 1993 through
April 1994 and via monthly aerial surveys in May and June 1994. Survival
rat~s (S) of radioed elk were calculated using the binomial estimator with a
variance, VAR(S) = S(l-S)/n (White and Garrot 1990)(Proc FREQ, SAS 1988). We
chose not to use the staggered entry approach and did not use a Kaplan-Meier
approach because no animals were censored (White and Garrot 1990). Life or
death status of all radioed calves was known for the period 2 December through
15 June. On 15 June, calves become yearlings for purposes of calculating
rates of calf survival. Life·or death status was known for 65 of 68 adult
females through 15 June with all females of known status through 28 April.
Sighting Bias
We conducted 110 aerial sighting bias trials that targeted individual radioed
elk located on search quadrats (Samuel et al. 1987). Trials were conducted on
25, 27, 28, and 31 January, l, and 14-17 February, and on 9 March. Search
quadrats were approximately 2.6 km (l mi2 ) in size with boundaries based on
topographic features
We used a Bell B-1-Soloy helicopter, the same pilot, and observation teams
composed of 2 persons selected from 3 observers and 2 navigators for all

V

�31

trials. The Bell-Soley offers good forward and lateral visibility.
Navigators were seated in the middle with the pilot to their left and the
primary observer to their right. Navigators were highly experienced at flying
sample quadrats and observers had high, moderate, low experience in flying
sample quadrats. However, all observers were well experienced in conducting
sex and age ratio helicopter survey flights for elk. The helicopter was flown
at speeds of 65-95 Janph at 25-40 m above the vegetation canopy when flying the
perimeter of search quadrats and weather permitting, at slower speeds and
lower heights when searching the interior of quadrats.
Searching time per
quadrat ranged from 10-50 minutes.
Sighting bias trails were usually conducted in 2 sessions each day. Op to 8
different radioed elk were located via telemetry with a Cessna 185 during each
early morning and mid-day session. Locations of elk were assigned to a
previously determined search quadrat. Assignment to a quadrat was confirmed
by a technician on the ground who checked Loran-c locations obtained by plane
with latitude-longitude locations of quadrats plotted on USGS 7.5 minute
topographic maps. The navigator was given a list of 5-8 target elk and
quadrats per session but no information as to where target elk were located
within quadrats. Usually within 2 hours of locating target elk with the
plane, the helicopter team searched the quadrat and counted all groups of elk
until either·the target radioed elk was seen or until the entire quadrat had
been searched and the target elk not seen. If a target elk was missed, the
helicopter team located the elk via telemetry immediately after completing
their search of the quadrat to determine whether the elk was on or off the
quadrat at the time they flew the quadrat.
The helicopter team recorded initial group size, total group size, activity
behavior, vegetation type, percent occlusion cover, and percent snow cover for
the portion of each group initially detected whether or not a group contained
a radioed elk (Appendix I). Snow type, light conditions, wind conditions were
assessed for each quadrat. When radioed elk were observed, they were usually
individually identified by the number/symbol code, and if a target elk, the
search was then terminated. Several radioed elk were often seen per quadrat.
After completing the search of a quadrat, observers located target elk that
were missed, and, if found on the quadrat, observers recorded all sighting
variables for the missed group.
Usually 10-12 trials were conducted each day. Successful trials occurred when
the target elk was on the assigned quadrat whether or not that elk was seen.
Unsuccessful tr-ials occurred when target elk were found off the assigned
quadrat immediately subsequent to the time the quadrat was flown. Elk were
off quadrats primarily due to their movements that occurred between the time
elk were located with the plane and the time the helicopter team flew the
quadrat.
We wanted to avoid any positive effects on sightability that might be gained
if an observer located a target elk during 1 trial and then was assigned that
same target elk during another trial. Thus, elk were targets for an
individual observer only once. However, the same navigator was involved in 2
trials with each of 2 elk, but the 2 trials were generally 2-4 weeks apart and
we suspect the navigator had little influence on the ability of the
·-·.observation team to detect ·the target elk. We subsequently targeted 90
different radioed elk: 70 were targeted 1 time and 20 were targeted 2 times
during the 110 trials and for 106 trials,· there was a unique combination of
observer and navigator attempting to detect the targeted elk.
Sighting bias models were developed using logistic regression (Pree GENMOD,
SAS). The dichotomous classification of groups seen or missed was the
dependent variable. Initial group size, total group size, activity behavior,
vegetation type, percent occlusion cover, and percent snow cover, etc. were
independent variables. Significance level for independent variables was PS
0.05 for univariate tests and PS 0.10 for stepwise regression in multivariate
models. Relative efficiency of models was assessed using AIC values (Akaike
Information Criterion= -2(-log likelihood value)+ 2[No. model parameters)).
Observer, navigator, trap method, elk sex, elk age, activity, vegetation type,

�32

snow type, and wind were treated as class variables and group size, percent
occlusion cover, and percent snow cover were treated as continuous variables.
Variances for estimates of total elk that were derived from sighting models
followed a modified version of that presented by Steinhorst and Samuel
(1989)(pers. comm. D. Bowden and G. White).

V

Movements
We located 34 radioed elk (17 adult females, 17 calves [9 males, 8 females)
at least once per month since capture via telemetry using a Cessna 185. These
elk were selected at random from within trap zones and equalized by age class.
These elk will be monitored seasonally to document general movements and areas
of use with results reported next year.
•
RESULTS ARD DISCUSSION

Survival
From 2 December 1993 through 15 June 1994, 6 calves died (4 male, 2 female)
and 3 adult females died (Table 2). Overwinter survial rate(± 951 CI) for
calves was 0.918 ± 0.063 and for adult females was 0.956 ± 0.049. These
survival rates were associated with a winter considered to be mild in both
temperature and snow depth.
Suspected· causes of death were primarily malnutrition and predation _for calves
and shooting and predation for adult females (Table 2). Those calves dying
from malnutrition had marrow fat values&lt; 131 at death and body weights&lt; 102
kg at capture. The 2 smallest male calves weighed (Table 3) died of suspected·
malnutrition (Table 2).
Male calves had larger body weights (P = 0.03), longer hind leg lengths (P =
0.07), and higher condition indexes (P = 0.03) than female calves. Total body
lengths were not different between sexes (P = 0.36)(Table 4).
Blood Assays
Brucellosis tests were negative for all 43 adult females sampled.
Progesterone assays indicated 25 (741) of 34 adult females were pregnant
(1.37-4.69 ng/ml), 2 (61) were possibly pregnant (1.02-1.04 ng/ml), and 7
(201) were not pregnant(~ 0.37 ng/ml) (Freddy 1989). Of the females judged
not pregnant, 5 were judged to be 2-4 years old and 2, 5-9 years old.
Sighting Bias
We completed 99 successful sighting trials involving 45 adult females and 54
calves of which 26 were males and 28 were females. Elk involved in 11
unsuccessful trials we1;e .6 adult females and 5 calves.
Overall, observers missed 15.41 of the targeted elk (Table S). The degree of
negative sighting bias was not different among observers (P = 0.53) ranging
from 12.2 to 21.91. Therefore, the simple binomial correction factor(± 951
CI) for detecting elk was 0.846 ± 0.071.
Of the 16 target elk missed during successful trials (representing 16 target
groups), 14 (881) were calves (SM, 9F) and 2 (121) were adult females.
Frequency of missing male and female calves was not different between sexes (P
= 0.28). Calves missed were in groups of~ 4 elk, except for 1 group of 30
elk. Capturing calves with a helicopter or corral trap had no effect on their
sightability (P = 0.66).
Univariate tests indicated elk age (calf or adult), initial group size,
log(ln) initial group size, total group size, log(ln) total group size,
activity behavior, vegetation type, percent occlusion cover, percent snow
cover, and wind conditions affected the probability of sighting elk (P ~ a.as,
Tables 6, 7). The ln total group size was the most efficient of these single
variable models (AIC = 74.678; intercept= 0.1215, group size coefficient=

V

�33

1.3073). Log transformations of either initial group size or total group size
provided more efficient models than untransformed values (Table 7).
The initial multivariate model for stepwise regression incorporated elk age,
ln total group size, activity behavior, vegetation type, percent occlusion
cover, percent snow cover, and wind conditions. Vegetation type, percent
occlusion cover, and wind were not significant (Model A, Table 8). Proceeding
in a step-down process, wind was dropped as the least significant variable
from model A, then percent occlusion cover from model B, to derive model C in
which elk age, activity behavior, vegetation type, ln total group size, and
percent snow cover were all significant. However, model C necessitated
estimates of coefficients for 12 parameters which makes this model unwieldy
and likely subject to highly imprecise estimates of corrected numbers of elk
although this model had a relatively low AIC value (Table 8).
other models having fewer parameters were assessed. In model D having 3
primary variables, elk age was not significant, but ln total group size,
percent occlusion cover, and the interaction of elk age and ln total group
size were significant (Table 8). This significant interaction term reflected
that although calves were the predominate class of elk missed, they were
almost always in small groups when found after completely searching quadrats.
We are not sure whether calves were missed because they were in separate small
groups (assumed, true sighting bias) or because they represented a fraction of
a larger group that was detected but the calves were not seen (count·ing bias).
Missed groups involving targeted calves were seldom the only group of elk on
the quadrat. Model E includes _ln total group size and percent occlusion cover
which mimics variables used in sighting-models developed in Idaho for elk
(Samuel et al. 1987). These models were surprisingly similar considering that
the Idaho model was developed in tall conifer habitats and based only on
sightability of adult elk (Samuel et al. 1987) (Table 9). Model F includes
only ln total group size and had the highest AIC value but probability of
detecting a·group increased rapidly to~ 0.90 for groups~ 6 elk (Table 8,
Fig. 1).

The degree to which selected models corrected number of elk counted and the
variances of corrected counts were assessed. The simple binomial correction,
model G, inflated counts the most (18%) and had nearly the highest variance
(Table 10). Inflated counts resulted from applying the 0.846 correction
factor to large groups of elk which had a sighting probability of nearly 1.0
(Fig. 1) and needed no adjustment in numbers. Models E and F having ln total
group size or ln total group size and percent occlusion cover had similarly
low variances and low corrections for counts of 3-4% (Table 10). These 2
models highlight the need to include group size as an adjustment variable for
correcting counts. Adding percent snow cover as an additional variable, model
H, markedly increased the variance and provided minimal additional correction
to counts (Table 10). We caution, however, that small variances and
potentially precise estimates about corrected counts per quadrat based on
adjustments for group size may not result in highly precise estimates of
population size because of variance associated with total counts of elk among
sample quadrats when a sampling system is employed (otten et al. 1993).
CORCLUSIORS

We obtained acceptably precise estimates of calf and adult survival rates
during winter and recommend continuing our current sampling effort of
monitoring 75 radioed calves and 75 radioed adult females in 1994-95. Efforts
to measure and develop criteria to adjust for negative bias in counts of elk
were promising and we.recommend conducting an additional 100 sighting bias
trials in 1994-95 to refine a sighting bias model. We are particularly
interested in evaluating effects of elk age (calves) on sighting bias and
assessing potential heterogeneity of sighting probabilities for individual elk
among years by resighting elk in 1994-95 that were involved in trials in 199394.

�34

LITERATURB CITED

Freddy, D. J. 1989. Effect of elk harvest systems on elk breeding biology.
Colo. Div. Wildl. Game Res. Rep. July(l): 35-60.
Freddy, D. J. 1993. Estimating survival rates of elk and developing
techniques to estimate population size. Colo. Div. Wildl. Game Res.
Rep. July: 83-117.
Samuel, M. D., E. O. Garton, M. W. Schlegel, and R. G. Carson. 1987.
Visibility bias during aerial surveys of elk in northcentral Idaho.
Wildl. Manage. 51:622-630.

J.

otten, M. R., J.B. Haufler, s. R. Winterstein, and L. c. Bender. 1993. An
aerial censusing procedure for elk in Michigan. Wildl. Soc. Bull. 21:
73-80.
SAS Institute Inc. 1988. SAS/STAT User's Guide, 6.03. SAS Institute, Inc.,
. Cary, NC. 1028pp.
Steinhorst, R. K., and M. D. Samuel. 1989. Sightability adjustment methods
for aerial surveys of wildlife populations. Biometrics 45:415-425.
White, G. c., and R. A. Garrot. 1990. Analysis of wildlife radio-tracking
data. Academic Press, Inc., San Diego. 383pp.

V

V

�35

Table 1. Capture objectives and numbers of elk radioed in 8 trapzones, Game
Management Unit 42, December, 1993.

\,.._,I

Trap

Zone
A

B

C
D
E

F

G
H

Blls Col11i;:ed•
I.2tBJ. He1f.g ~2D:11

Capture
O)zjectj.ve

Bame
Garfield
Gibson
Uncle Bob
West Divide
Hightower
Middle Kamm
West Kamm
Dry Hollow

8

Adult
Eel!H!lgs
4
12
12
10
10

8

8

10
10

25
29
21
17
0

19
29
21
17
0

0

8

6

6

0

44

35

0

35

7

9

1
19

150

141

100

41

36

37

68

20
24

26

All

Calve!
Hales [emale1
3
1
5
8
10
7
6
5
4
3
0
0
3
2

0
6
0
0
0

0

• Helio - Helic~pter net-gunning, Corral - corral-trap.

Table 2. Causes of mortality for radioed elk in Game Management Unit 42, l
December-ls June 1993-94.
Radiocollar

~

l!:!!S!H!DSX

Sex

tgg•

172.090/93
172.542/93
172.690/93
172.899/93
173.000/93
173.262/93
173.289/93
173.461/93
173.469/93

F
p

11 yrs
6 yrs
8 yrs
10 mos
11 mos
10 moo
10 mos

1

F
F

F
M
M
M

M

9'mos-

11 mos

Date
Dead

Batimated
cmase of Deatb

1/16/94
2/01/94
1/24/94
3/18/94
4/25/94
3/18/94
3/22/94
2/07/94
4/25/94

Wounding LOBS
cougar kill
Gunshot, poached
Cougar kill
Malnutrition
Possible predation
Undetermined
Malnutrition
Malnutrition

Body
wt:. Usg!b

Harrow Fat
E1;ce11Ji Da Hatte,
not available
18.0°

not available
2e.sd
12.6c
28.9d
not available
2.1°
2. ,c

86

102
·108
111
82
77

Approxlmata age at death.

b Whole body weight at capture in December 1993.

° Fat content of either the right-or left femur bone marrow.

d Fat content: of lower jaw bona marrow.

Table 3. Frequency distribution of whole body weights for male and female elk
·calves trapped in Game Management Unit 42, December, 1993. Percentage per weight
class shown in parentheses.
Bodv Wgigb~ glll! (kg!

100-109

110-119

120-129

130-139

140-149

Total

3 (8.6)

6 (17.1)

12 (34.3)

10 (28.1)

1 (2.9)

1 (2.9)

35 (100)

8 (22.9)

12 (34.3)

4 (11.4)

6 (17.1)

0 (0.0)

0 (O.O)

35 (100)

Sax

70-79

80-89

90-99

Mala

1 (2.9)

1 (2.9)

Pamala

1 (2.9)

4 ( 11. 4)

�36

Table 4. Body measurements for elk calves trapped in Game Management Unit 42,
December, 1993.

Mean

Meaeurement;

Body Weight (kg)
112. 7
191.2
Body Length (cm)
Bindfoot Length (cm) 56.3
0.59
Condition Index
(Wt./Body Length)

MaJ.e CaJ.veg
Min
Max

o

Mean

141.0 35
210.0 36
61.0 36
0.67 35

SD

13.7
10.2
2.2

77.0
164.0
52.0
0.43

o.os

Eemale ~iJ.ves
SD

Mi.n

HM

103.8

12.2

188.9
54.8

9.8

76.0
167.0
51.0

123.0 35
207.0 35

0~55

2.1

o.os

0.46

59.0
0.64

u
34
34

Table S. Summary of elk sighting bias trials conducted in Game Management
Unit 42, January-March 1994. Percentages shown in parentheses.

0bB8!::£8E

Trials
6tt:eme51

Trials•
Hot
Usem2J.!}

Trials
Uae!lzie

Trial
Blk
Detectgs!

Trial
Blk Hot
ggtected

JB

29

3
4

DK

36
45

26(90)
32(89)

22(84.6)

JE

4

41(91)

36(87.8)

4(15.4)
7(21.9)
5(12.2)

Totals

110

11

99(90)

83(84.6)

16(15.4)

25(78.1)

V
Table 6. Blk sightability survey.results by major independent variables from
Game Management Unit 42, January-March, 1994.
!IEialalSI

IISh SIEmll!I

,,.

6
7
1
1
0
0
0
1
0

0.57
0.59
0.92
0.86
1.00
1.00
1.00
0.93
1.00

Iii.lad Ian

4

5
6
7-15

~

16-30

31+

v-... 'fype

Cleariq/Ag
Ripuian

&amp;&amp;;Bruh

O&amp;Jcbnab

PiDyaa-Junipm:

6

Aap8D

3
2

Tall CODJ.far
ocal. COVU(~)
0-19
20-39
40-59
60-19
80-100

I

8
10
11

6
5

5
17
14

7

Baddad
Standing
Hoving

Navigator
GB
VG

9
1
3
40

26
3
1

DH

1.00
1.00
1.00
O.89
O.81

Bllc,,Aga

0.33

calf sax

o.so

i'amala

22
25
23
12
1

O.96
0.89
O.79

o.ao
0.25

!!Ei.llalSI

11,111£1 lama

~

snow cover (I)
9

2
53

2

28

5

11

5

45
38

0.29
0.86
0.93

a.so

0.88

0-19
20-49
50-99
100

4
7
5

5
9

Trap (All elk)
COffal Trap 4
BelJ.c:optar
12
Trap (calvaa) •
corral Trap 3
Balicoptar
11

y-,£.Iblilty (group• 11aen / gmup■ seen plua groups iiilaaacl).

22

0.85

25
36

O.78

43
40

a.ea

0.96
0.74

21
19

O.81
0.68

27
56

O.87
O.82

11

0.79
0.73

29

3

2

0.40

3

4
29
48

0.97
0.84

1
9

0.57

Snow Type
l're■h

Old

. Adult hmala 2
calf (H + I') 14
Hal.a

1
3
6
3
3

~

Obaerver
JB
JB

0
0
0
5

11521 SIES!HDII

lli.lllml IUD

Behavior

GJ:Oup S1:a

1
2
3

!1d1blo

Wind
Light
~ate
St=ng

4
12

21

16
0
0

67
14

62

2

0.84
0.84

0.81
1.00
1.00

Ll.gbt
Bright

Dull
Ba:y

12

52

0

11

4

20

0.81
1.00
0.83

V

�37

Table 7.
summary of variables ·tested in univariate tests using logistic
regression for elk sightability trials, Game Management Unit 42, January-March,
1994.
Likelihood Ratio
Prob. &gt;Chi-Square

Variable
Date of Sight Trial
Sigh't; Trial
Navigator
Observer
Individual Elk
Sex of Elk
Age of Elk
Capture Type
Initial Group Size
Log(ln) Initial Group Size
Total Group Size
Log(ln) Total Group Size
Elk Activity
Vegetation Type
Oc~lusion Cover I
Snow Cover I
Temperature
Wind Conditions
Light Conditions
snow Type
8 AJ:C

0.7152
0.5936
0.2763
0.5399
0.5650
0.6257
0.0022
0.5453
0.0166
0.0044
0.0027
0.0001 .
0.0014
0.0405
0.0010
0.0275
0.3127
0.0449
0.1233
0.9797

Sign./
Nonsign.
NSign
NSign
NSign
NSign
NSign
• NSign

Aic4

91.450
91.299
90.398
90.351
12.318
91.345
82.170
93.218

SIGN

NSign
SIGN
SIGN
SIGN
SIGN
SIGN
SIGN
SIGN
SIGN

85.844

83.468
82.589
74.678
82.435
90.417
80.703
86.725
91.023
89.376
91.397
93.583

NSign
SIGN

NSign
NSign

= Akalke's Information Criterion

Table 8. Multivariate analyses of factors affecting sighting probability based
on stepwise logistic regression for elk in Game Management Unit 42, JanuaryHarch, 1994.

Model
A

No. Parameters
+ Intercept
14

B

13

C
D

12
6

E
p

2

3

1 Ageaelk age class,

Aic6
Parameters Used•
Age , Act , Vega, Wind, LnGroup,
Covert, sncw1•
Age•, Act•, Vega•, LnGroup•,
Covert, Snow%•
Age•, Act•, Vega•, LnGroup•, Snow,•
Age, LnGroup•, Covert•
LnGroup•, Cover,•
LnGroup•

•

•

•

Value
58.32
58.96
59.16
62.61
68.89
74.68

Act::aelk activity class, Vege~egetatlon type class,
wind=wind class, LnGroup=log total group size, COvert=occlusion cover
percent, Snorimsnow cover percent, * Denotes variable as significant
. in model, Pm S 0.10).
b Lower AIC value denotes better fitting model.

�38

Table 9. Comparison of logistic regression models incorporating log(ln) group
· size and percent occlusion cover or percent vegetation cover for sightability
trials involving elk in Colorado and Idaho.
Variable
Coeffiecent
Constant-Colorado
1.98
constant-Idaho
1.22
ln Group Size-Colorado 1.23
ln Group Size-Idaho
1.55
I 0ccl. Cover-Coloraod -0.04
I Vege. Cover-Idaho
-o.os
1

SE
0.86
o. 674
0.40
0.37 4
0.02
0.01•

Calculated from Table 2 in Samuel et al. 1987.

Table 10. Estimated variance components and estimated corrected numbers of elk
for selected sightability models for elk in Game Management Unit 42, 1994.
Corrected
Percent
variance·
0
Totala
gqg;aqt;ion
Estimate0
COvarianca0
Model
Elk
49,264
1,666
610
2,534
118
a-Binomial1
46,121
1,454
543
103
284
12
246
l'-LnGroup
1,462
104
873
264
111
498
B-LnGroup+
COvarl
284,549
1,489
-805,323
806,283
283,588
106
B-LnGroup+
Covarl+
Snpwt
·
• Variance from binomial sighting probability of groups.
b Variance from predicted sighting probability_.
0
Variance frcm covariance of predicted sighting probability;;
d Variance of estimate of total elk.
•
f Binomial model uses simple sighting bias correction of 0.846 applied to all observed
groups of elk.
0
Total elk observed in groups u~ed to develop models was 1,405 elk in 99 groups.

V

V

�39

z

1.0

o·o.s
i==

U 0.8

w

ti 0.1
C 0.6

MEAN

LL

O 0.5

95 % Cl

~ 0.4

:l 0.3

m
&lt;C 0.2

m

0 0.1
£C

Q.

0

1

2

3

4

5

6

7

7

20

60

150

400

1100

LOG (In) TOTAL GROUP SIZE
3

TOTAL GROUP SIZE
RG. 1. Probability of detecting elk by group size, +/- 95% Cl, Game
Management Unit 42, January - March, 1994. Group sizes observed
during sighting ~ias trials ranged from 1 - 400.

�40

15
Appendix I. Procedures for flying quadrats and definitions of variables
assigned to each group of elk observed on guadrats.

A.

PROCEDURES FOR FLYING QUADRATS:

1. OBTAIN PROPER MAPS, ARRANGE IN ORDER OF NEED, DECIDE ON GENERAL ROUTE TO
QUADRAT, HIGHLIGHT QUADRAT BORDERS lJITH FELT MARKER, AND DETERMINE LIKELY
STARTING POINT. MAKE SURE NAVIGATOR HAS LISTING OF FREQUENCIES AND NECKBANDS
TO DETECT (MINIMIZE ANY TALK ABOUT TARGET ANIMALS) AND THAT TELONICS TR-2
RECEIVER IS LOADED AND READY TO GO. CHECK TELEMETRY SYSTEM ON HELICOPTER WITH
• DUMMY COLLAR.
2. FLY PERIMETER OF QUADRAT FIRST IN A CLOCKYISE MANNER SO THE INSIDE OF THE
QUADRAT IS TO THE RIGHT OF THE PRIMARY OBSERVER.
3. DETERMINE STATUS OF GROUPS OF ELK ON PERIMETER.
A. ELK MOVING OFF THE QUADRAT WHEN DETECTED ARE CONSIDERED ON THE
QUADRAT.
B. ELK MOVING ONTO THE QUADRAT WHEN DETECTED ARE CONSIDERED OFF THE
QUADRAT.
C. IF A GROUP IS STANDING ON THE PERIMETER, COUNT THOSE ELK INSIDE THE
QUADRAT.
D. RESIST THE TEMPTATION TO LEAVE THE PERIMETER TO COUNT A GROUP ON THE
INSIDE OF THE QUADRAT. USE YOUR BEST JUDGEMENT AT THE TIME OF
DETECTION.
E. IF A MARKED ELK IS DETECTED NEAR THE BORDER BE SURE TO NOTE ALL
IMPORTANT DATA VARIABLES AS THIS ELK COULD BE THE TARGET ELK.
4. FLY INTERIOR OF QUADRAT.
A. FLY THE INTERIOR OF THE QUADRAT SYSTEMATICALLY IN STRIPS OR STRIP.CONTOURS. USE PROMINENT TERRAIN FEATURES TO DIVIDE THE QUADRAT INTO
SMALLER COUNTING BLOCKS. IF DECIDE TO FLY STRIP-CONTOURS, WORKING FROM
THE HIGHEST TO LOWEST ELEVATION USUALLY . WORKS BEST.
B. BE PATIENT AND STRIVE FOR 100% COVERAGE.
5. WHEN MULTIPLE GROUPS OF ELK ARE DETECTED ·SIMULTANEOUSLY, FOLLOW THESES
GUIDELINES.
A. PRIMARY OBSERVER SHOULD BEGIN OBTAINING DATA ON GROUP NEAREST THE
HELICOPTER AND USE HELICOPTER TO KEEP GROUPS SEPARATED.
B. NAVIGATOR SHOULD FOCUS MOMENTARILY ON SECOND GROUP OBSERVED AND NOTE
LOCATION, ACTIVITY AND NUMBER OF ANIMALS FIRST SEEN.
C. AFTER COMPLETING DATA COLLECTION ON FIRST GROUP, PROCEED TO LOCATION
OF SECOND GROUP, DETERMINE VEGETATION TYPE, OCCLUSION%, AND SNOW COVER%
AT SITE OF DETECTION, THEN FIND AND COUNT SECOND GROUP.
6. RULES FOR MARKED ANIMALS
A. FOR EVERY MARKED ELK SEEN (UNTIL THE TARGET ELK IS DETECTED) ·oBTAIN A
POSITIVE IDENTIFICATION VIA THE NECKBAND NUMBER OR WITH TELEMETRY TO
DETERMINE THAT THE MARKED ELK IS OR IS NOT THE TARGET ANIMAL.
B. IF MARKED ELK ARE SEEN AFTER DETECTING THE TARGET ELK, OBTAIN AN
IDENTIFICATION FROM THE.NECKBAND WITHOUT UNDULY HARASSING THE ELK OR
USING TOO MUCH TIME.
7. RULES FOR DETECTING THE TARGET MARKED ELK
A. YOU WILL ESTABLISH A FLIGHT PATTERN TO COVER THE ENTIRE QUADRAT.
WHEN YOU HAVE COMPLETED THIS PATTERN, YOU ARE DONE FLYING THE QUADRAT.
IF YOU HAVE NOT DETECTED THE TARGET ANIMAL DURING THIS PATTERN, DO NOT

V

�41

16

RE-SEARCH THE QUADRAT AS THIS WOULD BE DISHONEST; IE, DO NOT SEARCH
FOREVER TO FIND THE TARGET ELK, IT MAY NOT BE THERE OR THERE MAY NOT BE
ONE TO FIND!
B. IF YOU DO NOT FIND THE TARGET ELK AFTER COMPLETING YOUR FLIGHT
PATTERN, TURN ON THE RECEIVER AND START SEARCHING THE QUADRAT FOR A
SIGNAL.
C. IF THE TARGET ELK IS ON THE QUADRAT, COUNT THE GROUP AS THOUGH IT WAS
ANY OTHER GROUP OF ELK, AND BE SURE TO OBTAIN ALL VARIABLES ASSOCIATED
WITH THAT GROUP. THIS IS THE MOST IMPORTANT DATA WE CAN COLLECT IN
REGARDS TO SIGHTING BIAS ADJUSTMENT FACTORS AS IT REPRESENTS AN ELK YOU
DID NOT SEE.
D. IF THE TARGET ELK IS DEFINITELY OFF THE QUADRAT SPEND SOME TIME
LOCATING IT BECAUSE IT COULD BE NEAR THE BOUNDARY AND MAY HAVE RUN OFF
THE QUADRAT (BACKTRACK TO DETERMINE IF LEFT QUADRAT). SPEND ENOUGH TIME
SEARCHING TO DETERMINE TO YOUR SATISFACTION THAT THE ELK WAS LIKELY OFF
THE OUADRAT DURING YOUR TIME ON THE OUADRAT.
E. NOTE NUMBER OF MARKED ANIMALS SEEN IN EACH GROUP, AND ID'S OF THOSE
ELK IF OBTAINED. LOCATIONS OF ELK SEEN ON A QUADRAT WILL BE ASSUMED TO
BE THE MIDDLE OF THE QUADRAT FOR PURPOSES ~F DISTRIBUTION AND MOVEMENT
INFORMATION UNLESS YOU OBTAIN A LORAN-C LOCATION FROM THE HELICOPTER.
B.

DEFINITIONS THAT APPLY TO EACH GROUP OF ELK DETECTED ON A QUADRAT.

OUR DEFINITIONS ARE BASED ON THE HYPOTHESIS THAT DETECTING ELK IS DEPENDENT ON
INITIALLY DETECTING SOME FRACTION OF EACH GROUP.
1. DETECTION GROUP SIZE:

NUMBER OF ELK INITIALLY DETECTED WEN AN OBSERVER
SEES A GROUP. THIS NUMBER WILL REPRESENT SOME PORTION OF THE TOTAL GROUP
SIZE.
2. ANIMAL ACTIVITY: THE ACTIVITY OF THE ELK INITIALLY DETECTED OR THE ACTIVITY
OF THE MAJORITY OF THE ELK INITIALLY DETECTED. ACTIVITY CLASSES WILL •• BE
BEDDED-B, STANDING-S, MOVING-M.
3. VEGETATION TYPE: THE PREDOMINATE TYPE OF VEGETATION FOR 30 METERS AROUND
THE INITIAL ELK SEEN. VEGETATION TYPES ARE:
OK--OAKBRUSH-TALL MOUNTAIN SHRUB
SG--SAGEBRUSH-(INCLUDING GREASEWOOD &amp; RABBITBRUSH)
AS--ASPEN
PJ--PINYON-JUNIPER
TC--TALL CONIFER (DOUGLAS FIR, ENGELMANN SPRUCE, LODGEPOLE
PINE)
• RP--RIPARIAN (COTTONWOOD/WILLOW BOTTOMS)
CA--CLEARINGS/AGRICULTURAL FIELDS (CLEARINGS CAN BE NATURAL
MEADOWS, CLEAR-CUTS COVERED WITH SNOW, DRILL-PADS, OR ANY SIZEABLE
OPENING THAT APPEARS TO BE A CLEARING DUE TO SHORT VEGETATION
AND/OR SNOW COVER)
4. % OCCLUSION COVER: AN ESTIMATE OF THE PERCENTAGE OF THE OBSBRVER'S VIEW
BLOCKED BY VEGETATION INTERFERING WITH THE OBSERVERS ABILITY TO SEE THE
INITIAL ELK DETECTED IN A SPACE OF 30 METERS AROUND THE ELK. OBSERVERS WILL
ESTIMATE IN INCREMENTS OF 10%, IE; 0, 10, 20, 30, ... , 100. DATA WILL BE
POOLED IATER. VEGETATION INCLUDES STEMS AND TRUNKS OF DECIDUOUS SHRUBS AND
TREES, TRUNKS AND LEAVES OF EVERGREEN CONIFERS, LEAVES AND STEMS OF ANY OTHER
EVERGREEN SPECIES. GRASS AND SHORT SAGEBRUSH SHOULD HAVE 0% OCCLUSION COVER

�42

17

EXCEPT POSSIBLY WHEN ELK ARE BEDDED·;.
5. %SNOW COVER: THE PERCENTAGE OF BARE GROUND COVERED BY SNOW FOR 30 M AROUND
_THE INITIAL ELK DETECTED. OBSERVERS WILL ESTIMATE IN INCREMENTS OF 10%, IE;
0, 10, 20, 30, .... 100. DATA WILL BE POOLED LATER.
6. TOTAL ELK IN GROUP: THE TOTAL NUMBER OF ELK COUNTED IN A GROUP. A GROUP
IS DEFINED AS A CLUSTER OF ELK ACTING INDEPENDENTLY EITHER IN BEHAVIOR OR
SPACE FROM ANOTHER CLUSTER OF ELK. GUIDELINES FOR DEFINING A GROUP ARE:
CLUSTERS OF ELK SEPARATED BY &gt;30 METERS OR CLUSTERS SHOWING DIFFERENT PATrERNS
OF BEHAVIOR. DEFINING A GROUP CAN BE SUBJECTIVE IF ELK ARE AT HIGH DENSITIES
ON THE QUADRAT.
THESE DEFINITIONS APPLY TO AMBIENT CONDITIONS EXISTING ON EACH QUADRAT·AT THE
TIME OF FLYING
1. WIND: WIND WAS :
LIGHT-L,
MODERATE-M, OR
STRONG-S
IN RELATION TO THE RELATIVE EFFECT OF THE WIND ON. THE ABILITY TO FLY THE
QUADRAT IN A SLOW, LOW AND DELIBERATE MANNER.
2. LIGHT CONDITIONS: LIGHT CONDITIONS WERE EITHER:
BRIGHT SUNSHINE WITH HIGH CONTRAST-B,
HAZY SUNSHINE WITH HIGH THIN CLOUDS-H, OR
DULL SUNSHINE DUE TO OVERCAST OF CLOUDS-D.
3. SNOW TYPE: SNOW TYPE IS EITHER
FR.ESH SNOW THAT HAS FALLEN WITHIN THE PAST 48 HRS-F, OR
OLD SNOW THAT IS OLDER THAN 48 HRS-0.
·sNOW CONDITIONS WILL LIKELY BE THE SAME FOR ALL GROUPS OF ELK DETECTED
ON A QUADRAT.
~
3. TEMPERATURE: TEMPERATURE (F) DURING THE MORNING AND AFTERNOON FLIGHTS AS
MEASURED AT THE BASE OF OPERATIONS FOR EACH FLIGHT

\
J
""--"

�63

Colorado Division of Wildlife
Wildlife Research Report
July 1995

JOB PROGRESS REPORT
State of

Colorado

Project No.

W-153-R-8

Mammals Research

Work Plan No.

3

Elk Investigations

Job No.

9

Estimating Survival Rates of Elk
and Developing Techniques to
Estimate Population Size

Period Covered:
Author:

July 1, 1994 - June 30, 1995

D. J. Freddy

Personnel: F. Barnes, J. Broderick, G. Byrne, A. Coriell, D. Crane, J.
Ellenberger, J . Frothingham, v. Graham, J. Gray, R. Hays, G. Loucks, P. Will,
R. Witt CDOW; D. Bowden, C. Vardeman, G. White, CSU; K. Crane, C. McCarty, D.
Ouren, volunteers; USFS Rifle, BLM Glenwood Springs, cooperating.
ABSTRACT
We radio-collared 69 calf elk (Cervus elaphus nelsoni) (6 months old) and an
additional 14 adult female elk(~ 1 year old) in December 1994 to estimate
survival rates during winter and used these same elk in 103 aerial sighting
bias trials to develop models for estimating degree of negative sighting bias
when counting elk with a helicopter on sample quadrats. Elk were captured
using portable corral traps and helicopter net-gunning . Survival rates(± 95%
CI) from December 1994 to June 1995 were 0 . 90 ± 0.07 for calves and 0 . 96 ±
0.04 for adult females.
Suspected causes of death were malnutrition and
predation for calves and shooting and predation for adult females. Calves
suspected of dying from malnutrition had marrow fat values &lt;13% at death and
body weights &lt;102 kg at capture while calves dying from predation had marrow
fat values of 3.7-35.6% and body weights of 86-140kg. For adults ~1 year-old,
hunting accounted for 88% of 24 deaths.
Average sighting probability of elk groups was 82.3% which equates to a 17.7%
negative sighting bias. There were no differences in sighting bias between
years (P &gt; 0.70) but there were differences in sighting bias among observers
(P = 0 . 06) which ranged from 9 . 3% to 22.4%. Univariate tests indicated elk
age (calf or adult), elk sex (calves only), initial group size, log(ln)
initial group size, total group size, log(ln) total group size, activity
behavior, vegetation type, percent vegetation occlusion cover, observer,
navigator, pilot, and trapping method affected the probability of sighting elk
(P ~ 06). Multivariate analyses incorporated elk age, ln total group size,
activity behavior, vegetation type, percent vegetation occlusion cover,
percent snow cover, navigator, observer, and year. The best sightability
model out of 2,048 possible models was a complex 12 parameter model involving
nearly all major variables. We are currently assessing the effects on
sighting probability of using less complex models.

�65

JOB PROGRESS REPORT
BSTIMM?IHG SURVIVAL RADS OP BLK ARD DBVBLOPIHG BCIIHIQUBS m
BSTIMAD POP~IOH SIZB

David J. Freddy
P. H. OBJECTIVE

Estimate survival rates of adult female and calf elk and develop techniques to
estimate population size.
SEGMEtr.r OBJECTIVES

1.

Radio-collar 75 calf and 15 adult female elk during December 1994 in Game
Management Unit 42 south of Rifle, Colorado.

2.

Estimate winter and annual survival rates of calf and adult female elk
from known fates of radioed elk.

3.

Estimate probability of sighting and counting elk during helicopter
surveys using radioed elk as a known population.

4.

Estimate density of elk in a portion of GMU-42 using a quadrat sampling
system.

5.

Analyze survival and sightability data and summarize annually in Federal
Aid Job Progress reports
INTRODUCTION

our objectives are to provide reliable estimates of survival rates for calves
and adult females during winter and for adult females throughout the year for
the period 1993-94 through 1997-98. Additionally, we will develop and test a
system for estimating population size that will incorporate estimates of
sighting bias in conjunction with a random sampling system using search
quadrats as sample units. our winter study area encompasses about 839 Jan2
(324 mi1 ) in the eastern half of Game Management Unit 42 south and east of
Rifle, COlorado. Elk winter range vegetation types include juniper-pinyon
woodland (Juniperus osteosperma-Pinus edulis), oakbrush-mountain shrub
(Quercus gambelii-Amelanchier alnirolia), aspen (Populus tremuloides),
sagebrush (Artemisia tridentata), and agricultural fields (Freddy 1993, 1994).
METHODS

Marking
We placed radio collars (172-176MHz) having mortality sensors on 69 calves (6
months old), of which 33 were males and 36 were females, and 14 adult females
(~ 1 year old). Of these, 65 calves and 2 adults were trapped from 7-11
December 1994 using helicopter net-gunning and 4 calves and 6 adult females
were trapped from 13-21 December using portable corral traps. Six adult
females were captured in corral traps 2 March 1995 to elucidate movements of
elk associated with a specific area of private land. Helicopter capture
occurred at 11 remote sites located primarily on public lands while corraltrapping occurred at 3 sites, 2 on private and 1 on public lands. Trapping
effort was allocated among 8 geographic trap zones to assure that radioed elk
were representative of most if not all segments of the population (Table 1).
Radio collars were of the same type used in 1993 (Freddy 1994).

�66

Calves captured by net-gunning were ferried by helicopter to processing points
usually within 1.6 Jan of capture sites. At processing points, body weight,
total body length, hind foot length, and rectal body temperature (F) were
measured and calves were then radio-collared and released. Similar
measurements were also made on calves that were corral-trapped and then
released at the trap site. Body measurements for calves were compared between
sexes using Proc FREQ, GLM, and REG (SAS 1988).

V

V

survival
We monitored life or death status of radioed elk during daily ground surveys
and aerial surveys conducted at 2-4 week intervals from December 1994 through
April 1995 and via monthly aerial surveys from May to November 1994 and May to
June 1995. Survival rates (S) of radioed elk were calculated using the
binomial estimator with a variance, VAR(S) = S(l-S)/n (White and Garrott
1990)(Proc FREQ, SAS 1988). We chose not to use the staggered entry approach
and did not use a Kaplan-Meier approach because few animals were censored
(White and Garrott 1990). Life or death status of all calves radioed in
December 1994 (68 with functional collars) was known for the period 7 December
1994 through 15 June 1995 (1 male calf collar, 173.949/94, failed 2 weeks
post-capture and although the calf was seen alive through 30 January 1995 it
was excluded from estimates of survival rates). On 15 June, calves become
yearlings for purposes of calculating rates of calf survival. Life or death
status for adult females, yearling females, and yearling males collared in
December 1993 or 1994 was known for 117 of 118 animals through 15 June 1995.
All 6 adult females collared 2 March 1995 were alive as of 15 June 1995 but
were not used in calculations of survival for time periods prior to 14 June
1995.
Fat content (percent dry matter) of femur marrow and estimates of age based on
dental cementum were obtained for dead radioed elk (Colo. Div. Wildl. Lab, Ft.
Collins).
Sighting Bias

V
V

Procedures for conducting aerial sighting trials were identical in 1994 and
1995 (Freddy 1994). In 1995, we conducted 103 sighting bias trials that
targeted radiocollared elk on 23, 24, 26, 28, and 30 January and 6-8 and 21
February. We again used a Bell-Soley helicopter and the same observers and
navigators as in 1994. The pilot which flew all trials in 1994 flew 77 (75%)
of the trials in 1995 with 2 additional pilots flying the remaining 26 trials.
Observers indicated that all pilots provided comparable and acceptable
service.
Sighting bias models were developed using logistic regression (Proc GENMOD,
SAS). The dichotomous classification of groups seen or missed was the
dependent variable. Initial group size (ln), total group size (ln), activity
behavior, vegetation type, percent occlusion cover, percent snow cover, snow
type, year, observer, navigator, trap method, temperature, wind, lighting
conditions, pilot, time interval, and time of day were independent variables.
Observer, navigator, pilot, trap method, elk sex, elk age, activity,
vegetation type, snow type, time interval, time of day, light conditions, and
wind were treated as class variables and group size, percent occlusion cover,
and percent snow cover were treated as continuous variables. Significance
level for independent variables was P ~ 0.06 for univariate tests. Relative
efficiency of models using all possible combinations of significant variables
was assessed using AIC values (Akaike Information criterion= -2(-log
likelihood value)+ 2[No. model parameters)).
Population Estimates
Elk population size in GMU 42 from East Alkali Creek to Beaver Creek was
estimated during January and February 1995. Three independent estimates of
size or density were obtained. On 19 January, a nonrandom elk sex/age

V

V

�67

classification flight using a helicopter was flown during which numbers of
marked (radiocollared) and unmarked elk were counted. From 22-24 February, 40
randomly selected quadrats approximately 1 mi2 (2.59 km2) in size were flown
using a helicopter and during these flights numbers of marked and unmarked elk
were counted. For these 2 flights, we used a simple Lincoln-Peterson
estimator based on ratios of marked and unmarked elk (White and Garrott 1990)
to estimate total numbers of elk. The third estimate of population size
resulted from projecting the average number of elk counted per sample quadrat
to the entire segment of winter range sampled by the quadrat system. The
number of elk counted by direct observation at the time of the flights that
were on private land areas not surveyed by the 3 flights were added to each of
the 3 estimates of population size to arrive at an estimate of total elk in
GMU 42 east of Beaver Creek. At this time, no adjustments have been make for
sighting bias for counts of elk on quadrats.
Movements
We continued to locate 37 radioed elk at least once per month since capture to
document seasonal movements via telemetry using a Cessna 185. These elk were
selected at random from within trap zones and equalized by age class.
As of 14 June 1995 these elk were classified as 15 adult females, 7 yearling
females, 4 female calves, 7 yearling males, and 4 male calves. During 199394, 6 of 34 elk monitored for locations died. These 6 were replaced at random
primarily with 6 month-old calves captured in December 1994 in the same trap
zone(s) as those elk that died. During June 1995, we selected an additional
28 adult females at random to document locations during the calving period.
As needed, we located other elk to document unusual movements.
RESULTS AND DISCUSSION

Survival

~

Between 1 December 1993 and 14 June 1995, 37 of 190 radiocollared elk died
(Appendix 1). Of these 37, hunting was apparently involved in 571 of the
deaths. For adults ~1 year-old, hunting accounted for as, of 24 deaths.
There were 2 periods of mortality during the year. Calves died from February
to May while adults died during fall and early winter when hunting seasons
occurred (Fig. 1).
Survival rates(± 951 CI) for calves during winter, 1 December - 14 June, were
0.92 ± 0.06 in 1993-94 and 0.90 ± 0.07 in 1994-95 (Table 3). Sex of dead
calves was 4 male and 2 female in 1993-94 and 4 females and 3 males in 1994-95
(Table 2). These survival rates were associated with winters considered mild
in temperature and having low or moderate snow depths. In 1994-95,
considerable snow fell during March and April but usually melted rapidly at
lower elevations.

~

Suspected causes of death for calves during winter were, mountain lion
predation (311), malnutrition (231), and unknown (461) (Table 4). For the
unknown category, bear predation was suspected once (3/1/95) as was lion
predation (3/18/94) (Table 2). Those calves dying from malnutrition had
marrow fat values &lt;131 at death and body weights &lt;102 kg at capture while
calves likely dying from predation had marrow fat values 3.7-35.61 and body
weights 86-140 kg (Table 2). There were no calf mortalities during capture
and no evidence that capture procedures directly induced mortality in either
year. In 1993-94 the first mortality involved an 82 kg female suspected of
dying from malnutrition at 59 days post-capture while in 1994-95 the first
mortality was an 86 kg female suspected of dying from mountain lion predation
at 72 days post-capture. At capture, this last female had an abnormally
articulating front shoulder which may have been injured during or prior to
capture but the injury appeared to minimally affect her mobility upon release
at capture.

�68

Survival rates(± 951 CI) for adult females during winter, 1 December - 14
June, were 0.96 ± 0.05.in 1993-94 and 0.96 ± 0.04 in 1994-95 (Table 3). Of 7
winter deaths during both years, 5 (711) were due to legal (1) and illegal (l)
hunting or wounding loss (3) during late rifle seasons (Table 4). Natural
deaths (2) were attributed to mountain lion predation and unknown but possible
lion predation. Of the 3 elk lost to wounding, 2 were suspicious kills. Both
of these elk died from 1 rifle shot to the upper neck or head in relatively
plain sight near or on an agricultural field where retrieval of the carcass
was not difficult. These animals may have been accidentally shot, maliciously
shot, or abandoned because of the radiocollar. Survival rates during winter
1994-95 were 1.00 for juvenile males and females age 18-23 months and
radiocollared as calves (Table 3).

V

u

Annual survival rate for adult females, 1 December 1993 - 30 November 1994,
was 0.77 ± 0.10 (Table 3). Of the 15 deaths involving adult females marked in
December 1993, 13 (87%) were associated with hunting. The 2 natural deaths
were due to lion predation during winter and an unusual breech birth that
occurred about 1 October 1994. Hunting deaths were attributed to legal
hunting (6, fall seasons), illegal hunting (1, late season), wounding loss (5,
4 fall seasons, 1 late season), and presumed hunting (1, fall seasons). We
examined all 5 carcasses attributed to wounding loss. Based on locations and
physical position of the carcasses, we found no compelling evidence that
hunters had likely found the animal and then left the carcass because it was
radiocollared. Thus, we do not believe at this time that wounding loss during
fall seasons is resulting from hunters being afraid to claim a radiocollared
animal.
Depending on the type of hunting season and GMU, yearling males with spike
antlers are not legal quarry. In general, yearling males are not legal quarry
in any part of the study area until the third combined rifle season in late
October. In August 1994, there were 32 yearling males alive that were
radiocollared as calves. Life/death status of all 32 was determined through
14 June 1995. Of these 32 yearlings, 4 (12.51) were known or presumed to be
illegally taken during hunting seasons. Three carcasses were recovered in the
following general condition: shot, eviscerated, and left in the field (1st
rifle season); shot, not eviscerated, and left in the field (2nd rifle
season); shot, eviscerated, head removed, partially packed-out, and
radiocollar buried under debris (3rd rifle season). The telemetry signal of
the fourth animal, presumed shot and removed, could not be heard after 4
October 1994.

V

Calf Body Size
Male calves had larger body weights (P = 0.001), longer total body length (P =
0.06), longer hind leg lengths (P = 0.06), and higher condition indexes (P =
0.06) than female calves (Tables 5, 6). Body weights and measurements were
not different between years for male or female calves (P &gt; 0.30). Predicting
body weight from body measurements does not look promising at this time,
although all regressions were significant (P &lt; 0.001). The multiple
regression using body length and hindfoot length as independent variables
provided the best correlation coefficients (.r) of 0.59-0.67.
Sighting Bias
In 1994 and 1995, we conducted 213 sighting trials of which 192 (90%) were
successful, and each observer was involved in 70-72 sighting trials during
both years (Table 7). Successful trials occurred when the targeted elk was
on the assigned flight quadrat whether or not that elk was seen by observers.
Unsuccessful trials occurred when the target elk was found off the assigned
quadrat immediately subsequent to the time the quadrat was flown by the
helicopter team. Elk were off quadrats primarily due to their movements
between the time elk were located with the Cessna 185 and the time the
helicopter team flew the quadrat. Usually only 1 elk was targeted per quadrat
even though several radiocollared elk may have been present on a quadrat to
insure that targeted elk were in separate and independent groups.

V
V

�69

During the 2 years, 143 different elk were used in 192 successful trials
(Table 8). Most elk were targeted only once during the 2 years. Targeted elk
included adult females, yearling females, female calves, yearling males
(spike-antlered), and male calves. Calves comprised 53-54% of the targeted
elk within each year. Yearling males were only available as targets during
1995 (Table 9).
We used as many different radiocollared elk as possible to avoid any positive
effects on sightability that might have occurred if an observer or navigator
had been involved in locating a target elk more than once. Observers were not
assigned the same target- elk within the same year, except in 1995 an observer
was given the same elk twice but the animal was on 2 different search
quadrats. During both years, there were 11 cases where a target elk was given
to the same observer for 2 trials. In 7 of these cases, the targeted elk was
a calf the first year and a yearling the second year, while in the 4 remaining
cases, the target elk was an adult in both years. In all 11 instances, elk
were on different search quadrats in both years. During both years, there
were 24 cases where a navigator was involved with the same target elk during 2
trials. Only 3 of these cases occurred in the same year and the targeted elk
was on a different search quadrat on each occasion.
Average sighting probability was 82.3% which equates to a 17.7% negative
sighting bias (Table 7). There were no differences in sighting bias between
years (P &gt; 0.70) but there were differences in sighting bias among observers
(P = 0.06) which ranged from 9.3% to 22.4% (Table 7).
Univariate tests indicated elk age (calf or adult), elk sex (calves only)
initial group size, log(ln) initial group size, total group size, log(ln)
total group size, activity behavior, vegetation type, percent occlusion cover,
observer, navigator, pilot, and trapping method affected the probability of
sighting elk (P ~ 0.06, Tables 11, 12). Adult females were more sightable
than calves (P = 0.03) as were male calves compared to female calves (P =
0.06). Elk caught in corral traps were more sightable than those caught with
a helicopter and this effect was primarily associated with adult females (P =
0.05), not calves.
Multivariate analyses incorporated elk age, ln total group size, activity
behavior, vegetation type, percent vegetation occlusion cover, percent snow
cover, navigator, observer, and year. According to AIC criteria, the best
sightability model out of 2,048 possible models was a complex 12 parameter
model involving nearly all major variables. Ln group size, percent vegetation
cover, and observer persisted as significant variables as number of parameters
was reduced (Table 13). Models incorporating elk age, observer, and navigator
are likely not practical for field application. We are currently comparing
these 12 best fitting models to assess what effects each model has on
predicting sightability of our known population of elk groups. This process
will hopefully produce a less complex sighting model.
When the same variables are used to build sighting models, results from Idaho
(Samuel et al. 1987) and Colorado strongly suggest there are common factors
affecting sightability of elk in broadly different landscapes. For coniferous
landscapes in Idaho the best elk sightability model was: Y = 1.22 +
l.55(LnGroupSize) - 0.05(% vegetation cover). For oakbrush landscapes in
Colorado, elk sightability was: Y = 1.23 + l.08(LnGroupSize) - 0.03(%
vegetation cover). Effects on sightability of group size and vegetation cover
are shown in Fig. 2. Unfortunately at this time, this 3 parameter model
ranked 1,165 out of 2,048 Colorado models. The most efficient 3 parameter
model incorporated elk activity instead of vegetation cover (Table 13).
Group size is a variable that must be incorporated into any sighting model to
correct for the propensity to miss groups containing &lt;7 elk (Fig. 2). our
data indicates that groups of elk observed but not targeted for sighting
trials were smaller than our target groups (P =0.02). This indicates our
radiocollared elk groups biasly represented all possible groups of elk which

�70

V

likely reflects a trapping bias. This data however, also strongly suggests
that the need to correct for group size will be greater in actual surveys.
Population Estimates
Initial estimates of elk population size ranged from 2,049 to 4,339 and were
generally imprecise (Table 10). For mark-resight estimators, the nonrandom
flight provided the most precise estimate(± 271) because more unmarked and
marked elk were observed compared to the quadrat flight(± 47% precision).
However, both mark-resight flights provided estimates of similar magnitude:
3,810 and 4,339 elk. The lower quadrat estimate of 2,049 elk probably reflects
a need to restratify and reallocate sample units.
Precision of the quadrat sample estimate can likely be improved by altering
strata, increasing sample size, and increasing the quadrats allocated to high
density strata. The imprecision of both the quadrat and quadrat mark-resight
estimates(+ 471) indicate more quadrats need to be flown along with refining
strata boundaries. Count data indicates that major changes are needed in
delineating the Garfield High and East Divide creek low strata. Of the 15
(38%) quadrats where no elk were counted, 8 occurred in these 2 strata.
Consideration will be given to assigning each individual quadrat to high and
low strata even if quadrats are adjacent to each other.
Elk Movements
As of 15 April 1995, 22 radioed elk had dispersed to a winter range outside
the winter range in GMO 42 where they had originally been trapped in December
1993 (Table 14). Of 35 females collared as calves in December 1993 and
recruited into the population as yearlings in June 1994, 8 (231) dispersed
during summer-fall 1994 to another winter range. Likewise, of 32 male calves
recruited as yearlings in June 1994, 6 (191) dispersed during summer-fall to
another winter range. Eight (12%) of 65 adult females alive in June 1994
dispersed during summer-fall to another winter range.
Seven (321) of the dispersing elk moved to areas outside of DAU E-14, with 6
of these elk moving into GMO 43 immediately east of DAU E-14 (Table 14). The
longest dispersal movement involved an adult female elk (172.480/93) that
moved to Beaver Creek west of Gunnison, a straight line distance of about 80
miles. This elk had been neckbanded as a young adult in Beaver Creek in 1991
(GMO 54), then radiocollared in GMO 42 in 1993, and subsequently returned to
the drainage where it was originally marked in January 1994 (visual and
telemetry location). As of June 1995, this elk had returned to GMO 42.
We are currently creating a GIS land database for the area frequented by
radiocollared elk. This is a volunteer cooperative effort through the
National Biological Service. We believe plots of elk locations and movements
using this database will be forthcoming in 1996.
CONCLUSIONS

We obtained acceptably precise estimates of calf and adult survival rates
during winter and recommend continuing our current sampling effort of
monitoring 75 radioed calves and &gt;75 radioed adult females in 1995-96.
Efforts to measure and develop criteria to adjust for negative bias in counts
of elk were promising and we are currently assessing the relative efficiency
of several sighting models. We recommend conducting the planned replicate
surveys using sample quadrats to estimate elk density from mark-resight
estimators and sighting bias correction models in 1995-96.

V

�71

LITERATURE CITED

Freddy, D. J. 1993. Estimating survival rates of elk and developing
techniques to estimate population size. Colo. Div. Wildl. Game Res.
Rep. July: 83-117.
Freddy, D. J. 1994. Estimating survival rates of elk and developing
techniques to estimate population size. Colo. Div. Wildl. Game Res.
Rep. July: 27-42.
Samuel, M. D., E. o. Garton, M. w. Schlegel, and R. G. Carson. 1987.
Visibility bias during aerial surveys of elk in northcentral Idaho.
Wildl. Manage. 51:622-630.
SAS Institute Inc. 1988. SAS/STAT User's Guide, 6.03. SAS Institute, Inc.,
Cary, NC. 1028pp.
White, G. c., and R. A. Garrott. 1990. Analysis of wildlife radio-tracking
data. Academic Press, Inc., San Diego. 383pp.

Prepared by ___________________
David J. Freddy
Life/Science Researcher

J.

�Table 1. Capture objectives and numbers of elk radioed in 8 trapzones, December 1993 and
December 1994 1 GMU 42. Objectives and elk ca~tured for 1994 are in ~arentheses.
Elk Collared8
Capture
Calves
Adult
Trap
Objective
Total
Helio
Corral
Males
Females
Females
Zone Name
8 ( 6)
3 ( 3)
Garfield
0( 0)
8( 6)
1( 3)
8( 5)
4( 0)
A
Gibson
25(17) 19 ( 7)
6.(10)
20( 8)
5( 5)
8( 6)
12 ( 6)
B
Uncle Bob
24(13)
29(13) 29(13)
0( 0)
10( 7)
7 ( 6)
C
12( 0)
26(13)
0( 0)
5 ( 1)
21(11) 21(11)
West Divide
D
6( 8)
10( 2)
17(17) 17(17)
Hightower
0( 0)
10(10)
4( 9)
3( 8)
10( 0)
E
0(13)
0(13)
Middle Mamm
10( 8)
0( 0)
0( 8)
0( 5)
F
0( 0)
8( 8)
2 ( 0)
3 ( 0)
West Mamm
6( 0)
6( 0)
0( 0)
G
1( 0)
35 ( 6 )b 0( 0) 35( 6)
Dry Hollow
44(21)
7 ( 0)
9( 0)
19( 6)
H
141(83) 100(67) 41(16)
36(33)
37(36)
150(86)
68(14)
All
a Belio
b All

~

= Helicopter net-gunning, corral= corral-trap.

6 adult females captured 2 March 1995

Table 2. Causes of mortality and body condition for radioed calf elk in GMU 42,
1 December 1993 - 14 June 1995.
Date
Estimated
Body
Marrow Fat
Radiocollar
Dead
Cause of Death
Sex
Age8
Freggency
Wt. 'kg}b
Percent Drl!: Matter
172.899/93
173.000/93
173.262/93
173.289/93
173.461/93
173.469/93
173.870/94
174.119/94

174.140/94
173.789/94
173.640/94
174.170/94
173.589/95

F
F

M
M
M

M
F
M
M
F
F
M
F

9 mos
10 mos
9 mos
9 mos
8 mos
10 mos
8 mos
9 mos
9 mos
9

mos

9 mos
10 mos
12 mos

3/18/94
4/25/94
3/18/94
3/22/94
2/07/94

4/25/94
2/21/95
3/01/95
3/14/95
3/20/95
3/30/95

4/25/95
6/01/95

Mt.Lion kill
Malnutrition
Unknown, Predation?
Unknown
Malnutrition
Malnutrition
Mt.Lion kill
Unknown, Predation?
Mt.Lion kill
Unknown
Unknown
Mt.Lion kill
Unknown

86
102
108
111
82

28.54
12.6c
28.9 4

not available
2.lc

77

2. 7c

86
140
112
100
89
140
117

not available
3. 7c

35.6c
76.2c
not available
17.4c

not available

a Approximate age at death, assume 15 June birthdate.
body weight at capture in December 1993 or 1994.
c Fat content of either the right or left femur bone marrow at death.

b Whole

d Fat

C C

content of lower jaw bone marrow at death.

CC

C C

�(

(

( (

(

(

Table 3. Survival rates of radiocollared elk in GMU 42 for different age and sex classes during 4 time periods
from 1 December 1993 through 14 June 1995. Survival rates calculated as a simple binomial of elk alive at end
of time period divided by elk alive at beginning of time period with a variance of S(l-S)/n. Calves were 6-12
months old and collared at 6 months of age. Yearlings were 12 - 18 months old and juveniles were 18 - 23
months old and both were collared as 6 month old calves in December 1993. Adult females were ~l year-old when
captured or recruited in December.
Time Period
Age/Sex
Class

1 DEC 93 - 14 JUN 94
A8
0 6 Surv. Ratec

Calves

73

6

15 JUN 94 - 30 NOV 94
A
D Surv. Rate

1 DEC 93 - NOV 30 94
A
D Surv. Rate

0.92 ± 0.06

1 Dec 94 - 14 JUN 95
A

D

Surv. Rate

68

7

0.90 ± 0.07

28
34f

0
O

-1.00
1.00

94

4

0.96 ± 0.04

190

11

M + F

Yearlings
Male
Female

32
35

4d
le

0.88 ± 0.12
0.97 ± 0.06

Juveniles
Male
Female
Adult
Females

68

3

Totals

141

9

0.96 ± 0.05

648 12h
131

17

0.81 ± 0.15

67

15

67

15

0.77 ± 0.10

Number of radiocollared elk alive at beginning of time period.
radiocollared elk dying during time period.
c Survival rate± 95% confidence interval.
d One elk (173.309/93) disappeared during October hunting seasons and presumed dead.
e One elk (172.800/93) disappeared during November hunting seasons and presumed dead.
f Yearling females are included in adult female survival rates during this time period.
8 One elk (172.011/93) censored from calculations because animal was missing.
h One elk (172.649/93) disappeared during October hunting seasons and presumed dead.
8

b Number of

�74

Table 4. Causes of deaths in radiocollared elk from GMO 42 between 1 December
1993 and 14 June 1995. Calves were 6-12 months old and collared at 6 months
of age. Yearling males and females were 12-18 months old and collared as 6
month old calves. Juvenile males and females were 18-23 months old and
collared as 6 month old calves. Adult females were ~l year-old when collared
or recruited in December.

Cause of Death

Calves

Malnutrition
Predation-Lion
Accident
Legal Bunting
Archery/Muzzle
Rifle
Rifle/Late
Wounding Loss
Archery/Muzzle
Rifle
Rifle/Late
Illegal Bunting
Presumed Bunting
Unknown

3
4
0
0

Total

Yearl.
Males
0
0
0
0

0
0
0
0
0
0

0
6

13

4

0
0
0

1

0
0
0

0

0

Total

1

7

7

2
4

1
7

0
0
0

0
0
0

V

3
5

1
1
0
0
0

0
0
0

0
0
0

Adult
Females
0

0

0

0
0
0
0

3
1a
0

0

0
0
0

0
0
0

0
0
0
0

0
0
0
0

0
0
0
0

0

0

Elk Age/Sex Class
Yearl.
Juv.
Juv.
Females
Males
Females

V

7

1
3
3

4
3
7

19

37

Elk (173.309/93) was a spike-antlered male that disappeared during October
hunting seasons and presumed dead and illegally shot.
b Elk (172.800/93) disappeared during November hunting season and is a
presumed hunting mortality.
c Elk (172.649/93) disappeared during October hunting seasons and is a
presumed hunting mortality.
a

V

�(

(

( (

(

Table 5. Frequency distribution of whole body weights for male and female elk calves trapped in Game
· Management Unit 42. December, 1993 and 1994. Percentage per weight class shown in parentheses.
Year

Sex

70-79

80-89

90-99

Body Weight Class (kg)
100-109
120-129
110-119

130-139

140-149

Total

1993
1994

M
M

1(2.9)
1(3.0)

1(2.9)
1(3.0)

3(8.6)
2(6.0)

6(17.1)
6(18.2)

12(34.3)
13(39.4)

10(28.6)
6(18.2)

1(2.9)
2(6.0)

1(2.9)
2(6.0)

35(100)
33(100)

1993
1994

F
F

1(2.9)
2(5.7)

4(11.4)
4(11.4)

8(22.9)
7(20.0)

12(34.3)
10(28.6)

4(11.4)
10(28.6)

6(17.1)
2( 5.7)

0(0.0)
0(0.0)

0(0.0)
0(0.0)

35(100)
35(100)

Table 6.

Body measurements for elk calves trapped in Game Management Unit 42. December, 1993. 1994.
SD

112.7
191.2
Body Length (cm)
Hindfoot Length (cm) 56.3
Condition Index
0.59
(Wt./Body Length)

13.7
10.2
2.2

14.2

Measurement

1993

Body Weight (kg)

1994

Male Calves
Min
Max

Mean

Year

Body Weight (kg)
113.5
190.3
Body Length (cm)
Bindfoot Length (cm) 56.9
Condition Index
0.59
(Wt./Body Length)

o.os
9.2

1.8

o.os

Female Calves
Min
Max

n

Mean

SD

77.0
164.0
52.0
0.43

141.0 35
210.0 36
61.0 36
0.67 35

103.8
188.9
54.8

12.2
9.8
2.1

76.0
167.0
51.0
0.46

123.0 35
207.0 35
59.0 34
0.64 34

71.0
168.0

140.0 33
204.0 32
59.0 32
0.69 32

103.0
186.3
55.1

13.3

70.0
166.0

128.0 35
207.0 36
59.0 36
0.65 35

so.a

0.42

o.ss o.os

o.ss

a.a

2.1
0.06

so.a
0.42

n

(

�76

V

Table 7. Summary of elk sighting bias trials conducted in GMU 42 during 1994
and 1995.
Trials
Target
Target
Trials
Not
Trials
Elk
Elk Not
Observer
Yr
lttem;eted Useable
Detected
Useable
Detected
Broderick
Ellenberger
Masden
Totals

94
95
94-95
94
95
94-95
94
95
94-95
94
95
94-95

29
42
71
36
36
72
45
25
70
110
103
213

3

7
10
4
1
5
4
2
6
11

10
21

26(90%)
35(90%)
61(90%)
32(89%)
35(97%)
67(93%)
41(91%)
23(92%)
64(91%)
99(90%)
93(90%)
192(90%)

22
27
49
25
27
49
36
22
58
83
76
159

------

V

4(15.4%)
8(22.9%)
12(19.&amp;%)
7(21.9%)
8(22.9%)
12(19.7%)
5(12.2%)
1( 4.3%)
6( 9.3%)
17(17.2%)
17(18.3%)
34(17.7%)

Table 8. Numbers and frequency of individual elk targeted during successful
sighting bias trials in GMU 42. 1994 and 1995.
No.
No. Elk
No. Elk
No. Elk
Elk
Used in
Used in
Used in
Total
Year
Used
1 Trial
2 Trials
3 Trials
Trials
1994
1995
1994-95

77
90
143

67
87
101

16
3

35

99
93
192

0
0
7

V
Table 9. Age and sex of elk targeted during successful sighting bias trials in
GMU 42. 1994 and 1995.
Female
Male
Year
Adult
Yearling
Calf
Calf
Total
Yearling
1994
39(39%)
1995
20(21%)
1994-95 59(31%)

6( 6%) 28(28%)
10(11%) 26(28%)
16( 8%) 54(28%)

0( 0%)
15(16%)
15( 8%)

26(26%)
22(24%)
48(25%)

99(100%)
93(100%)
192(100%)

Table 10. Summary of population estimates for elk in GMU 42, January and
February. 1995.
Estimate
Private
Total
Densit!
Land Elkb
Elk/mi c
Method
Estimate
Date
+ 95% CI8
Mark-Resight
+399
3,810
3,411±27%
14 (267 mi2 )
1/19/95
NonRandom Flight
+565
4,339
Mark-Resight
3,744±47%
19 (234 mi2 )
2/24/95
Random Quadrats
Flight
Random Quadrats
+565
2,049
1,484±47%
9 (234 mi2 )
2/24/95
Flight
8

Number of elk estimated In survey area actually flown.
b Elk directly counted on private land area not included in survey flight.
c Density for area represented by survey flight area plus private land area.

V
V

�(

(

( (

(

Table 11. Elk sightability survey results by major independent variables from Game Management Unit 42,
Januaa-March, 1994 and 1995.
No. Grou:gs
Missed Seen

Variable

ya

Variable

0.52
0.63

Behavior
Bedded
standing
Moving

Group Size
12
9
2
5
0
1
4

1
2
3
4
5
6
7+

Vega. Type
Clearing/Ag
Riparian
Sagebrush
Oakbrush
Pinyan-Juniper
Aspen
Tall Conifer

13
15
21
14
15
12
69

0.91
0.74
1.00
0.92
0.94

JE
0

0
1
14
9
7
2

13
1
6
89
42
7
1

1.00
1.00
0.86
0.86
0.82
o.so
0.33

Occl. Cover(\)
0-19
20-39
40-59
60-79
80-100

2
11
10
6
4

4 V=visibility

•

Navigator
GB
VG
FB
Observer
JB

35
60
43
18
3

0.95
0.85
0.81
0.75
0.43

DM
Elk Age
Adult Female
Calf (M + F)
Yearling
Calf Sex
Male
Female
Trap (All elk)
Corral Trap
Helicopter
Trap (calves)
Corral Trap
Helicopter

No. Grou:12s
Missed Seen

Variable

Missed

Seen

Snow Cover (%)
9
4
20

6
41
112

0.40
0.91
0.85

0-19
20-49
50-99
100

3
5
5
20

9
9
47
94

0.75
0.64

22
11
0

68
81
10

0.76
0.88
1.00

Snow Type
Fresh
Old

5
28

35
124

0.88

12
15
6

49
52
58

o.80
0.78
0.91

Wind
Light
Moderate
Strong

32
1
0

137
20
2

0.81
0.95
1.00

4
21
8

55
81
23

0.93
0.79
0.74

Light
Bright
Dull
Hazy

22
3
8

97
24
38

0.82
0.89
0.83

6
15

42
39

0.88
0.72

32
0
1

139
10
10

0.81
1.00
0.91

9
24

61
98

0.87
o.80

4
29

45
114

0.92
0.80

3
18

14
67

0.82
0.78

Pilot
ET
BB
pp

0.90
0.82

0.82

Time

(groups seen I groups seen plus gr~ups missed).

AM

PM

(

�78

Table 12. Variables tested in univariate tests using logistic regression for
elk sightability trials, Game Management Unit 42, January-March, 1994 and
1995. Significance level at P &lt; 0.06.

Variable

Significant

Date of Trial
Sex of Elk Calves
Age of Elk
Initial Group Size
Log(ln) Initial Group Size
Total Group Size
Log(ln) Total Group Size
Elk Activity
Vegetation Type
Occlusion Cover %
Observer.
Navigator
Pilot
Snow Cover %
Snow Type
Temperature
Wind Conditions
Light Conditions
Time Interval
Time of Day
Trap Type

No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
Yes

Sign.
Year
Effect

Sign.
Year
Interaction

No
No
No
No
No
No
No
No
No
No
No
No
Yes
No
No
No
No
No
No
No

No
Yes
No
No
No
No
No
No
No
No
No
No
Yes
No
No
No
No
No
No
Yes

Table 13. The best fitting sightability model at each level of 1 to 12
parameters according to Akaike Information Criterion (AIC). Rank is the
relative rank of each model among 2,048 models which used variables in all
possible combinations. "Yes" denotes variables used in models.
Variables In Models
No.
Ln
Elk
Group Elk
Vege. %Vege. %Snow
AIC
ParamObs.
Cover
Cover
Nav.
Year
eters
Age
Size
Act.
Tv1&gt;8
Rank
1
2
7

4
48
61
152
463
869
1019
1403
1890
2028

12
11
10
9
8
7

6
5

4
3

2
2
1a

Yes
Yes
Yes
Yes
Yes
Yes
Yes

Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes

Yes
Yes
Yes
Yes

Yes
Yes
Yes
Yes
Yes

Yes
Yes
Yes

Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes

Yes
Yes

Yes
Yes

V

V

V

Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes

Yes

a The one parameter model includes only the intercept which equates to the

average sightability of elk which was 0.823.

V

�79

V

·~

Table 14. Radiocollared elk captured in GMU 42 during Deceri&gt;er 1993 and thought to have dispersed out of
GMU 42 to a new winter ranse as of 15 Aeril 1995. Locations ,GMUs2 determined~ aerial telemetrx.
New
Trap
Location Descrietion
Sex
GMU
Zone Age0
Freauencx
3+
Fourmile Ck (Loe.Elk)
F
43
D
172.207/93
3+
421,42
Beaver-Buzzard Cks, Alkali Ck. (Loe.Elk)
F
172.219/93
D
5+
Ees t Muddy Ck
F
521
C
172.249/93
2+
Middle Th0[1')Son Ck
F
172.308/93
D
43
3+
Beaver Ck, Gumisonb
F
54
172.480/93
H
5+
N.Fk.Gwv,ison, Near Paonia
172.459/93
F
521
E
2+
Roaring Fk R., Glenwood Sprgs. (Loe.Elk)
172.509/93
F
43
H
1+
F
421
Hawxhurst Ck
172.830/93
B
1+
Threemile Ck, Roaring Fk. River
F
172.849/93
A
43
1+
East Muddy Ck, Paonia Reservoir
F
172.921/93
C
521
1+
Redstone; Porcupine Ck
F
172.929/93
C
43
1+
East Muddy Ck, Paonia Reservoir
172.961/93
F
D
521
1+
Hawxhurst Ck, Brush Ck
173.010/93
F
421
G
1+
173.020/93
F
421
Hawxhurst Ck, Brush CK
G
2+
173.070/93
F
42,West
Parechute;Monunent Gulch
E
1+
173.090/93
F
Roering Fk River, Crystal Ranch
H
43
1+
173.279/93
East Muddy Ck, Paonia Reservoir
C
M
521
1+
173.300/93
C
M
521
East Muddy Ck
1+
173.332/93
Clover Gulch, Hawxhurst Ck
D
M
421
1+
173.370/93
E
M
421
Plateau Ck/Salt Ck
1+
173.390/93
West Muddy Ck, Pilot Knob
D
M
521
1+
173.450/93
Kimball Ck, Wallace Ck
M
421
H
6

Age of elk in years as of April 1995
b This elk returned to GMU 42 during June 1995, a movement distance of about 80 airline miles.

~

\.._,,,I

~

\,,,..,/'

Appendix 1. Mortalities of radiocollared elk from 1 Deceri&gt;er 1993 - 14 June 1995. Age is approximate age
in years of elk at death; C=calf 6·12 months old, Y=yearling 12-18 months old. Body weight measured in
Deceni&gt;er when eLk caetured as calves.
Body
Frequency ID/
Date
Tree
Cause of Death
Year caetured
Site Zone
Sex Age
Wt.,kg}
Heard Dead
172.039/93
Undetermined mortality
GR B
F 2+
06/14/95
172.080/93
GM A
F 5+
11/05/94
Legal harvest rifle season
172.090/93
F 5+
01/16/94
Wounding loss late rifle season
GR B
172.160/93
Legal harvest rifle season
cc C
F 2+
10/23/94
172.181/93
F 2+
MC C
11/03/94
Wounding loss rifle season
172.201/93
GS C
Wounding loss rifle season
F 2+
11/15/94
HY C
F 2+
10/04/94
Legal harvest archery/nuzzle season
172.258/93
172.277/93
F 2+
GS C
10/04/94
Wounding loss archery/nuzzle season
F 5+
172.290/93
SG
10/23/94
Legal harvest rifle season
172.369/93
AC
F 2+
09/18/94
Legal harvest archery/nuzzle season
172.409/93
AC
F 5+
12/29/94
WOWlding loss late rifle season
172.542/93
FS
F 9+
02/01/94
Mountain lion predation
172.570/93
F 9+
11/03/94
WOWlding loss rifle season
PG
172.581/93
F 2+
Legal harvest rifle sea·son
PG
10/17/94
172.610/93
F 2+
PG
10/04/94
Accident, breech birth of calf
172.649/93
PG
F Y+
11/15/94
Disappear rifle season
F 2+
172.670/93
01/16/95
Legal harvest late rifle season
PG
172.678/93
F 9+
12/22/94
Wounding loss late rifle season
PG
FM
F 5+
172.690/93
01/24/94
Illegal harvest, poached
172.800/93
SR
F Y+
11/15/94
Disappear rifle season
172.899/93
BC
F C
86.0
03/18/94
Mountain lion predation
173.000/93
WM
G
F C
102.0
04/25/94
Malnutrition
M y
173.190/93
BC C
Illegal harvest rifle season
10/29/94
111.0
BR A
173.232/93
M y
105.0
11/15/94
Illegal harvest rifle season
173.262/93
BC C
M C
108.0
03/18/94
Undetermined mortality
173.289/93
MC C
M C
111.0
03/22/94
Undetermined mortality
173.309/93
HY C
M y
11/15/94
124.0
Disappear rifle season
173.320/93
HY C
M y
118.0
10/20/94
Illegal harvest rifle season
173.461/93
M C
02/07/94
Malnutrition
PG H
82.0
173.469/93
FS H
M C
04/25/94
Malnutrition
77.0
173.589/94
0G
B
F C
117.0
06/01/95
Undetermined mortality
173.640/94
MC C
F C
89.0
03/30/95
Undetermined mortality
173.789/94
F C
MR E
100.0
03/20/95
Undetermined mortality
173.870/94
F C
86.0
02/21/95
SM D
Mountain lion predation
174.119/94
F
M C
03/01/95
MM
140.0
Undetermined mortality
174.140/94
M C
F
112.0
03/14/95
MM
Mountain lion predation
174.170/94
FM B
M C
04/25/95
140.0
Mountain lion predation

�87

Colorado Division of Wildlife
Wildlife Research Report
July 1996

JOB PROGRESS REPORT

State of

Colorado

Project No.

W-153-R-9

work Plan No.

Mammals Research

_..&gt;L,.__________

Job No. _ _ _ _.....,.____________

Elk Investigations
Estimating Survival Rates of Elk and
Developing Techniques to Estimate

Population size
Period Covered:
Author:

July 1, 1995 - June 30, 1996

D. J. Freddy

Personnel: J. Broderick, G. Byrne, A. Coriell, D. crane, J. Ellenberger, D.
Fox, J . Frothingham, v. Graham, J. Gray, G. Loucks, D. Masden, C. Mehaffy, J.
Ritchie, L. Stevens, P. Will, CDOW; D. Bowden, G. White, CSU; CSU Diagnostic
Laboratory; K. Crane, c. McCarty, N. Miers, D. Ouren, A. Ryel, volunteers;
BLM Glenwood Springs, NBS Ft. Collins, Rocky Mountain Elk Foundation, USFS
Rifle, cooperating.

ABSTRACT
We captured and radio-collared 71 calf elk (Cervus elaphus nelsoni) 6-months
old in December 1995 to estimate survival rates during winter 1995-96 and to
increase numbers of radiocollared elk available for experiments utilizing
mark-resight models to estimate population density. Elk were captured using
helicopter net-gunning and portable corral traps. Survival rates(± 95% CI)
for 6-11 month old calves during winter-spring were 0 . 92 ± 0.06, 0.90 ± 0.07,
and 0.88 ± 0.08 in 1993-94, 1994-95, and 1995-96, respectively. Survival was
similar among years (P &gt; 0.50) and sexes (P &gt; 0.70). Suspected primary causes
of death for calves were predation (57%) and malnutrition (33%). Survival
rates for adult females(~ 12 months old) during winter-spring were 0 . 96 ±
0 . 05, 0.96 ± 0.04, and 0.95 ± 0.04 also during 1993-94, 1994-95, and 1995-96
and survival was similar among years (P &gt; 0.70). Hunting was the primary
cause of death (57%) for adult females during winter-spring. Annual survival
rates (l December-30 November) for adult females were 0.78 ± 0 . 10 and 0.84 ±
0.09 in 1993- 94 and 1994-95, respectively. Survival was similar between years
(P &gt; 0.50) and hunting annually accounted for 88% of the adult female deaths.
Hunting removed 79 % of the adult 2-year old males. Survival of males from 6month old calf to 35-month old adult were 0.09 ± 0.10 compared to 0.86 ± 0.12
for females of the same cohort. Wounding loss on adult males was 9% and
illegal loss of yearling males averaged 10%. Estimates of population size
based on mark-resight estimators ranged from 3, 2 72 -3,618 elk or about 26
elk/mi2 of winter range. The IEJHE mark-resight model using data pooled from

1~~
1ffil1~ii11 ~~1ffif
BDOW01 □ 789

�4 aeria l flights provided the best estimate of population size which was 3,415
elk wit h a 95% CI of 3,129-3,807. Estimates based on counts of elk on
randoml y selected 1 mi2-quadrats during 2 replicate flights were 2,165 and
3,175 e lk. Sighting bias models to adjust for negative bias of quadrat counts
are cur rently being evaluated. We believe stratified sampling systems using
quadrat s as sample plots and with counts corrected for sighting bias holds
promise for providing reasonable estimates of population size.

�:~JXf._

li10,)fh
f

..:.1

:.

87

... "--~

.:/{
\

.. ' /

Colorado Division of Wildlife
Wildlife Research Report
July 1996

JOB PROGRESS REPOR~

state of

Colorado

Project No.

W-153-R-9

Mammals Research
Elk Investigations

Work Plan No.
Job No.

____ __________
__.._

:

Estimating Survival Rates of Elk and
Developing Techniques to Estimate

Population size
Period Covered:
Author:

;~~~

:;;;tt·\:

(
~~

July 1, 1995 - June 30, 1996

D. J. Freddy

Personnel: J. Broderick, G. Byrne, A. Coriell, D. Crane, J. Ellenberger, D.
Fox, J. Frothingham, v. Graham, J. Gray, G. Loucks, D. Masden, C. Mehaffy, J.
Ritchie, L. Stevens, P. Will, CDOW; D. Bowden, G. White, CSU; CSU Diagnostic
Laboratory; K. Crane, c. McCarty, N. Miers, D. Ouren, A. Ryel, volunteers;
BLM Glenwood Springs, NBS Ft. Collins, Rocky Mountain Elk Foundation, USFS
Rifle, cooperating.

ABSTRACT
We captured and radio-collared 71 calf elk (Cervus elaphus nelsoni) 6-months.
old in December 1995 to estimate survival rates during winter 1995-96 and to
increase numbers of radiocollared elk available for experiments utilizing
mark-resight models to estimate population density. Elk were captured using
helicopter net-gunning and portable corral traps. Survival rates(± 95% CI)
for 6-11 month old calves during winter-spring were 0.92 ± 0.06, 0.90 ± 0.07,
and 0.88 ± 0.08 in 1993-94, 1994-95, and 1995-96, respectively. Survival was
similar among years (P &gt; 0.50) and sexes (P &gt; 0.70). Suspected primary causes
of death for calves were predation (57%) and malnutrition (33%). Survival
rates for adult females(~ 12 months old) during winter-spring were 0.96 ±
0.05, 0.96 ± 0.04, and 0.95 ± 0.04 also during 1993-94, 1994-95, and 1995-96
and survival was similar among years (P &gt; 0.70). Hunting was the primary
cause of death (57%) for adult females during winter-spring. Annual survival
rates (l December-JO November) for adult females were 0.7~ ± 0.10 and 0.84 ±
0.09 in 1993-94 and 1994-95, respectively. Survival was similar between years
(P &gt; 0.50) and hunting annually accounted for 88% of the adult female deaths.
Hunting removed 79% of the adult 2-year old males. Survival of males from 6month old calf to 35-month old adult we~e 0.09 ± 0.10 compared to 0.86 ± 0.12
for females of the same cohort. Wounding loss on adult males was 9% and
illegal loss of yearling males averaged 10%. Estimates of population size
based on mark-resight estimators ranged from 3,272-3,618 elk or about 26
elk/mi2 of winter range. The IEJHE mark-res.ight model using data pooled f rem

1iiiHi1ili •
BDOWD1 □ 789

�4 aerial flights provided the best estimate of population size which w~s
elk with a 95% CI of 3,129-3,807. Estimates based on counts of- elk on " ,, .. :-.
randomly selected 1 mi2 -quadrats during 2. replicate flights -were '2,'16sJka"/\.:.
3 I 175 elk. Sighting bias models to adjust for negative bias of quadr~t''9otii1€e :.
are currently being evaluated. We believe stratified sampling ·systems ~:11~~?9 · •
quadrats as sample plots and with counts corrected for sighting bias holds'·
:&gt; •
~.
promise for providing reasonable estimates of population size.
,'

�89

BS!rIMA!rIHG SURVIVAL RADS OF ELK AND DEVELOPING !rECBRIQlJBS m
BS~IMAm POPULA~IOH SIZE

David J. Freddy

P, ff, OBJECTIVE
Estimate survival rates of adult female a·nd calf elk and develop techniques to
estimate population size.

SEGMEHT OBJECTIVES
1.

Radio-collar 75 calf and 15 adult female elk during December 1995 in
Game Management Unit 42 south of Rifle, COlorado.

2.

Estimate winter and annual survival r~tes of calf and adult elk from
known fates of radioed elk.

3.

Estimate density of elk in a portion of GMU-42 using 2 replicate flights
of a quadrat sampling system. Apply sighting bias corrections to adjus~
numbers of elk counted during each replicate. Compare biase adjusted
estimates with mark-resight estimates based on numbers of marked elk
seen during the 2 replicate flights plus 2 nonrandom mark-resight
flights.

4.

Analyze data and summarize annually in Federal Aid Job Progress reports

5.

Prepare_ draft of manuscript on sighting bias models developed from data
collected in 1994 and 1995.

6.

Continue to monitor locations and movements of selected radiocollared
elk.

INTRQDUCTXQH
Our objectives-are to provide reliable estimates of survival rates for calves
and -adult females during winter and for adult females throughout the year for
the period 1993-94 through 1996-97. Additionally, we will develop and test a
system for estimating population size that will incorporate estimates of
sighting bias in conjunction with a random sampling system using search
quadrats as sample units. our winter study area encompasses about 839 Jan2
(324 mi2 ) in the eastern half of Game Management Unit 42 south and east of
Rifle, Colorado. Elk winter range vegetation types include juniper-pinyon
woodland (Juniperus osteosperma-Pinus edulis), oakbrush-mountain sh~ub
(Ouercus gambelii-Amelanchier alnifolia), aspen (Populus tremuloides),
sagebrush (Artemisia tridentata), and agricultural fields (Freddy 1993, 1994).

�90

METHODS
• Marking

We placed radio collars (172-176MBz) ·having mortality sensors on 71 calves (6
months old), of which 37 were males and 34 were females. Of these, 68 calves
were trapped from. 8-11 December 1995 using helicopter net-gunning and 3 calves
were trapped on 21 December using portable corral trap.a. Helicopter capture
occurred at 10 remote sites located primarily. on public lands while corraltrapping occurred at 1 site on public lands. Trapping effort was all9cated
among 8 geographic trap zones to assure that radioed elk were representative
of most if n9t all segments of th~ population (Table 1). Radio collars were
of the same type used in 1993 and 1994 (Freddy 1994).
Calves captured by net-gunning were ferried by helicopter to processing points
usually within 1. 6 Jan of capture sites. At processing points·, body weight,
total body length, hind foot length, and rectal body temperature (F) were
measured and calves were then radio-collared and released. Similar
measurements were also made on calves that were_ corral-trapped and then
released at the trap site. Body measurements for calves were compared between
sexes and years using Pree FREQ, GLM, and REG (SAS 1988)·.

survival
We monitored life or death status of radioed elk during daily ground surveys
and aerial surveys conducted at 2-4 week intervals from December 1995 through
·April 1996 and via monthly aerial surveys from M~y to November 1995 and May to.
June 1996. Survival rates (S) of radioed elk were calculated using the
binomial estimator with a variance, VAR(S) ~ S(l-S)/n (White and Garrott 1990)
(Pree FREQ, .SAS 1988). Survival rates are expressed as the mean estimate ±
the 95% confidence interval. We used x2 -contigency tests to compare
survival rates. we· chose not to use the staggered entry approach and did not
use a Kaplan-Meier approach because elk were captured in~ short time interval
and few animals were censored (White and Garrott 1990). We defined 4 major
time intervals for survival analyses: winter-spring was 1 December to 14 June,
summer-fall was 15 June to 30 November, annual was 1 December to 30 November
to coincide with timing of capture and radiqcallaring, and yearly for yearling
elk aged 12-23 months was 15 June to subsequent.14 June.
Life or death status of all calves radioed in.December 1995 (71) was known for
the period 8 December 1995 through 15 June 1996 except for 1 male calf collar,
174.619/95 which apparently slipped off the elk in May 1996. on 15 June·,·
calves become yearlings for purposes of calculating rates of calf surviYal.
Life or death status for adult females, adult males, yearling females, and
y~arling males collared iri December 1993 or 1994 was known for 198 of 205 elk
through_ 15 June 1996.
Causes of death were-estimated from multiple sources of evidence including:
presence or absence of gunshot wounds, presence or absence of bite wounds on
carcass and predator tracks or ~cat at carcass site, p:tiysical positioning of
carcass remains whether buried, covered, scattered, or consolidated, re.lative
amount of internal fa~ and marrow fat if pre~~nt with carcass, and results of
histopathology an~ marrow fat analyses (Wade ~nd Browns 1982, Halfpenny and
Biesiot 1986). Fat co_ntent (percent dry matter) of .bone· marrow and estimates
of age based on d~ntal cementum were obtained for dead elk by the Colorado
Division of Wildlife Laboratory while histopathology analyses were provided by

(
/
\

�91

the Colorado State University Veterinary Diagnostic Laborat.ory. Photographs
were taken of nearly all mortalities so that physical evidence could be
reviewed and judged by outside experts (pers. comm. A. Anderson, T. Beck, w.
Andelt).

Pgpulation Estimates
Elk population size in GMU 42 from East Alkali Creek west to. Grass Mesa was
estimated during mid-January and early March 1996. We counted elk using a·
Bell-Soley helicopter on 4 flights. Two replicate flights involved counting
elk on 53 quadrats about 1 mi 2 (2.59 km2 ) in size representing.a 40%
strati£ ied random sample of t.he 132 mi2 winter range. • Each potential quadrat
in 8 geograhic. blocks were ranked as a high or low density quadrat resulting
in 14 strata. Intensity of sampling was 60% in high density and 32% in low
density strata with a minimum of 3 quadrats in any one strata~ Two flights
involved counting elk.encountered on a nonrandom route that traversed the same
132 mi 2 area. One flight of each type was conduct~d during the time periods
15-20 January and 29 February-3 March 1996. During helicopter surveys, fixedwinged flights were conducted to locate 219 radiocollared elk to determine
whether these marked elk were within or outside the 132 mi2 sample area.
During all flights, numbers of marked and unmarked elk were tallied by
observers. We gener~ted estimates of population size using several markresight estimators for each individual flight, pairs of flights, and all 4
flights pooled using program NOREMARK (White 1996). We considered. estimates
based on all 4 flights pooled to be our best estimate of population size- and
the b~nchmark against which individual flights, especially·quadrats, would be
compared. Estimates from quadrat sampling were computed using program DEAMAN
(Colo. Div. Wildl. software). At this time, we have~ applied sighting bias
correction factors to the counts of elk observed on quadrats •(Freddy 1995) .•

Movements
We continued to locate selected radioed.elk at least once per month since
capture to document seasonal movements via telemetry using a Cessna 185.
These elk were selected at random from within trap zones and equalized by age
class in Janaury 1994. Elk from the original sample that died were replaced
each subsequent January primarily with randomly selected 6 month-old calves of·
the same sex from the same trap zone(s) as elk that died. As of 1 January
1996, these 4·4 elk were classified as 22 adult females, 4 yearling females, 6 •
female ca·lves, 2 adult males, 4 yearling males, and 6 male calves. During
June 1996, we agaln located 28 adult ·females that. were selected at random in
1995 to document locations during the calving period. As needed, we located
other elk to document· unusual movements.

RESULTS AND DISCUSSION

c;apture
Two elk calves died during helicopter net-gunning activities. These have been
the only deaths during capture of 235 elk using the helicopter. one calf died_
of a bro~en neck during capture and one calf (174.800/95) di~d within 10 days
of capture due to the effects of capture myopathy (histopathology, CSU
Diagnostic Lab) and was subsequently censored from survival analyses.

�92

survival
~

Between 1 December 1993 and 14 June 1996, 86 radiocollared elk died (Table 2,
Appendix 1). Hunting was apparently· involved in 661 of the deaths. For
adults ~1 year-old, hunting accounted for 87% of 65 deaths. There were 2
periods of mortality during the year. Calves died from February to May while
adults died during fall and early winter when hunting seasons occurred (Fig.
1) . .

Calves

survival rates for 6-11 month old calves during winter-spring were 0.92 ±
0.06, 0.90 ± 0.01, and a.as± o.oa in 1993-94, 1994-95,· and 1995-96,
respectively (Table 3). We failed to detect differences in survival of calves
among years (X 22 = 0.40, P &gt;0.50), between sexes· pooled among year·s (X21 =
0.58, P &gt;0.70), and between sexes within each yearly cohort (X21 S 0.79, P &gt;
0.70) (Tables 3, 5, 6). Sex of dead calves for all years was 12 male and 9
female (Table 2). These survival rates were associated with winters
considered mild in temperature and having low or moderate snow depths. In
1994-95, considerable snow fell during March and April but usually melted
rapidly at lower elevations.
Causes of death for calves during winter-spring were suspected malnutrition
(33%), mountain lion predation (33%), ·suspected predation (19%), bear
predation (5%), and unknown cause (10%) (Tables 2, 4). Percent fat in bone
marrow of calves suspected of dying from predation was 82 for males {(range 6495, n = 6) and 48 for females (range 29-63, n = 3) and for calves dying from
suspected malnutrition, 14 for males (range 0.2-41, n = 3) and 11 for females
(rang~ 8-15, n = 3) (Table 4).
Yearlings

-:i

survival rates for elk 12-23.months of age were 0.86 ± 0.09·for males (n = 57)
and 0.95 ± 0.05 for females (n = 66) when yearlings were pooled among years
and hunting mortalities were included (Tables 5, 6). Excluding or censoring
hunting mortalities increased survival rates to 0.98 ± 0.04 for males and 0.98
± 0.03 for females. Males had lower survival rates when hunting mortalities
were included (X2 1 = 3.38, P = 0.07) but not when hunting mortalities were •
excluded (x\ = 0.03, P &gt; 0.50). Of the 11 deaths involving elk 12-23 months
old, 9 (82%) were hunting related (Table 3).
Adult FemalQs

·Survival rates for adult females(~ 12 months of age) during winter-spring and
inclusive· of hU:ntin_g mortalities were 0.96 ± 0.05, 0.96_ ± 0.04, and 0.-95 ±
0.04 in 1993-94, 1994-95, and 1995-96, respectively. Excluding hunting
mortalities increased·survival to 0.98 ± 0.03, 0.99 ± 0.02, and 0.97 ± 0.03 in
the same 3 years (Table 7). We failed to detect differences in survival among
years inclusive (x22 = 0.37, P &gt;= 0.50) or exclusive (X22 = 1.52, P &gt; 0.70) of
hunting mortalities.
Of 14 winter-spring deaths, 8 (57_1) were related to late-season rifle hunting:
4 legal and 1 illegal harvest and 3 wounding losses (Table 2). Six natural
deaths included 2 suspected predation, 3 of unknown cause,_ and 1 calvingrelated~ Of the 3 elk lost to wounding, 2 were suspici9us kills. Both of
these elk died from 1 rifle shot to the upper neck or head in relatively plain

(
(

�93

sight near or on an agricultural field where retrieval of the carcass was not
difficult. These animals may_have been accidentally shot, maliciously shot,
.or abandoned because of the radiocollar.
Survival rates for adult females(~ 12 months of age) during summer-fall and
-inclusive of hunting mortalities were 0.87 ± 0.07 and 0.94 ± 0.04 in ·1994 and
1995, respectively. Excludlng hunting mortalities increased survival to 0.99
± 0.02 and 1.00 in the same 2 years (Table 7). We failed to detect
differences in survival among years inclusive (X21 = 3.13, P = 0.09) or
exclusive (x\ = 1.38, P &gt; 0.70) of hunting mortalities. Hunting accounted
for 20 (95%) of 21 summer-fall deaths. The one natural death was ~alvingrelated.
During hunting seasons in Fall 1994 and 1995, 100 and 129 radiocollared adult
females, respectively, were a~ailable to hunters (Table 7). Proportions of
these marked elk lost to hunting-related mortalities were 12 1k in 1994 and 8%
• in 1995.
Annual survival rates for adult females(~ 12 months of age) marked as a
cohort in December 1993, inclusive of hunting mortalities, were 0.78 ± 0.10
and 0.84 ± 0.09 in 1993-94 and 1994-95, respectively. Excluding hunting
mortalities increased survival to 0.96 ± 0.05·and 0.98 ± 0.04, respectively
(Table 8). We failed to detect differences in survival among years inclusive
(X21 = 0.19, P &gt; 0.50) or exclusive (x\ = 0.15, P &gt; 0.50) of hunting
mortalities. For this cohort of adult females, hunting accounted for 22 (88%)
of 25 deaths during both years.
Adult Males

Survival of males from 6-month old calf t~ 35 months of age was 0.09 ± 0.10
compared to 0.86 ± 0.12 for females of.the same calf cohort (Table 5).
Hunting was the overwhelming cause of mortality among male elk. From the
1993-94 calf cohort of 36 male calves, 28 (78%). lived to become 2-year old·
legal branch-antlered bulls for ·the 1995 hunting seasons. Of these 28, 22 or
79% were harvested in the Fall of 1995 inclusive of 2 wounding losses (9% of
22). Rifle seasons accounted for 16 (73%) of the hunting mortalities (Table
2) . . Most of these 2.-year old bulls were harvest~d .in the Grand Mesa DAU or in
adjacent GMO 43 .. One.exception was a bull taken during archery ·season in GMO
63 on Black Mesa about 100 miles south of its capture site in GMO 42. One
surviving bull was located in March 1996 in GMO 4.7 east of Basalt, co about 35
miles southeast of its capture site in GMO 42.
Yearling spike-antlered bulls were generally not legal quarry during hunting
seasons. In 1994, 32 yearling bulls from the 1993-94 calf cohort entered the
hunting seasons presumably as spike-antlered bulls and 4 (12.5%) were
illegally taken with 3 taken during rifle seasons and 1 taken prior to rifle
seasons. In 1995, 30 yearling bulls from the 1994-95 calf cohort entered the
hunting season and 2 (7%) were illegally taken and 1 (3%) was fatally wounded
during ar9hery season in an ar~a where the bull was legal q,.Jarry.

cal:f Body ·size
Body weights of male and females calves were largest in 1995 with the inerease
most pronounced for males (Tables 9, 10).. Increases in weights were not
unexpected as the locally moist summer of 1995 wa·s favorable to forage
production on summer ranges.
However, we failed to detect.differences in

�94

body·weights among years (P = 0.206) and any interaction between year and sex
(P = 0.380). overall, male calves had larger body weights (P = 0.0001),
longer total body length (P = 0.0386), longer hind leg lengths (P = 0.0001),
and higher condition indexes (P = 0.0001) than female calves (Table 10).
Accurately predicting body weight from total body length, hind foot length, or
a combination of·these 2 measurements does not look promising at this time,
although all regressions were significant (P &lt; 0.0001). The multiple
regression using body length and hindfoot length as independent variables
provided the best correlation coefficients (r2) of 0.63 for female calves,
0.69 for.male calves, and 0.69 for sexes combined.
Calves suspected of dying from predation (Table 4) averaged 121 kg in weight
for males (range 100-140 kg, n = 6) and 91 kg for females (range 79-117, n =
5). Predators thus appeared to take larger than average males and smaller
than average females (Table 10). Calves suspected of dying from malnutrition
(Table 4) averaged 95 kg in weight for males (~ange ~7-127, n = 3) and 107 kg
for females (range 100~120, n = 3). Malnutrition thus appeared to affect
smaller than average males .and average sized females (Table 10).

Pgpulation Estimates
Our elk population was not geographically or demographically closed during
the time interval encompassing flights. During our first pair of flights,
some elk were still moving down in elevation in response to heavy snow in
early January resulting in.fewer than expected radiocollars on the sample
area. By the March flights, all elk had reached elevations encompassed by the
sample area but some elk moved lower in elevation onto private lands outside
of but adjacent to the sample area and some elk moved to winter ranges
adjacent to but also outside the sample area. These movements resulted in
radiocollared elk moving into and out of a "pool" of elk that was different
and larger than the elk population encompassed. by the. sample area. Between
pairs of flights, 2 radiocollared elk died indicating some los~ of elk was
occurring during our flight time interval. Fortunately, both quadrat and
nonrandom flights reflected proportionately similar and positive changes in
total elk and total marked elk counted between pairs of flights indicating
that movements of marked and unmarked elk into the sample area were similar
(Table 11).

(
(

Population estimates from 4 mark-resight estimators ranged from 3,272-3,618
elk or 24.8-27.4 elk/mi2 of winter range within the sample area (Table 12).
At· this time, the estimate of 3,415 elk generate~ by the
Immigration/Emigration JHE mark-resight estimator is probably the best
estimate of population size on the sample area because it accounts for
movement of elk on and off the sample area. Adding the 165 elk directly
counted on private lands in lower Divide Creek and Hunter.Mesa (57 mi 2 area)
increased the population to 3,580 elk in the intensive study area. In January
1995, a single nonrandom flight produced a Lincoln-Peterson mark-resigh~
estimate of 3,411 elk and adding 399 elk counted on private lands in lower
Divide creek and Hunter Mesa.to this estimate.increased the_ population to
3,810 elk in the intensive study area in 1995 (Freddy 1995).
Population estimates for the larger "pool" of elk within which radiocollared
elk were moving ranged from 3,969-4,004 elk as estimated by the IEJHE and BE
mark-resight estimators (Table 12). This "pool" ~stimate wo~ld include el~ on
the Divide creek and Hunter Mesa private lands and some addit!onal elk on
areas ~djacent to the western boundary of the intensive study area.

(

G

�95

Population estimates from quadrat flights 1 (2,165 elk) and 2 (3,175 elk) were
lower than the IEJHE mark-resight estimate (3,415) (Table 12). Although both
quadrat flights were subject to sampling error, the lower . estimate from the
first flight may reflect a less favorable distribution of elk ~uring that
flight. Confidence intervals overlapped between quadrat flight 2 and IEJHE
suggesting estimates were not different. Quadrat estimates will be adjusted
upward for sighting bias and at that time more conclusive comparisons to markresight estimators will be made (Freddy 1995, Samuel et al . 1987). Elk
densij:ies ~ 50/mi2 occurred within the Garfield Creek High, West Divide Creek
2
West High, and Grass Mesa Low strata which together encompass about 25 mi of
winter range (Table 13).

Elk Movements
In December 1994, 33 male and 36 female calves and 8 adult females were
radiocollared. Of these elk, 27 male and 31 female calves and all 8 adults
survived to 30 November 1995. None of the adult females dispersed during
winter 1995-96 to a winter range outside of the intensive study area in GMO
42. However, 25 (9M, 16F) or 43% .of the surviving yearling elk dispersed to
winter ranges outside the intensive study area (Table 14). Rates of dispersal
were 33% for males and 52% for females. Calves trapped in zones E and F,
which encompass Alkali, Dry Hollow, and the Mamm creeks, comprised 68% (17) of
the dispersing yearlings but only 45% of the surviving yearlings. Calves
trapped in zones E and F dispersed to winter ranges near the towns of
Collbran, Parachute-Rulison, and Paonia. Calves trapped in zones C and D
which encompass West Divide Creek comprised 28% of the dispersing juveniles
and these elk primarily moved south to winter ranges near Paonia and Paonia
Reservoir.
We are. currently creating a GIS land database for the area frequented by
radiocollared elk. This is a cooperative effort through the National
Biological Service and Rocky Mountain Elk Foundation . We believe plots of elk
locations and movements using this database will be forthcoming in 1996.

12

lililllll CAL VE S
10
-

~

ADULT lfALES

l&lt;&lt;&lt;·&gt;I ADULT FEtlALES

8

•••••• •••4••• •• •••• •••••• ••••••

••••••••

•• •••••••••••• • •••••n•--• • ••• • •• •••u•••••••• • •••••• • ••••••••• • ••• • ••••• ••••••

o o o o o o o o o o O o o U OO • • o • • O o o O oOOOO

00000000•

• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • O oOo O O OOO O OOOOOO

H
Q

P!
r..i

6

•o• o o••••

~

~

4
2

···········-······· ···········~-,................................ .

0

Figure 1. Timing of deaths for calf and adult elk, 1993-1996.
12 months old and adults were &gt;12 months old.

Calves were 6-

�96

CQNCLUSXQRS
\._/

We obtained acceptably precise estimates .of calf and adult survival rates and
recommend continuing our current sampling effort of capturing and
radiocollaring 70 calves in 1996-97 and co~tinuing to monitor&gt; 75 radioed
adult females and&gt; 25 radioed adult males in 1996-97. We recommend
conducting replicate aerial surveys in 1996-97 to estimate elk density ~sing
sample quadrats, mark-resight estimators, and sighting bias correction models
to complete our evaluation evaluating techniques to estimate elk density.

LITERATURE CITED
Freddy~ D. J. 1993. Estimating survival rates of elk and developing
techniques to estimate population size. Colo. Div. Wildl. Game Res.
Rep.· July: 83-117.
Freddy, D. J. 1994. Estimating survival rates of elk and developing
techniques to estimate population size. Colo. Div. Wildl. Game Res.
Rep. July: 27-42.
Freddy, D. J. 1995. Estimating survival rates of elk and developing
techniques to estimate population size. Colo. Div. Wildl. Game Res.
Rep. J~ly.
Halfpenny, J. c., and E. A. Biesiot. 1986. A field guide to mammal tracking
in North America. Johnson Books, Boulder, co. 161pp. •
Samuel, M. D., E. o. Garton, M. W. Schlegel, and R. G. Carson. 1987.
Visibility bias during aerial surveys of elk in northcentral Idaho.
Wildl. Manage. 51:622-630.

J.

SAS Institute Inc. 1988. SAS/STAT User's Guide, 6.03. SAS Institute, Inc.,
Cary, NC. 1028pp.
Wade, D. A., and J. E. Browns·. 1982. Procedures for evaluating predation on
livestock and wildlife. Texas Agric. Expt. Sta. Publ. B-1429. 42pp.
White, G. c. 1996. NOREMARK: Population estimation from mark-resighting
surveys. Wildl. Soc. Bull. 24:50-52.
White, G. c., and R. A. Garrott. 1990. Analysis of wildlife radio-tracking
data. Academic Press, Inc., San Diego. 383pp·.

Prepared by ____________________
David J. Freddy
Life/Science Researcher

�(

in 8 trapzones. December 1993.1994. and 1995 within Game Management Unit 42.
Table 1. El.k capture objectives and numbers of elk radiocollared
Elk Col lared1
Calves Collared
·Elk Captur~
Years
Corral
Objectives
Males
TotalLYeac Helicoeter
Females
Years
Adult Females Collared
Trap
93 94 95 93 94 95 Total
93 94 95 93 94 95
93 94 95
93 94 95
Total
Zone Name
93 94 95 Total
A
B

C
D

E

F
G

H

Garfield
Gibson
Uncle Bob
West Divide
Hightower
Middle Manm
West Manm
Dry Hollow

All

5
8
13
13
10
8
8
21

6
12
11
11
10
9
10
6

8 6 4
25 17 7
29 13 14
21 11 18
• 17 17 14
0 13 9
6 ·O 5
35 6b 0

8 6 4
19 7 4
29 13 14
21 11 18
17 17 14
0 13 9
6 0 5
0 0 0

0 0 0
6 10 3
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
35 6 0

18
49
56
50
48
22
11
41

150 86

75

141 83 71

100 67 68

41

295

8
20
24
26
10
10
8
44

16 3

3

4
0
2
7

3 1
5 4
7 10
1 8
9 ·8
8 5
0 1
0 0

36

·33 37

5

10

5

1
8
7
6
3
0
3
9

3 3
6 3
6 4
8 10
8 6
5 4
O· 4
0 0

37 36 34

14
31
44
38 •
22
10

4
12
12
10
10 •
0
1

16

19

0 0
6 0
0 0
2 0
0 0
0 0
0 0
6 0

213

68

14 0

38

4
18

12
12
10
0
1
25

82

•Helicopter= Helicopter net-gunning, Corral= corral-trapping.
6 adult females cap~ured 2 March 1995

b All

Table _3. Survival rates of calve~ with sexes pooled for 1 December - 14 June each year 1993-94, 1994-95,
and 1995-96. Survival· rates (S) calculated as a mean estimate of (alive)/(alive + dead) and variance S(lS)/n collars.
Elk Age and Time Period (dates)
• Calves
Cal~,es
Calves

Survival
'L 95\- CI
U 9~%' CI

n collars
Censored1
Died
Nonhunting
Hunting

12/01/9306/14/94

12/01/9406/14/95

12/01/9506/14/96

0.92
0.85
0.98
73

.0. 90
0.83
0.97

0.88
0.81
0.96'
69

0
6
6
0

69b
0
7
7
0

2c
8

8
0

• Censored denotes collar failure and/or animal life/death status not known.
b Includes (173.949/94) male whose collar'failed 12/94 but seen alive 1/95, 1/96.
c Censored elk were (174.619/95) for slipped collar and (174.800/95) for trap-related mortality.

�98

~

Table 2. Causes of deaths in radiocollared elk between 1 December 1993 and 14
June 1996. Calves (M=male, F=female) were 6-12 months old and collared at 6
months of age. Yearling males and females were 12-18 months old and collared
as 6 month old calves. Juvenile males and females were 18-23 months old and
collared as 6 month old calves. Adult males and females were .2. 24-months old
at time of death.
Elk AgelSex Class at Death
Total
Adult
Juvenile
Calves
Yearl±ng
All
Cause of Death
M
F
F
MF
M
F
F
M
M

Malnutrition
Unknown-Suspect
Malnutrition
Predation-Lion
Predation-Bear
Unknown Predator
Unknown-Suspect
Predation
Ac'cident-Birthing

'....,_/

')

2

2

0

0

0

0

0

1

2

5

2

1

0

0

1

0
0
0
0

0
0
0
0

0
0
0
0

0
0
0
0

0
0
0
0

1

2
0

0
0

0
0

1

0

0
0

0
0

Legal Hunting
Archery
Muzzleloading
Archery/Muzzle
Rifle-First
Rifle-Second
.·-·
Rifle-Third
Rifle-Late

0
0
0
0
0
0
0

0
0
0
0
0
0
0

0
0
0

1

0
0
0

5

1

Wounding Loss
Archery/Muzzle
Rifle-Regular
Rifle-Late

0
0
0

0
0
0

1

Illegal Hunting
Rifle-Regul'ar
Out-of-Season

0
0

0
0

s•

Presumed Hunting
Disappear-Rifle
Seasons

0

Unkl'lown Cause
Totals

0

0

·o

0

2

2

4

0

1
5

2

3

3

8

1

0

0

1

1
1

1

2

2

0

3
2

5
2

1

5

2

7

0

1

0

1
0
0

0

0

1

0

1

1
1

0

2
4

6
2

2·
4

6

0
0

0
()
0

6
2
4
0

2

4
0

2

0
0
0

0
2
0

1

0

0
0
0

0

0
0

0
0

0
0

0
0

0

lb

lb

0

0

2

0

0

1

·o

12

·9

7

3

1

O·
0
0
0

0
0

0

0
0
0
0
0
0
0

o.
.o

5

5

1

8

6
5

1
2

4

2
6

0

3

3

.5
0

0

5

1

1

1

2b

2b

3

3

6

0

0

2

2

3

5

0

22

32

42

44

86

4
3

0

(

(

• These elk were illegally shot as spike-antlered yearling males: (173.190/93), (173.232/93), (173.320/93), (113.919/94), (174.059/94).
"Th~ elk disappeared during rifle hunting seasons and are.presumably dead and legally harvested: (17_2.207/93), (172.649/93),
(172.800/93), (173.309/93), (173.390/93), (173.439/93). One exception may b-..; spike:..anttered yearling male (173.309/93) that disappeared
during the first rifle season in 1994 when spike-antlered bulls were not legal.

( \

\J

�(

(

Table 4. Estimated causes of mortality and associated body condition for 21 radiocollared calf elk 6-11
14 June 1996.
months old, 1 December 1993
Ag~•
Body&gt;
Marrow.
Trap
Frequency ID/
t Fat
Date Dead
Cause of Death &amp; Code No.
Sex {months}
Wt. {kg}
zone
Year Ca12tured

-

172.899/93
173. 000/93
173. 262/93
173.289/93
173.461/93
173.469/93
173.589/94
173.640/94
173.789/94
173.870/94
174.119/94.
174.140/94
174.170/94
174.220/95

174.230/95
174.240/95
174.339/95
174.500/95
174 .·609/95"
174.689/95
.·174 ;789/95

C
G
C

C
H
H
B
C

E

D
F
F
B
F
F
E
E

F
F

M
M
M
M
F
F
F
F
M
M
M
M
M
M
F

C

F

B
o·
C

F
M
M

9
10
·9
9
8
10
12
9
9

86.0
102.0
108.0
111.0
82.0
77.0
117.0
89.0
100.-0

03/18/94
04/25/94
03/18/94
03/22/94
02/07/94
04/25/94
06/01/95
03/30/95
03/20/95

8

86.0
140.0
112.0
140.0

02/21/95
03/01/95
03/14/95
04/25/95

. 127. 0
120.0
115.0
79.0
78.0
120.0
100.0

04/08/96
. o~/24/96
04/17/96
03/27/96
04/16/96
04/15/96
02/05./96
05/22/96

9
9.
10

9
10
10
9
10
10
7
11

• Approximate age at death assuming rs June binhdate.
• Whole body weight at capture in December of 1993, 1994, or 1995.
c Fat content as percent dry matter of bone marrow from either femur of carcass.
• Fat content as percent dry matter of bone marrow from either ~andible of carcass.
• Fat content as percent dry matter of bone marrow from either humerus of carcass.

28. 50d

8. 03c
2a. sad
0 .21c
0. 27c
51. 71c
14 ."•71c
94. 97c
64 _44·c
76. osc

41. oac
86. 2ac
62. 97c
34. 56c
10. 2ac
91. 90c

75. 32e

Lion Predation-3
Malnutrition-6
Unknown-11
Unknown-11
Malnutriton-6
Malnutrition-6
Unknown; suspect predation-30
Unknown; suspect p:t:edation-30
Unknown; suspect malnutrition-31
Lion Predation-3
Bear Predation-35
Lion·Predation-3
Lion Predation-3
Unknown; suspect malnutrition-31
Lion Predation-3
. Lion Predation-3
Unknown Predator-5
Unknown; suspect malnutrition-31
Malnutrition-6
Lion Predation-3
Unknown; suspect predat;.ion-30

�(
.....

8

Table 5. Survival rates.for the cohort of 6-month old elk calves radiocollared in December 1993 for 6 time
periods from. 1 December 1993 through 14 June 1996·when elk were 35 months old. Survival rates for male and
female calves pooled when 6-11 months old were. 0.92 (95% CI 0.86-0.98, n=73). Survival rates (S) calculated
as a mean estimate of (alive)/{alive + dead) and variance S(l-S)/n collars.
Elk Age (months) and Time Period (dates)
12 - 17
18 - 23
24 - 29
30 - 35
6 - 11
6 - 35
06/15/9412/01/9406/15/95.12/01/9512/0l/9312/01/9311/30/94
06/14/95
11/30/95
~6/14/96
06/14/94
06/14/96
MALES

Survival
L 95% CI
U 95% CI
n collars
Censored1
Died
Nonhunting
Hunting

0.89
0.78
0.99
36
0
4
4

0.88
·o.76
0.99
32
0
4b

1.00
28
0
0
0
0

0

0
4

0.95
0.87
1.00
37
0
2
2

0.97
0.92
1.00
35
0
1'
0

1.00

0

1

0

0.21
0.06
0.37
28c
0

1.00
0.00
o. 00.
3

22d

0
0
0

0
22

3e

0.09
0.00
0.19
33
3
30
4
26

FEMALES

Survival
L 95% CI
U 95% CI
n collars
Censored1
Died
Nonhunting
HUiiting

34
0
0
0

0.97
0.91
1.00
34
0
l

0
1

• Censored denotes collar failure and/or anima1 life/death status not known.
1&gt; Collar (173~309/93) "disappeared" during Fall 1994 hunting seasons and assumed dead.
' Includes collar (173.241/93) that failed in August 1995 but bull seen alive Januacy 1996.
d Three collars (173..390/93, 173.402/93, 173.439/93) "disappeared" during Fall 1995 hunting seasons and assumed dead.
• Three collars censored; (173.241/93) failed, (173.340/93) not heard spring 1996, (173.381/93) slipped off 12/01/95.
' Collar (172.800/93) "disappeared" during Fall 1994 hunting seasons and assumed dead.

0.97
0.9~
1.00
33
0
1
0
1

0.86
0.98
0.75
37
0
5
2
3

�(

(

Table 6. Survival r.ates for the cohort· of 6-month old elk calves radiocollared in December 1994 for 4 time
periods from 1 December 199~ through 14 June 1996 and survival rates for the cohort of 6-month elk calv.es
radiocollared in December 1995 for one time period .. Survival rates for male and female caives pooleq when
6-·11 months old were 0.90 in 1994 (95% CI. 0.83-0.97, n=69) and 0.88 in 1995 (95% CI 0.81-0.96, n=69).
Survival rates (S}calculated as a mean estimate of (alive)/(alive + dead) and variance S{l-S)/n collars.
Elk Age (months) and Time Period (dates)
•
____________1=9-9-4___C=a=l=f__C=o=h=o=r-t____· _ _ _ _ _ _
1995 Calf-Cohort
12 - 17
18 - 23.
6 - 24
6 - 11
6 - 11
06/15/~512/01/95-·
12/01/9412/01/9512/01/9411/30/95
06/14/96
06/14/96.
06/14/96
06/14/95
MALES

Survival
L 95% CI
U 95% CI
n colla_rs
Censored•
Died
Nonhunting
Hunting
FEMALES
Survival
L 95% CI
U 95% CI
n collars
Censored•
Died
Nonhunting
Hunting

0.91
0.81
1.00

0.90
0.79
1.00

33b

30b

0
3
3
0

0
3
0
3

0.89
0.78
0.99
36
0
4
4
0

0.97
0.91
1.00
32
0
1
0
1

0.95
0.87
1.00
22
5c

1
1
0.
0.97
0.90
1.00
30
1c

1
1
0

0.75
0.59
0.91
28

0.86
0.74
0.98
35

5
7
4
3

2d

0.83
Q.70
0.96
35
1
6
5
1

0.91
0.81
1.00

5
5

0

34

0
3
3·
0

• Censored denotes collar failure and/or animal life/death status not known.
11
Includes collar (173.949/94} that failed in December 1994 but male seen alive in January 199~
' Censored elk were (173.949/94) failure, (173.981/94}~ (174.019/94), (174.090/94), (174.160/95) not heard spring 1996.
• Censored elk were (174.619/95}slipped collar, (174.800/95)capture mortality.
c Cenosred elk was (173.719/94) slipped collar.

_.,
0
_.,

�(

(

(
....
2

Table 7. Survival rates for all radiocollared adult female elk &gt;12-months old during 5 periods from 1
December 1993 through 14 June 1996. Survival rates (S) calculated as a mean estimate of (alive)/(aliye +
dead) and variance S (1-S) /n collars·.
Elk Age and Time Period (dates)
Adult
Adult
Adult
Adult
Adult
06/15/94.12/01/9406/15/9512/01/9512/01/9311/30/95
06/14/96
06/14/95
11/30/94
06/14/94
0.87
0.96
0.94
0.95
0.96
Survival
0.90
0.91
0.80
0.92
0.91
L 95% CI
1.00
0.98
0.99
0.94
1.00
U 95% CI
95bg
129bh
68bc
100bf
119 1
n collars
2j
0
0
0
0
Censored•
9d
13c
7
4
3
Died
0
4
1
1
1
Nonhunting
8
3
12
3
2
H~ting
• Censored denotes collar failure and/or animal life/death stams unknown.
b Includes collar (172.011 /93) that failed 4/ 1994 but seen alive in 1/ 1996
c Collars (172.800/93, 172.649/93) "disappeared" Fall 1994 hunting seasons.assumed dead.
4 Collar (172.207/93) "disappeared" Fall 1995 hunting·seasons, assumed dead.
• Composition is 6 females 18+ and 62 females 30+ _months old.

r Composed of 35-12+, 6-24+, and 59-36+ months old females.
'Composed of 34-18+, and 61-30+ montho old females.
h Composed of 32-12+, 34-24+, and 63-36+-month old females.
1 Composed.of 30-18+ and 80-30+ monthos old females.
J Censored (172.011/93) failure and (173.719/94) slipped collar.

·Table 8. Survival rates for the group of adult female elk &gt;12-months old radiocollared in December 1993 for
8 time periods from 1 December 1993 through 14 June 1996. Survival rates (S) calculated as a mean estimate
of (alive)/(alive + dead). and variance S(l-S)/n collars.
Elk Age and.Time Period (dates)
• Adult
Adult
Adult
·Adult
Adult
Adul-t
Adult
Adult
12/01/9406/15/9512/01/9512/01/9312/01/9412/01/9306/15/9412/0l/9311/30/94'
06/14/95
11/30/95
06/14/96'
11/30/95
06/14/96
11/30/94
06/i4/94
0.93
0.88
0.93
0.78
0.84
0.58
0.82
0.96
Survival
0.85
0.78
0.68
0.85
0. 75.
0.46
0.72
0.91
L 95% CI
0.88
0.70
0.97
1.00
0.93
0.99
0.91
1.00
U 95%-CI
53b f
68b r .
68bc
67f
65br
53br
49b r
42'
n collars
1
11
.
0
.o
0
0
0
1
0
Censored•
29cd
15c
10d
4 ·
6d
3
3
Died
6'
l·
2
1
0
3
1
.Nonhunting
3
6
0
22
13
9
2
Hunting
• Censored denotes collar failure and/or animal life/death stams unknown.
11 Includes collar (172.011/93) failed 4/1994 but seen alive 1/1996.
c Collar (172.649/93) "disappeared" Fall 1994 hunting seasons, assumed dead.
d Collar (172.207/93) "disappeared" Fall 1995 hunting seasons, assumed dead .

.,----

I.

\

• Composed of 6-18+ and 62-30+ month old females.
r Composed of 100% females 24+ months old.
'Censored (172.011/93) failure of unknown status Spring 1996.

�(

(

,,

Table 9. Frequency distribution of whole body weights for male and female elk calves trapped in Game
Management Unit 42. December. 1993. 1994, and 1995. Percentage per weight class shown in parentheses.
Bod~ Weight Class {kg}
Year

Sex

60-69

70-79

80-89

90-99

100-109

110-119

120-129

130-139

140-149

Total

1993
1994
1995

M
M
M

0(0.0)
0(0.0)
0(0.0)

1 (2. 9)
1(3.0)
0(0.0)

1(2.9)
1(3.0)
0(0.0)

3(8.6)
2(6.0}
4(11.4)

6·(.17 .1)
6(18.2)
3(8.6)

12(34.3)
13(39.4)
8 (22. 9}

10(28.6)
6(18.2)
9(25.7)

1 (2. 9)
. 2(6.0)
10(28.6)

1 (2. 9}
2(6.0)
1(~.9}

35(100)
· 33 (100)
35(100)

1993
1994
1995

F
F
F

0(0.0)
0(0.0)
1(3.1)

1(2.9)
2(5.7)
2(6.3)

4(11.4)
4 (11. 4)
1(3.1)

8(22.9)
7(20.0)
3 (9.4)

12(34.3)
10(28.6)
14(43.8)

4 (11. 4)
10(28.6)
5(15.6)

6(17.1)
2( 5.7)
6(18.8)

0(0.0)
0(0.0)
0(0.0}

0(0.0)
0(0.0)
o·(o. 0)

35 (100}
35(100)"
32 (100)

Bod~ measurements for elk calves traooed in Game Management Unit 42. December. 1993, 1994·, 1995.
Male Calves
Female-Calves
• Min
Mean
Max
SD
Min
Max
n
SD
n
Mean
Measurement

Table 10.
Year
1993

112.7 13.7
Body Weight (kg)
191.2 10.2
Body Length (cm}
Hindfoot Length (cm} 56.3 • 2 .2
Condition Index8
0.59 o.~5

77.0
164.0
52.0
0.43

141.0
210.0
61. 0
0.67

35
36
36
35

103.8
188.9
54.8
0.55

12.2
9.8
2.1
0.05

76.0
167.0
51.0•
0.46

123.0 35
207.0 ·35
59.0 34
0.64 34

1994

113.5 14.2
Body Weight (kg}
190.3
9.2
Body Length (cm)
1.8
Hindfoot Length (cm} 56.9
0. 59. 0.05
Condition Index

71.0
168.0
50.0
o.42

140.0
204.0
59.0
0.69

33
32
32
32

103.0
186.3
55.1
0.55

13.3
8.8
2.1
0.06

70.0
166.0
50.0
0.42

128.0
207.0
59.0
0.65

35
36
36
35

1995

119.1 .13. 6
Body Weight (kg}
194.0
9.3
Body Length (cm}
Hindfoot Length (cm} 57.4
2~2
0.61 0.05
Condition Index

92.0
166.0
53.0
0.50

141.0
206 .0.
61.0
0. 71

35
36
36
34·

105.7
189.4
54.9
0.56

-15.2
11.4
2.3
0.06

60.0
158.0
47.0
0.38

129.0
203.0
59.0
0.66

32
34
34
32

71.0 ·1~1.0 103
164.0 210.0 104
SO. O·
6LO 104
0.71 .101
0.42

104.l·
188.2
54.9
0.55

13.5
10.0
2.1
0.06

60.0
158.0
47.0
0.38

129.0 102
207.0 105
59.0 104
0.67 101

115.1
All .. Body Weight (kg)
191.9
Years Body Length (cm)
'Hindfoot Length (cm} 56.9
0.60
Condition Index

14.0
9.6
2.1
0.05

• Condition index= (Weight/body length).

...

8

�104

Table 11. Summary of flights to estimate elk population size and density on
132 mi 2 of winter range in GMU 42 south of Rifle and Newcastle, Colorado,
January/March 1996.
Total
Flight
Marked
Marked Unmarked
• Elk
Flight
Elk
Elk
Date
Elk
Time (hrs)
Flight
(M/D)
Available Counted Counted Counted
Quadrat 1,
NonRandom 1
NonRandom 2
Quadrat 2
4 Flights
Pooled
Flight
Quadrat 1
NoriRandom 1
NonRandom 2
Quadrat 2 •

1/15-18
1/19.-20
2/29
3/1-3

128
128
137·
137

32
54
80
49

853'
1300
1918
1324

885
1354
1998
1373

19.6
8.5
• 8.0
19.1

154•
Marked/
Unmarked
0.0375
0.0415
0.0417
0.0370

Marked/
Marked+Unmarked
0.0362
0.0399
0.0400
0.0357

Proportion of Available
Marks Seen {+/- 95% CI)
0.2500 (0.0749)
0.42.19 (0.0~57)
0.5839 (0.0825)
0.3577 (0.0803)

--------- ----------------------------------------------------------------

Changes in Total' Elk Observed:
Quadrat 1 vs. Quadrat 2: +488 elk or 55% increase over Quadrat 1
NRandom l vs. NRandom 2: +644 elk or·48% increase-over NRandom 1
Changes in Total Marked Elk Observed:
Quadrat 1 vs. Quadrat 2: +17 marked elk or 53% increase over Quadrat 1
NRandom 1 vs . NRandom 2 : +2.6 marked elk or 4 8 %- increase over NRandom 1
Marked Elk Deaths:
During the population estimate interval (1/15i96 - ·3/3/96), 2.
radiocollared elk died: 174.689/95 male calf on 2/5/96 and. 172.070/93
~dult female on 2/12/96 .

. • Marked elk available with inunigration/emmigration·movements involving 41 elk; 25 elk moved onto and 16 moved off'. the intensive •
sampling area during the time interval between 1/20/96 and 2/29/96.

")

Table 12. Estimates of population size and density for elk on 132 mi 2 of
winter range in GMU 42 south of Rifle ~nd Newcastle, Colorado, January/March
1996.
Density Pvt.
Model
Population
'.
Flights
·95% Conf: Int.
Land1
Estimator
Estimate
/mi2
JHEb
165
4 Flights Pooled
3,168-3,840
26.3
3,47~
IEJHEC
4 Flights Pooled
3, 129-3, 8_07
165
25.9
3,415
BEd
Quad l+NonRandom 1
2,764-3,872
24.8
165
3,272
Quad 2+NonRandom-2
BE
3,169-4,130
27.4
165
3,618
4 Flights Pooled
3, 969c
3,621-4,446
IEJHE
4 Fligh~s Pooled
4, 004f
BE
3,560-4,504
StRSg
Quadrats-1;-'light 1
1,356-2,974 11
16.4
165
2,165
Q~adrats Flight 2
165
StRS
3,175
24.1
2' 205-4' 145 11
• Elk on p(ivate land enumerated by dir~ct counts must be added to p~pula.tion estimate for estimated total elk in the intensive study area.
" Joint Hypergeometric Mark-Resight Estimator that"assumes a geographically closed population and homogeneous sighting probabilities of
individual elk.
•
• Immigration/Emigration Joint Hypergeometric Mark-Resight Estimator that allows for mqvement of elk on/off intensive study· area but
assumes homogeneous sighting probabilities of elk.
d Bow.den Mark-Resight estimator allows for some violation of ,a geographically closed population but allows for heterogeneous sighting
probabilities of elk.
c Estimate of total pool of elk within which radiocollared elk are distributed on or just off the intensive study area; equates to N' estimate."
r Estimate of total pool of elk; equates to fir.
•
1
Stratified random sample of qua:drats with counts of elk not adjusted for sighting bias.
h 90% confidence intervals.

('

u

I

t

�(

,,(

(

:!

Table 13. Counts of elk on quad.rats during 2 replicate flights in February and March, 1996-in GMU 42 south
of Rifle and Newcastle, Colorado.
Strata
Qyadrats
Elk
ElklQyadrat
Po:eulation Size
Size {mi2&gt;
n
Counted
Mean
N
StdErr.
Strata
Total± 90% CI
Quad.rat Flight 1
10
10
133
26.60
5
16.l07
26_5
Garfield High
266
83·
20.75
16
4
17.970
. 16
332
473
Garfield Low
· 8 .80
16
16
5
44
4.023
106
141
E. Divide.Low
6
6
4
23.75
95
11. 800
143
116
w. Div.· East High
10
15. 0,0
10
3
45
6.535
150
107
w. Div. East Low
·3
5
28
5
9.33
5.283
47
43
W. Div. West High
9
3
13
4.33
2.762
9
41
w. Div. West Low
39
8
4
44
11.00
8
4.103
88
Hightower High
54
6
185
30.83
19
19
16.425
586
513
Hightower Low
3
3
15
5.00
0.000
3
15
0
D. Hollow High
3
0
0.00
0.000
9
9
0
0
-D. Hollow Low
5
161
53.. 67
27.282
268
5
3
224
w. Mamm High
,7
65'
3
13.00
3
5.674
7
91
w. Mamm·Low
0
0.00
0.000
0
9
9
3
0
Grass Mesa Low
·16.40
52
885
132
2165
809
Totals
90% Conf. Int ..on Population: 1356 to 2974

90% Conf. Int. as percen~ of estimte·: 37.38%

-----------~-------------------------------------------------------------------- --------------------Quad.rat Flight· 2Garfield High
Garfield Low
E. Divide Low
W.·Div. East High
W. Div. East Low
w. Div. West iiigh
W. Div. West Low
Hightower High
Hightower Low
D. Hollow High
D. Hollow Low
w. Mamm High
w. Mamm Low
Grass Mesa Low
Totals

10
16
16
6
10
5
9
8
19
3
9
5
7
9
132

10
16
16
6
10
5
9
8
19
3
9
5
7
9

5
5
5
4
3
3
3

386
121
34
147
53
149

4

56
41

6
3
3
3
3
3
53

90%' Conf. Int. dn Population: 2205 tc;&gt; 4145

11

6

77
87
16
189
1373

77 .20
24.20
6.80
36.75
17.67
4~L67
3.67
14.00
6.83
2.00
25.67
29.00
5.33
63.00
24.05

38.032
7.976
2.627
9.937
8.030
6.786
1.905
7 .9·21
3.608
0.000
20.957
10.973
1.764
39.466

772
387
10_9
221
177
248
33
112
130
6

231
145

37
567
3175

626
210
69
98
132
56
28
104
113
0
310
90
20
584
970

90% Conf. Int. as percent of estimate: 30.56%

....

~

�108

Table 14. Radiocollared elk captured on winter range in GMU 42 during
December 1994 that dispersed out of GMU 42 to a new winter range as of 27
March 1996. Locations (GMUs) determined by aerial telemetry.
Trap
New
Location.Description
Age• Sex GMU
Frequency
Zone
173.621/94
LOWER WEST MUDDY CREEK
C
1+
F
521
173.659/94
MCCLURE PASS HIGHWAY
C
1+
F
521
DEADHORSE CREEK
173.66.9/94
D
1+
F
521
173.679/94
TERROR CREEK
D
1+
F
521
HIGHTOWER MT. BUZZARD CREEK
173. 689/94
E
1+
421
F
173.699/94
E
SMALLEY GULCH
1+
F
421
173.709/94
D
DEADHORSE CREEK
1+
F
521
173.719/94
D
VEGA RESERVOIR
1+
421
F
173.739/94
E
MCCLURE PASS HIGHWAY
1+
F
521
173.750/94
1+
E
LEROUX CREEK
F .52
173.760/94
E
COLLIER CREEK
1+
F
421
173.799/94
F
1+
MORRISANA MESA
F
42 West
173.829/94
PARACHUTE, WALLACE CREEK
F
1+
F
42 West
173.840/94LE
MCCLURE PASS HIGHWAY
1+
F
F
521
173.859/94
D
TERROR CREEK
1+
F
521
173.990/94
C
PAONIA RESERVOIR
1+
M
521
BUCK.MESA SOMMERSET
174.030/94LE
E
1+
M
521
174.039/94
E
HAWXHURST CREEK
1+
M
421
174.049/94
F
VEGA RESERVOIR
1+
M
421
174.069/94
E
HUBBARD CREEK
1+
M
521
174.080/94
E
HAWXHURST CREEK
1+
421
-~
.• M
174.109/94LE
F
1+
GRASSEY GULCH
421
174.129/94
F
1+
LEROUX CREEK
M
52
174.150/9:4
F
1+
PORCUPINE CREEK
F
42 West
174.181/94
B
1+
LOWER EAST MUDDY CREEK
M
521
1

Age of elk in years as of March 1996
b LE= Location elk rout~nely located.

(

(

�107

~

(

\..I

)

(

\-.I

Appendix I. Mortalities of 86 radiocollared elk from 1 ·oeceniJer 1.993 through 14 June 1996. Age is
approximate age in years of elk at death; c=calf 6-12 months old, Y=yearling 12-18 months old. Body weight
measured in December when elk caetured as calves.
Frequency ID/
!;!ate
Trae
Bodi
Site Zone Sex Ase \IT. ,ksl Heard Dead cause- of Death &amp;Code Nunber
Year caetured
Legal harvest rifle season-28
BR
A
172.030/93
5+
10/27/95·
F
Unknown; suspect predation-30
GR
B
2+
06/14/95
172.039/93
F
Unknown-11
A
02/12/96
172.070/93
BR
F
11
Legal harvest rifle season-28
172.080/93
GM
11/05/94
A
F 5+
Wounding loss late rifle season-26
172.090/93
01/16/94
GR
B
F
11
Wounding loss rifle season-25
172.139/93
BC
C
10/19/95
F
17
Legal harvest rifle season-28
cc
2+
10/23/94
172.160/93
C
F
Woun&lt;Hng loss rifle season-25 •
172.181/93
11/03/94
MC
C
F 3
Wounding loss rifle season-25
172.201/93
11/15/94
GS
C
3
F
Disappear rifle season-22
172.207/93
SG
11/30/95
D
F 2+
Legal -harvest archery/muzzle season-27
172.258/93
HY
10/04/94
C
F 2+
Wounding loss archery/muzzle season-24
GS
10/04/94
112.2n193
C
F 3
Legal harvest· rifle season-28
172.290/93
SG
D
10/23/94
F 5+
Legal harvest archery season-33
172.369/93
AC
E
09/18/94
F 2+
Legal- harvest late rifle season-29
172.369/94
FM
2+
01/14/96
B
F
Wounding loss late rifle season-26
AC
E
12/29/94
172.409/93
F
8
Legal ·harvest rifle season-28
FS
172.509/93
10/21/95
H
F 3
Lion predation-3
FS
172.542/93
02/01/94
H
F 6
Legal harvest late rifle season-29
5+
172.549/93
PG
H
11/28/95
F
Wounding loss rifle season-25
PG
172.570/93
11/03/94
F
16
PG·
Legal harvest rifle season-28
172.581/93
2+
10/17/94
F
Legal harvest late rifle season-29
FM
12/08/95
172.581/94
F 2+
Unkncwn-11
2+
172.590/93
PG
04/24/96
F
Accident; birthing/calving-32
172.610/93
10/04/94
PG
F 3
Accident; birthing/calving-32
172.639/93
06/19/96
PG
F 16
Disappear rifle season-22
172.649/93
PG
11/30/94
F 2
Legal harvest late rifle season-29
172.670/93
PG
01/16/95
F ·4
Wounding loss late rifle season-26
172.678/93
PG
12/22/94
F 9
Illegal kill-7
172.690/93
FM
F
8
01/?4/94
Legal harvest rifle season-28
172.699/93
FM
5+
11/05/95
F
y
Disappear rifle season-22
. SR
172.800/~
F
105.0 11/30/94
Lion predation-3
172.899/93
BC
C
C
86.0 03/18/94
F
Legal harvest rifle season-28
GH
172.950/93
D
2
107.0 10/18/95
F
Malnutrition-6
173.000/93
\lM
G
C
102.0 04/25/94
F
Legal harvest rifle season-28
173.041/93
GM
A
M 2
107.0 10/19/95
Legal harvest -late rifle season-29
173.060/93
MH
E
99.0 12/27/95
F 2
Legal harvest rifle season-28
173.120/93
GM
A
99.0 10/14/95
M 2
Illegal kill rifle season-9
173.190/93
BC
C
111.0 10/29/94
M y
Wounding loss rifle season-25
GR
173.201/93
106.0 11/30/95
B
M 2
Legal harvest rifle season-28
173.210/93
GC
B
M 2
108.0 10/19/95
Legal harvest rifle season-28
173.219/93
BC
111.0 11/06/95'
C
M 2
Illegal kill rifle season-9
173.232/93
BR
A
M y
101.0 11/15/94
BC
Unknown-11
173.262/93
C
·108.0 03/18/94
M C
Legal harvest rifle season-28
173~269/93
MC
C
M 2
121.0 11/06/95
•
173.289/93
MC
C
111.0 03/22/94 .Unknown-11
M C
173.300/93
Legal harvest rifle season-28
GS
C
119.0 10/24/95
M 2
Disappear rifle season-22
173.309/93
HY
C
M y
-124.0 11/30/94Illegal kill rifle season-9
173.320/93
HY
C
118.0 10/20/94
M y
1.egal harvest muzzleloading season-34
173.332/93
GH
D
M 2
125.0 09/12/95
SG
Legal harvest rifle season-28
173.351/93
D
.M 2
103.0 11/05/95
Legal harvest archery season-33
173.359/93
AC
E
111.0 09/06/95
M 2
Legal harvest rifle season-28
173.370/93
MH
E
. 141.0 11/08/95
M 2
Disappear rifle season-22
173.390/93
MG
D
113.0 11/30/95
M 2
·Legal harvest rifle season-28
MG
173.402/93
D
2
M
118.0 10/18/95
Wounding loss rifle season-25
173.410/93
WM
G
M 2
90.0 11/02/95
Legal harvest rifle season-28
173.420/93
G
WM
125.0 10/24/95
M 2
_Legal harvest archery season-33
173.429/93
MH
.E
M
2
126.0 09/14/95
173.439/93
PG
H .M 2
o.o 11/30/95 Disappear rifle season-22
Legal harvest rifle season-28
173.450/93
PG
H
M 2
113.0 10/15/95
173.461/93
Malnutrition-6
PG
H
M C
82.0 02/07/94
173.461/94
CM
A
M y
123.0 09/19/95' Wounding loss archery/muzzle season-24
. 173.469/93
FS
H
M
C
n.o 04/25/94 Malnutrition-6
173.479/93
Legal harvest archery ~eason-33
FS
H
M 2
122.0 09/10/95
Legal harvest archery season-33
173.492/93
FS
H
M 2
110.0 09/03/95
Legal harvest archery season-33
FM
173.510/93
B
M 2
91.Q 08/28/95
Legal harvest rifle season-28
173.521/93
FM
B
M 2
124.0 10/17/95
Legal harvest archery season-33
173.549/94
HM
B
F y
106.0 09/07/95
y
Unknown-1l
PR
173.580/94
A
114.0 12/21/95
F

-----------------------------------------------------------. -------. -----------------·----------

�108

~

Appendix I.

Frequency ID/
Year Captured
173.589/94
173.640/94
173.789/94
173.870/94
173.919/94
174.059/94
174.101/94
174.119/94
174.140/94
174.170/94
174.220/95
174.230/95
174.240/95
174.339/95
174.500/95
174.609/95
174.689/95
174.789/95

Continued.
Trae
Date
~
sue Zone Sex Age \IT. Ckg&gt; Heard Dead cause of Death
OG

-B

MC
MR

C

SM

D

BC
MR
MM
MM
MM

C

FM

MS
MS
MO
MO
LB

GB
AP

w

E

E
F
F

f.
B
F

F
E
E
C

B
D
C

F
F
F
F

M
MM
M
M
M
M
M
M

F
F
F
M
M

C
C
C
C

y
y

Y+
C
C
C
C
C
C
C
C
C
C
C

117.0 06/01/95
89.0 03/30/95
100.0 03/20/95
86.0 02/21/95
114.0 11/02/95
126.0 "10/17/95
117.0 05/24/96
.140.0 03/01/95
112.0 03/14/95
140.0 04/25/95
127.0. 04/08/96
120.0 . 04/24/96
115.0 04/17/96
79.0 03/27/96
78.0 04/16/96
120.0 04/15/96
100.0 02/05/96
0.0 05/22/96

Unknown; suspect predation-30
Unknown; suspect predatfon-30
Unknown; suspect malnutrition-31
Lion predation-3
Illegal kill rifle season-9
Illegal kill rifle season-9
Unknown; suspect predation-30
Beer predation-35
Lion predation-3
Lion predation .. 3
Unknown; suspect malnutrition-31
Lion predation-3
Lion predation-3
Unknown predator-5
Unknown; suspect malnutrition-31
Malnutrition-6
Lion predation-3
. Unknown; suspect predat i on-30

(

L

-o-···_1ii_
1
:'
..
:i
\;~:g)'.,

•

�47

Colorado Division of Wildlife
Wildlife Research Report
July 1997
JOB PROGRESS REPORT
State of

Colorado

Project No.

W-153-R-10

Mammals Research

work Plan No. - -&gt;&lt;-- - -- -- - - - -

Elk Investigations

Job No. _ _ _ _.,___ _ _ _ _ _ _ _ _ __

Estimating Survival Rates of Elk
Developing Techniques to Estimate

Population Size
Period Covered:;
Author:

July 1, 1996 - June 30, 1997

D. J. Freddy

Personnel: J. Broderick, G. Byrne, J. Ellenberger, D. Fox, J. Frothingham, V.
Graham, D. Masden, C. Mehaffy, M. Okata, J. Ritchie, P. Will, R. Winn, CDOW;
D. Bowden, G. White, CSU; Diagnostic Laboratory, CSU; N. Miers, D. Ouren,
volunteers; BLM Glenwood Springs, CO, NBS Ft. Collins, CO, USFS Rifle, CO,
Rocky Mountain Elk Foundation, cooperating .

Abstract
We captured and radio-collared 70 calf elk (Cervus elaphus nelsoni) 6-months
old in December 1996 to estimate survival rates during winter 1996-97 and to
increase numbers of radiocollared elk available for experiments utilizing
mark-resight models to estimate population density. Elk were captured using
helicopter net-gunning and portable corral traps. Survival rates(± 95% CI)
for 6-11 month old calves during winter-spring averaged 0.89 ± 0.04 with
yearly rates ranging from 0.86 to 0.92 between 1993-94 and 1996-97. Survival
was similar among years (P &gt; 0.50) and sexes (P &gt; 0 . 50). Primary causes of
death for calves were suspected predation (58%) and suspe cted malnutritio n
(26%) . Survival of adult females(~ 12 months old) during winter-spring
averaged 0.96 ± 0.02 and was similar among years (P &gt; 0 . 60) with yearly rates
ranging from 0 . 94 to 0.98 between 1993-94 and 1996-97 . Hunting was the
primary cause of death (59%) for adult females during winter-spring. Survival
of elk 18-23 -months of age during winter-spring averaged 0.97 ± 0.03 for
males and 0.97 ± 0.04 for females. Annual survival (1 December-30 November )
of adult females averaged 0.81 ± 0 . 06 from 1993-94 through 1995-96 and
survival was simi lar among years (P &gt; 0.50) with hunting accounting for 81% of
the deaths . Survival during summer-fall for adult females averaged 0.90 ±
0.03 with hunting accounting for 95% of the deaths. Survival during summerfall for elk 12-17 -months of age averaged 0.87 ± 0.07 for males and 0.94 ±
0.05 for females with all deaths attributed to hunting . Surviv al during
summer-fall for male elk 24-months old averaged 0.15 ± 0.10 with all deaths
due to hunting. Elk population size in 1997 was 1,854 ± 194 (95% CI) based on
random quadrat sampling and 3,610 ± 641 based on the JHE pooled mark-resight
estimator. These estimates were different (P &lt; 0.05) and continued the
disturbing trend of quadrats estimating only 51-93% of the numbers of elk
estimated by mark-resight estimators. Adjusting quadrat estimates with

�48

sightin g bias formulas did not meaningfully narrow differences observed
between quadrats and mark-resight estimators. Discrepancies in estimators
reflect the possibility that we may be violating major assumptions(s)
underlying either mark-resight or quadrat theory. We believe further field
testing to evaluate potential sources of bias will be necessary to evaluate
these techniques to estimate population size.

✓

�49

JOB PROGRESS REPORT
ESTIMATING SURVIVAL RATES OF ELK AND DEVELOPING TECHNIQUES TO
ESTIMATE POPULATION SIZE

David J. Freddy

P. B, OBJBCTXVB
Estimate survival rates of adult female and calf elk and develop techniques to
estimate population size.

SEGMENT QBJICZXDI
1.

Radio-collar 35 male and 35 female calf elk in December 1996 in GMU-42.

2.

Estimate winter and annual survival rates of calf and previously
radiocollared adult female and male elk from known fates of
radiocollared animals.

3.

Estimate density of elk in a portion of GMU-42 using 4 helicopter flights
involving 2 nonrandom mark-resight flights and 2 flights using a random
quadrat sampling system. Apply sighting bias corrections to adjust
numbers of elk counted on quadrat flights. compare bias adjusted
quadrat estimates with mark-resight estimates based on numbers of marked
elk seen during all 4 flights.

4.

Analyze data and summarize annually in Federal Aid Job Progress reports.

5.

Prepare draft of manuscript on sighting bias models developed from data
collected in 1994 and 1995.

6.

Continue to monitor locations and movements of selected radiocollared elk.

INTRQDUCTXOB
our _objectives are to provide reliable estimates of survival rates for calves
during winter and for adult females and males throughout the year for· the
period 1993-94 through 1996-97. For adults, we are especially interested in
survival rates inclusive ~f hunting mortalities which reflects human-induced
rates of removal and exclusive of hunting mortalities which reflects natural
rates of survival. Additionally, we will develop and test a system for
estimating population size that will incorporate estimates of sighting bias in
conjunction with a random sampling system using search quadrats as sample
units. our winter study area encompasses about 839 lan2 (324 mi2 ) in the
eastern half of Game Management Unit 42 south and east of Rifle, Colorado.
Elk winter range vegetation types include juniper-pinyon woodland (Juniperus
osteosperma-Pinus edulis), oakbrush-mountain shrub (Quercus gambeliiAmelanchier aJ.nirolia), aspen (Populus tremuloides), sagebrush (Artemisia
tridentata), and agricultural fields (Freddy 1993, 1994).

METHODS
Cftpt;ura apd Markip,g
we placed radio collars (172-176MHz) having mortality sensors on 70 6-month
old calves, of which 35 were males and 35 were females. Calves were trapped

�50

from 7-10 Deceml:&gt;er 1996 using helicopter net-gunning. Helicopter capture
~ccurred at 10 remote sites located primarily on public lands. Trapping
effort was allocated among 8 geographic trap zones to assure that radioed elk
were representative of most if not all se~ents of the population (Table·l).
Radio collars were of the same type used in previous years (Freddy 1994).

V

Calves captured by net-gunning were ferried by helicopter to processing points
usually within 1.6 Jan of capture sites. At processing points, body weight,
total body length, hind foot length, and rectal body temperature (F) were
measured and calves were then radio-collared and released. Body measurements
for calves were compared between sexes and years using Proo FREQ and GLM (SAS
1988).

sury,iya1
We monitored life or death status of radioed elk during daily ground surveys
and aerial surveys conducted at.2-4 week intervals from December 1996 through
April 1997 and via aerial surveys at 2-4 week intervals from July to November
1996 and May to June 1997. Life or death status of all calves radioed in
December 1996 (70) was known for the period 7 December 1996 through 14 June
1997 which is the time period over which survival rates for calves, age 6-11
months, are calculated. On 15 June, calves by definition become 12-mon~h old
yearlings. Life or death status of 151 female and male elk previously
collared in December 1993-1995 that had survived to 14 June 1996 was known for
148 of these elk through 15 June 1997.
survival ·rates (S) of radioed elk were calculated using the binomial estimator
with a variance, VAR(S) = S(l-S)/n (White and Garrott 1990). Survival rates
are expressed as the mean estimate± the 95% confidence interval. We used x2
-contingency tests to compare survival rates. We defined 4 major time
intervals for survival analyses: winter-spring was 1 December to 14 June,
summer-fall was 15 June to 30 November, annual was 1 December to 30 November
to coincide with timing of capture and radiocallaring, and yearly, only for
yearling elk aged 12-23 months, was 15 June to subsequent 14 June.

V

Causes of death were estimated from multiple sources of evidence including:
presence or absence of gunshot wounds, presence or absence of bite wounds on
carcass and predator tracks or scat at carcass site, physical positioning of
carcass remains whether buried, covered, scattered, or consolidated, relative
amount of internal fat and marrow fat if present with carcass, and results of
histopathology and marrow fat analyses (Wade and Browns 1982, Halfpenny and
Biesiot 1986). Fat content (percent dry matter) of bone marrow and estimates
of age based on dental cementum were obtained for dead elk by the COlorado
Division of Wildlife Laboratory while histopathology analyses were provided by
the Colorado State University Veterinary Diagnostic Laboratory. Photographs
were taken of nearly all mortalities so that physical evidence could be
reviewed and judged by outside experts (pers. comm. A. Anderson, T. Beck, w.
Andelt).
•
•

Pgpu1at,ion 11t,imates
We continued to evaluate methods to estimate elk population size or density
during winter in that portion of GMU 42 from East Alkali Creek west to Grass
Mesa, south of Rifle, co. In previous years, 951 confidence intervals about
population estimates based on quadrat sampling exceeded± 301 of the estimated
population size. We addressed this problem by refining strata boundaries and

\...,,)

�51

by sampling 100\ of those quadrats in high density strata, effectively
reducing sampling error to 0 in these high density strata.
About 30% of the
quadrats in low density strata were randomonly sampled which was similar to
previous years. With this strategy, we selected 72 quadrats in 15 strata .
representing a 53% sample of the 137 mi 2 (351 Jan2 ) winter range (Table 14).
As in winter 1996, each potential quadrat was ·rated as high or low in expected
density, individual quadrat boundaries remained unchanged from previous years
and were based on topographic features, and quadrats were about 1 mi2 (2.6Jan2 )
in size. We felt this strategy to increase numbers of quadrats flown during 1
flight, instead of flying 2 replicates of a smaller sample of quadrats per
flight as originally planned, would be more cost-effective in addressing
problems of precision.
We counted elk during 3 flights using a Bell-Soley helicopter having a pilot,
observer, and navigator-observer, all of whom could potentially detect elk
during surveys. One flight per day was flown on 10 and 13 February 1997 to
count as many marked and unmarked elk as possible encountered along a
nonrandom route within the 137 mi2 area with flying time limited to about 7.5
hours per flight. On 11 and 12 February, marked and unmarked elk were counted
on quadrats. Two helicopters were used each day and assigned to different
strata to shorten the total time interval over which quadrats were completed.
Total flight time for both helicopters was 29 hours. Pilots were common to
all 3 flights. The primary observer on nonrandom flights did not participate
in quadrat flights. The navigator-observer for the nonrandom flights was 1 of
3 primary observers used on quadrat flights while navigator-observers for
quadrat flights only flew quadrats. On February 11 and 12, fixed-wing flights
were conducted to confirm locations of 223 radiocollared elk to determine
whether these elk were within or outside of the 137 mi2 sample area.
We generated estimates of population size for each individual flight and 3
flights pooled using several mark-resight estimators in program.NOREMARK
(White 1996). We considered estimates based on a11· 3 flights pooled to be our
best estimate of population size and the benchmark against which estunates
based on quadrat sampling would be compared. Estimates of population size
based.on stratified random quadrat sampling were computed using program DEAMAN
(COlo. Div. Wildl. software). We then applied a sighting bias correction
formula to each group of elk counted on each quadrat, resulting in adjus~ed
counts per quadrat, and recalculated populations estimates based on quadrat
sampling. To correct for negative sighting bias, we used a s~ple 2 parameter
formula to correct for the probability of detecting an individual group:
Ycc:orrectedCJrOup size&gt; = l.1619(Log Group Size(countec1&gt;) + 0.0806 (Freddy 1995).

Movements
We continued to locate selected radioed elk at least once per month since
capture to document seasonal movements via telem~try using a Cessna 185.
These elk were originally selected at random from within trap zones ·and
equalized by age class in January 1994. Elk from the original sample that
died were replaced each subsequent January primarily with randomly selected 6
month-old calves of the same sex from the same trap zone(s) as elk that died.
As of 1 January 1997, these 44 elk were classified as 23 adult females, 4
yearling females, 5 female calves, 1 adult male, 5 yearling males, and 6 male
calves. Durlng June 1997, we again located an additional 28 adult females,
that were originally selected at random in 19.95, to document locations during
the calving period. Females from the original sample that died were replaced
each subsequent June with adult females randomly selected from the same trap

�52

zones of elk that died.
movements.

As needed, we located other elk to document unusual

RESULTS ANP pxscussJoR

V

capture
There were no acute deaths of calves during capture. One male calf
(174.619/96) died within 14 days of capture due to the effects of capture
myopathy (histopathology, CSU Diagnostic Lab) and was subsequently censored
from survival analyses ~Table 3).

suryiyal
Between 1 December 1993 and 14 June 1997, 146 radiocollared elk died (Table 2,
Appendix 1). Hunting was apparently involved in 71% of the deaths. For
adults ~12 months old, hunting accounted for 901 of 115 deaths. There were 2
periods of mortality during the year. Adults died primarily from September to
January when hunting seasons occurred (Fig. 1) while calves died primarily
from February to May (Fig. 2).
calves
survival for calves during winter-spring averaged 0.89 ± 0.04 (n = 280) with
yearly rates ranging from 0.86 to 0.92 (Table 3). We failed to detect
differences in survival of calves among years (X23 = 1.5, P &gt;0.50), between
sexes pooled among years (X21 = 0.43, P &gt;0.50), and between sexes within each
yearly cohort (x21 ~ 0.79, P &gt; 0.40) (Tables 3, 5, 6, 7). Sex of dead calves
for all years was 17 male and 14 female (Table 2).

These survival rates were associated with winters considered mild in
temperature. Snow was usually low or moderate in depth except in 1995 when
considerable snow fell during March and April but usually melted rapidly at
lower elevations, and in 1997 when a storm in January delivered at least 40 cm
of snow on lower elevation winter ranges. Rain in January 1997 subsequently
settled this snow to about 25 cm and caused severe crusting of snow. Elk in
some segments of the lower winter range moved in excess of 24 Jan to·areas at
even lower elevations along the Colorado River near Rulison and Parachute, co
soon after this storm occurred. Survival rates of elk, however, remaineq high
and apparently were not greatly affected by this weather event.
Primary causes of death for all calves during winter-spring were malnutrition
(131), suspected malnutrition (13%), mountain lion predation (35%), suspected
predation (23%), and unknown cause (10%) (Tables 2, 4). Timing of deaths
peaked in March and April for both males and females (Fig. 3). Deaths
attributed to predation occurred from January into June and those attributed
to malnutrition occurred from February to May (Fig. 2) but both presumed
causes of mortality peaked in March and April suggesting a functional change
in vulnerability of calves during these months. However, percent fat content
in marrow of calves lost to predation and malnutrition suggested that
malnutrition may not have predisposed calves to predation. Percent fat in
bone marrow of calves suspected of dying from predation was 69 for.males
(range 2-95, n = 10) and 36 f~r females (range 8-63, n = 8) and for calves
dying from suspected malnutrition, 11 for males (range 0.2-41, n = 4) and 18
for females (range 8-31, n = 3) (Table 4). Possibly elk become more sedentary
during March and April to conserve energy reserves and thus more predictable
in behavior allowing predators, especially mountain lions, to hunt calves
efficiently.

V

�53

Calf Body Size

Averaged over all years, male calves had larger body weights, longer total
body length, longer hind leg lengths, and higher condition indexes (PS 0.023)
than female calves (Tables 11, 12). Differences in body size were greatest
for weight, as males (115 kg) were about 81 larger in mass than females (106
kg). Differences between sexes in other body dimensions were &lt;31. This
advantage in mass, however, did not translate into higher rates of survival
for male calves.
Bddy weights were largest for males in 1995 (119 kg), for females in 1996 (110
kg), and for sexes combined in 1995 (113 kg) (Table 12), but we failed to
detect differences in body weights among years (P = 0.15) and there was no
interaction between year and sex (P = 0.34). Increases in weights in 1995
were not unexpected as the locally moist summer was favorable to forage
production on summer ranges.
Weights measured at capture in December for calves suspected of dying from
predation (Table 4) averaged 116 kg for males (range 72-140 kg, n = 9) and 96
kg for females (range 78-120, n = 10). Predators thus appeared to take males
of average and females of smaller than average size (Table 12). Weights of
calves suspected of dying from malnutrition (Table 4) averaged 93 kg for males
(range 77-127, n = 5) and 101 kg for females (range 100-102, n = 3).
Malnutrition thu~ appeared to affect smaller than average sized males and
females (Table 12). Weights of calves dying from all causes aver-aged 108 kg
for males (range 72-140, n = 16) and 97 kg for females (range 78-120, n = 14)
(Table 4), which was about 71 below average weights at capture for both sexes.
Yearlings
Yearly survival for elk 12-23 -months of age was 0.84 ± 0.08 for males (n =
90) and 0.91 ± 0.06 for females (n = 97) when averaged among years with
hunting deaths included (Tables 5, 6, 7). Survival among years for males
ranged from 0.79 to 0.88 and for females from 0.81 to 0.97. We failed to
detect differences in yearly survival rates among years for males (X22 = 0.88,
P &gt; 0.50) but survival was lower (0.81) for females in 1996-97 (X22 = 5.75, P
= 0.06). Yearling males were subjected to about the same rate of illegal
hunting during all years which accounted for most of the male mortality, while
in 1996-97, females had a lower survival rate because 5 of 6 deaths were
hunting related (Tables 5, 6, 7). With hunting deaths included, we failed to
detect differences in survival between sexes within (x\ s 2.25, P &gt; 0.15) and
among years (x\ = 1.71, P &gt; 0.25). Of 23 deaths, 19 (831) were hunting
related. Bunting deaths involved 12 males of which 9 (75%) were classified as
illegal kills (Table 2). •

Yearly survival for elk 12-23 -months of age was 0.97 ± 0.03 for males (n =
79) and 0.98 ± 0.02 for females (n = 91) when averaged among years with
hunting deaths censored (Tables s, 6, 7). Survival among years for males
ranged from 0.96 to 1.00 and for females from 0.97 to 1.00. We failed to
detect differences· in yearly survival rates among years for males (X22 = 1.14,
P &gt; 0.50) and for females (x22 = 1.23, P &gt; 0.50), and between sexes within and
among years· (x\ s 0.007, P &gt; 0.90).
survival during summer-fall for yearling elk 12-17 -months of age was 0.87 ±
0.07 for males (n c 91) and 0.94 ± 0.05 for females (n = 98) when averaged
among years ·and inclusive of hunting deaths, and 1.00 for both males (n = 79)
and females (n = 92) with hunting deaths censored (Tables 5, 6, 7). survival
among years for males ranged from 0.83 to 0.90 and for females from 0.87 to

�54

0.97 inclusive of hunting mortalities. We failed to detect differences in
survival rates among years for both males (X22 = 0.70, P &gt; 0.50) and females
(x22 = 3.63, P &gt; 0.20) inclusive or exclusive of hunting deaths. Survival
rates of females (0.94) were higher than males (0.87) when averaged among
years and inclusive of hunting deaths (x2 1 = 2.73, P = 0.10). There were no
non-hunting deaths during summer-fall for either males or females (Table 2).

V

survival during winter-spring for yearling elk 18-23 -months of age was 0.97 ±
0.03 for males (n = 78) and 0.97 ± 0.0.04 for females (n = 91) when averaged
among years and inclusive of hunting deaths, and 0.97 ± 0.93 for males (n =
78) and 0.98 ± 0.03 for females (n = 90) wi~h hunting deaths·censored (Tables
5, 6, 7). We failed to detect differences in survival rates among years for
both males (X22 = 1.16 P &gt; 0.50) and females (X22 &lt; 2.59, P &gt; 0.30) inclusive
or exclusive of hunting deaths. We also failed to detect differences in
survival rates between sexes within and among years inclusive or exclusive of
hunting deaths (X2 1 &lt; 0.24 P &gt; 0.50). During winter-spring, there were 2 nonhunti~g deaths each for males and females and 1 illegal hunting death for a
female (Table 2).
Yearling spike-antlered males were·generally not legal quarry during hunting
seasons. In 1994, 32 yearling males from the 1993-94 calf cohort entered the
hunting seasons presumably as spike-antlered males and 4 (131) were illegally
taken during rifle seasons. In 1995, 30 yearling males from ~he 1994-95 calf
cohort entered the hunting season and 2 (71) were illegally taken and 1 (31)
was fatally wounded during archery season in an area where the elk was legal
quarry. In 1996, 29 yearling males· from the 1995-96 calf cohort entered the
hunting seasons and 4 (14%) were illegally taken during rifle seasons and 1
(3%) was an assumed wounding loss during rifle seasons because the animal had
a 3 x 3 antler point configuration that may have resembled a legal branchantlered male (Tables 2, 5, 6, 7).
•

V

Adult Females

Survival during winter-spring for all adult females ~12-months of age was 0.96

± 0.02 (n = 409) when averaged among years and inclusive of hunting deaths and
0.98 ± 0.01 (n = 399) with hunting deaths censored. Survival among years
ranged from 0.94 to 0.98 and from o.·97 to 0.99, inclusive and exclusive of
hunting mortalities, respectively. We failed to detect differences in
survival among years inclusive (X23 = 1.93, P &gt;= 0.50) or exclusive (X23 =
2.85, P &gt; 0.60) of hunting mortalities (Table 8). There were 17 winter-spring
deaths, of which 10 (591) involved hunting: 5 were killed and 3 were wounded
during rifle late-seasons and 2 were illegally shot out of hunting seasons
(Table 2)'. Seven natural deaths were attributed to mountain lion predation
(1), suspected predation (2), complic~tions while calving (1), and unknown
cause (3) (Table 2).
survival during summer-fall for all adult females ~12-months of age was 0.90 ±
0.03 (n = 372) when averaged among years and inclusive of hunting deaths and
0.99 ± 0.01 (n = 337) with hunting deaths censored. Survival among years
ranged from 0.87 to 0.94 and from 0.99 to 1.00, inclusive and exclusive of
hunting mortalities, respectively. We failed to detect differences in
survival among years inclusive (X22 = 3.31, P &gt; 0.15) or exclusive (x22 = 1.24,
P &gt; 0.50) of hunting mortalities (Table 8). Hunting was involved in 35 (95%)
of 37 summer-fall deaths: 24 were killed, 8 were wounded, and 3 disappeared
during archery, muzzleloading, and rifle seasons. Natural deaths were
attributed to suspected predation (1) and complications while calving (1)
(Table 2). At the beginning of hunting seasons in fall 1994, 1995, and 1996

V ·

�55

there were 99, 129, and 142 radiocollared adult females (~12-months of age),
respectively, available to hunters (Table 8, non-hunting deaths censored).
Percent of marked elk removed by all types of hunting-related mortalities
averaged 101 annually (range= 6-12).
Annual survival for adult females ~12-months of age marked as a cohort in
December 1993 was 0.81 ± 0.06 (n = 163) when averaged among years and
inclusive of hunting deaths and 0.96 ± 0.04 (n = 138) with hunting deaths
censored. Survival among years ranged from 0.78 to 0.88 and from 0.92 to
0.98, inclusive and exclusive of hunting mortalities, respectively. We failed
to detect differences in survival among years inclusive (X21 = 0.19, P &gt; 0.50)
or exclusive (x21 = 0.15, P &gt; 0.50) of hunting mortalities (Table 9). For
this cohort of adult females, hunting was involved in 25 (81%) of 31 deaths
during all years: 13 were killed, 9 were wounded, and 2 disappeared during
archery, muzzleloading, and rifle seasons and 1 was illegally killed out of
hunting seasons. Natural deaths were attributed to mountain lion predation
(1), suspected predation (1), and complications while calving (2).
Adult Males
Survival during summer-fall for all adult males 24-months of age was 0.15 ±
0.10 (n = 53) when averaged among years and inclusive of hunting deaths and
1.00 (n = 8) with hunting deaths censored. Survival among years ranged from
0.08 to 0.21 inclusive of hunting mortalities. We failed to detect
differences in survival among years (x2 1 = 1.86, P &gt; 0.20) (Table 5, 6). All
deaths were attributed to hunting. At 24-months of age, males are branchantlered and therefore become legal quarry for hunters. Two of 4 males that
lived to be 36-months old survived their second hunting season as legal
quarry.

Survival during winter-spring for adult males &gt;30-months of age was 1.00 (n =
8) during all years (Tables 5, 6). There were no non-hunting deaths of adult
males.
Hunting was the cause of mortality among male elk ~24-months of age. From the
1993-94 cohort of 36 male calves, 28 (78%) lived to become 24-month old
·branch-antlered males and enter the 1995 hunting seasons. Of these 28, 22
(791) were harvested in 1995 inclusive of 2 that disappeared during hunting
seasons and 2 wounding losses (9% of 22). From the 1994-95 cohort of 33 male
calves, 25 lived to 24-months and entered the 1996 hunting seasons. Of these
25, 23 (921) were harvested in 1996 inclusive of 2 that disappeared during
hunting seasons, 1 illegally taken during rifle season, and 1 wounding loss
(41 of 23). Regular rifle seasons accounted for 33 (701) of the hunting
mortalities (Table 2). Most 24-month old males were harvested in the Grand
Mesa DAU or in adjacent GMU 43. Exceptions were 3 males killed in GMUs 63 and
52 about 160 Jan south of where these males were captured as calves in GMU 42.
The differential impact of hunting on survival and recruitment of males and
femal~s to young adult age classes is demonstrated by net survival rates of
calf cohorts. For 1993-94 and 1994-~5 calf cohorts, net survival from 6 to 36
months of age averaged 0.09 for males and 0.80 for females (Tables 5, 6).
Survival Rates and Population Modeling

We incorporated estimates of survival rates, population size, and composition
into a simple spreadsheet model to assess potential for population growth or
decline (Table 13). We used natural survival rates (hunting deaths censored)

�58

for summer-fall and winter-spring time periods for adult males, yearling
males, adult females, yearling females, and calves. Hunting deaths were
incorporated as ha~vest removal rates for each sex/age class. We assumed
survival of calves o-s months of age during summer was 1.0 because the model
uses post-season calf:cow ratios ·(measured in January) as an estimate of net
calf recruitment to the beginning of winter (December). We also assumed that
the recruited sex ratio calves to December is 1:1.
Modeling suggests that if harvest rates of antlered elk remained as measured
and harvest rates of antlerless elk were reduced to 0, the population could
grow at an annual rate of 17%. Current rates of ant~erless harvest allow
annual growth rates of 71. To stabilize population growth, harvest rates on
antlerless age classes must increase nearly two-fold. Obtaining this level of
harvest could be a formidable management challenge.

Pqpulation Estimates

Elk population size in 1997 was 1,854 ± 194 (951 CI) based on quadrat sampling
and 3,610 ± 641 based on the JHE pooled mark-resight estimator (Tables 14, 15,
16). The quadrat sample was lower than the JBE estimate (P s 0.05). We
achieved our primary goal of improving precision of the quadrat estimate to
facilitate detecting differences in quadrat and mark-resight estimators (Table
16).
A disturbing trend has emerged in estimates of population size during the last
3 years. Quadrats provided estimates of size that represented only 51 to 931
of the numbers of elk estimated by pooled mark-resight estimators, excluding
initial and preliminary quaclrat sampling in 1995 when the quadrat estimate was
39% of the mark-resight estimate. Mark-resight estimates have ranged from
3,177-3,924 elk based on pooled or individual flights while quadrat estimates
have ranged from 1,854-3,387 elk (Table 16). The consistent magnitude in
discrepancy among mark-resight and quadrat estimates was demonstrated well in
1997 as the 3, one-sample Lincoln-Peterson mark-resight estimates, whether
based on marked and unmarked elk counted on nonrandom flights or on quadrats,
were 3,289-3,924 elk while the estimate based on stratified quadrat sampling
was 1,854 elk (Table 16). The 3 mark-resight estimates were based on 3
flights that were independent in methodology, strongly suggesting that the
probability of detecting marked elk is consistent among different combinations
of observers and types of flight patterns. A similar trend among estimates
occurred in 1996 (Table 16).
We adjusted quadrat estimates for sighting bias using a simple 2 parameter
sighting bias model. Adjusting for sighting bias increased quadrat estimates
only 7-14% (Table 16). Using more complex sighting models did not
meaningfully narrow the differences observed between quadrat and mark-resight
estimates.
Discrepancies in estimators reflect the real possibility that we may be
violating a major assumption(s) underlying either mark-resight estimators or
quadrat sampling with sighting bias corrections. Three important potential
sources of bias are: 1) detecting and accurately counting groups of elk but
missing marked elk within detected groups would inflate mark-resight
estimates, 2) overestimating numbers of marked elk within the sample area at
the time of flights would inflate mark-resight estimates, and 3) detecting a
lower than expected percentage of elk groups on quadrats would deflate quadrat
estimates. If bias 1) is true, we suggest that behavior of marked elk when
approached by a helicopter would be different than other elk in the same group

V

�57

with the possibility that marked elk either do not move with the group when
the group is initially disturbed or they move away from the group reducing the
chances of observers seeing marks. Another possibility is that some fraction
of the white collars used as marks were not visible due to discoloration but
we tend to discount this possibility because collars that were returned by
hunters or were removed from other recovered mortalities were still white. If
bias 2) is true, accuracy in determining elk locations during specific census
location flights was much poorer than our measured accuracy of ~300 m. We
cannot eliminate this source of bias, but each marked elk was located and the
estimated GPS location verified on maps delineating the sample area. If bias
3) is true, our estimated sightability of elk groups on quadrats which was 82%
and developed during 199 test trials (Freddy 1995) greatly 9verestimates the
true detection rate achieved during manag~ent application of quadrat
sampling, even though observers used during testing and application remained
the same individuals. The magnitude of discrepancy between estimators would
further suggest that we not only missed groups on quadrats, but groups
relatively large in size, even though sightability of groups ~7 in size
exceeded 0.90 (Freddy 1995). We are currently trying to evaluate the most
likely source(s) of bias and then develop procedures to test the appropriate
hypothesis during winter 1997-98.

Elk Movements
In December 19·95, 35 male and 34 female calves were radiocollared and of these
elk, 24 males and 27 females survived to become 18-months old on 1 December
1996 (Table 7). By the end of winter 1996-97, 21 (7M, 14F) or 41% had
dispersed to a winter range outside of the intensive winter range study area
in GMU _42 where these elk were initially captured (Table 17). Rates of
dispersal were 29% for males and 52% for females. Calves trapped in zones E,
F, and G which encompass Alkali, Dry Hollow, and the Mamm creeks, comprised
43% (9)·of the dispersing yearlings and these elk moved priJnarily west to
winter ranges near the towns of Collbran and Parachute-Rulison. Calves
trapped in zones C and D which encompass West Divide Creek, also comprised 43%
of the dispersing juveniles and these elk moved south and southwest to winter
ranges near Paonia Reservoir and Hotchkiss.
We completed initial draft maps (1:100,000 scale) of a GIS land database for
the area frequented by radiocollared elk as part of a cooperative effort
through the National Biological Service, Rocky Mountain Elk Foundation, USFS,
and BLM. Layers of GIS information include topography, based on 1:24,000
scale USGS quadrangles, land ownership, hydrology, transportation,
transportation management zones, winter trapzones for elk, all elk locations,
locations of female elk in June, and locations of all elk mortalities. Maps
will be reviewed for accuracy by cooperating agencies. we will acquire.
vegetation-type coverage for the area and develop a relational database
between elk locations and GIS layers to allow descriptive analyses of areas
frequented by elk.

sighting Bias Draft Manuscript
Discrepancies in estimates of population size based on quadrats, sighting-bias
adjusted quadrats, and mark-resight estimators prompted us to re-evaluate
potential sources of bias in all of these estimators. We therefore, have
delayed drafting and submitting for peer review a manuscript evaluating
sighting bias adjusted estimates of population size.

�58

CQRCLUSJQHS
We obtained acceptably precise estimates of calf and adult survival rates and
recommend monitoring survival of remaining radiocollared adult male and female
elk during the next 2 years. We recommend conducting aerial surveys in 199798 to estimate bias in detecting and counting marked elk on sample quadrats
and mark-resight surveys to complete our evaluation of techniques to estimate
elk density.

LXUMTQRB CJUP
Freddy, D. J. 1993. Estimating survival rates of elk and developing
techniques to estimate population size. Colo. Div. Wildl. Game Res.
Rep. July: 83-117.
•

Freddy, D. J. 1994. Estimating survival rates of elk and developing
techniques to estimate population size. COlo. Div. Wildl. Game Res.
Rep. July: 27-42.
Freddy, D. J. 1995. Estimating survival rates of elk and developing
techniques to estimate population size. Colo. Div. Wildl. Game Res.
Rep. July.
Halfpenny, J. c., and E. A. Biesiot. 1986. A field guide to mammal tracking
in North America. Johnson Books, Boulder, co. 161pp.
SAS Institute Inc. 1988. SAS/STAT User's Guide, 6.03. SAS Institute, Inc.,
Cary, NC. 1028pp.
Wade, D. A., and J. E~ Browns. 1982. Procedures for evaluating predation on
livestock and wildlife. Texas Agric. Expt. Sta. Publ. B-1429. 42pp.
White, G. c. 1996. NOREMARK: Population estimation from mark-resighting
surveys. Wildl. Soc. Bull. 24:50-52.
White, G. c., and R. A. Garrott. 1990. Analysis of wildlife radio-tracking
data·. Academic Press, Inc., San Diego. 383pp.

Prepared by - 1 . . U ~ ~ ~ ~ ~ ~ ~ ~ L - - - - - D
L

V

�(

(

(

Zone

Name

93 24 95 96

umbers of elk rad oco lared i
Decerrber
Ca
Elk Col lac
Corral
HelfcS!Qter
Years
Males
Iota laea£
93 94 5 6 93 94 95 96 Total
93 94 95 96
93-24 95 9

A
B

Garfield
Gibson .
·Uncle Bob
West Divide
Hightower
Middle Manm

8 5 6 8
20 8 12 12
24 13 11 12
26 13 11 10
10 10 10 .10
10 8 9 10
8 8 10 8
44 21 6 0

8 6 4 9
25 17 7 7
29 13 14 14
21 11 18 10
17 17 14 12
0 13 9 4
6 0 5 14
35 6b O 0

8 6 4 9
19 7 4 7
29 13 14 14
21 111810
17 17 14 12
0 13 9 4
6 0 5 14
0 0 0 0

.0 0
6 10
0 0
0 0

0 0
3 0
0 0
0 0
0 0 0 0
0 0 0 0
0 0 o •o·
35 6 0 0

27
56
70
60
60
26
25
41

3 3 1 3
5 5 4 4
10 7 10 7
5 1 8 3
4 9 8 7
0 8 5 2
2 0 1 9
7 0 0 0

3
7
7
5
2
5
0

38

150 86 75 70 141 83 71 70

100 67 68 70

41 16 3 0

365

36 33 37 35 37 36 34 35

Table
Trap

C

o.
E
F

G

H

ap ure

West Manm

Dry Hollow

All

Obfectjves

and 1996 in G
Years
Total
1
8
7
6

3 3
6 3
6 4
8 10
3 ·s 6
0 5 4
3 0 4
9 0 0

6

Adult Females Collared
93 94 95 96 Total

48
50
26
24
16

4
12
12
10
10
0
1
19

0
6
0
2
0
0
0
6

0
0
0
0

283

68 14

0

23

58

0

0
0
0

0
0
0

0
0
0

0
0
0

4
18
12
12
10
0
1
25

82

•Helicopter= Helicopter net·gtmning, Corral= corral-~rapping.
b All 6 adult females captured 2 March 1995

Table 3. Survival rates of 6-11 month old calves with sexes pooled for the winter-spring time period 1
December - 14 June each year i993-94 through 1996-97. Survival rates (S) calculated as a mean estimate of
(alive)/(alive + dead) and variance S(l-S)/n collars.
Elk Age and Time Period (dates)
Calves
Calves
Calves
Calves
Calves
12/01/9312/01/9•12/01/95All Years
12/01/96•06/14/94
06/14/95
06/14/96
Pooled
06/14/97
Survival
L 951 CI
U 951 CI
n collars
Censored'
Died
Nonhunting
Bunting

0.92
0.85
0.98
73
0
,6

6
0

0.90
0.83
0.97
69b
0
7
7
0

0.88
0.81
0.96
69
2c
8
8

0

• Censored denotes collar failure and/or animal life/death status not known.
' Includes (173.949/94) male whose collar failed 12194 but seen alive 1195, 1196.
c Censored elk were (174.619195) male for slipped collar and (174.800195) male for trap-related mortality.
• Censored elk was (174.619196)male for trap-related mortality.

0.86
0.77
0.94
69
ld

10
10
0

0.89
0.85
0.93
280
3c,d
31
31
0

�60

Table 2. Causes of deaths in radiocollared elk between 1 December 1993 and 14
June 1997. Calves (M=male, F=female) were 6-11 months old and collared at 6
months of age. Yearling males and·females were 12-17 months old and juvenile
males and females were 18-23 months old and all were collared as 6-month old
calves. Adult-males and females were&gt; 24-months old at time of death.
Elk AgeLSex Class at Death
cause of Death
Calves
Yearling
Juvenile
Adult
Total
and -Code
M F
F
M
F
M
F
All
M
F
M
Natural Causes
Malnutrit;i.on-6
2 2
0
2
2
4
0
0
0
0
0
Unknown-Suspect
3
Malnutrition-31
4
0
0
1
3 1
0
0
0
0
7
7
12
5
Predation-Lion-3
4
0
1
0
0
0
0
Predation-Bear-JS
1 0
1
0
0
0
1
0
0
0
0
0
Unknown Predator-5
0
0 1
0
0
1
1
0
0
0
Unknown-suspect
Predation-30
2
11
2
5
3
8
0
1
1
0
0
Accident-Birthing-32 0 0
2
0
2
0
2
0
0
0
0
Accident-Fell-10
0 0
·J
1
0
0
1
0
1
0
0
2
2
Unknown Cause-11
2 1
0
0
6
0
1
0
Subtotals
17 14
42
.Q.
Q
.Q.
1· ll 23
a a

•

Legal Bunting
Archery-33
Muzzleloading-34
Archery/Muzzle-27
Rifle-First-28
Rifle-Second-28
Rifle-Third-28
Rifle-Late-29
Subtotals

0
0
0
0
0
0
.Q.

0

0

.Q.

.Q.

0
.i

Wounding Loss
Archery/Muzzle-24
Rifle-Regular-25
Rifle-Late-26
Subtotals

0
0
0
Q

0
0
0
.Q.

1
1

1
0

:Illegal Bunting
Rifle-Regular-9
OUt-of-Season-7
Subtotals

0 0
o· 0
Q .Q. •

0
0
.Q.

Presumed Bunting
Disappear-Rifle
Seasons-22
Disappear-Archery/
Muzzle-21
Subtotals
Totals

0

0
0
0
0
0
0

0
0
0
0

0
0

2
2
0
0
0
0

0
0
0

0
0
0

0

8

0

4

0
0
0
0

0
13
7
7

0

0

6

.Q.

39

25

0

0
0
0
Q

1
2

1

0

3

1.

9•

.2

0
0
.Q.

0
0
.Q.

0
1
1.

0

lb

lb

0

0
.Q.

.o

0

1.

1.

·17' 14

12

6

0

7
4

0

a

0

4

.Q.

0
0
.Q.

0

2
1
1

6

8

4

4

3
1

0

12
7

1
17
14
11
6

13
7
7
0
39

29

il

2
3

2
6

4

4

7
4
6

9
3
16

.J. 10

0
3
.2 ll

1

0

10

0

-0

0
10

2

1.

1
1.

a

0

3b

2b

4

3

0
.Q.

0
.Q.

0

a

1
.2

0

1

!.

.J.

§..

2

3

47

45

78

68

146

1

10
2

12

7

• These elk were illegally shot as spike-andeml yearling males: (173.190/93), (173.232/93),(173.320/93), (173.919/94), (174.0S9/94)
(174.140/95), (174.200/95), (174.679/9S), (174.719/95).
• These elk clisappearcd during rifle hunting seasons and arc presumably dead and legally harvested: (171.207/93), (172.649193),
(171.8()()/93), (173.309/93), (173.390/93), (173.439/93), (174.001/94), (174.181194). One exception may be yearling male (173.309/93)
that disappeared during die first rifle season in 199:4 when spikc-antleml bplls were not legal. •

V

�(

(

(

Table 4. Estimated causes of mortality and associated body condition for 31 radiocollared calf elk 6-11
months old 1 December 199 - 14 June 1
Marrow
Frequency ID/
Trap
Age•
Date Dead
t Fat
Cause of Death &amp; Code No.
Year Captured
Zone
Sex (months)
28. soa
86.0
03/18/94
Lion Predation-3
172.899/93
C
F
9
8. 03c
102.0
04/25/94
Malnutrition-6
173.000/93
G
F
10
28. 88d
108.0
03/18/94
Unknown-11
173.262/93
C
M
9
111.0
03/22/94
Unknown-11
173.289/93
C
M
• 9
N/A1
0.21c
82.0
02/07/94
Malnutrition-6
173.461/93
H
M
8
0.27c
77 .-0
04/25/94
Malnutri'tion-6
173.469/93
H
M
10
51.71c
1_17. 0
06/01/95
Unknown; suspect predation-30
173.S89/94
B
F
12
89.0
17~.640/94
C.
F
9
03/30/95
Unknown; suspect predation-30
N/A'
14. 71c
100.0
03/20/95
Unknown; suspect malnutrition-31
173.789/94
E
F
9
86.0
02/21/95
Lion Predation-3
173.870/94
D
F
8
N/A'
94. 97c
140.0
Bear Predation-35
03/01/95
174.119/94
F
M
9
64. 44c
.112.0
03/14/95
Lion Predation-3
174.140/94
F
M
9
76. 05c:
140.0
04/25/95
Lion Predation-3
174.170/94
B
M
10
41. osc
127.0
04/08/96
unknown; suspect malnutrition-31
174.220/95
F
M
10
2 .47c
120.0
04/24/96
Lion Predation-3
174.230/95
F
M
10
86. 2ac
115.0
04/17/96
Lion Predation-3
174.240/95
E
M
10
62. 97c
79.0
03/27/96
unknown Predator-5
174.339/95
E
F
9
34. 56c:
78.0
04/16/96
unknown; suspect predation-JO
174.500/95
C
F
10
10. 29c
120.0
04/15/96
unknown; suspect predation-30
174.609/95
B
F
10
91. goc
100.0
02/05/96
Lion. Predation-3
174.689/95
D
M
8
05/22/96
unknown; suspect predation-30
75. 32°
174.789/95
C
M
11
79. 99c
72.0
01/08/97
Lion Predation-3
173.370/96
E
M
7
69. 36c
116.0
02/19/97
173.381/96
E
M
8
unknown; suspect predation-30
30. soc
173.640/96.
A
F
9
102.0
03/16/97
Malnutrition-6
8 .age
89.5
174.520/96
A
F
10
04/25/97
Lion Predation-3
103.0
174.689/96
G
M
11
None1
05/14/97
Urµcnown; suspect malnutrition-31
51. 99c
04/09/97"
125.0
174.800/96
E
M
10
Lion Predation-3
83. 94c
105.5
174.910/96
D
F
8
02/27/97
unknown; suspect predation-JO
91.5
175.059/96
C
F
8
02/13/97
N/A1 •
Unknown-11
8.03c
111.0
175.130/96
A
F
9
03/24/97
Lion·Predation-3
77. 5.
l. 99c
175.170/96
D
M
9
03/26/97
unknown; suspect malnutrition-31
• Approximate age at death assuming 15 June birthdate.
• Whole body weight at capture in December of 1993, 1994, 1995, or 1996.
c Pat content as percent dly matter· of bone manow from either femur of carcass.
• Pat content as percent dly matter of bone marrow from either mandtl&gt;le of carcass.
• Pat content as peicent dly matter of bone marrow from either humerus of carcass.
' No suitable bones remaining with carcass.
• No marrow observ~ in one long bone remaining with carcass.

�Table 5. Survival rates for winter-spring and summer-fall time periods from 1 December 1993-14 June 1997·
for the cohort of 6-morith old calves radiocollared in December 1993. Survival rates for male and female
calves pooled when 6-11 months old were 0.92 (95% CI 0.86-0.98, n=73). Survival rates (S) calculated as a
mean estimate of Calive)/Calive + dead) and variance SCl-S)/n collars.
Elk Age (months) and Time Period (dates)
18 - 23
24 - 29
30 - 35
36 - 41
42 - 47
6 - 47
12 - 17
6 - 11
12/01/96._
12/01/9406/15/9512/01/9506/15/9612/01/9306/15/9412/01/9306/14/95
11/30/95
06/14/96
11/30/96
06/14/97
11/30/94
06/14/97
06/14/94
MALES

Survival
L 951 CI
U 951 CI
n collars
Censored•
. Died
Nonhunting
Hunting

0.89
Q.78
0.99
36

0.88
0.76
0.99
32

1.00

0.21
0.06
0.37

1.00
0.00
0.00

1.00

28

4

4

0
4
4

0

0

29c
0

0.50
0.00
1.00

2c

0

2'
0

4b

0

0

2

0

32

0
4

0

22d
0

0

0

0

·4

0

22

0

2

0

28

0.97
0.92
1.00
35

1.00

0.97
0.91
1.00

0.84
0.71
0.97

1.00

34

0~97
0.91
1.00
34

33

32

27

0.73
0.58
0.88
37

0
1'

0

0

0

0

0

0

0

1

l
0
l

5

0

·10

0

0
0

2
8

0

FEMALES

Survival
L 951 CI
U 951 CI
n collars
Censored•
Died
Nonhuriting
·Hunting

0.95
0.87

1.00

37
0
2
2
0

0
1

0

0

0

1

• Censored denotes collar failure and/or animal life/death status not known.
11 Collar (173.309/93) •disappeatecr during Fall 1994 hunting seasons and assumed dead.
c Includes collar (173.241/93) that failed in August 1995 but bull seen alive January 1996.
• Two collars (173.390/93), (173.439/93) "disappeared" during Fall 1995 hunting seasons and assumed dead.
• Two collars censoml: (173.241/93) failed, (173.381/93) slipped off 12/01/95.
' Collar (172.800/93) •disappeared" during Fall 1994 hunting seasons and assumed dead.
• Includes (173.340193) alive 5/17/'Tl.

C

C

5

0.06
0.00
0.14
34
2c

�(

(

(

Table 6. Survival·rates for winter-spring and summer-fall time periods from 1 December 1994-14 June .1997
for the cohort of 6-month old cal v.es radiocollared 'in December 1994. Survival rates for male and female
calves·pooled when 6-11 months old were 0.90 (95% CI 0.83-0.97, na69). Survival rates (S) calculated as a
mean estimate of {alive)/{alive + dead) and variance S(l-S)/n collars.
.
Elk Age (months) and Time Period (dates)
12 - 17
18 - 23
24 - 29
30 - 35
6 - 35
6 - 11
06/15/9512/01/9506/15/9612/01/9612/01/9412/01/9406/14/96
11/30/96
06/14/97
06/14/97
11/30/95
06/14/95
MALES

Survival

0.91

L 951 CI

0.81

U 951 CI
n collars
Censored•
Died
Nonhunting
Bunting

1.00
33b
0

3
3

0

0.90
0.79
1.00
30b

0
3
0
3

FEMALES

Survival
L 951 CI.
U 95' CI
n collars
Censored•
Died
• Nonhunting
Bunting

0.89

0.78
0.99
36
0
4

4
0

0.97
0.91
1.00
32
0
1
0
1

0.96
0.88

1.00
26
1c
1
1

0
0.97
0.90
1.00
30
ld

1
l·

0 .

0.08
0.00
0.19
25
0
23
0
23

·1.00

0.93
0.83
1.00
29
0
2
0
2

0.96

• Censored denotes collar failure and/or animal life/death status not known.
~ Includes collar (173.949/94) that failed in December 1994 but male seen alive in January 1996
• Censored elk was (173.949/94)failure. which was killed in first rifle season 1996.
• Censored elk was (173.719/94) slipped collar.
• Includes (174.030/94)alive 6/4/97.

2e

0
0
0
0

0.89

1.00
27
0
1
0
1

0.06
0.00
0.15
32

1c

3Q
4
26
0.74
0.59
0.89
35

ld

9
5
4

�Table 7. Survival rates for winter-spring and summer-fall time periods from l December 1995-14 June 1997
for the cohort of 6-month old calves radiocollared in December 1995 and survival rates for winter-spring for
6-11 month old elk calves radiocollared in December 1996. Survival rates for male and female calves pooled
when 6-11 months old were 0.88 in 1995 (95% CI 0.81-0.96, n=69) and 0.86 in 1996 (95% CI 0.77-0.94, n=69).
Survival rates (Sl calculated as a mean estimate of (alive)/(alive+dead) and variance of S{l-S)/n collars.
Elk Age {months) and Time Period (dates)
•
·1995 Calf Cohort
1996 Calf Cohort
6·;_ 11
6 - 23
18 - 23
12 - 17
6 - 11
12/01/9612/0l/9506/15/9612/0l/9512/0l/9606/14/97
06/14/97
11/30/96
06/14/96
06/14/97
MALES

Survival
L 951 CI
U 951 CI
n collars
Censored•
Died
Nonhunting
Bunting

0.86

0.74
0.99·
35

2b.

5
5
0

FEMALES

Survival
L 951 CI
U 951 CI
n collars
Censored•
Died
Nonhunting
Hunting

0.91
0.81
1.00
34
0
3
3
0

0.83
·o.68
0.97
29
1c
5
0
5

0.96
0.87
1.00
24
0
l
1

0.68
0.51
0.84
34
3b,c
11
6

0

5
5

5

0

0.87
0.75
0.99
31
0

0.93
0.82
1.00
27
0

0.86
0.98
0.74
35
0

4

0

2
1

4

l

0.74
0.58
0.89
34
0
9
4
5

0.85
0.73
0.98
34
ld

5

5

0

• Censored denotes collar failure and/or animal life/death stablS not known.
• Censored elk were (174.619/95) slipped collar, (174.800/95) capture mortality.
• Censored elk was (174.660195) slipped collar July 1997.
• Censored elk was (174.619196) male trap-related mortality.

C

C

C

�(

(

(

Table 8. Survival rates for winter-spring and sununer-fall. time periods from 1 December 1993 - 14 June 1997

for all radiocollared adult female elk ~12-months old. Survival rates .(S) calculated as a mean estimate of
(alive)/(alive + dead} and variance S(l-S)/n collars.
Elk Age and Time Period (dates)
Adult
Adult
Adult
Adult
Adult
Adult
Adult
06/15/9412/01/9406/15/9512/01/9506/15/9612/01/9612/01/9311/30/94
11/30/95
06/14/95
11/30/96
06/14/97
06/14/9~
~6/14/94

Survival
L 951 CI
U 951 CI
n collars
censored•
Died
Nqnhunting
Hunting

0.96

0.91
1.00
68be
0
3
1
2

0.87
0.80
0.94

0.96
0.92
1.00

lOObf .

95b1

0
13c
1
12

0
4
1
3

0.94
0.90
0.98
129bh
0
9d

0
8

• Censored denotes collar fa11ure and/or animal life/death stams unknown.
c Collars (172:800/93,172.649/93)"disappemc:r Fall 1994 hunting seasons,assumeddead.
• Composition is 6 females 18+ and 62 females 30+ months old.
• Composed of 34-18+, and 61-30+ months old females.
1 aomposed of 30-18+ ·and 89-30+ months old females.
k Composed of 31-12+. 29-24+, and 83-36+ months old females.

0.94
0.90
0.98
1191 •
2J
7
4
3

0.89
.0.84
0.94
1431t
0
'16
1
15

0.98
0.95
1.00
1271
0
3
1
2

11
Includes collar (172.011/93) that failed 4/1994 but seen alive in 1/1996
• Collar (172.207/93) "disappeared" Fall 1995 hunting seasons, assumed dead.
' Composed of 35-12+, 6-24+, and 59-36+ months old females.
h Composed of 32-12+, 34-24+, and 63-36+ months old females.
J Censored (172.011/93) failwe and (173.719/94) slipped collar.
1
Composedof27-18+ and 100-30+ month old females.

Table 9 . . survival rates for winter-spring and sumroer-fail time periods from 1 December 1993 - 14 June 1997
for the group of adult female elk that were ~12-months old when radiocollared in December 1993. survival
rates (S) calculated as a mean estimate of Calive)/(alive + dead) and variance S(l-S)/n collars.
Elk Age and Time Period (dates)
Adult
Adult
Adult
• Adult
Adult
Adult
Adult
12/01/93- 06/15/94- 12/01/94- 06/15/95- 12/01/95- 06/15/96- 12/01/9606/14/94
11/30/94
06/14/95
11/30/95
06/14/96
11/30/96
06/14/97
0.82
0.96
0.93
0.88
0.93
0~92
Survival
1.00
0.72
0.91
0.85
0.78
0.85
0.84
L 951 CI
0.91
1.00
0.99
0.97
1.00
1.00
U 951 CI
68be
65bf
53b f
49b f
42f
39 1
36r
n collars
0
0
1i
0
Censored•
0
0
0
4
6d
3
3
3
Died
0
Nonhunting
1
1
0
3
0
0
2
Bunting
3
6
0
3
0
• Censored denotes collar failure and/or animal life/death status unknown
• Collar (172.649/93) "disappeared" Fall 1994 hunting seasons, assumed dead.
• . Composed of 6-18+ and 62-30+ month old females.
1 . Censored (172.011/93) failure of unknown status spring 1996.

11

Includes collar (172.0ll/93)failed 411994 but seen alive 1/1996.
• Collar (172.207/93) •disappeared" Fall 1995 hunting seasons, assumed dead.
r Composed of 100% females 24+ months old.

ffl

�Table 10. Annual ·survival rates from 1 December 1993-30 November 1996 for the group of adult female elk
that were ~12-months old when radiocollared in December 1993. Survival rates (S) calculated as a mean
estimate of (al~ve)/(alive+dead) and variance S(l-S)/n collars.

Adult
Survival
L 951 CI
U 951 CI
n collars
Censored•
Died·

Nonhunting
Bunting

Elk Age and.Time Period (dates)
Adult
Adult

Adult

12/01/93~11/30/94
0.78
0.68
0.88

12/0i/94-11/30/95
0.84
0.75
0.93

12/01/95-11/30/96
0.86.
0.75
0.97

12/01/93-06/14/97
0.54
0.42
0.66

. 68b,f

53b,f

42f
19·

67f
19

6
3

31

3

25

0
15c

0

·2

1.
9

iOd

13

• Censored denotes collar failure and/or animal Jif~d~th etatua unknown.
• Collar (172.649/9~) "disappeared" Fall 1994 bunting seasons, assumed dead.
• Compoeed of 6-18+ and 62-30+ month old females.
•
1 Censored (172.011/93) failure 4/1996.

6

b Includes collar (172.011/98) failed 4/1994 but seen alive 1/1996.

Collar (172.207/93) "disappeared" Fall 1995 bunting seasons, assumed dead.
' Composed of 100% females 24+ months old.

d

Table 13. Data matrix for simple population model using spreadsheet software. We used a post-hunt
(December) population composition of 50 calves:100 females (age 2 12-months) and 4 adult males:16 yearling:
100 females and an estimated population of 3,600 e~k. Annual population growth rate is about 7% when using
this matrix
Fall.Hunting
Survival Rate
Survival Rate
Harvest Rate •
Elk Sex/Age Class
Winter-Spring
summer-Fall
Elk Sex/Age Class·
Adult Males
0.82
1.00
1.00
Adult Males
Age 230 months
Age 24-29 months
Yearling Males
Age 12-17 months

:t.00

0.13

Yearling Males
Age 1·8-23 months

0.97

Adult Females
Age 224 months

0.99

0.10

Adult Females
Age ~30 months

0.98

Yearling Females
Age 12-17 months

1.00

0.06

Yearling Females
Age 18-2·3 months

0.97

Calves
Age o-s months

1.00

o. 02

.Calves
Age 6-11 months

0.89

1

~stimated from harvest surveys.

(

C

(

�(

(

(

Table 11. Frequency distribution of whole body weights for male and female elk calves trapped in Game
Management unit 42. December. 1993~1996. Percentage per weight class shown in parentheses.
Body Weight Class (kg)
•
Year sex
60-69
70-79
80-89
90-99 100-109
110-119
120-129
130-139
140-149
Total
1993
1994
1995
1996
ALL

1993
1994
1995
1996
ALL

M
M
M
M
M

F
F
F
F
·F

0 (0. 0)
0 (0. 0)

• 0(0.0)
0(0.0)
0(0.0)
0(0.0)
0(0.0)
1 (3 .1)

0(0.0)
1(0.7)

1 (2. 9)

1(3.0)
0(0.0)
3(8.6)
5(3.6)
1(2.9)
2(5.7)
2(6~3)
0(0.0)
5(3.7)

1( 2~9)
1( 3.0)

3( 8.6)
2( 6.0)

6(17.1)
6(18.2)

0 ( 0. 0)

4 ( 11. 4)

3 ( 8. 6)

0( 0.0) 3( 8.6) 6(17.1)
2( 1.4) 12( 8.7) 21(15.2)

12(34.3)
13(39.4)
8(22.9)
5(14.3)
38(27.50

4(11.4) 8(22.9)
4(11.4) 7120.0)
1( 3.1) 3( 9.4)
l(' 2.9)
6(17.6)
10( 7.4) 24(17.6)

4(11.4)
10(28.6)
5(15.6)
10(29.4)
29(21.3)

12(34.3)
10(28.6)
14(43.8)
8(23.5)
44(32.4)

10(28.6)
6(18.2)
9(25.7)
13(37.1)
38 (27 -:5)

4 (2. 9)

35(100)
33(100)
35(100)
35(100)
138(100)

0(0.0)
0(0.0)
0(0.0)
0(0.0)
0(0.0)

35(100)
35(iOO)
32(100)
34 (100)
136(100)

1 ( 2. 9)

1(2.9)

2c

2 (6. 0)
1 (2. 9)

6·.o&gt;

10(28.6)
5(14.3)
18 ('13. 0)

6(17~1)

0 ( 0. 0)

2 ( 5. 7)
6 (18 .·8)

0( 0.0)

8(23.5)
22(16.1)

1 ( 2. 9)
1 ( 0. 7)

0 ( 0. 0)

0(0.0)

Body measurements for elk calves trapped in Game Management Unit 42. December. 1993-1996.
Male Calves
Female Calves
Mean
SD
Min
Max
n
Mean
SD
Min
Max
n
Measurement
112.7 13.7
77.0 141.0 35
103.8 12.2
76.0 123.0 35
Body Weight (kg)
·191.2 10.2
164.0 210.0 36
188.9
9.8
167.0 207.0 35
Body Length. (cm)
2.2
52.0
61.0 36
54.8
2.1
51.0
59.0 34
Hindfoot Length (cm) 56.3
0.59 0.05
0.43
0.67 35
0.55 0.05
0.46
0.64· 34
Condition Ind~r

Table 12.
Year
1993

113.5
Body Weight (kg)
Body Length (cm)
190.3
Hindfoot Length (cm) 56.9
0.59
Condition Index

14.2
9.2
1.8
0.05

71.0
168.0
50.0
0.42

140.0
204.0
59.0
0.69

33
32
32
32

103.0
186.3
55.1
0.55

13.3
2.1
0.06

70.0 128.0
166.0' 207.0
50.0
59.0
0.42
0.65

1995

Body Weight (kg)
119.l
194.0
Body Length (cm)
Hindfoot Length (cm) 57.4
0.61
Condition Index

13.6
9.3
2.2
0.05

92.0
166.0
53.0
0.50

141.0
206.0
61.0
0~71

35
36
36
34

105.7
189.4
54 ..9
0.56

15.2
11.4
2.3
0.06

60.0
158.0
47.0
0.38

129.0 • 32
203.0 34
59.0 34
0.66 32

1996

114.3
Body Weight (kg)
Body Length (cm)
187.6
Hindfoot Length (cm) 57.7
0.61
Condition Index

17.1

11.5
2.3
0.07

72.0
160.0
52.0
0.44

136.0
202.5
60.5
0.70

35
35
34
35

109.5
187.4
56.8
0.58

12.4
9.0
2.4
0.05

81.5
170.5
52.5
0.47

136.0
210.0
62.0
0.69

'114.9
Al.1- Body Weight {kg)
190.8
Years Body Length (cm)
Hindfoot Length (cm) 57.1
0.60
Condition Index

14.8
10.3·
2.2
0.06

71.0
160.0
50.0
0.42-

141.0 1·38
210.0 139
61.0 138
0.71 136

105.5
188.0
55.4
0.56

13.4
9.8·
2.3
0.06

60.0
158.0
47.0
0.38

136.0-136
210.0 140
62.0 138
0.69 135

1994

• Condition index= (Weight/body length).

8.8

35
36
36
35

34
35
34
34

�20
Table 14.
Colorado.

Counts of elk on quadrats 11 and 12 February, 1997 in GMO 42 south of Rifle .and Newcastle,
Strata
Size (mi2&gt;

Strata

Totals

10
17
16
6
11

10
17
16
6
11

Garfie;Ld High
Garfield Low
B. Divide Low
w. Div. Bast High·
w. Div. Bast Low
W. Div. West High
W. Div. West Low
Hightower Low
Upper Alkali Ck. High
Upper Alkali Ck. Low
Low.Alkali Ck. Low
Upper DryHollow Low
Lower Mamm Ck. Low
W.Mamm-Grass Mesa Low
W.Mamm-Grass Mesa High

Qyadrats
N
n

5

5

9
9
4
5
10
10
13

9
9
4
5
10
10
13

10
8
3
6
4
4
3
3
4
3
5

Elk
Counted
191
54
8
205
49
89

27
0
88
48
85

ElklQJaadrat
Mean
StdErr.

Po:gulation Size
Total+ 90% CI

19.10
6.75
2.67
34.17
12.25
22.25
9.00
0.00
22.00
16.00
17.00

191
115
43
205
135
111
81
0

4

. '58

86

14

17.20
4.67

244

34.86

1246

13.54

5

5

7

7

5
3
7

137

137

72

14.50

0.000
1.859
2.404

0.000
3.573
2.991
2.449

0.000
0.000
5.514
4 .• 738
3.309
2.423
1.520
0.000

0
52
63
0
65
25
36
0

88

0

80
170

45
78
54
52

145
224

23
244

13
0

1854

164

Table 15. Summary of helicopter flights used to estimate· elk population size and density on 137 mi2 of
winter range in GMO 42 south of Rifle and Newcastle, Colorado, during February. 1997.
Proportion
~arked
Total Elk
Marked Elk
Marked Elk
Elk
Proportion
Flight
Available• Counted
Counted
Counted
Hours
Counted
Dates
Marked
Type
NonRandoml 2/10
Quadrats
2/11-12
NonRandom2 2/13

7.5
29.0
7.8

120
120
120

31
43
33

29
40
29

0.2583
0.3583
0.2750

838
1203
1069

869
1246

1102

0.0357
0.0345
0.0299

~umber of marked elk within the 132 mi2 sample area.
"Number of marked elk individually identified during flights based on number/symbol identifier seen on
collar.

(

C

�(

(

Table 1.6 .• Summary of flights to estimate .elk population size from 1994-1997 in GMU 42 south of Rifle and
Newcastle 1 ColoradQ.
Area (mi2)
Minimum Elk
95% C. I.
Population
Approximate
Method
Flownllirs•
%Precision
CountedLFlight
Estimate
95% Conf. Int.
Estimator
Flight Date
Feb. 1997
Feb. 1997
Feb. 1997
Feb. 1997
Feb .. 1997
'All 1997

Quadrats-StRSb
Quadrats~stRS~sBAc
Quadrats-StRS-LPd
NonRandom Flight,REPl-LP
NonRandom Flight,REP2-LP
3 Flights Pooled-JHEC

137/29.0
137/29.0
137/29.0
137/ 7.5
137/ 7.8
137/44.3

1246
1246
1246
869
1102
1246

1.854
2105
3428
3289
3924
3610

1660-2048
1851-2359
2643-4213
2344-4233
2839-5010
3116-4251

11
12
23
-29
28
18

Jan. 1996
Jan. 1996
Jan. 1996
Mar. 1996
Mar. 1996
Mar. 1996
Jan. 1996
Mar. 1996
All 1996
All 1996

Quadrats,REPl-StRS
Quadrats,REPl-StRS-SBA
Quadrats,REPl.-StRS-LP
Quadrats,REP2-StRS
Quadrats,RBP2-StRS-SBA
Quadrats,REP2-StRS-LP
NonRandom Flight,REPl.-LP
NonRandom Flight,REP2-LP
4 Flights Pooled-JHE
4 Flights Pooled-IEJHEe

132/19.6
132/19.6
132/19.6
132/19.l
132/1"9 .1
132/19.l
132/ 8.5
132/ 8.0
13·2/55. 2
132/55.2

885
885
885
1373
1373
1373
1354
1998
1998
1998

2165
2336
3463
3175
3387
3791
3177
3405
3472
3415

1265-3065
1294-3378
2477-4448
2098-4252
2189-4585
2975-4607
2560-3795
2941-3869
3168-3840
3129-3807.

42
45
28
34
35

Feb. 1995
Feb. 1995
Feb. _1995

Quadrats-StRS
Quadrats-StRS-SBA
Quadrats-StRS-LP

177/17.5
177/17.5
177 /11. 5

361
36.l
361

1484
169_8
3774

787-2181
928-2468
1993·-5555

8Hours of helicopter time per flight.
'Stratified random ·sampte of quadrats with counts of elk not adjusted for sighting bias.
•Stratified random sample of quadrats with counts of elk adjusted for sighting bias.
'One sample Lincoln-Peterson mark-resight estimator.
•Joint Hypergeometric mark-resight estimator for nonrandom and quadrat(unadjusted)flights pooled.
.
'Immigration/Emigration Joint Hypergeometric mark-resight estimator that allows for movement of elk on/off intensive study area.

22

19
14
11
12
47
45
47

�70

Table 17. Radiocollared elk captured as calves on winter range in GMO 42
during December 1995. that dispersed out of GMO 42 to a new winter range as of
Locations {GMOs} determined b~ aerial telemetry.
March 1~97.
Trap
New
Fregyency
Age• Sex GMO
Zone
Location Descri~tion
173.899/95
F
21
F
42 West
Battlement Creek
F
173.909/95LE
21
F
421
Hawxhurst Creek
174.301/95
E
21
F
Porucpine Creek
42 West
174-. 360/95
E
21
F
Wallace Creek
42 West
174.370/95
E
21
F
521
Drift Creek
F
174.391/95
D
21
Paonia Reservoir
521
174.431/95LE
D
21
F
Buck Mesa
521
174.451/95
D
21
F
Thompson _Creek
43
174.491/95
C
21
F
Holms Mesa
42 West
B
174.532/95
21
F
Thompson Creek
43
174.551/95
G
21
F
Porcupine Creek
42 West
174.580/95
G
21
F
.Porcupine Creek
42 West
174.589/95LE
G
21
421
Hawxhurst Creek
F
A
174.600/95
21
F
42 West
Holms Mesa
174.119/95
B
21
M 42 West
Holms Mesa
E
174.629/95LE
21
M 42 West
Rulison
D
174.719/95
21
Buck Mesa
M 521
Grassey·Gulch
C
174.770/95
21
M 421
C
Anthracite Creek
174.780/95
21
M ·53
174.809/95
C
21
Sommerset
M 521
174.851/95
C
21
M 52
Oak Mesa

V

• Age of elk in months as of March 1997.
b LE-~ Location elk routinely located.
~

V

�71

30

25

'--/

c::::n ADULTMALES

0

w

20

a::
w
en

15

z

10

a

:i!:
::,

-

ADULT FEMALES

~~

~

n=61
n=54

5
0

,

~&lt;I:-

.,

~~

~"

#'

'b&lt;8

MONTH
Fig. 1. Timing of deaths for adut elk &gt;=12-months of age, 1993-94-1996-97.

12
-

10
0

w

8

w
m

6

z

4

0
a::

:E
::,

~

CALVES
n =31

!!!!!!!

PREDATION

U;lmmm MALNUTRITION

:I I I ______O_T_H_E_R_ _ _ _ _ __

mi..............

2
0

JAN

FEB

MAR

MAY

APR

JUN

MONlH
Fig. 2. liming and estimated causes of deaths for calf elk 1993-94 - 1996-97. Calves were of both sexes and 6-11
months of age.

7

6
0

5

-

Uiliilii!i!I FEMALES n = 14 •

MALES n=17

w

c

0:::

4

w

~
=&gt;
z

·111111 _______________

3

UnH
·::::

2

1
0
~·

JAN

FEB

APR

MAR

MAY

JUN

MONlH
Fig. ·3. limi~ of deaths for male and female calf elk 1993-94 -1996-97. Calves were 6-11 montt:,s of age.

�72

Appendix I.

Mortalities of 146 radiocollared elk from 1 Oeced)er 1993 through 14 -June 1997. Age is
eeeroxfmate e9e in iears of elk at death: C=calf 6-11 months old 1 Y:Xearlf!JS 12-23 months old.
Frequency 10/
Death
Tree
Year caetured Site Zone Sex Age
Date
Cause of Death &amp;Code Nu:nber
172.030/93
F
BR A
5
27-0ct-95
Legal kill rifle season-28
172.039/93
GR B
F
Unknown-suspect predation-30
4
14-Jun-95
172.070/93
BR A
F
11 12-Feb-96
Unknown-11
172.080/93
GM A
F
6
05-Nov-94
Legal kill rifle season-28
GR B
F
11 16-Jan-94
172.090/93
Wounding loss late rifle season-26
172.101/93
F
SR B
Legal kill rifle season-28
•
8
14-oct-96
GC B
F
172.128/93
8
31-0Ct-96
Wounding loss rifle season-25
F
172.139/93
BC C
17 19-0Ct-95
Wounding loss rifle season-25
F
172.160/93
cc C
3
23-oct-94
Legal kill rifle season-28
172.181/93
MC C
F
3
03-Nov-94
Wounding loss rifle season-25
172.201/93
GS C
F
3
15-Nov-94
Wounding l_oss rifle season-25
172.207/93
SG D
F
4
30-Nov-95
Disappear rifle season-22
.
172.258/93
HY C
F
3
04-0ct-94
• Legal kill archery/n1.1zzle season-27
GS C
172.277/93
F
3
04-0ct-94
Wounding loss archery/n1.1zzl~-24
172.290/93
F
SG D
6
23-0ct-94
Legal kill rifle season-28
172.290/94
SM D
F
4
16-Sep-96
Legal kill nuzzleloading season-34
172.369/93
F
AC E
18-Sep-94
3
Legal kill archery season-33
172.369/94
F
FM B
4
Legal kill late rifle season-29
14-Jan-96
172.409/93
F
AC E
29-Dec-94
8
Wounding loss late rifle season-26
MH E
F
8
172.459/93
Legal kill rifle season-28
24-0Ct-96
FS ff
F
3
21-0Ct-95
172.509/93
Legal kill rifle season-28
FS
ff
172.542/93
F
6
01-Feb-94
Mountain lion predation-3
172.549/93
PG ff
F
28-Nov-95
7
Legal kill late rifle season-29
172.570/93
PG ff
F
16 03-Nov-94
Wounding loss rifle season-25
172.581/93
PG H
3
F
Legal kill rifle season•28
17-oct-94
F
172.581/94
FM B
3
08-Dec-95
Legal kill late r.ffle season-29
F
172.590/93
PG ff
5
24-Apr-96
Unknown-11
F
172.610/93 •
PG ff
3
04-0Ct-94
Accident, birthing/calving-32
F
172.639/93
PG ff
16 14-Jun-96
Accident, birthing/calving-32
172.649/93
F
PG ff
2
30-Nov-94
Disappear rifle season-22
172.670/93
F
PG H
Legal kill late rifle season-29·
16-Jan-95
4
PG H
F
9
22-Dec-94
Wounding loss late rifle season-26
172.678/93
F
FM
B
8
172.690/93
Illegal kill-7
24-Jan-94
172.699/93
FM
B
F
7
05-Nov-95
Legal kill rifle season-28
172.749/95
LS ff
F
11 07-Aug-96
Unknown-suspect predation-30
y
SR B
172.800/93
F
30-Nov-94
Disappear rifle season-22
172.821/93
EG B
F
3
08-Sep-96
Legal kill archery season-33
F
172.890/93
BC C
3
06-Nov-96
Legal kill rifle season-28
172.899/93
BC C
F
C
18-Mar-94
Mountain lion predation-3
172.950/93
GH D
F
2
18-0ct-95
·Legal kill rifle season-28
F
173.000/93
WM
G
C 25-Apr-94
Malnutrition-6
173.041/93
GM
A
M
2
19-0Ct-95
Legal kill rifle season-28
MH E
F
2
27-Dec-95
173.060/93
Legal kill late rifle season-29
173.081/93
FS
H
F
Legal kill rifle season-28
3
22-0ct-96
GM A
173.120/93
M
2
14-0ct-95
Legal kill rifle season-28
173.140/93
PG H
F
3
31-0Ct-96
Wounding loss rifle season-25
FS H
173.160/93
F
3
13-Nov-96
Legal kill rifle season-28
y
173.190/93
BC C
M
29-oct-94 .
Illegal kill rifle season-9
173.201/93
GR B
M
2
30-Nov-95
Wounding loss rifle season-25
173.210/93
GC B
M
2
19-0ct-95
Legal kill rifle season-28
BC C
M
173.219/93
06-Nov-95
2
Legal kill rifle season-28
y
173.232/93
BR A
M
15-Nov-94
Illegal kill rifle season-9
173.262/93
BC C
M
C
18-Mar-94
Unknown-11
173.262/94
HM B
M
2
12-0ct-96
Legal ki U rifle ~eason-28
173.269/93
MC C
M
2
06-Nov-95
Legal kill rifle season-28
3
MC C
173.279/93
M
12-0Ct-96
Legal kill rifle season-28
173.289/93
C
22.;.Mar-94
MC
M
C
Unknown-11
173.289/94
PR A
M
2
18-Sep-~6
Legal kill nuzzleloading season-34
GS C
173.300/93
M
2
Legal kill rifle season-28
24-0ct-95
y
173.309/93"
HY C
M
30-Nov-94
Disappear rifl_e season-22
y
173.320/93.
HY C
M
20-0ct-94
Illegal ldll rifle season-9
173.320/94
HM B
M
2
Legal kill archery season-33
14·Sep·96
173~332/93
GH
D
M
2
12-Sep-95
Legal kill nuzzleloading season-34
SG · D
173.351/93
M
2
05-Nov-95
Legal kill rifle season-28
173.359/93
AC
E
M
2
06-sep-95
Legal kill archery season-33
173.370/93
MH
E
M
2
08-Nov-95
Legal kill rifle season-28
M·
RG E
173.370/96
C
08-Jan-97
Mountain lion predation-3
RG E
173.381/96
M
C
19-Feb-97
Unknown-suspect predation-30
MG D
173.390/93
M
2 • 30-Noy.:.95
Disappear rifle season-22
MG D
M
Legal kill rifle season-28
173.402/93
2
18-0ct-95
G
173.410/93
Wounding loss rifle .season-25
WM
M
2
02-Nov-95
f7.f~420/93
M
WM G.
2
24-oct-95
Legal ~~ Ll rff le season-28__

--------------------------------------------------- --------------------------------~---------------

V

V'

V

�73

Appendix 1. &lt;continued&gt;
Frequency ID/
Trap
Year Captured Site Zone Sex
173.429/93
MH E
M
173.439/93
PG H
M
173.450/93
PG H
M
173.461/93
PG H
M
173.461/94
CM A
M
173.469/93
FS H
M
PR A
M
173.469/94
173.479/93
FS H
M
173.492/93
FS H
M
173.502/93
FS H
M
173.510/93
FM B
M
173.521/93
FM B
M
OG B
M
173.540/94
173.549/94
HM B
F
173.580/94
PR A
F
173~589/94
OG B
F
173.640/94
MC C
F
GM A
F
173.640/96
BG E
F
173.689/94
173.789/94
MR E
F
173.829/94
MM F
F
SM D
F
173.859/94
173.870/94
SM D
F
173.919/94
BC C
M
173.929/94
BC C
M
173.939/94
BC C
M
.173.959/94
BC C
M
173.970/94
MC C
M
173.981/94
MP D
M
BC C
M
173.990/94
174.001/94
BG E
M
174.009/94
BG E
M
174.019/94
BG E
M
174.039/94
MR E
M
174.049/94
MM
F
M
174.059/94
MR E
M
174.069/94
BG E
M
174.090/94
MR E
M
174.101/94
MM F
M
174.109/94
MM F
M
174.119/94
MM F
M
174.129/94
MM F
M
174.140/94
MM F
M
GB B
M
174.140/95
174.150/94
MM F
M
174.160/94
MM F
M
174.170/94
FM B
M
174~181/94
FM B
M
174.200/95
MS F
M
174.220/95
MS F
M
174.230/95
MS F
M
174.240/95
MD E
M
174.319/95
MS F
F
174.329/95
MD E
F
174.339/95
MD E
F
174.360/95
MD E
F
174.401/95
AP
D
F
174.500/95
LB C
F
174.520/95
KR B
F
174.520/96
GM A
F
BL A
F
174.560/95
174.609/95
GB B
F
174.679/95
HG E
M
174.689/95
AP D
M
174.689/96
EW G
M.
174.729/95
VM D
M
174.789/95
WD C
M
174.800/96
BG E
M
174.809/95
W
C
M
174.861/95
KR B
M
. ,174.910/96
LM D
F
175.059/96
BC C
F
175.130/96
GM A
F
175.170/96
LM D
M

Death
Date
l 14-Sep-95
2
30-Nov-95
2
15-0ct-95
C
07-Feb-94
Y
19-Sep-95

Age

C

25-Apr-94

2

20-0ct-96

2
2
3
2
2
2
Y
Y
C
c
C

c
2

10·Sep·95
03·Sep·95
13-Nov-96
28-Aug-95
17-0ct-95
13-0ct.:.96 .
07-Sep-95
21-Dec-95
01-Jun-95
30-Mar-95
16-Mar-97
31-0ct-96
20-Mar-95
10-Jan-97

2

23-0ct-96

2

C • 21-Feb-95
Y 02-Nov-95
2
2

2
2
2
2
2
2
2
2
2
Y
2
2
Y
2
C
2
c
Y
2

2

16-0ct-96

18-Sep-96
02-Nov-96
20-0ct-96
02-Nov-96
20-0ct-96
30-Nov-96
12-0ct-96
13-Nov-96
05-Sep-96
14-Sep-96
17-0ct-95
26-Sep-96
20-0ct-96
. 24-May-96
19-oct-96
01-Mar-95
14-oct-96
14-Mar-95
30-Nov-96
14-0ct-96
15-Sep-96

C

25-Apr-95

2
Y
C
C
C
Y
Y
c
Y
2

30-Nov-96
18-0ct-96
08-Apr-96
24-Apr-96
17-Apr-96
02-0ct-96

C
Y

C
Y
C
Y
C

C

v

03-Sep-96

27-Mar-96
22-Apr-97
22-Sep-96

16-Apr-96

21·Sep·9~
25-Apr-97
14-May-97
15-Apr-96

13-Nov-96

0S·Feb-96

14-May-97

17-oct-96

C
C
Y
Y

09-Apr-97
22-Apr-97
31-0ct-96

C
C

- 13-Feb:.97

c
C

22-May-96

27-Feb-97

24-Mar-97
26-Mar-97

Cause of Death &amp; Code Nllli)er
Legal kill archery season=33
Disappear rifle season-22
Legal kill rifle season-28
Malnutrition-6
Wounding loss archery/111.1zzle·24
Malnutrition-6
Legal kill rifle season-28
Legal kill archery season-33
Legal kill archery season-33
Legal kill rifle season-28
Legal kill archery season~33
Legal kill rifle season-28
Legal kill rifle season-28
Legal kill archery season-33
Unknown-11
Unknown-suspect predation-30
Unknown-suspect predatfon-30
Malnutrition-6
Legal kill rifle season-28
Unknown-suspect malnutrition-31
leg~l kill late rifle season-29
Legal kill rifle season-28
Mmntain lion predation-3
Illegal kill rifle season-9
Legal kill rifle season-28
Legal kill archery season-33
Legal kill rifle season-~8
Legal kill rifle season-28
Legal kill rifle season-28
Legal kill rifle season-28
Disappear archery/111.1zzle season-21
Legal kill rifle season-28.
Illegal kill rifle season-9
Legal kill archery season-33
Legal kill 111.1zzleloading season-34
Illegal kill rifle season-9
Wounding loss archery/111.1zzle-24
Legal kill rifle season-28
Unknown-suspect predation-30
Legal kill rifle season-28
Bear predation-35
Legal kill rifle season-28
Mountain lion predation-3
Illegal kill rifle season-9
Legal kill rifle season-28
Legal Id l.l n.izzleloading season-34
Mountain lion predation-3
Disappear rifle season-22
Illegal kill rifle season-9 .
Unknown-suspect malnutrition-31
Mountain lion predation-3
Mountain lion predation-3
Wounding loss archery/n.izzle-24
Legal kill archery season-33
Unknown predator-5
Unknown-suspect predation-30
Legal kill 111.1zzleloading season-34
· Unknown-suspect predation-30
Legal kill n.izzleloading season-34
Mountain lion predation-3
Illegal kill-7
Unknown-suspect predation-30
Illegal kill rifle season-9
Mountain lion predation-3
Unknown-suspect malnutrition-31
Illegal kill rifle season-9
Unknown-suspect predation-30
Mountain lion predation-3
Accident, fell-10
Wounding loss rifle season-25
Unknown-suspect predatfon-30
Unknown· 11
•
Mountain· lion predation-3
Unknown-suspect malnutrition-3'1

�177
Colorado Division
Wildlife Research
July 1998

of Wildlife
Report

JOB PROGRESS
state

Work

Colorado

of

Project

No.

Package

W-153-R-11

Mammals

3002

Elk Inyestigations

Task No.

Period
Author:

REPORT

Research

Estimating
Developing
PQpulation

Covered:i

July

Survival Rates of Elk and
Techniques to Estimate
Size

1, 1997 - June 30, 1998

D. J. Freddy

Personnel: R. Adams, T. Beck, J. Broderick, G. Byrne, D. Crane, R. Del
Piccolo, J. Ellenberger,
J. Frothingham, V. Graham, D. Homan, R. Kahn, K.
Madariaga, D. Masden, C. Mehaffy, P. Neil, J. olterman, J. Thompson, P. Will,
K. Wright, S. Yamashita, D. Younkin, CDOW; W. Andelt, D. Bowden, G. White,
CSU; Diagnostic Laboratory, CSU; D. Ouren, USGS-BRO, BLM Glenwood springs, CO,
USFS Rifle, CO, Rocky Mountain Elk Foundation, cooperating.

Abstract
During 1997-98 we monitored survival of 210 adult elk radio-collared
in
previous years and we conducted an applied sighting bias trial to further test
methods of estimating elk density.
We summarized average survival rates (±
95% CI) for elk between 1993-94 and 1997-98.
Survival during summer-fall for
females age ~12 months averaged 0.90 ± 0.03 inclusive of hunting deaths (n=524
elk-years) and 0.99 ± 0.01 with hunting deaths censored (n=476 elk-years).
Survival during winter-spring
for females age ~18 months averaged 0.97 ± 0.01
inclusive of hunting deaths (n=547 elk-years) and 0.99 ± 0.01 with hunting
deaths censored (n=536 elk-years).
Survival during summer-fall for males age
~24 months was 0.20 ± 0.09 inclusive of hunting deaths (n=82 elk-years) and
1.00 with hunting deaths censored (n=16 elk-years).
'Survival during winterspring for males age ~30 months was 1.00 (n=13 elk-years).
Hunting related
deaths were the primary cause of mortality for adult elk and annually removed
80% of the adult males, 11% of the yearling males, and 9% of the adult
females.
For adult females, deaths due to wounding and illegal kills exceeded
the absolute number of females dying from natural 'causes during 5 years.
High
adult and calf natural survival rates allow this population to grow an
estimated 7% annually with current levels of hunting mortality.
Further tests
of sighting bias revealed that failure to count all, elk in groups, as opposed
to failure to detect groups, is likely the primary cause of negatively biased
estimates of elk density based on quadrat sampling.
Counting error may
approach 25%.
Therefore, sighting bias models developed to account for errors
in detecting elk on quadrats do not adequately increase estimates of elk
numbers.
We did not find evidence indicating mark-resight
estimates of elk
numberS were positively biased.

�179

ESTIMATING

SURVIVAL

JOB PROGRESS REPORT
RATES OF ELK AND DEVELOPING
ESTIMATE POPULATION SIZE
David

TECHNIQUES

TO

J. Freddy

P. H. OBJECTIVE
Estimate survival rates of adult ,female, adult male,
techniques to estimate population size.
SEGMENT

and calf elk and develop

OBJECTIVES

1.

Estimate winter, summer, and annual survival rates of adult female
male elk from known fates of previously radio-collared
elk.

2.

Estimate density of elk in a portion of GMU-42 using a helicopter and
employing mark-resight
density estimators and random quadrat density
estimators to evaluate potential errors in meeting assumptions of markresight theory and sighting bias correction theory.

3.

Analyze

data

and summarize

annually

in Federal

Aid Job Progress

and

Report.

INTRODUCTION
Our objectives are to provide reliable estimates of survival rates for calves
during winter and for adult females and males throughout the year and to
develop and test a system to estimate elk densities on winter ranges.
Estimates of calf survival were obtained during winters 1993-94 through 199697 and summarized in Freddy (1997).
We are continuing to obtain estimates of
survival for adult males and females.
For adults, we are interested in
survival rates inclusive of hunting mortalities to document human-induced
rates of survival and exclusive of hunting mortalities to estimate natural
rates of survival.
We are evaluating a system for estimating population size
or density that incorporates estimates of sighting bias in conjunction with
random sampling of search quadrats as sample units.
OUr winter study area
encompasses about 839 km2 (324 mi2) in the eastern half of Game Management
Unit 42 south and east of Rifle, Colorado.
This area is part of the Grand
Mesa Elk Data Analysis Unit E-14.
Elk winter habitats include juniper-pinyon
woodland (Juniperus osteosperma-Pinus
edulis), oakbrush-mountain
shrub
(Quercus gambelii-Amelanchier
alnifolia), aspen (Populus tremuloides),
sagebrush (Artemisia tridentata), and agricultural
fields below elevations of
9,800 ft.
In summer, elk use oakbrush-mountain
shrub, aspen, and subalpine
fir-Engelmann
spruce (Abies lasiocarpa-Picea
engelmannii) meadow systems
throughout the Grand Mesa region up to elevations of 12,000 ft. (Freddy 1993).
METHODS
We placed radio collars (172-176MHz) having mortality sensors on elk calve.s
age 6 months and adults age ~18 months during December 1993-1996 (Freddy
1997). Elk were captured using helicopter net-gunning and portable corral
traps (Freddy 1997).
During 1997-98, we monitored 210 adult elk having
functioning radios as of July 1997.
Collars were white and had black
identification
symbols on dorsal surfaces of collars to allow observers in
helicopters to individually
identify elk.

�180

Estimating Elk Survival Rates
We monitored life or death status of radioed elk with aerial surveys using a
Cessna 185 at 2-4 week intervals from December 1993 to June 1998 and with
daily ground surveys from December-April
each year from 1993-94 to 1996-97.
Survival rates (5) of radioed elk were calculated using the binomial estimator
with a variance, VAR(S) = S(l-S)/n collars (White and Garrott 1990).
Survival
rates are expressed as the mean estimate ± the 95% confidence interval. We
used
x2-contingency tests to compare survival rates between sexes and among
time intervals (PROC FREQ, SAS 1988).
Sample sizes refer to numbers of
individual radioed elk except when referenced as elk-years which denotes that
individual radioed elk, because they survived for several years, were used
repeatedly in successive yearly time intervals to calculate pooled average
survival rates among years. Elk-years represents the numbers of times elk were
at risk during time intervals.
We defined 4 major time intervals for survival analyses: winter-spring
was 1
December to 14 June, summer-fall was 15 June to 30 November, annual was 1
December to 30 November to coincide with timing of capture and collaring, and
yearly was 15 June to subsequent 14 June used only for yearling elk aged 12-23
months.
For adult elk during these time intervals, we calculated survival
rates inclusive of natural and hunting-related
mortalities,
exclusive of
hunting mortalities,
and exclusive of natural mortalities.
Excluding, or
censoring hunting mortalities,
provided estimates of natural survival rates.
Excluding natural mortalities but including hunting mortalities provided
estimates of hunting removal rates. Censoring elk associated with categories
of mortalities
reduced sample sizes used to estimate survival rates. Elk were
also censored if radios failed or if their life/death status was unknown after
an extended period of time.
Archery, muzzleloading,
and rifle hunting seasons occurred from about 1
September to 15 November each year during the summer-fall time interval. Laterifle seasons restricted hunters to taking only antlerless elk and occurred
yearly from about 25 November-3l January which included portions of the
summer-fall and winter-spring
time intervals.
Yearling spike-antlered
males
were generally not legal quarry in most areas frequented by radioed elk.
Male
elk become legal quarry when branch-antlered
usually at age 2 years.
Cause of death of radioed elk recovered in the field was estimated from
presence or absence of gunshot wounds or bite wounds on carcass, predator
tracks or scat at carcass site, physical positioning of carcass remains
whether buried, covered, scattered, or consolidated
(Wade and Browns 1982,
Halfpenny and Biesiot 1986), relative amount of internal fat and marrow fat if
present with carcass, and results of histopathology
and marrow fat analyses.
Fat content (percent dry matter) of bone marrow and estimates of age based on
dental cementum were obtained for dead elk by the Colorado Division of
Wildlife Laboratory while histopathology
analyses were provided by the
Colorado State University Veterinary Diagnostic Laboratory.
Photographs were
taken of nearly all mortalities
so that physical evidence could be reviewed
and judged by outside experts (pers. comm. T. Beck, W. Ahdelt).

Estimating Elk Densities
During 3 applied surveys in winters 199~ and 1997, we estimated numbers of elk
on 132-137 mi2 of winter range with helicopter counts of marked (radioed) and
unmarked elk on random quadrats and along nonrandom flight paths.
Estimated
numbers of elk for the 3 surveys based on actual counts of elk on quadrats
were 51, 63, and 93% of the estimated numbers of elk obtained from markresight formulas using counts of marked and unmarked elk.
Adjusting actual

�181
quadrat counts with previously developed sighting bias models did not
meaningfully increase quadrat estimates in comparison to mark-resight
estimates (Freddy 1996, 1997). We had 3 important concerns: 1) sighting bias
corrections developed during previous testing trials were biased high and
provided inadequate corrections for applied surveys, 2) observers failed to
see marks on elk in groups that were detected and counted accurately causing
inflated mark-resight estimates of elk numbers, and 3) observers failed to
count all elk within groups that were detected on quadrats with elk not
counted inclusive of both marked and unmarked elk causing deflated counts of
elk on quadrats.
This last concern represented counting error that would not
be accounted for by sighting bias corrections.
In 1998, we conducted an applied sighting bias trial on quadrats along with
mark-resight surveys to again compare estimates of elk numbers based on
quadrat counts and mark-resight surveys.
We selected 44 mi2 in West Divide
and Alkali creeks that were a portion of the winter range sampled with
quadrats and mark-resight surveys in 1996 and 1997 and a portion of the area
used to conduct sighting bias trials in 1994 and 1995. This area was
dominated by oakbrush and pinyon-juniper habitats.
For this test, all marked
elk were age ~18 months unlike previous sighting tests and winter range
surveys that also included marked calves age 6 months.
Locations of all radioed elk within this 44 mi2 area were obtained by
telemetry using a Cessna 185 and ARNAV Star5000 GPS system on 26 February,
1998. Radioed elk represented a population of known size which we used to
evaluate the magnitude of sighting detection bias.
During 3 days from 27 February to 1 March, elk were counted on all 44, 1-mi2
quadrats using a Bell-Soloy helicopter flown at 40-50 mph. A flight crew was
a pilot, navigator, and observer and crews changed each day among 3 observers,
2 navigators, and 1 pilot all of whom were involved in previous sighting bias
tests and winter range surveys.
Members of flight crews had no knowledge of
the number or locations of marked elk within the survey area. Flight crews
flew nearly 7 hours each day to complete quadrats which was similar to daily
flying time and fatigue commonly associated with applied surveys.
Quadrats were flown using the same helicopter and counting procedures that
were used in previous sighting tests and surveys (Freddy 1994-1997).
Observers recorded the standard sighting bias variables of group size, elk
behavior, habitat type, percent screening cover, and percent snow cover for
all groups seen. As flight crews completed quadrats, they maintained a list
of marked elk seen and their GPS locations (Garmin Pilot III) and whether or
not marked elk were or could have been individually identified.
Those marked
elk not seen or those seen but not individually identified during counts were
then found by a second independent flight crew using a Bell-Soloy helicopter
and telemetry.
These missed elk were found on the same day an average 3.6
hours after quadrats were flown. For every missed' or unidentified marked elk
group, the second flight crew recorded the GPS location (Garmin Pilot III) of
the group and standard sighting bias variables.
Those elk seen but not
individually identified by quadrat crews were assigned as a specific
individual elk based upon proximity of locations of where such elk were seen
by quadrat crews compared to locations of these elk when found by the second
flight crew. Locations and status of all marked elk were therefore known
during the time quadrats were flown.
A sighting trial occurred when marked elk were detected during quadrat counts
and when marked elk were missed and later found by the second flight crew. To

�182

maintain independent observations of marked elk, only 1 sighting trial
occurred if there was more than 1 marked elk in a group. Otherwise, detecting
or missing a marked elk constituted a sighting trial.
Two mark-resight flights using the same helicopters were conducted on 1 and 2
March after quadrat counts were completed.
These flights followed a nonrandom
path through the same 44-mi2 with the intent of counting as many elk as
possible within allotted flight time. The navigator for both flights had not
participated in quadrat counts.
The observer for the first flight was an
observer during part of the quadrat counts while the observer for the second
flight had not participated in quadrat counts.
These 2 observers were the
same persons who conducted mark-resight flights during winter range surveys in
1996 and 1997. At the conclusion of the second mark-resight flight, locations
of collared elk not seen were confirmed to be within the sample area using the
helicopter and telemetry.
Weather conditions during flights were variable but similar to conditions
experienced during previous winter range surveys.
Quadrats were flown with
generally acceptable visibility in hazy to bright sunshine and light to
moderate wind speeds although brief snow squalls occurred on 27 and 28
February.
Nonrandom flights were flown during hazy to bright sunshine and low
wind speeds.
Snow cover was nearly 100% in all areas with depths estimated to
be 0.5 to 2.5 ft. Fresh snow was received on 24 and 25 February.
Minimum
night temperatures were 2-13 OF and were the coldest measured during the 14
days previous to flights.
Maximum day temperatures were 27-35. OF.
Number of elk on the search area was estimated using 3 approaches: from actual
counts of elk on quadrats, from adjusting quadrat counts with sighting bias
correction models, and from using the Bowden (BE) and lmmigration-EmigrationJHE (lMJHE) mark-resight estimators in program NOREMARK (White 1996). Elk
counted on quadrats were potentially a total count because 100% of the search
area was flown and because all 44 sample units were flown, there was no
sampling variance associated with estimates based on quadrats.
To adjust for
elk groups likely missed on quadrats, we applied sighting bias corrections to
elk groups counted on each quadrat which adjusted counts per quadrat and
provided a sighting bias corrected total population estimate.
We used 3
sighting correction models based on all sighting trials (n = 224) to .correct
for probabilities of detecting elk groups, where probability of detection is
[n = eU / 1 + eU] with u representing the linear regression of variables
affecting the probability of detecting a group:
1. u = 1.342(LogGroupSize(countedd - 0.131
2. u = 1.230(LogGroupSize(co=ted» - 2.127(Bedded) + 0.291
3. u = 1.135(LogGroupSize(co=ted» - 1.822(Bedded) - 0.031(%Cover) + 1.517
probability of detecting an elk group was adjusted for group size, for bedded
or not bedded behavior when detected, and for percent vegetation screening
cover
(Samuel et al. 1987, Freddy'1995).
Relative AlC model performance
values of 172, 160, and 154 for models 1-3, respectively, indicated model 3
was the most parsimonious model. We pooled counts of marked and unmarked elk
seen during quadrat counts and mark-resight flights.
Estimated numbers of elk
based on all 3 flights pooled was considered to be the best estimate of
population size and the benchmark against which quadrat counts were compared.
Both the BE and lEJHE estimators account for movement of elk on and off the
search area but the BE better accounts for heterogenous sighting probabilities
among individual elk (Bowden 1995, White 1996).

�183
Moyements
We continued to precisely locate selected radioed elk at least once ~r month
since their capture to document seasonal movements using a Cessna 185.
These
elk were originally selected at random from within trap zones and equalized by
age class in January 1994.
Elk from the original sample that died were
replaced each subsequent January with randomly selected elk that were usually
of the same sex, age class, and trap zone as elk that died.
All replacement
elk in January 1998 were yearling or older because additional calves were not
marked in December 1997.
As of 1 January 1998, these 44 elk were classified
as 27 adult females, 5 yearling females, 4 adult males, and 8 yearling males.
During June 1998, we again located an additional 28 adult females that were
originally selected at random in 1995 to document their locations during the
calving period.
Females from the original 1995 sample that died were replaced
each subsequent June with adult females randomly selected from the same trap
zones of elk that died.
As needed, we located other elk to document unusual
movements.
RESULTS

AND DISCUSSIQH

Survival Estimates
Between 1 December 1993 and 14 June 1998, 181 radioed elk died of which 31
were calves 6-11 months old and 150 were adults ~12 months old (Table 1,
Appendix I).
Calves died of natural causes (Freddy 1997) while for adults ~12
months old, hunting accounted for 92% of 150 deaths.
Yearlings
Survival during summer-fall for yearling elk age 12-17 months was 0.89 ± 0.06
for males (n = 120) and 0.95 ± 0.04 for females (n = 128) when averaged among
4 years and inclusive of hunting deaths, and 1.00 for both males (n = 107) and
females (n = 122) with hunting deaths censored.
All deaths for males and
females during summer-fall were due to hunting. Survival among years for males
ranged from 0.83 to 0.97 and for females from 0.87 to 1.00 inclusive of
hunting deaths.
We failed to detect differences
in survival between sexes
within years (P ~ 0.13) and among years for both males (P ~ 0.39) and females
(P ~ 0.09) inclusive of hunting deaths.
Survival of females (0.95) tended to
be higher than males (0.89) when averaged among years and inclusive of hunting
deaths (P = 0.07) Cl'ables 2-5).
Survival during winter-spring
for yearling elk age 18-23 months was 0.98 ±
0.02 for males (n = 106) and 0.97 ± 0.0.03 for females (n = 121) when averaged
among 4 years and inclusive of hunting deaths, and 0.98 ± 0.02 for males (n =
106) and 0.98 ± 0.02 for females (n = 120) with hunting deaths censored.
Survival among years for males ranged from 0.96 to 1.00, inclusive or
exclusive of hunting deaths.
Survival for females ranged from 0.93 to 1.00
and 0.96 to 1.00 inclusive and exclusive of hunting deaths, respectively.
We
failed to detect differences
in survival among ye~rs for both males (P ~ 0.51)
and females (P ~ 0.22) inclusive or exclusive of hunting deaths.
We also
failed to detect differences
in survival between sexes within years (P ~ 0.62)
and among years (P ~ 0.76) inclusive or exclusive of hunting deaths (Tables 25). During winter-spring,
there were 2 nonhunting deaths each for males and
females and 1 illegal hunting death for a female (Table 1).
Yearly survival for elk age 12-23 months was 0.87 ± 0.06 for males (n = 119)
and 0.93 ± 0.05 for females (n = 127) when averaged among 4 years with hunting
deaths included.
Survival among years for males ranged from 0.79 to 0.97 and
for females from 0.81 to 1.00.
We failed to detect differences
in yearly
survival among years for males (P = 0.27) but survival was lower (0.81) for

�184
females in 1996-97 (P = 0.02). Yearling males were subjected to about the
same rate of illegal hunting during all years which accounted for most of the
male mortality, while in 1996-97, females had a lower survival rate because 5
of 6 deaths were hunting related (Tables 2-5). With hunting deaths included,
we failed to detect differences in survival between sexes within (P ~ 0.13)
and among years (P = 0.15). Of 24 deaths involving yearling elk, 20 (83%)
were hunting related (Table 1).
With hunting deaths censored, yearly survival for elk age 12-23 months was
0.98 ± 0.02 for males (n = 106) and 0.98 ± 0.02 for females (n = 120) when
averaged among 4 years. Survival among years for males and females ranged from
0.96 to 1.00. We failed to detect differences in yearly survival among years
for males (P = 0.51) and for females (P = 0.50), and between sexes within and
among years (P ~ 0.90) (Tables 2-5).
Yearling spike-antlered males were generally not legal quarry during hunting
seasons.
Each year from 1994-1997, 29-32 yearling males radioed as calves
entered the fall hunting seasons presumably as spike-antlered males. OVer 4
years, illegal harvest removed 10% of the yearling males with yearly rates
ranging from 3 to 17%. Of 12 elk illegally killed, 11 were taken during rifle
seasons and 1 during archery seasons.
In addition to these 12 elk, 1 male was
fatally wounded during archery season in an area where the elk was legal
quarry.
Overall, 11% of the yearling males were annually removed by hunting
(Tables 1, 2-5).
Adult Females
Survival during summer-fall for all adult females age ~12 months was 0.90 ±
0.03 (n = 524 elk-years) when averaged among 4 years and inclusive of hunting
deaths and 0.99 ± 0.01 (n = 476 elk-years) with hunting deaths censored.
Survival among years ranged from 0.87 to 0.94 and from 0.99 to 1.00, inclusive
and exclusive of hunting mortalities, respectively.
We failed to detect
differences in survival among years inclusive (P = 0.30) or exclusive (P =
0.46) of hunting mortalities (Table 6). Hunting was involved in 48 (96%) of
50 summer-fall deaths: 32 were killed, 12 were wounded, and 4 disappeared
during hunting seasons and presumed legally killed.
One natural death was
attributed each to suspected predation and complications while calving.
At
the beginning of fall hunting seasons, there were 99, 129, 142, and 152
radioed adult females age ~12 months available to hunters in 1994, 1995, 1996
and 1997, respectively, representing 522 elk-years (Table 6, nonhunting deaths
censored). During summer-fall, 9% of these radioeq elk were removed annually
by all types of hunting mortality (range = 6-12%).
Survival during winter-spring for all adult females age ~18 months was 0.97 ±
0.01 (n = 547 elk-years) when averaged among 5 years and inclusive of hunting
deaths and 0.99 ± 0.01 (n = 536 elk-years) with hunting deaths censored.
Survival among years ranged from 0.94 to 0.99 and from 0.97 to 0.99, inclusive
and exclusive of hunting mortalities, respectively.
We failed to detect
differences in survival among years inclusive (P = 0.34) or exclusive (P =
0.40) of hunting mortalities (Table 6). There were 19 winter-spring deaths,
of which 11 (58%) involved hunting with 5 killed and 3 wounded during rifle
late-seasons and 3 illegally killed out of hunting seasons.
Natural deaths
were attributed to mountain lion predation (1), suspected predation (2),
complications while calving (1), accidental fall (1), and unknown cause (3)
(Table 1). During winter-spring, 2% of these radioed elk were removed
annually by all types of hunting mortality.

�185
Estimates of adult female survival using all females age ~12 months could be
biased because of the constant yearly recruitment of yearling females into
this radioed population of adults afforded by many radioed calves surviving to
yearling age and no similar yearly recruitment of additional older adult
females into the radioed population.
We therefore estimated survival rates
for adult females age ~24 months by excluding recruitment of yearlings age 1223 months and for 68 adult females initially collared as a cohort in December
1993 whose age at capture ranged from 18 months (n=6) to 10+ years.
Survival during summer-fall for adult females age ~24 months was 0.89 ± 0.03
(n = 396 elk-years) when averaged among 4 years and inclusive of hunting
deaths and 0.99 ± 0.01 (n = 354 elk-years) with hunting deaths censored.
Survival among years ranged from 0.82 to 0.93 and from 0.99 to 1.00, inclusive
and exclusive of hunting mortalities,
respectively.
We failed to detect
differences
in survival among years inclusive (P = 0.17) or exclusive
(P =
0.38) of hunting mortalities
(Table 7). Hunting was involved in 42 (95%) of
44 summer-fall deaths.
During summer-fall,
11% of these radioed elk were
removed annually by all types of hunting mortality
(range 7-17%).
Survival during winter-spring
for adult females age ~30 months was 0.96 ± 0.02
(n = 420 elk-years) when averaged among 5 years and inclusive of hunting
deaths and 0.98 ± 0.01 (n = 410 elk-years) with hunting deaths censored.
Survival among years ranged from 0.93 to 0'.99 and from 0.97 to 0.99, inclusive
and exclusive of hunting mortalities,
respectively.
We failed to detect
differences
in survival among years inclusive (P = 0.15) or exclusive
(P =
0.39) of hunting deaths (Table 7). There were 16 winter-spring
deaths with 10
(63%) attributed to hunting.
During winter-spring,
2% of these radioed elk
were removed annually by all types of hunting mortality
(range 1-5%).
Using the 1993 cohort of adult females, survival during summer-fall was 0.88 ±
0.05 (n = 189 elk-years) when averaged among 4 years and inclusive of hunting
deaths and 0.99 ± 0.01 (n = 167 elk-years) with hunting deaths censored.
Survival among years ranged from 0.82 to 0.94 and from 0.98 to 1.00, inclusive
and exclusive of hunting deaths, respectively.
We failed to detect
differences
in survival among years inclusive (P = 0.20) or exclusive
(P =
0.55) of hunting mortalities
(Table 8). Hunting was involved in 22 (96%) of
23 summer-fall deaths.
Percent of these radioed elk removed during summerfall by all types of hunting-related
mortalities averaged 12 annually (range =
6-17%).
Interestingly,
as this cohort collectively
increased in age from 1994
to 1997, the annual percentage of elk removed by hunting during summer-fall
steadily declined from 17 to 6%.
For the 1993 cohort, survival during winter-spring
age was 0.95 ± 0.03 (n =
233 elk-years) when averaged among 5.years and inclusive of hunting deaths and
0.98 ± 0.02 (n = 227 elk-years) with hunting deaths censored.
Survival among
years ranged from 0.92 to 1.00 and from 0.93 to 1.00, inclusive and exclusive
of hunting mortalities,
respectively.
We failed
detect differences
in
survival among years inclusive (P = 0.47) or exclusive (P = 0.17) of hunting
deaths (Table 8).
There were 11 winter-spring
deaths, of which 6 (55%)
involved hunting.
During winter-spring,
3% of these radioed elk were removed
annually by all types of hunting mortality.

to

Overall, survival rates for adult females during summer-fall and winter-spring
were the same among age groups of adult females.
Natural survival rates
exceeded 0.98 for all time intervals and groupings (Table 9).

�186
Annual survival rate using the 1993 cohort was 0.83 ± 0.07 (n = 199 elk-years)
when averaged among 4 years and inclusive of hunting deaths and 0.97 ± 0.03 (n
= 170 elk-years) with hunting deaths censored. Survival among years ranged
from 0.78 to 0.94 and from 0.92 to 1.00, inclusive and exclusive of hunting
mortalities, respectively.
We failed to detect differences in survival among
years inclusive (P = 0.17) or exclusive (P = 0.34) of hunting mortalities
(Table 10). Annually, 14% of these radioed elk were removed by all types of
hunting mortality (range 8-20%).
Removal rates of females by hunting during summer-fall were compared between
yearling females age 12-17 months and adult females age ~24 months.
Removal
rates were higher for adult females (0.11) than yearling females (0.05) when
averaged among 4 years (P = 0.04). This difference was caused by extremes in
removal rates in 1994 when 17% of adults and 3% of yearlings were removed (P
=0.05) and in 1997 when 11% of adults and 0% yearlings were removed (P =
0.06).
In 1995 and 1996, removal rates were not different (P &gt; 0.41) but
rates for yearlings (3%) tended to be lower than for adults (7-9%). These
rates suggest that vulnerability of yearling and adult females to hunting is
different.
Adult Males
Survival during summer-fall for adult males age 24-29 months was 0 •.
17 ± 0.09
(n = 75) when averaged among 3 years and inclusive of hunting deaths and 1.00
(n = 13) with hunting deaths censored.
Survival among years ranged from 0.08
to 0.23 inclusive of hunting mortalities.
We failed to detect differences in
survival among years (P &gt; 0.32) (Tables 2-4). All deaths were attributed to
hunting resulting in removal rates averaging 83% collectively for all fall
hunting seasons each year.
Through fall 1997, 7 males had survived at least 1 year of hunting seasons and
were available during at least 1 additional year of hunting seasons as 3 or 4
year-olds.
Survival during summer-fall for adult males age ~24 months was
0.20 ± 0.09 (n = 82 elk-years) when averaged among 3 years and inclusive of
hunting deaths and 1.00 (n = 16 elk-years) with hunting deaths censored.
Survival among years ranged from 0.14 to 0.24 inclusive of hunting
mortalities.
We failed to detect differences in survival among years (P &gt;
0.61) (Tables 2-4). All deaths were attributed to hunting resulting in
removal rates averaging 80% collectively for all legal males during fall
hunting seasons each year.
Survival during winter-spring for adult males age ~30 months was 1.00 (n = 13
elk-years) during all years (Tables 2-5). There were no hunting or nonhunting
deaths of adult males during winter-spring.
Hunting was the cause of mortality among male elk age ~24 months.
From the
1993-94 cohort of 36 male calves, 28 lived to age 24-months with 22 (79%)
harvested in 1995 inclusive of 2 that disappeared 'and 2 wounding losses during
rifle seasons.
From the 1994-95 cohort of 33 male calves, 25 lived to 24months and 23 (92%) were harvested in 1996 including 2 that disappeared during
seasons, 1 illegally taken during rifle seasons, and 1 wounding loss during
archery/muzzleloading
season.
From the 1995-96 cohort of 33 male calves, 22
lived to 24-months and 17 (77%) were harvested in 1997 including 1 that
disappeared, 1 illegally taken, and 4 wounding losses during rifle seasons.
Comparative Survival of Adult Males and Females
The differential impact of hunting on survival and recruitment of males and
females to young adult age classes is demonstrated by net survival rates of

�187
calf cohorts.
For 1993-94, 1994-95, and 1995-96 calf cohorts, net survival
from age 6 to 35 months averaged 0.10 for males and 0.73 for females (Tables
2-4). Only 3 (4%) of a potential 69 males survived from age 6 months to 48
months (Tables 2,3).
Hunting

Mortality

Per Season

Distribution of all types of hunting mortalities for male elk age &gt;12 months
during hunting seasons 1994-1997 was: Archery 15%, Muzzleloading 5%, RifleFirst 42%, Rifle-Second 25%, Rifle-Third 13%, Rifle-Late 0%, Illegal out-ofSeason 0%. Distribution of all hunting mortalities for female elk age &gt;12
months was: Archery 14%, Muzzleloading 7%, Rifle-First 19%, Rifle-Second 31%,
Rifle-Third 10%, Rifle-Late 15%, Illegal out-of-Season 4%.
All female and nearly all male elk killed by hunters died within the Grand
Mesa DAU E-14 or adjacent GMU 43. Exceptions were 6 adult males that
dispersed long distances and were killed near Ruedi Reservoir, Black Mesa,
Tomichi Dome, Gothic, and Anthracite Creek in GMUs 47, 63, 54, 55, 551, and
521 up to 100 mi south or east of their capture sites. These 6 males
represented 9% of adult males age ~24 months that were taken by hunters.
Adjusting

Hunting

Harvest

Estimates

Surveys used to estimate legal hunter harvest do not account for wounding
losses or illegal kills. Estimates of the proportion of the legal kill that
these additional deaths represent were made based on fates of radioed elk
during hunting seasons 1994-97.
We defined legal kill to be the number of
radioed elk known to be harvested plus those whose radio signals disappeared
during hunting seasons and were subsequently assumed to be legally killed.
This legal kill would most likely represent the kill estimated by harvest
surveys.
Wounding losses and illegal kills represented deaths not accounted
for by surveys.
Total kill which was known for radioed elk could thus be
expressed as (legal kill)*(X)= total kill where (X) represents a correction
factor.
correction factors by sex/age class were 1.16 for adult males, 1.11 for
yearling males, and ~ 1.4 for all categories of adult females (Table 11).
Rifle and late-rifle seasons involving adult female elk had high correction
factors of 1.35-2.00.
Losses of adult females not reported or estimated can
be important in modeling populations.
Total unreported losses of adult
females during hunting seasons 1994-1997 was 18 which was 1.8x the 10 natural
deaths of adult females in the comparative time interval of 1 December 1993-14
June 1998 (Tables 6, 11). An argument could be made that estimating
unreported losses is as important as estimating natural mortality rates.
Survival

Rates

and Population

Modeling

Survival and removal rates were incorporated into a simple spreadsheet model
to assess trends in population growth (Table 12). Natural survival rates
(hunting deaths censored) were used for summer-farl and winter-spring time
intervals for adult males, yearling males, adult females, yearling females,
and calves.
Hunting deaths of all types were incorporated as total harvest
removal rates for each sex/age class. Using total removal rates is a simpler
method than using correction factors to account for unreported .harvest. This
model assumed survival of calves 0-5 months of age during summer was 1.00
because the model uses post-season calf:cow ratios measured in January as an
estimate of net calf recruitment to December.
Recruited sex ratio of calves
to December was assumed to be 1:1.

�188
Modeling suggests that if harvest rates of antlered elk remained as measured
and harvest rates of antler less elk were reduced to 0, the population could
grow at an annual rate of 18%. Current rates of antlerless harvest allow
annual growth rates of about 7.5%. To stabilize population growth, harvest
rates on adult and yearling female and calf age classes must increase nearly
2X.
population

Estimates

Movements of marked elk on and off the survey area during days when flights
were conducted resulted in 34 marked elk (27 female, 7.male) and 38 marked elk
(31 female, 7 male) within the area during quadrat and mark-resight flights,
respectively.
Elk movements were usually &lt;600 yards and near sample area
boundaries. Ratios of marked/unmarked elk counted were similar among quadrat
and nonrandom flights ranging from 0.029 to 0.036 (Table 13). These ratios
were generally lower than ratios of 0.031-0.042 observed during extensive
survey flights in 1996 and 1997 when marked calves were available in addition
to marked adults.
Observers used 19.7±2.1 (95% CI) minutes to count 17.5 elk per quadrat
(range=0-68).
Observers 1B and 2E encountered similar densities of elk and
had similar search times in oakbrush habitat while observer 3M had lower elk
densities and higher search times in pinyon-juniper habitat (Table 14).
During 3 extensive surveys in 1996 and 1997, these same observers used 17.6,
16.9, and 19.8 minutes to count 17.0, 25.9, and 17.3 elk, respectively, per
quadrat (n=177).
Searching effort during the 1998 sighting trial was
therefore representative of searching effort during previous extensive
surveys.
During nonrandom flights, detection rates of marked elk were 0.32 and 0.45
with effective searching rates of 4.9 and 6.00 minutes per mi2 of search area
during flights 1 and 2, respectively (Table 13). During nonrandom flights for
extensive surveys in 1996 and 1997, detection rates of marked elk were 0.260.58 with effective searching rates of 3.3-3.9 minutes per mi2 of search area.
Nonrandom flights in 1998 were therefore representative of flights during
extensive surveys.
Observers completed 32 sighting trials while counting elk on quadrats.
Average sighting bias or detection rate for marked elk groups among observers
was 0.78±0.15 (95% CI) (Table 14). This sighting bias rate was similar to the
average sighting bias rate of 0.82+ 0.06 (95% CI) for these same 3 observers
during sighting bias test trials (n=192) conducted in 1994 and 1995.
Therefore, sighting bias rate estimated from test trials appears to be
representative of sighting bias during applied surveys.
Observers failed to detect 7 marked elk during sighting trials.
When found
after quadrats were completed, 6 of these elk were in groups of ~2 elk, 4 were
bedded and appeared to have been bedded for several hours, 5 were in screening
cover densities ~60%, and 5 were reluctant to move even when disturbed at
close distances with the helicopter (Table 15). Importantly, the white
collars were easily visible and thus, failure to detect marked elk was not
likely due to failure to see marks.
Of these 7 missed elk, 3 were males and 4
were females resulting in detection rates of 0.57 for adult males and 0.85 for
adult females.
Of the 7 missed elk, 3 were found in close proximity to other groups that were
likely counted by quadrat crews. This lends credence to the possibility that
some marked elk were not counted within detected groups because not all elk,

�189
both marked and unmarked, were seen when groups were detected.
This type of
counting error is plausible as groups detected in dense pinyon-juniper or
oakbrush often begin to move and observers concentrate on counting the moving
elk and fail to see elk in the group that remain bedded or move in a different
direction.
Estimated number of elk on the search area was 1,179 based on the BE markresight estimator (Table 17). The 771 elk counted on quadrats represented 65%
of the BE while sighting bias adjusted quadrat counts represented 73-75% of
the BE. We propose that the 25% difference between sighting adjusted
estimates and the BE represents counting error.
This degree of counting error
would equate to adding 2.2 elk per group to an average group size of 5.2 elk
for the 148 groups detected (Table 18). Counting error, as opposed to
detection error, appears to be the primary cause of negatively biased
estimates of elk density based on quadrat sampling.
Elk Moyements
Yearling elk originally trapped as calves and surv1v1ng to age 18 months
dispersed to winter ranges not affiliated with their natal capture winter
range at rates of 43, 42, and 33% in winters 1995-96, 1996-97, 1997-98,
respectively.
Each year, 40-52% of the yearling females dispersed while only
25-33% of the yearling males dispersed.
Yearling elk moved primarily west or
south to winter ranges near the towns of Rulison, Parachute, Collbran,
Hotchkiss, Paonia, and Paonia Reservoir.
Specifically for the 1996 cohort of radioed calves, 28 males and 30 females
survived to age 18 months in December 1997 (Table 5). By end of winter 199798, 19 (7M, 12F) or 33% had dispersed to other winter ranges (Table 19).
Calves trapped in Alkali, Dry Hollow, and the Mammm creeks (zones E, F, G)
comprised 79% of the dispersing yearlings and these elk moved primarily west
to winter ranges near Collbran, Rulison, and Parachute. Calves trapped in West
Divide Creek (zone D) comprised 16% of the dispersing yearlings and these elk
moved to winter ranges near Collbran and also south towards Paonia Reservoir.
We continue to cooperate with the USGS-BRO, USFS, and BLM with the support of
the Rocky Mountain Elk Foundation to develop a GIS database allowing analyses
relating elk locations, movements, and home ranges to habitat components.
CONCLUSIQNS
Hunting related mortalities were the primary cause of death for adult female
and male elk. For adult males, all deaths to age 48 months were related to
hunting.
For adult females, deaths due to wounding and illegal kills exceeded
the absolute number of females dying from natural causes during 5 years.
Natural survival rates for adult females and males were ~0.98 during winterspring and summer-fall.
High adult and calf survival rates allow this
population to potentially increase 18% annually in the absence of hunting
antlerless elk. Current hunting removal rates of 9% for adult females age ~12
months allows the modeled population to grow 7% annually.
Failure to count all elk in groups, as opposed to failure to detect groups,
appears to be the primary cause of negatively biased estimates of elk density
based on quadrat sampling.
Counting error may approach 25%. Sighting bias
models developed to account for errors in detecting elk on quadrats
inadequately increased estimates of elk numbers when compared to numbers
estimated by mark-resight formulas. We did not find evidence indicating markresight estimates of elk numbers were positively biased.

�190
LITERATURE

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1993.
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colo. Div. Wildl. Game Res.
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Freddy, D. J.
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Estimating survival rates of elk and developing
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Colo. Div. Wildl. Game Res.
Rep. July: 47-73.
Hal.fpenny, J. C., and E. A. Biesiot.
1986.
A field guide to mammal
in North America.
Johnson Books, Boulder, CO. 161pp.

tracking

Samuel, M. D., E. O. Garton, M. w. Schlegel, and R. G. Carson.
1987.
Visibility bias during aerial surveys of elk in northcentral
Idaho.
Wildl. Manage. 51:622-630.
SAS Institute Inc.
1988.
Cary, NC. 1028pp.

SAS/STAT

User's

Guide,

1982.
Procedures
Texas Agric. Expt.

6.03. SAS Institute,

J.

Inc.,

for evaluating predation on
Sta. Publ. B-1429.
42pp.

Wade,

D. A., and J. E. Browns.
livestock and wildlife.

White,

G. C.
1996.
NOREMARK: Population estimation
surveys.
Wildl. Soc. Bull. 24:50-52.

White,

G. C., and R. A. Garrott.
1990. Analysis of wildlife
data.
Academic Press, Inc., San Diego.
383pp.

from mark-resighting

radio-tracking

�191
Table 1. Causes of deaths in radio-collared
elk between 1 December 1993 and
14 June 1998.
Calves (M=male, F=female) were age 6-11 months and collared at
age 6 months.
Yearling males and females were age 12-17 months and juvenile
males and females were age 18-23 months and all were collared at age 6 months.
Adult males and females were ase &gt;24 months at time of death.
"Elk Ase!Sex Class at Death
Yearling
Juyenile
Adult
Total
Cause of Death
Calves
All
M
F
M
F
M
F
M
F
and -Code
M F
Natural causes
o
o
4
o
o
o
2
2
Malnutrition-6
2 2
o
Unknown-Suspect
o
o
o
3
1
4
Malnutrition-31
3 1
o
o
o
o 1
5
13
Predation-Lion-3
o o
o
o
8
8
4
o o
o o
o
Predation-Bear-35
o o
o
o
o 0
o o
o 1
1
Unknown Predator-5
o 1
o o
o
o
Unknown-Suspect
o 2
3
8
11
Predation-30
2 5
o o
1
1
2
o 0
o
o 2
o 2
Accident-Birthing-32
o o
o
o 1
1
2
Accident-Fell-10
o 0
o
o
1
o
1
1
o
2
2
4
6
Unknown Cause-11
2 1
o
o
o
Subtotals
.Q
.Q
.Q
.a.
.l.2. II
sa
2.
111l
2.
Legal Bunting
8
2
12
o 0
2
8
4
o
Archery-33
o
o
4
2
4
4
8
Muzzleloading-34
o 2
o
o
o 0
o
1
o
1
1
o
Archery/Muzzle-27
o 0
o o
o
29
22
7
22
7
Rifle-First-46
o 0
o
o
o
o
20
o 0
10 10
10 10
o
Rifle-Second-47
o o
o
8
5
8
5
13
o 0
o
Rifle-Third-48
o o
o
o 6
o
6
6
Rifle-Late-29
o 0
o
o
o o
Subtotals
.Q
.Q
.6..2.
.Q
.Q .Q
sa aa
sa II
.i
Wounding Loss
1
o 0
2
o
1
1
1
Archery/Muzzle-24
o o
o
3
o 0
o
o 1
1
2
Archery-52
1
1
o
3
2
o 0
o
1
1
2
Rifle-First-43
o o
o
9
o 0
o
3
6
3
6
Rifle-Second-44
o o
o
2
1
1
1
1
Rifle-Third-45
o 0
o o
o
o
1
1
o
1
o
Rifle-Unk.Reg.-25
o 0
o
o
o
o
3
o 3
o 3
Rifle-Late-26
o 0
o
o
o
o
Subtotals
.Q
.Q .Q
.Q
aa
1. II
.a. .15.
~
~
Illegal Bunting
5
o o
5
o
Rifle-First-49
o 0
o
o
o
5
6
1
o
6
o
Rifle-Second-50
o 0
5
o
o
o
1
o o
o
o 0
o
o
1
Rifle-Third-51
1
o
o 0
1
1
o
1
o
Rifle-Unk.Reg.-9
o
o
o
o
1
o o
1
o
Archery Season-8
o 0
1
o
o
o
3
o 2
o
3
Out-of-Season-7
o 0
o
o
o
1
Subtotals
.Q
.Q .Q
11
2.
2.
II
.3.
.u: .Q
~
Presumed Buntin~
1
1
Missing-ArchMuzz-21
o 0
o o
o
o
o
1
o
o 0
5
o
2
3
3
2
Missing-Rifle
1st-40
o
o
o
3
1
Missing-Rifle
2nd-41
o 0
o 1
o
1
1
2
o
o 0
o
o
o
o
o
o
Missing-Rifle
3rd-42
o
o
o
Subtotals
.Q
.Q .Q
.Q
.Q
.2.
.3.
.5.
.5.
.i
~
Totals

17 14

13

6

2

3

66

60

98

83

181

• These elk were illegally shot as spike-antlered yearling males: (173.190/93) (173.232/93)
(173.309/93) (173.320/93) (173.919/94) (174.059/94) (174.140/95) (174.200/95) (174.679/95)
(174.729/95) (174.861/95) (173.210/96).
(173.309/93) disappeared in 1994 during first rifle season
when spike-antlered yearling males were not legal and was assumed to have been taken illegally.
All
other illegal deaths were confirmed.
• These elk disappeared during hunting seasons and remained missing for several months and are assumed
dead and legally harvested: (172.207/93) (172.649/93) (172.800/93) (172.961/93) (173.390/93)
(173.439/93) (174.001/94) (174.181/94) (174.770/95).

�Table 2.
Survival rates, inclusive of nonhunting and hunting mortalities,
for winter-spring
(WS, 1
December-14 June) and summer-fall
(SF, 15 June-30 November) time periods from 1 December 1993-14 June 1998
for the cohort of calves age 6 months radio-collared
in December 1993.
Survival rate for male and female
calves pooled when age 6-11 mohths was 0.92 (95% CI 0.86-0.98, n=73).
Survival rates (S) calculated as a
mean estimate of (alive)/(alive + dead) and variance S(1-S)/n collars.
Elk Elk Age (months) and Time Period (WS or SF dates)
18-23
24-29
30-35
36-41
42-47
6-59
6-11 (mos) l2.:.ll
~
~
.WS
WS
SF
WS
SF
WS
SF
WS
SF
ALL
1994-95
1995
1995-96
1996
1996-97
1997
1997-98
1994
1993-98
1993-94
MALES
Survival
L 95% CI
U 95% CI
n collars
censo.redDied
Nonhunt
Hunt

0.89
0.78
0.99
36

0.88
0.76
0.99
32

0

o
b

1.00

28

o
o
o
o

0.21
0.06
0.37
28°

1. 00
0.00
0.00

0.50
0.00
1. 00

1. 00

0.00

0.00

4

4

2f

o

22d

o
o
o

2

o
o
o
o

1
19

33

o

2e

1

33

4
4
0

4

0.95
0.87

0.97
0.92

1. 00

1. 00

1. 00

0.97
0.91
1. 00

37

35

34

34

33

0.84
0.71
0.97
32

censo red-

o

o

o

o

o

Died
Nonhunt.
Hunt

2
2

1h

1

1

5

o

o

o

o

1

o
o
o
o

1

1

5

FEMALES
Survival
L 95% CI
U 95% CI
n collars

o
4

o

1. 00

o
22

0.97
0.91

o
2

1. 00

27

o
o
o
o

3e,9

o

4

1

29

0.89
0.76
1. 00
27

0.96
0.87
1. 00
24

0.62
0.46
0.78
37

o

o

o

31

o

1
1

3

3

o

11

•

Censored denotes collar failure and/or animal life/death status not known.
Collar (173.309/93) disappeared 1994 hunting seasons and assumed dead.
• Includes (173.241/93) collar failure August 1995 but seen January 1996.
d
Two collars (173.390/93). (173.439/93) disappeared 1995 hunting seasons and assumed dead.
• Two collars censored; (173.241/93). collar failed August 1995. (173.381/93) slipped off December
Includes (173.340/93) alive May 1997.
9
Censored elk was (173.249/93) slipped collar September 1997.
• Collar (172.961/93) disappeared 1997 hunting seasons and assumed dead.
h
Collar (172.800/93) disappeared 1994 hunting seasons and assumed dead.
b

1995.

14

,_.
It)
(IJ

�Table 3. Survival rates, inclusive of nonhunting and hunting mortalities,
for winter-spring
(WS, 1
December-14 June) and summer-fall
(SF, 15 June-30 November) time periods from 1 December 1994-14 June 1998
for the cohort of calves age 6 months radio-collared
in December 1994.
Survival rate for male and female
calves pooled when age 6-11 months was 0.90 (95% CI 0.83-0.97, n=69).
Survival rates (S) calculated as a
mean estimate of (alive)/(alive + dead) and variance S(l-S)/n collars.
Elk Age (months) and Time Period (WS or SF dates)
18-23
24-29
30-35
36-41
42-47
~
6-11 (mos) l2...:.l1
WS
SF
WS
SF
WS.
ALL
SF
WS
1996-97
1997
1995-96
1996
1997-98
1994-98
1995
1994-~5
MALES
Survival
L 95% CI
U 95% CI
n collars
censozedDied
Nonhunt
Hunt

0.91
0.81
1. 00
33b
0
3
3
0

0.90
0.79
1. 00
30b

0.96
0.88
1. 00
26

0.08
0.00
0.19
25

o

o
23

o

1c
1
1

3

o

23

o
o
o
o

FEMALES
Survival
L 95% CI
U 95% CI
n collars

0.89
0.78
0.99
36

0.97
0.91
1. 00
32

0.97
0.90
1.00
30

0.93
0.83
1. 00
29

0.96
0.89
1. 00
27

0.85
0.70
0.99
26

censo.red=

o

o

o

o

o

Died
Nonhunt
Hunt

4
4

1

2

1

4

o

1e
1
1

o

o

o

o

1

o

2

1

4

3

o

1. 00

2d

0.50
0.00
1. 00
2

1. 00

o

o
o
o
o

1

o
1

1

C

31
4

27

1.00

22

o
o
o
o

Censored denotes collar failure and/or animal life/death status not known.
b
Includes (173.949/94) collar failure December 1994 but seen January 1996
Censored elk was (173.949/94) collar failure, which was killed in first rifle season
d
Includes (174.030/94) alive June 1997 .
• Censored elk was (173.719/94) slipped collar May 1996.

0.03
0.00
0.09
32
lC

0.63
0.46
0.79
35
1d
13
5
8

1996.

I-'

10
W

�Table 4. Survival rates, inclusive of nonhunting and hunting mortalities,
for winter-spring
(WS, 1
December-14 June) and summer-fall
(SF, 15 June-30 November) time periods from 1 December 1995-14 June 1998
for the cohort of calves age 6 months radio-collared
in December 1995.
Survival rate for male and female
calves pooled when age 6-11 months was 0.88 in 1995 (95% CI 0.81-0.96, n=69).
Survival rates (S) calculated
as a mean estimate of (alive)/(alive+dead)
and variance of S(l-S)/n collars.
Elk Age (months) and Time Period (WS or SF dates)
6-11(mos)
12-17
18-23
24-29
30-35
6-35
WS
SF
WS
SF
WS
ALL
1997
1997-98
1995-98
1996-97
1996
1995-96
MALES
Survival
L 95% CI
U 95% CI
n collars

0.86
0.74
0.98
35

censored-

2h

0.83
0.68
0.97
2,9.
F
5

0.96
0.87
1. 00
24

o

0.23
0.04
0.41
22
1d
17

o

1
1

5

o

17

0.93
0.82

1. 00

4
1e

0.13
0.01
0.24
32
sh,e,d,e

o
o
o

28

1.00

Died
Nonhunt'
Hunt

5
5
0

FEMALES
Survival
L 95% CI
U 95% CI
n collars

0.91
0.81
1. 00
34

0.87
0.75
0.99
31

27

0.83
0.66
0.99
23

18

0.58
0.40
0.76
31

0

o

o

2f

.19

3f,9

3
3
0

4

2

4

o

1
1

o

o
o
o

4

cenaoredDied
Nonhunt
Hunt
• Censored
b Censored
Censored
d Censored
• Censored
, Censored
9 Censored
C

4

1. 00

o

4

6
22

13
9

denotes collar failure and/or animal life/death status not known.
elk were (174.619/95) slipped collar May 1996, (174.800/95) capture mortality.
elk was (174.660/95) slipped collar July 1996.
elk was (174.671/95) likely collar failure July 1997 .
elk was (174.190/95) slipped collar May 1998.
elk· were (174.441/95) slipped collar August 1997. and (174.580/95) likely collar
elk was (174.470/95) likely collar failure December 1997.

failure

July 1997.

•....
10
,j:o

�Table 5: Survival rates, inclusive of nonhunting and hunting mortalities,
for winter-spring
(WS, 1
December-14 June) and summer-fall
(SF, 15 June-30 November) time periods from 1 December 1993-14 June 1998
for the cohort of calves age 6 months radio-collared
in December 1996.
Survival rate for male and female
calves pooled when age 6-11 months was 0.86 (95% CI 0.81-0.96, n=69).
Survival rates (S) calculated as a
mean estimate of (alive)/(alive+dead)
and variance of S(l-S)/n collars.
Elk Age (months) and Time Period (WS or SF dates)
6-11(mos)
12-17
18-23
6-23
ALL
WS
SF
WS
1996-98
1997-98
1997
1996-97
MALES
Survival
L 95% CI
U 95% CI
n collars

cenaor-ed-

0.85
0.73
0.98
34
1b

Died
Nonhunt
Hunt

5
5
0

FEMALES
Survival
L 95% CI
U 95% CI
n collars
censo.redDied
Nonhunt
Hunt

0.86
0.74
0.98
35
0
5
5
0

• Censored
b Censored

1. 00

0.97
0.90
1. 00
29
0
1
0
1

28
0
0
0
0

1. 00

1. 00

30
0
0
0
0

30
0
0
0
0

0.82
0.69
0.96
34
1b
6
5
1

0.86
0.74
0.98
35
0
5
5
0

denotes collar failure and/or animal life/death
elk was (174.619/96) capture mortality.

status not known.

I-'
1.0
til

�Table 6. Survival rates, inclusive of nonhunting and hunting mortalities, for winter-spring (WS 1 December14 June) and summer-fall (SF, 15 June-30 November) time periods from 1 December 1993 - 14 June 1998 for all
Survival rates (S) calculated as a mean estimate of
radio-collared adult female elk age ~12 months.
(alive)/(alive + dead) and variance S(l-S)/n collars.
Elk Age and Time Period (WS or SF dates)
Adult
Agylt
Adult
Adult
Adult
Adyl!;;
Adylt
AQylt
AQJ.!.lt
WS
SF
WS
SF
SF
WS
WS
SF
WS
1996
1995
1995-96
1996-97
1997
1997-98
1994-95
1994
1993-94
0.94
0.89
0.98
0.94
0.91
0.96
0 ..
99
0.'87
0.96
Survival
0.90
0.84
0.95
0.90
0.87
0.97
0.92
0.80
0.91
L 95% CI
0.94
0.98
1.00
0.98
0.96
1.00
1.00
0.94
1.00
U 95% CI
129b h
1271
100b f
68b e
95b 9
119i
143k
152m
138
n collars
j
n
1P
2
0
0
2
0
0
0
0
censoxed"
7
16
8d
3
13
2
4
13c
3
Died
4
1
1
0
0
1
1
1
1
Nonhunt
3
15
2
8
13
1
3
12
2
Hunt
----

0

b
Includes (172.011/93) collar failure April 1994, seen January 1996
• Censored denotes collar failure or life/death status unknown.
d Collar
(172.207/93) disappeared 1995 hunt seasons, assumed dead.
• Collars (172.800/93,172.649/93)
disappeared 1994 hunt seasons.
f
Composed of 35-12+, 6-24+, and 59-36+ months old females.
• Composed of 6-18+ and 62-30+ months old females.
h Composed
of 32-12+, 34-24+, and 63-36+ months old females.
9 Composed
of 34-18+ and ·61-30+ months old females.
j Censored
(172.011/93) failure and (173.719/94) slipped collar.
1 Composed
of 30-18+ ~d 89-30+ months old females.
I Composed
of 27-18+ and 100-30+ month old females.
k composed
ot 31-12+, 29-24+, and 83-36+ months old females.
m Composed
of 30-12+, 23-24+, and 99-36+ months old females.
n Censored
(174.4-41/95) slipped collar August 1997 (174.580/95) likely failure June 1997
p Censored
(174.470/95) likely collar failure August 1997.
o Composed
of 30-18+ and 108-30+ months old females.

I-'
10
0'1

�Table 7. Survival rates, inclusive of nonhunting and hunting mortalities, for winter-spring (WS 1 December14 June) and summer-fall (SF, 15 June-30 November) time periods from 1 December 1993 - 14 June 1998 for
radio-collared adult female elk age ~24 months.
Survival rates (S) calculated as a mean estimate of
(alive)/(alive + dead) and variance S(l-S)/n collars.
Elk Age and Time Period (WS or SF dates)
Adult
Adyl!;;
Adult
8,gult
Agylt;
8,gylt;
Agylt
8,gylt;
Agyl!;;
WS
SF
WS
SF
SF
WS
WS
SF
WS
1995
1995-96
1996·
1996-97
1997
1997-98
1994-95
1994
1993-94
0.93
0.89
0.93
0.99
0.89
0.98
0.82
0.93
0.95
Survival
0.84
0.88
0.88
0.97
0.84
0.96
0.87
0.72
0.90
L 95% CI
0.98
0.99
0.95
1. 00
0.95
1.00
0.91
0.99
1.00
U 95% CI
112
97
89
100
122
108
61
65
62
n collars
1b
1d
0
0
0
2c
0
0
cenaoxed0
7
6
12
1
13
2
4
12
3
Died
3
1
0
0
0
1
1
1
1
Nonhunt
·3
11
7
1
13
1
3
11
2
Hunt
• Censored
o Censored

denotes
collars

collar failure or life/death
(174.441/95) (174.580/95)

status unknown.

S
d

Censored
Censored

collar
collar

(172.011/93)
174.470/95)

Table 8. Survival rates, inclusive of nonhuntng and hunting mortalities, for winter-spring (WS, 1 December14 June) and summer-fall (SF, 15 June-30 November) time periods from 1 December 1993 - 14 June 1998 for the
group of adult female elk age ~18 months when radio-collared in December 1993. Survival rates (S)
calculated as a mean estimate of (alive)/(alive + dead) and variance S(l-S)/n collars.
Elk Age and Time Period (dates)
Adult
Adult
8,dylt
Agylt;
8,dult
Agyl!;;
Adyl!;;
8,gl.l.lt My,lt
WS
SF
SF
WS
WS
SF
WS
SF
WS
1995
1995-96
1996
1994-95
1996-97
1997
1994
1997-98
1993-94
0.93
0.92
0.88
1. 00
0.93
0.94
0.82
0.97
0.96
Survival
0.85
0.78
0.84
0.85
0.87
0.72
0.92
0.91
L 95% CI
0.97
1.00
1.00
0.99
1.00
0.91
1.00
1.00
U 95% CI
49b h
53b f
42h
65b f
68b e
391
361
36j
34j
n collars
19
0
0
0
0
0
0
0
censor-ed- 0
d
c
3
3
6
0
4
2
12
1
3
Died
0
3
0
0
1
0
0
1
1
Nonhunt
0
3
6
0
3
2
11
1
2
Hunt
• Censored denotes collar failure or life/death status unknown
o Collar
(172.649/93) disappeared 1994 hunt seasons.
• Composed of 6-·18+ and 62-30+ month old fe!llales.
• Censored (172.011/93) collar failure April 1994.
, Composed of 100% females 48+ months old.

Includes (172.011/93) collar failure April 1994 but seen Jan. 1996.
Collar (172.207/93) disappeared 1995 hunt seasons, assumed dead.
, Composed of 100% females 24+ months old,
h Composed
of 100% females 36+ months old.
l Composed
of 100% females 60+ months old.
b
d

I-'
10
-.J

�Table 9. Summary of summer-fall
(15 June-30 November) and winter-spring
(1 December-14 June) survival rates
inclusive and exclusive of hunting deaths among different age groupings of adult females averaged among
years, 1993-94 - 1997-98. Survival rates (S) calculated as a mean estimate of (alive)/(alive + dead) and
variance S(l-S)/n elk-years.
Winter-Spring
Average 5 Years
Summer-Fall Average 4 Year's
Age Grouping
survival
±95% CI Elk-years
Age Grouping
Survival
±95% eI Elk-years
Includes Hunting
Age ~12 monthsb
Age ~24 monthsC
1993 Cohortd

Deathsa
0.90
0.89
0.88

0.03
0.03
0.05

524
396
189

Age ~18 months
Age ~30 months
1993 Cohort

0.97
0.96
0.95

0.01
0.02
0.03

547
420
233

Excludes Hunting
Age ~12 monthsb
Age ~24 monthsC
1993 cohortd

Deathse
0.99
0.99
0.99

0.01
0.01
0.01

476
354
167

Age ~18 months
Age ~30 months
1993 Cohort

0.99
0.98
0.98

0.01
0.01
0.02

536
410
227

"Includes
"Includes
dIncludes
"Includes

hunting and natural deaths.
bIncludes all females age ~12 months.
only females age ~24 months by censoring yearling females recruited from calves.
only females in 1993 trapped cohort having age 18 months to 10+ years.
only natural deaths and represents natural survival rate.

Table 10. Annual survival rates from 1 December-30 November each year 1993-94 - 1996-97 and overall
survival through 14 June 1998 for the group of adult female elk age ~18 months when radio-collared
in
December 1993.
Survival rates (S) calculated as a mean estimate of (alive)/(alive+dead)
and variance S(1S)/n collars.

Survival
L 95% CI
U 95% CI
n collars
censor-ed"
Died
Nonhunt
Hunt

Adult
19931994
0.78
0.68
0.88
68b•e
0
15C
2
13

Elk Age and Time Period
Agult
Adult
Adult
19961995
1994
1997
1996
1995
0.94
0.86
0.84
0.87
0.75
0.75
1. 00
0.97
0.93
53b•f
36i
429
1h
0
0
d
2
6
10
0
3
1
2
3
9

" Censored denotes collar failure or life/death status unknown.
" Collar (172.649/93) disappeared 1994 hunt seasons.
• Composed of 6-18+ and 62-30+ month old females.
9 Composed
of 36+ month old females.
I Composed
of 48+ month old females.

(dates)
AgyH
19931998
0.51
0.39
0.63
67
1h
33
6

27
Includes collar (i72.011/93) failed 4/1994 but seen alive 1/1996.
Collar (172.207/93) disappeared 1995 hunt seasons, assumed dead .
' Composed of 100% females 24+ months old.
h Censored
(172.011/93) failure 4/1996.

b
d

•....
10

co

�Table 11.
Correction factors calculated to estimate total numbers of elk removed by all sources of hunting
mortality from total numbers of elk 'legally removed' by hunting during 1994-1997
hunting seasons.
Wounding
Illegal
Legal
Total
Correction
Elk Sex/Age Class Or
Loss Killb .xi u&gt;
xu iKilledc
Factord
Hunting Season

fQ~ ~~~L8S~ ~lg~~~~
57

7

2

66

0

1

12

13

1.16
1.11 e

41

15

3

59

1.44

35

12

3

50

1. 43f

37

14

2

53

1. 43

5

1

1

7

1.40

44

6

2

52

1.18

26

9

0

35

1.35

Rifle Late Season for
Females Age ~ 12 months

6

3

3

12

2.00

Archery for
Males Age ~

99

0

0

9

1. 00

4

3h

0

7

1. 75

4

1

0

5

1.25

Males Age ~ 24 months
Males Age 12-23 months
Females Age ~ 12 months
Females Age ~ 12 months
Females Age ~ 24 months
Females Age 12-23 months

EQ~ Hynting ~easQn~
Rifle pt, 2nd, &amp; 3rd for
Males Age ~ 24 months
Rifle pt, 2nd, &amp; 3rd for
Females Age ~ 12 months

24

Archery for
Females Age ~

months
12

mbnths

Muzzleloading for
Males Age ~ 24 months
Muzzleloading for
Females Age ~ 12 months

0
5
0
5
1. 00
• Legal kill equals known-killed plus dl.sappeared during hunting seasons and assumed legally killed.
These eLk represent
kill that could be estimated by hunter harvest surveys.
b Wounding
loss and illegal kills would not be estimated by hunter harvest surveys.
Total elk removed by all sources of hunting.
d Multiply
legal kill by correction factor to estimate total elk removed by hunting. For yearling males, mUltiply modeled
numbers of yearlings by 1.11 if yearling males are not legal quarry .
• Removal rate measured from known illegal hunting.
! Correction
factor calculated without including mortalities associated with late rifle seasons.
9 Includes
one legal kill that may have been from either archery or muzzleloading
seasons.
h Includes
one wounding loss that may have been from either archery or muzzleloading
seasons.

the legal

C

estimates

of

I-'
10
10

�Table 12. Data matrix for simple population model using spreadsheet software.
We used a post-hunt
(December) population composition of 50 calves:100 females age L12 months and 4 adult males:16 yearling
males:100 adult females and an estimated population of 3,600 elk.
Fall Hunting
Natural Survival
Natural Survival
Removal Rate
Elk Sex/Age Class
Rate Winter-Spring
Rate Summer-Fall
Elk Sex/Age Class
0.80
Adult Males
1. 00
1. 00
Adult Males
Age L30 months
Age 2.24 months
Yearling Males
Age 12-17 months

1. 00

0.11

Yearling Males
Age 18-23 months

0.98

Adult Females
Age L 24 months

0.99

0.11

Adult Females
Age 2.30 months

0.98

Yearling Females
Age 12-17 months

1. 00

0.05

Yearling Females
Age 18-23 months

0.98

Calves
Age 0-5 months

1. 00

0.02a

Calves
Age 6-11 months

0.89

• Estrmated

from harvest

surveys.

IIJ

o
o

�201
Table 13. Elk counted during quadrat and nonrandom flights on 44 mi2 in West
Divide and Alkali creeks, GMU 42, 27 February-2 March,1998.
Survey
Marked Elk
Unmarked
Total
Marked/ Flight
Flight
Available Seen
Elk Seen Elk Seen
Unmarked Hours
Quadrats
34A
27
744
771
0.036
17.2
NonRandom-1
38
12
420
432
0.029
3.6
NonRandom-2
38
17
534
551
0.032
4.4
Totals
38
56
1698
1754
0.033
25.2
a Four elk off sample area during quadrat counts were on sample area during
nonrandom flights.

Table 14. Summary of quadrat flights for each observer, 27 February - 1
March, 1998.
Total
Minutes
Marked
Elk/
Sighting Trial
Seen/
Flown/.
Observer Quadrats
Total
Unmarked Quadrat Quadrat
Marked Elk
(Date)
Flown
(Range) (Range)
Seen(%) Missed
Elk Seen
Seen
20.6
1B
18
371
0.039
18.5
14
1
(0-68)
(2/28)
(0.93)
(10-27)
2E
(2/27)

17

3M
(3/01)

9

loa

5

314

0.040

18.5
(0-55)

17.8
(10-35)

1

86

0.012

9.6
(0-29)

25.4
(18-39)

(0.67)
1

(0.50)

17.5
19.7
771
0.036
25
7
(0-68)
(10-39)
. (0.78)
aTwo elk groups each contained 2 marked elk that were seen but each group
represented only 1 sighting trial. Observer 2E saw a total of12 marked elk.

Totals

44

Table 15. Status of marked elk missed on quadrats during sighting trials and
subsequently found using telemetry.
Marked
Statul2When Marked Elk Foynd
%Snow
%Screening
Group
Elk
Cover
Cover
Habitat
Observer
Missed
Size
Behavior
Sex
100
Juniper
50
Standing
1
1
IB
M
2E

5

F
F
M
F
M

1

sa
1
1A
1

Bedded
Bedded
Bedded
Moving
Bedded

Oakbrush
Oakbrush
Oakbrush
Oakbrush
Oakbrush

70
70
70
70
60

100
100
100
100
100

2A
50
30
Juniper
Standing
3M
1
F
AThese 3 elk may represent groups or portions of groups of elk that were
detected during quadrat counts but marked elk and other elk in the group were
not seen due to elk behavior or vegetation. For all 3 groups, additional
marked or unmarked elk were seen in close proximity.

�202

Table 16.
Frequencies
at which individual marked elk were seen during quadrat
and nonrandom flights, 27 February-2 March, 1998.
Maximum frequency equals 3.
Frequencies represent heterogeneity
of sighting probabilities
among elk
Total Marks
Frequency Seen During Flightsa
Frequency Seenb
Seen
0
1
2
3
1
56
5
20
8
5
5
a Of the 56 marked elk seen, 46 or 82% were individually
identified by
numbers/symbols
on the collars or telemetry frequency.
Elk not identified had
lost the numbers/symbols
on collars and were seen during nonrandom flights.
b Includes 5 observations
of elk seen but not individually identified.
C Of
the 5 elk not seen, 3 were females and 2 were males.

Table 17. Estimated numbers of elk in survey area based on quadrats, sighting
bias adjusted quadrats, and Bowden and Immigration-Emigration
Joint
Hypergeometric
mark-resight
estimators calculated using program NOREMARK.
Both mark-resight
estimators account for populations not closed to movement
during time of surveys.
Conf. Int. Width
25% Conf. Limits
Total Elk
Upper
Percenta
Lower
Elk
Estimator
Estimate
771
Quadrats
944
14
124
882
820
Quadrats Adj. Model 1b
c
952
814
16
138
Quadrats Adj. Model 2
883
14
116
915
857
799
Quadrats Adj. Model 3d
1,430
457
973
39
Bowden Estimator
1,179
1,337
370
33
967
Imm/EmmJHE Estimator
l,115e
a Width as percent of total estimate.
b Quadrat counts adjusted;
(LOG GROUP SIZE)+(INTERCEPT); AIC=172.
C Quadrat counts adjusted;
(LOG GROUP SIZE)+(BEDDED)+(INTERCEPT); AIC=160.
d Quadrat counts adjusted;
(LOG GROUP SIZE)+(BEDDED)+(%COVER)+(INTERCEPT); AIC=154.
e Represents daily population estimate on sample area.
Extant population
estimate was 1,162 elk.

Table 18.
February-1
Total
Groups
148

Number and size of elk groups seen during quadrat
March 1998.
FI:~gyen!;;;:l!:
of Grou:Q Sizes Seen
25-30
10-24
7-9
4-6
1
2-3
2
18
21
34
35
38

counts,

27

Average
Group Size
5.2

�203

Table 19. Radio-collared
elk captured as calves on winter range in GMU 42
during December 1996 that dispersed out of GMU 42 to a new winter range as of
March 1998.
Locations
(GMUs) determined by aerial telemetry.
Trap
New
Frequency
Zone
Agea
Sex
GMU
Location Description
porcupine Creek-Holms Mesa
172.899/96
G
21
F
42 West
173.450/96
Wallace Creek-Samson Mesa
G
21
M
42 West
East Fork Wallace Creek
173.789/96
42 West
G
21
F
Low Beaver Creek
173.870/96
G
21
F
42 West
Plateau Creek-Hayes Mesa
174.059/96
G
21
M
421
Taughenbauh-Grass
Mesas
174.220/96
F
21
42 West
M
Porcupine Creek-Holms Mesa
174.789/96LE
G
21
M
42 West
174.929/96
D
421
Pole Gulch-Collier
Creek
21
F
East Muddy-Little Henderson Creek
174.949/96LE
D
21
521
F
Hawxhurst Creek~Grassy Gulch
174.969/96
D
421
F
21
East Muddy-Little Henderson Creek
174.998/96
E
521
21
F
Hawxhurst Creek
175.020/96
F
421
21
F
Low Beaver Creek
175.039/96
G
F
42 West
21
West Muddy-Ault Creek
175.050/96LE
E
521
F
21
42 West
Wallace Creek-Sugarloaf
Mtn.
175.070/96
E
F
21
Low Fourmile Creek
175.089/96
A
F
43
21
Wallace Creek-Sugarloaf
Mtn.
175.180/96
E
M
42 West
21
Plateau
Creek-Red
Mountain
175.189/96LE
E
M
421
21
Low Wallace Creek-High Mesa
175.199/96
G
M
42 West
21
a
b

Age of elk in months as of March 1998.
LE = Location elk routinely located.

�204
Appendix I. Mortalities of 181 radio-collared elk from 1 December 1993 through 14 June 1998. Age is
aBeroximate age in years of elk at death: C=calf age 6-11 months, Y=yearling age 12-23 months.
Frequency 101
Q~ath
Ira!2
Age
Year Ca~tured Site Zone Sex
Date
Cause of Death &amp; Code Number
172.030/93
BR
A
F
5
27-0ct-95
Legal kill second rifle season-47
172.039/93
GR
B
F
4
14-Jun-95
Unknown-suspect predation-30
172.070/93
BR
A
F
11
12-Feb-96
Unknown-11
172.080/93
GM
A
F
6
05-Nov-94
Legal kill third rifle season-48
172.090/93
GR
B
F
11
16-Jan-94
Wounding loss late rifle season-26
172.101/93
SR
B
F
8
14-0ct-96
Legal kill first rifle season-46
172.128/93
GC
B
F
8
31-0ct-96
Wounding loss second rifle season-44
172.139/93
F
BC
C
17
19-0ct-95
Wounding loss first rifle season-43
172.160/93
CC
C
F
3
23-0ct-94
Legal kill second rifle season-47
172.181/93
MC
C
F
3
03-Nov-94
Wounding loss second rifle season-44
172.201/93
GS
C
F
3
15-Nov-94
Wounding loss second rifle season-44
172.207193
SG 0
F
4
30-Nov-95
Disappear first rifle season-40
172.258/93
HY
F
C
3
04-0ct-94
Legal kill archery/muzzle season-27
1n.277/93
GS
C
F
3
04-0ct-94
Wounding loss archery/muzzle-24
172.290/93
SG 0
F
6
23-0ct-94
Legal kill second rifle season-47
172.290/94
SM 0
F
4
16-Sep-96
Legal kill muzzleloading season-34
172.300/93
AC
E
F
8
30-0ct-97
Wounding loss second rifle season-44
172.369/93
AC
E
F
3
18-Sep-94
Legal kill archery season-33
172.369/94
FM B
F
4
14-Jan-96
Legal kill late rifle season-29
172.409/93
AC
F
E
8
29-0ec-94
Wounding loss late rifle season-26
172.459/93
MH
E
F
8
24-0ct-96
Legal kill second rifle season-47
172.509/93
FS
H
F
3
21-0ct-95
Legal kill second rifle season-47
172.542/93
FS
H
F
01-Feb-94
Mountain lion predation-3
6
172.549/93
PG
H
F
7
28-Nov-95
Legal kill late rifle season-29
172.570/93
PG
H
F
16 03-Nov-94
Wounding loss second rifle season-44
172.581/93
PG
H
F
3
17-0ct-94
Legal kill first rifle season-46
172.581194
FM B
F
3
08-0ec-95
Legal kill late rifle season-29
172.590/93
PG
H
F
24-Apr-96
Unknown-11
5
172.610/93
PG
F
04-0ct-94
Accident, birthing/calving-32
H
3
172.639193
PG
F
14-Jun-96
Accident, birthing/calving-32
H
16
172.649193
PG
F
30-Nov-94
Disappear first rifle season-40
H
2
172.658/93
PG
F
Legal kill third rifle season-48
H
5
02-Nov-97
16~Jan-95
172.670/93
PG
H
F
Legal kill late rifle season-29
4
172.678/93
PG
H
F
22-0ec-94
Wounding loss late rifle season-26
9
172.690/93
FM B
F
24-Jan-94
Illegal kill-7
8
172.699/93
Legal kill third rifle season-48
FM B
F
7
05-Nov-95
Unknown-suspect predation-30
172.749/95
LS
H
F
11 07-Aug-96
172.800/93
Disappear second rifle season-41
SR
B
F
Y
30-Nov-94
172.821/93
EG
Legal kill archery season-33
B
F
3
08-Sep-96
Legal kill third rifle season-48
172.890/93
F
06-Nov-96
BC
C
3
Mountain lion predation-3
172.899/93
BC
C
F
18-Mar-94
C
Legal kill first rifle season-46
172.950/93
GH 0
F
18-0ct-95
2
172.961/93
F
30-0ct-97
Disappear second rifle season-41
MG
0
4
173.000/93
25-Apr-94
Malnutrition-6
\lM
G
F
C
07-Jan-98
Accident-fell-10
173.010/93
\lM
G
F
4
Legal kill first rifle season-46
173.041/93
M
19-0ct-95
GM A
2
27_'Oec-95
Legal kill late rifle season-29
173.060/93
MH
E
F
2
Illegal kill-7
03-Mar-98
173.070/93
MH
E
F
5
Legal kill second rifle season-47
173.081193
FS
H
F
3
22-Oct-96
Legal kill second rifle season-47
24-0ct-97
173.090/93
FS H
F
4
Legal kill second rifle season-47
173.100/93
F
30-0ct-97
FS H
4
Legal kill first rifle season-46
.14-Oct-95
173.120/93
GM A
M
2
Wounding loss second rifle season-44
31-0ct-96
173. 140i93
PG
H
F
3
Legal kill third rifle season-48
173.160/93
FS
F
13-Nov-96
H
3
Illegal kill second rifle season-50
BC
29-0ct-94
173.190/93
C
M
Y
Wounding loss thtrd rifle season-45
173.201193
GR
M
30-Nov-95
B
2
Legal ki II first rifle season-ee
19-0ct-95
173.210/93
GC
B
M
2
Illegal kill archery/muzz. season-8
30-0ct-97
173.210/96
LM 0
M
2
Legal kill third rifle season-48
06-Nov-95
173.219/93
BC
M
2
C
Illegal kill second rifle season-50
15-Nov-94
M
Y
173.232193
BR A
18-Mar-94
173.262/93
BC
M
C
Unknown-"
C
Legal kill first rifle season-46
M
12-0ct-96
173.262/94
HM
B
2
Legal kill third rifle season-48
06-Nov-95
173.269/93
MC
C
M
2
Legal ki LL. first rifle season-46
12-0ct-96
MC
3
173.279/93
C
M
Unknown-11
22-Mar-94
MC
C
M
C
173.289/93
Legal kill muzzleloading season-34
M
18-Sep-96
173.289/94
PR
A
2
Legal kill second rifle season-47
24-Oct-95
GS
C
M
2
173.300/93
Illegal kill first rifle season-49
30-Nov-94
HY
C
M
Y
173.309/93
Illegal kill first rifle season-49
20-0ct-94
HY C
M
Y
173.320/93
Legal kill archery season-33
14-Sep-96
HM
M
2
173.320/94
B
!~~}~L~~
_____
~~__E_____
~____
~___
~~~~~~:?]
______
~~2!_~L~~~!~~~~2~l~[_s:2~~~:~~ __________________

.

�205
A~ndix
I. (continued)
Frequency 10/
Ira~
Year CaE!tured Site Zone
173.340/93
D
SG
173.351/93
SG
D
173.359/93
AC
E
173.370/93
MH
E
173.370/96
RG
E
173.381/96
RG
E
D
173.390/93
MG
173.402193
MG
D
173.410/93
WM
G
WM
173.420/93
G
173.429/93
MH
E
173.439/93
PG
H
173.450/93
PG
H
173.461/93
PG
H
173.461/94
CM
A
173.469/93
FS
H
173.469/94
PR
A
173.479/93
FS
H
173.492/93
FS
H
173.502193
FS
H
173.510/93
FM
B
173.521/93
FM B
173.540/94
OG
B
B
173.549/94
HM
173.569/94
PR
A
A
173.580/94
PR
173.589/94
OG
B
173.610/94
BC
C
173.640/94
MC
C
173.640/96
GM
A
173.649/94
BC
C
BG
173.689/94
E
173.789/94
E
MR
MM
F
173.819/94
MM
F
173.829/94
173.859/94
SM
D
173.870/94
SM
D
173.919/94
BC
C
173.929/94
BC
C
173.939/94
BC
C
BC
173.959/94
C
C
173.970/94
MC
173.981/94
MP
D
173.990/94
BC
C
174.001/94
BG
E
E
174.009/94
BG
BG
E
174.019/94
MR
E
174.039/94
174.049/94
MM
F
E
174.059/94
MR
E
174.069/94
BG
174.080/94
MR
E
E
174.090/94
MR
,174.101/94
F
MM
174.109/94
MM
F
F
174.119/94
MM
174.119/95
GB
B
F
174.129/94
MM
174.140/94
MM
F
B
174~140/95
GB
F
174.150/94
MM
F
174.160/94
MM
FM B
174.170/94
FM
B
174.181/94
MS
F
174.200/95
MS
F
174.210/95
MS
F
174.220/95
MS
F
174.230/95
MD
E
174.240/95
MS
F
174.319/95
MD
E
174.329/95

Sex
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
F
F
F
F
F
F
F
F
F
F
F
F
F
F
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
F
F

Q~ath
Date
20-0ct-97
05-Nov-95
06-Sep-95
08-Nov-95
08-Jan-97
19-Feb-97
30-Nov-95
18-0ct-95
02-Nov-95
24-0ct-95
14-Sep-95
30-Nov-95
15-0ct-95
07-Feb-94
19-5ep-95
25-Apr-94
20-0ct-96
10-Sep-95
03-Sep-95
13-Nov-96
28-Aug-95
17-0ct-95
t3-0ct-96
07-Sep-95
16-0ct-97
21-Dec-95
01-Jun-95
14-Nov-97
30-Mar-95
16-Mar-97
11-0ct-97
31-0ct-96
20-Mar-95
30-0ct-97
10-Jan-97
23-0ct-96
21-Feb-95
02-Nov-95
16-0ct-96
18-Sep-96
02-Nov-96
20-0ct-96
02-Nov-96
20-0ct-96
30-Nov-96
12-Oct-96
13-Noy-96
05-Sep-96
14-Sep-96
17-0ct-95
26-Sep-96
11-0ct-97
20-Oct-96
24-May-96
19-0ct-96
01-Mar-95
30-Noy-97
14-0ct-96
14-Mar-95
30-Noy-96
14-0ct-96
15-Sep-96
25-Apr-95
30-Nov-96
18-0ct-96
11-Oct-97
08~Apr-96
24-Apr-96
17-Apr-96
C
02-Oct-96
Y
03-Sep-96
Y

Age
4
2
2
2
C
C
2
2
2
2
2
2
2
C
Y
C
2
2
2
3
2
2
2
Y
3
Y
C
3
C
C
3
2
C
3
2
2
C
Y
2
2
2
2
2
2
2
2
2
2
2
Y
2
3
2
Y
2
C
2
2
C
Y
2
2
C
2
Y
2
C
C

!~~~3)2L~~ _____ ~~ ___~ ____ ~ ____ ~___

Cause of Death &amp; Code Number
Legal kill second rifle season-47
Legal kill third rifle season-48
Legal kill archery season-33
Legal kill first rifle season-46
Mountain lion predation-3
Unknown-suspect predation-30
Disappear first rifLe season-40
Legal kill first rifle season-46
Wounding loss second rifle season-44
Legal kill second rifle season-s?
'Legal kill archery season-33
Disappear first rifle season-40
Legal kill first rifle season-46
Malnutrition-6
Wounding loss archery season-50
Malnutrition-6
Legal kilL second rifLe season-47
Legal kill archery season-33
Legal kiLL archery season-33
Legal kill third rifle season-48
Legal kiLL archery season-33
Legal kill first rifle season-46
Legal' kill first rifle season-46
Legal kiLL archery season-33
Wounding loss first rifle season-43
Unknown-11
Unknown-suspect predation-30
Wounding loss third rifLe season-45
Unknown-suspect predation-30
Malnutrition-6
Legal kill first rifle season-46
Legal kiLL first rifle season-46
Unknown-suspect maLnutrition-31
Legal kill second rifle season-47
LegaL kill late rifle season-29
Legal kill second rifle season-47
Mountain lion predation-3
Illegal kill second rifle season-50
Legal kill first rifle season-46
Legal kill archery season-33
Legal ki II third riHe season-48
Legal kill second rifle season-47
Legal kill third rifle season-48
Legal kill second rifle season-47
Disappear archery/muzzLe season-21
Legal kill first rifle season-47
ILlegal kiLL rifle season-9
Legal kill archery season-33
Legal kilL muzzleloading season-34
Illegal kill first rifLe season-49
Wounding loss archery/muzzle-24
Legal kill first rifle season-46
Legal kill second rifle season-47
Unknown-suspect predation-30
Legal kilL second rifle season-47
Mountain lion predation-3
Wounding loss rifle season-25
Legal kill first rifle season-46
Mountai'n lion predation-3
Illegal kill third rifle season-51
Legal kill first rifle season-46
Legal kill muzzleloading season-34
Mountain lion predation-3
Disappear second rifle season-41
Illegal kilL first rifle season-49
Legal,kill first rifle season-46
Unknown-suspect malnutrition-31
Mountain lion predation-3
Mountain lion predation-3
Wounding Loss archery season-52
Legal kill archery season-33

lI~~~~:?~
______
u_n!~2~JP~~~!~~:?
_________________________________
:

�206

Appendix I. (continued)
Frequency 101
Ie!!!:!
Year Captured Site Zone
174.349/95
MD
E
174.360/95
MD
E
174.401/95
AP
D
174.420/95
AP
D
\JI)
174.478/95
C
174.491195
lB
C
174.500/95
lB
C
174.520/95
KR
B
174.520/96
GM
A
174.560/95
Bl A
174.609/95
GB
B
174.629/95
MD
E
174.639/95
MD
E
174.679/95
HG
E
174.689/95
AP
D
174.689/96
EW
G
174.700/95
AP
0
174.710/95
AP
0
VM
0
174.729/95
VM
174.740/95
0
VM
174.750/95
0
174.770/95
WD
C
WD
C
174.780/95
174.789/95
WD
C
174.800/96
BG
E
174.809/95
WD
C
174.820/95
WD
C
174.830/95
lB
C
174.851/95
lB
c
174.861/95
KR
B
lB
c
174.870/95
KR
B
174.880/95
174.889/95
we G
Bl
A
174.899/95
lM 0
174.910/96
Be
c
175.059/96
175.130/96
GM
A
lM
0
175.170/96

[1g!!!1:!

Sex
F
F
F
F
F
F
F
F
F
F
F
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
F
F

Age
2
Y

F

c

M

2

2
2
2
C
Y
C
y'

C
2
2
Y

C
C
2
2
Y

2
2
2
2
C
C
Y

2
2
2
Y
2

2
2
2

c

c
c

Date
13-0ct-97
22-Apr-97
22-Sep-96
11-0ct-97
13-Sep-97
10-Sep-97
16-Apr-96
21-Sep-96
25-Apr-97
14-May-97
'15-Apr-96
11-0ct-97
21-0ct-97
13-Nov-96
05-Feb-96
14-May-97
16-0ct-97
15-0ct-97
17-0ct-96
08-Nov-97
05-Nov-97
16-0ct-97
11-0ct-97
22-May-96
09-Apr-97
22-Apr-97
14-0ct-97
13-0ct-97
22-0ct-97
31-0ct-96
30-0ct-97
11-0ct-97
20-0ct-97
30-0ct-97
27-Feb-97
13-Feb-97
24-Mar-97
26-Mar-97

Cause of Death &amp; Code Number
legal kill first rifle season·46
Unknown-suspect predation-30
legal kill muzzleloading season·34
legal kill first rifle season-46
legal kill muzzleloading season-34
Wounding loss archery season-52
Unknown-suspect predation-30
legal kill muzzleloading season·34
Mountain lion predation-3
Illegal kill-7
Unknown-suspect predation-30
legal kill first rifle season-46
legal kill second rifle season-47
Illegal kill second rifle season-50
Mountain lion predation-3
Unknown-suspect malnutrition-31
Wounding loss first rifle season-43
legal kill first rifle season-46
Illegal kill first rifle season-49
legal kill third rifle season-48
legal kill third rifle season-48
Disappear first rifle season-40
legal kill first rifle season-46
Unknown-suspect predation-30
Mountain lion predation-3
Accident, fell-10
legal kill first rifle season-46
legal kill first rifle season-46
Illegal kill second rifle season-50
Illegal kill second rifle seasonc50
Wounding loss second rifle season·44
legal kill first rifle season-46
legal kill second rifle season-47
Wounding loss second rifle season·44
Unknown-suspect predation·30
Unknown-11
Mountain lion predation·3
Unknown-suspect malnutrition-31

�172

�171

Colorado Division of Wildlife
Wildlife Research Report
July 1999

JOB PROGRESS REPORT

Smteof

~C~o~lo~r~ad~o~

_

Mammals Research
Project No.
---'W.:.,.--=1...:,5;::;..3-..:.R::....-=12=--_
Elk Investigations
Work Package __ --=3::...:0:;,,::0:,:2'-_
Task No.
---=-1
_
Estimating Survival Rates of Elk and Developing
Techniques to Estimate Population Size
Period Covered:

July 1, 1998 - June 30, 1999

Author: D. 1. Freddy
Personnel:

R. Adams; T. Beck J. Broderick, G. Byrne, D. Crane, R. Del Piccolo, J. Ellenberger, V.
Graham, D. Homan, R. Kahn, K. Madariaga, D. Masden, C. Mehaffy, P. Neil, J.
Olterman.J, Thompson, P. Will, K. Wright, S. Yamashita, D. Younkin, CD OW; D.
Bowden, G. White.T, Gross, M. Kneeland, W. Andelt, CSU; D. Ouren, D. Schneider, T.
Fancher USGS-BRD, BLM Glenwood Springs, CO, USFS Rifle, CO, Rocky Mountain
Elk Foundation, cooperating.

ABSTRACT
We monitored survival and movements of 169 previously radio-collared elk composed of 136
adult females and 33 adult males from 1 July 1998 through 30 June 1999. Survival of adult females
during summer-fall was 0.77 ± 0.07 (n = 136) inclusive of hunting deaths and 1.00 (n = 105) with
hunting deaths censored while survival during winter-spring was 0.98 0.03 (n = 103). The 2 deaths
of adult females during winter-spring were attributed to accident and malnutrition. Survival of adult
males during summer-fall was 0.34
0.17 (n = 32) inclusive of hunting deaths and 1.00 (n = 11) with
hunting deaths censored while survival during winter-spring was 1.00 (n = 11). A combination of
unlimited either-sex elk hunting licenses and high numbers of antlerless elk hunting permits during rifle
hunting seasons in 1998 contributed to removing 23% of the adult females which was sufficient to
temper population growth. Progress continues towards developing habitat use models to predict areas
important to managing elk. Draft manuscripts on elk survival rates and techniques to estimate
population size are progressing.

±

±

�173

ESTIMATING

SURVIVAL RATES OF ELK AND DEVELOPING
ESTIMATE POPULATION SIZE

TECHNIQUES

TO

David 1. Freddy

P. N. OBJECTIVE
Estimate survival rates of adult female, adult male, and calf elk and develop techniques to
estimate population size.

SEGMENT OBJECTIVES
1. Estimate winter, summer, and annual survival rates of adult female and male elk from fates of
previously radio-collared elk.
2. Develop an initial habitat use prediction model for elk inhabiting oakbrush dominated habitats based
upon locations of radio-collared elk obtained from 1993 -98.
3. Analyze data, summarize annually in Federal Aid Job Progress Report, and prepare draft
manuscripts regarding elk survival rates and techniques to estimate population size.

INTRODUCTION
Our objectives are to provide reliable estimates of survival rates for calves during winter and for
adult females and males throughout the year and to develop and test a system to estimate elk densities
on winter ranges. Estimates of calf survival were obtained during winters 1993-94 through 1996-97
and summarized in Freddy (1997). We are continuing to obtain estimates of survival for adult males
and females. For adults, we are interested in survival rates inclusive of hunting mortalities to document
human-induced rates of survival and exclusive of hunting mortalities to estimate natural rates of
survival. We are evaluating a system for estimating population size or density that incorporates
estimates of sighting bias in conjunction with random sampling of search quadrats as sample units.
Our winter study area encompasses about 324 rnf (839 knr') in the eastern half of Game Management
Unit 42 south and east of Rifle, Colorado. This area is part of the Grand Mesa Elk Data Analysis Unit
E-14. Elk winter habitats include juniper-pinyon woodland (Juniperus osteosperma-Pinus edulis),
oakbrush-mountain shrub (Quercus gambelii-Amelanchier alnifolia), aspen (Populus tremuloides),
sagebrush (Artemisia tridentata), and agricultural fields below elevations of9,800 ft. In summer, elk
use oakbrush-mountain shrub, aspen, and subalpine fir-Engelmann spruce (Abies lasiocarpa-Picea
engelmannii) meadow systems throughout the Grand Mesa region up to elevations of 12,000 ft.
(Freddy 1993).

METHODS
We placed radio collars (172-176MHz) having mortality sensors on elk calves age 6 months and
adults age 2:18 months during December 1993-1996 (Freddy 1997). Elk were captured using
helicopter net-gunning and portable corral traps (Freddy 1997). During 1998-99, we monitored 169
adult elk, 136 females and 33 males, having functioning radios as of July 1998. Collars were white
and had black identification symbols on dorsal surfaces of collars to allow visual identification of
individual elk.

�174

Estimating Elk Survival Rates
We monitored survival of radioed elk with aerial surveys using a Cessna 185 at 2-4 week intervals
from December 1993 to June 1999 and with daily ground surveys from December-April each year
from 1993-94 to 1996-97. Survival rates (S) of radioed elk were calculated using the binomial
estimator with a variance, V AR(S) = S(I-S)/n collars (White and Garrott 1990). Survival rates are
expressed as the mean estimate
the 95% confidence interval. We used x2-contingency tests to
compare survival rates between sexes and among time intervals (pROC FREQ, SAS 1988). Sample
sizes refer to numbers of individual radioed elk.
We defined 3 major time intervals for survival analyses: winter-spring was 1 December to 14
June, summer-fall was 15 June to 30 November, and annual was 1 December to 30 November to
coincide with timing of capture and collaring. For adult elk during these time intervals, we calculated
survival rates inclusive of natural and hunting-related mortalities, exclusive of hunting mortalities, and
exclusive of natural mortalities. Excluding, or censoring hunting mortalities, provided estimates of
natural survival rates. Excluding natural mortalities but including hunting mortalities provided
estimates of hunting removal rates. Censoring elk associated with categories of mortalities reduced
sample sizes used to estimate survival rates. Elk were also censored ifradios failed or if their life/death
status was unknown after an extended period of time.
Archery, muzzleloading, and rifle hunting seasons occurred from about 1 September to 15
November each year during the summer-fall time interval. Late-rifle seasons occurred in some years
. and restricted hunters to taking only antlerless elk from about 25 November-31 January which included
portions of the summer-fall and winter-spring time intervals. Yearling spike-antlered males were
generally not legal quarry in most areas frequented by radioed elk. Male elk were legal quarry when
branch-antlered usually at age 2 years.
Cause of death of radioed elk recovered in the field was estimated from presence or absence of
gunshot wounds or bite wounds on carcass, predator tracks or scat at carcass site, physical positioning
of carcass remains whether buried, covered, scattered, or consolidated (Wade and Browns 1982,
Halfpenny and Biesiot 1986), relative amount of internal fat and marrow fat if present with carcass, and
results of histopathology and marrow fat analyses. Fat content (percent dry matter) of bone marrow
and estimates of age based on dental cementum were obtained for dead elk by the Colorado Division of
Wildlife Laboratory while histopathology analyses were provided by the Colorado State University
Veterinary Diagnostic Laboratory. Photographs were taken of nearly all mortalities so that physical
evidence could be reviewed and judged by outside experts (pers. comm. T. Beck, W. Andelt).

±

Elk Movements and Habitat Use Models
We continued to precisely locate selected radioed elk at least once per month since their capture to
document seasonal movements using a Cessna 185. These elk were originally selected at random from
within trap zones and equalized by age class in January 1994. Elk from the original sample that died
were replaced each subsequent January with randomly selected elk that were usually of the same sex,
age class, and trap zone as elk that died. All replacement elk in January 1999 were ;:::2-years old. As
of 1 January 1999, these 43 elk were classified as 32 adult females and 11 adult males males. During
June 1999, we again located an additional 28 adult females that were originally selected at random in
1995 to document their locations during the calving period. Females from the original 1995 sample
that died were replaced each subsequent June with adult females randomly selected from the same trap
zones of elk that died. As needed, we located other elk to document unusual movements.
We continue to cooperate with the USGS-BRD, USFS, and BLM with the support of the Rocky
Mountain Elk Foundation to create a GIS database allowing analyses relating elk locations,
movements, and home ranges to habitat components with the intent of developing a predictive habitat
use model. During 1998, initial efforts were undertaken to develop a model with Dr. 1. Gross at the
Natural Resource Ecology Laboratory at Colorado State University.

�175

Elk habitat models are being developed by using a staged process. Major stages included initial
data analysis and reduction, development of predictive variables (i.e., GIS coverages), and .
development and statistical analysis of alternative habitat models.
Initial data analysis included an extensive process to locate and correct errors in the data set,
create new variables (e.g., age, class, season), and to subset the data so that analyses included only the
animals of interest. This first stage of this process was accomplished by developing a database
application in MicroSoft Access© that validated data records and produced new tables with the data
needed for further analysis. The entire data set consisted of 5,321 elk locations. We reduced the data
set to include only data from elk that were randomly selected and systematically located during years
1993-1998. This reduced total elk locations to 2,888.
Locations were subset into groups by sex, age (calf, yearling, adult), and season. Seasons were
biologically defined as spring (1 April- 30 May), summer (1 June - 31 August), fall (1 September - 30
November), and winter (1 December - 31 March). Using ArcInfo© and Ar~VieW©, we linked each
location to GIS coverages for elevation, slope, aspect (EW and NS), distance to a road, and to tasselcap indices for brightness, greenness, and wetness. To evaluate the ability of these variables to predict
elk observations, we used ordinary least squares (Upton and Fingleton 1985) to identify significant
relationships arid coefficients that were used for logistic regression.

RESULTS AND DISCUSSION
Between 1 December 1993 and 14 June 1999,235 radioed elk died of which 31 were calves 611 months old and 204 were adults ~12 months old (Table 1, Appendix I). Calves died of natural
causes (Freddy 1997) while for adults hunting accounted for 93% of 204 deaths. Hunting accounted
for 98% of 102 deaths for adult males and 88% of 102 deaths for adult females.
.

Survival Estimates
Adult Females Summer-Fall
Survival during summer-fall 1998 for adult females all age 2:.24 months was 0.77 ± 0.07 (n = 136)
inclusive of hunting deaths and 1.00 (n = 105) with hunting deaths censored (Table 6). Net survival in
1998 was the lowest measured during 5 summer-fall periods due to increased hunting deaths that
resulted in a hunting removal rate of 23%. Reduced survival due to hunting in 1998 was evident in all
cohorts offemales (Tables 2-5,7,8). Natural survival rates remained &gt;0.99 during all 5 years (Table

6).
Increased hunting removal rates were caused by a combination of increased numbers of limitedentry rifle antlerless permits and first-time use of unlimited over-the-counter rifle either-sex permits.
Unlimited either-sex permits were valid in Game Management Units (GMUs) 43,52, and 521 during
the second and third rifle seasons while limited antIerless permits were available for GMUs 42 and 421
for the first, second, and third rifle seasons. These GMUs collectively encompassed the area inhabited
by radioed female elk. Approximate locations of each radioed female were obtained prior to each
season, each elk was assigned to a GMU, and life/death status of each elk was known prior to and
following each season.
During the second rifle season, adult female removal rates were greater in areas having unlimited
either-sex permits (26%) than in areas having limited antIerless permits (6%) (P=O.OOI, X2 =10.7,
dJ=I). During third rifle season, removal rates were not different between types of permits (P=0.53, X2
=0.39, dJ=I)(Table 10). Removal rates with antlerless permits were consistent between seasons while
removal rates with either-sex permits declined drastically during the third season (Table 10). In this
geographic area, unlimited either-sex permits provided a burst of female removal only during the
second season.

�178
Prepared

by

_

David J. Freddy
Life/Science
Researcher

Table l. Causes of deaths in radio-collared elk between 1 December 1993 and 14 June 1999. Calves
(M=male, F=female) were age 6-11 months and collared at age 6 months. Yearling males and females
.were age 12-17 months and juvenile males and females were age 18-23 months and all were collared at age
6 months. Adult males and females were age &gt;24 months at time of death.
Elk Age/Sex Class at Death
Adult
Total
Cause of Death
Calves
Yearling
Juvenile
M
F
M
All
and -Code
M
F
M
F
M
F
F
Natural Causes
0
3
Malnutrition-6
2
0
0
0
2
5
2
0
Unknown-Suspect
Malnutrition-31
0
0
3
1
3
1
0
0
0
0
4
Predation-Lion-3
0
0
1
8
5
13
8
4
0
0
0
0
Predation-Bear- 35
0
0
0
0
0
0
0
0
0
0
0
0
0
Unknown Predator-5
0
0
0
0
0
1
1
1
Unknown-Suspect
0
Predation-30
2
1
1
2
3
8
11
5
0
0
Accident-Birthing-32
0
0
0
2
0
2
0
0
0
0
2
Accident-Fell-IO
0
1
0
0
2
2
0
0
0
1
3
Unknown Cause-l l
2
0
0
2
4
1
0
0
1
2
6
Subtotals
10
26
45
14
Q
Q
Q
£
£
12
11
Le~1 Hunting
Arc ery-33
0
0
0
0
9
3
9
5
0
2
14
·4
Muzzleloading-34
0
0
0
0
8
2
8
12
0
2
0
0
0
0
0
1
0
1
0
0
1
Arch~lMuzzle-27
28
28
Rifle- irst-46
0
0
0
0
0
0
11
11
39
15
15
17
Rifle-Second-47
0
0
0
0
0
17
32
0
0
0
9
12
9
12
Rifle- Third-48
0
0
0
0
21
0
0
0
0
0
6
6
6
Rifle-Late-29
0
0
0
69
52
56
69
125
Subtotals
Q
Q
Q
Q
Q
1.
Wound~Loss
0
2
2
2
Archery uzzle-24
0
0
0
0
0
2
4
0
0
0
1
1
2
3
Archery-52
0
0
1
1
0
0
1
3
1
Rifle-First-43
0
0
0
0
3
4
Rifle-Second-a-t
0
0
0
0
0
4
10
4
10
14
0
2
2
Rifle- Third-45
0
0
0
0
0
1
1
3
0
0
r
1
Rifle-Unk.Reg.-25
0
0
0
0
0
0
0
1
0
0
0
Rifle-Late-26
0
0
0
0
0
3
3
3
10
20
Subtotals
32
Q
Q
Q
Q
11
£1
1
1
Illegal Hunting
0
5
Rifle-First-49
0
5
0
0
0
0
5
0
0
6
Rifle-Second-50
0
5
0
0
I
0
0
6
0
0
-. 0
0
Rifle-Third-51
1
0
0
0
0
1
0
1
0
0
0
1
0
0
Rifle-Unk.Reg.-9
0
0
0
0
1
1
0
I
0
0
0
0
1
0
1
Archery Season-8
0
0
Out-of-Season-7
0
0
0
1
0
2
0
3
3
0
0
0
12"
Subtotals
}.
Q
Q
Q
11
1
£
£
11
Presumed Hunting"
Missing-ArchMuzz-21
0
0
1
0
0
0
0
0
0
1
1
3
3
Missing-Rifle Ist-40
0
0
0
0
0
0
3
3
6
Missing-Rifle 2nd-41
0
0
0
2
6
2
7
0
1
0
9
Missing-Rifle 3rd-42
0
0
0
0
0
0
0
0
0
0
0
Subtotals
10
16
Q
Q
Q
Q
.2
Q
.2
.2
1
Totals

17

14

13

6

2

3

87

93

119

116

235

• These elk were illegally shot as spike-antlered yearling males: (173.190/93) (173.232/93) (173.309/93) (173.320/93) (173.919194)
(174.059/94) (174.140/95) (174.200/95) (174.679/95) (174.729195) (174.861195) (173.210/96). (173.309/93) disappeared in 1994 during first
rifle season when spike-antlered yearling males were not legal and was assumed to have been taken illegally. All other illegal deaths were confirmed.
b These elk disappeared during hunting seasons and remained missing for several months and are assumed dead and legally harvested:
(172.207193) (172.269193) (172.308193) (172.498193) (172.649/93) (172.800/93) (172.961/93) (172.991193) (173.390/93) (173.439193)
(173.760/94) (174.001/94) (174.181/94) (174.770195) (174.929/96) (175.199/96).

�Table 2. Survival rates, inclusive ofnonhunting and hunting mortalities, for winter-spring (WS, 1 December-14 June) and summer-fall (SF, 15
June-30 November) time periods from 1 December 1993-14 June 1999 for the cohort of calves age 6 months radio-collared in December 1993.
Survival rate for male and female calves pooled when age 6-11 months was 0.92 (95% CI 0.86-0.98, n=73). Survival rates (S) calculated as a mean
estimate of (alive)/(alive + dead) and variance S(1-S)/n collars.
Elk Elk Age (months) and Time Period (WS or SF dates)
6-11 (mos)

12-17

18-23

24-29

30-35

36-41

42-47

48-53

54-59

60-65

66-71

6-71

WS

SF

WS

SF

WS

SF

WS

SF

WS

SF

WS

ALL

1993-94

1994

.1994-95

1995

1995-96

1996

1996-97

1997

1997-98

1998

1998-99

1993-99

0.88
0.78
0.99
32
0
4b
0
4

1.00
0.76
0.99
28
0
0
0
0

0.21

1.00
0.06
0.37
4
0
0
0
0

0.50
0.00
0.00
4
22
0
2

1.00
0.00
1.00
2r
0
0
0
0

0.00

0.97
0.87
1.00
35
0

1.00
0.92
1.00
34
0
0
0
0

0.97
0.91
1.00
33
0
1
0
1

0.84
0.91
1.00
32
0
5
0
5

1.00
0.71
0.97
27
0
0
0
0

0.89

MALES
Survival 0.89
L 95%CI
U 95%CI
n collars 36
Censored"
Died
4
Nonhunt 4
Hoot
0

28&lt;
0
224
0
22

1
0
1
0
1

0.00

33
1&amp;

3-'&amp;
33
4
29

FEMALES
Survival 0.95
L95%CI
U95%CI
n collars 37
Censored"
Died
2
Nonhunt 2
Hoot
0

Ih
0
1

0.97

34
0
1
0
1

27
0
31
0
3

0.96
0.76
1.00
24
0
1
1
0

0.87
0.87
1.00
23
0
31
0
3

1.00
0.72
1.00
18
0
0
0
0

0.51
0.34
0.69
35
21t
17
'3
14

2

• Censored denotes collar failure and/or animallifeldeath status not known.
b Collar (173.309/93) disappeared 1994 hunting seasons and assumed dead.
e Includes (173.241193) collar failure August 1995 but seen January 1996.
d Collars (173.390/93),(173.439/93)
disappeared 1995 hunting seasons and assumed dead.
• Censored elk; (173.241193) failed August 1995, (173.381193) slipped collar December 1995.
r Includes (173.340/93) alive May 1997.
I Censored elk (173.249/93)
slipped collar September 1997.
k Collar (172.800/93) disappeared 1994 hunting seasons and assumed dead.
i Collar (172.961193) disappeared 1997 hunting seasons and assumed dead.
j Collar (172.991193) disappeared 1998 hunting seasons and assumed dead.
k Censored elk (172.849/93) failed May 1999, (173.151193) failed February 1999.

.....
.....)
\0

�Table 3. Survival rates, inclusive ofnonhunting and hunting mortalities, for winter-spring (WS, 1 December-14 June) and summer-fall (SF, 15
June-30 November) time periods from 1 December 1994-14 June 1999 for the cohort of calves age 6 months radio-collared in December 1994.
Survival rate for male and female calves pooled when age 6-11 months was 0.90 (95% CI 0.83-0.97, n=69). Survival rates (S) calculated as a mean
estimate of (alive)/(alive + dead) and variance S(1-S)/n collars.
Elk Age (months) and Time Period (WS or SF dates)
6-11 (mos)

12-17

WS

SF

1994-95

1995

0.91
0.81
1.00
33b
0
3
3
0

0.90
0.79
1.00
30b
0

.0.97
0.78
0.99
32
0
1
0
1

0.97
0.91
1.00
30
0
1
1
0

18-23
./

24-29

30-35

36-41

42-47

48-53

54-59

6-59

WS

SF

WS

SF

WS

SF

WS

ALL

1995-96

1996

1996-97

1997

1997-98

1998

1997-98

1994-98

0.96
0.88
1.00
26
1c
1
1
0

0.08
0.00
0.19
25
0
23
0
23

1.00

1.00

0.00

0.00

2d
0
0
0
0

0.50
0.00
1.00
2
0
1
0
1

1
0
0
0
0

0
18
0
0
0

31
2
31
4
27

0.93
0.90
1.00
29

0.96
0.83
1.00
27
0
1
0
1

0.85
0.89
1.00
26
0
4
0
·4

1.00
0.70
0.99
22
0
0
0
0

0.64

1.00
0.42
0.85
14
0
0
0
0

MALES
Survival
L 95%CI
U 95%CI
n collars
Censored"
Died
Nonhunt
Hunt

3

0
3

FEMALES
Survival 0.89
L 95%CI
U 95%CI
n collars 36
Censored"
Died
4
Nonhunt 4
Hunt
0

I"
2
0
2

• Censored denotes collar failure and/or animallifeldeath status not known.
Includes (173.949194) collar failure December 1994 but seen January 1996
• Censored elk:(173.949194) collar failure, which was killed in fJISt rifle season 1996.
d Includes (174.030/94) alive June 1997.
• Censored elk: (173.719194) slipped collar May 1996.
f Collar (173.760/94) disappeared 1998 hunting seasons and assumed dead.
• Censored elk: (174.030/94) slipped collar September 1998.
b

22
0
gf
0
8

0.40
0.23
0.57
35
0
21
5
16

•...•
00
0

�Table 4. Survival rates, inclusive ofnonhunting and hunting mortalities, for winter-spring (WS, 1 December-14 June) and summer-fall (SF, 15
June-30 November) time periods from 1 December 1995-14 June 1999 for the cohort of calves age 6 months radio-collared in December 1995.
Survival rate for male and female calves pooled when age 6-11 months was 0.88 in 1995 (95% CI 0.81-0.96, n=69). Survival rates (S) calculated
as a mean estimate of (alive)/(alive+dead)
and variance of S(I-S)/n collars.
Elk Age (months) and Time Period (WS or SF dates)
24-29
36-41
18-23
30-35
SF
WS
SF
WS
1996-97
1997
1997-98
1998

6-11(mos}
WS
1995-96

12-17
SF
19.96

MALES
Survival
L 95%CI
U 95%CI
n collars
Censored"
Died
Nonhunt
Hunt

0.86
0.74
0.98
35
2b
5
5
0

0.83
0.68
0.97
29
1c
5
0
5

0.96
0.87
1.00
24
0
1
1
0

0.23
0.04
0.41
22

4

Id

I'

17
0
17

0
0
0

FEMALES
Survival
L 95%CI
U 95%CI
n collars
Censored'
Died
Nonhunt
Hunt

0.91
0.81
1.00
34
0
3
3
0

0.87
0.75
0.99
31
0
4
0

0.93
0.82
1.00
27
0
2
1
1

0.83
0.66
0.99
23
2f
4
0
4

1.00

4

1.00

18
I'

0
0
0

0.25
0.00
0.86
4
0
3
0
3
0.89
0.73
1.00
18
0
2
0
·2

42-47
WS
1998-99

1.00
1
0
0
0
0
1.00
16
0
0
0
0

6-47

ALL
1995-99
0.03
0.00
0.10
32
5
31
6
25
0.52
0.33
0.70
.31
3
15
4
11

• Censored denotes collar failure and/or animal life/death status not known.
Censored elk (174.619/95) slipped collar May 1996, (174.800/95) capture mortality.
• Censored elk (174.660/95) slipped collar July 1996.
d Censored elk (174.671195) likely collar failure July 1997.
• Censored elk (174.190/95) slipped collar May 1998.
r Censored elk (174.441195) slipped collar August 1997 and (174.580/95) collar failure July 1997.
I Censored elk (174.470195) collar failure December 1997.
.
b

....
00
....

�Table 5. Survival rates, inclusive ofnonhunting and hunting mortalities, for winter-spring (WS, 1 December-14 June) and summer-fall (SF, 15
June-30 November) time periods from 1 December 1993-14 June 1999 for the cohort of calves age 6 months radio-collared in December 1996.
Survival rate for male and female calves pooled when age 6-11 months was 0.86 (95% CI 0.81-0.96, n=69). Survival rates (S) calculated as a mean
estimate of (alive)/(alive+dead) and variance ofS(I-S)/n collars.
Elk Age (months) and Time Period (WS or SF dates)
6-11 (mos)

12-17

18-23

24-29

30-35

6-35

WS

SF

WS

SF

WS

ALL

1996-97

1997

1997-98

1998

1998-99

1996-98

0.85
0.73
0.98
34

0.97
0.90
1.00
29
0
1
0
1

1.00

1.00

28
0
0
0
0

0.36
0.17
0.54
28
0
184
0
18

0.29
0.14
0.45
34
1
24

1.00

0.80

MALES
Survival
L 95%CI
U 95%CI
n collars
Censored'
Died
Nonhunt
HWlt

Ib
5
5
0

10
0
0
0
0

5
19

FEMALES
Survival 0.86
L 95%CI
U 95%CI
n collars 35
Censored'
Died
5
Nonhunt 5
Hunt
0

1.00
0.74
0.98
30
0
0
0
0

30
0
0
0
0

30
0
6&lt;
0
6

• Censored denotes collar failure and/or animallifeldeath status not known.
Censored elk. (174.619/96) capture mortality.
C Collar (174.929/96) disappeared
1998 hunting seasons and assumed dead.
d Collar (175.199/96) disappeared
1998 hunting seasons and assumed dead.
b

1.00
0.65
0.95
24
0
0
0
0

0.69
0.53
0.85
35
0
11
5
6

o

•...
00

N

�Table 6. Survival rates, inclusive ofnonhunting and hunting mortalities, for winter-spring (WS 1 December-14 June) and summer-fall (SF, 15 June30 November) time periods from 1 December 1993 - 14 June 1999 for all radio-collared adult female elk age 2:,12months. Survival rates (S)
calculated as a mean estimate of (alive)/(alive + dead) and variance S(1-S)/n collars.
Adult
WS

Adult
SF

Adult
WS

Elk Age and Time Period (WS or SF dates)
Adult
Adult
Adult
Adult
Adult
SF
WS
SF
WS
SF

1993-94

1994

1994-95

1995

1995-96

1996

1996-97

0.94
0.90
0.98
129bh
0
8d
0
8

0.94
0.90
0.98
119i
2)
7
4
3

0.89
0.84
0.94
1431:
0
16
1
15

0.98
0.95
1.00
1271
0
3
1
2

.1

Survival
L 95%CI
U 9S%CI
n collars
Censored"
Died
Nonhunt
Hunt

0.96
0.91
1.00
68b•
0

0.87
0.80
0.94
100bf
0

3

13&lt;

1
2

I
12

0.96
0.92
1.00
9Sbl
0
4
1
3

• Censored denotes collar failure or life/death status unknown.
b Includes (172.011/93) collar failure April 1994, seen January 1996
, Collars (172.800/93,172.649/93) disappeared 1994 hunt seasons.
d Collar (172.207/93) disappeared 1995 hunt seasons, assumed dead.
• Composed of 6-18+ and 62-30+ months old females.
f Composed of35-12+, 6-24+, and 59-36+ months old females.
• Composed of34-18+ and 61-30+ months old females.
b Composed of32-12+, 34-24+, and 63-36+ months old females.
I Composed of30-18+ and 89-30+ months old females.
J Censored elk (172.011/93) failure and (173.719/94) slipped collar.
k Composed of31-12+,
29-24+, and 83-36+ months old females.

Adult
WS

Adult
SF

Adult
WS

1997

1997-98

1998

1998-99

0.91·
0.87
0.96
152m
2D
13
0
13

0.99
0.97
1.00
138·
IP
2
1
1

0.77
0.70
0.84
136&lt;1
0
31'
0
31

0.98
0.95
1.00
103'
21
2
2
0

I Composed of27-18+ and 100-30+ month old females .
••Composed of30-12+, 23-24+, and 99-36+ months old females.
• Censored elk (174.441/95) slipped collar August 1997 and (174.S80/95) likely failure June 1997.
• Composed of30-18+ and 108-30+ months old females .
P Censored elk (174.470/95) likely collar failure August 1997.
q Composed of30-24+ and 106-36+ months old females.
r Collars (172.269/93,172.308/93,172.498/93,172.991/93,
173,760/94, 174.929/96) disappeared 1998 hunt seasons
and assumed dead.
• Composed of24-30+ and 81-42+ months old females.
I Censored elk (172.849/93,
173.151/93) failed collars.

,_.
OQ
W

�186

APPENDIX I. Mortalities of235 radio-collared elk from 1 December 1993 through 14 June 1999. Age is
aQQfoximate age in ~ears of elk at death: C=calf age 6-11 monthsz Y=yearling age 12-23 months.
Frequency ID!
Death
TraQ
Year caEtured
Site Zone
Sex Age
Date
Cause of death &amp; code number
172.030/93
172.050/93
172.039/93
172.070/93
172.080/93
172.090/93
172.090/94
172.101193
172.128/93
172.139/93
172.160/93
172.181193
172.201193
172.207/93
172.229/93
172.258/93
172.269/93
172.277/93
172.290/93
172.290/94
172.300193
172.308/93
172.369/93
172.369/94
172.409/93
172.448/93
172.459/93
172.498/93
172.509/93
172.519/93
172.530/93
172.542/93
172.542/94
172.549/93
172.570/93
172.581193
172.581194
172.590/93
172.610/93
172.620/93
172.639/93
172.649/93
172.658/93
172.670/93
172.678/93
172.690/93
172.699/93
172.730/95
172.749/95
172.758/95
172.800/93
172.821/93
172.890/93
172.899/93
172.950/93
172.961193
172.991193
173.000/93

BR
EG
GR
BR
GM
GR
SM
SR
GC
BC
CC
MC
GS
SG
MC
HY
MC
GS
SG
SM
AC
GH
AC
FM
AC
·MH
MH
FS
FS
FS
FS
FS
FM
PG
PG
PG
FM
PG
PG
PG
PG
PG
PG
PG
PG
FM
FM
LS
LS
LS
SR
EG
BC
BC
GH
MG
SG
WM

A
B
B
A
A
B
D
B
B
C
C
C
C
D
C
C
C
C
D
D
E
D
E
B
E
E
E
H
H
H
H
H
B
H
H
H
B
H
H
H
H
H
H
H
H
B
B
H
H
H
B
B
C
C
D
D
D
G

F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F

5
12
4
11
6
11
11
8
8
17
3
3
3
4
8
3
12
3
6
4
8
8
3
4
8
12
8
12
3
6
8
6
15
7
16
3
3
5
3
5
16
2
5
4
9
8
7
19
11
15

Y
3
3
C
2
4
5
C

27-Oct-95
31-Oct-98
14-Jun-95
12-Feb-96
05-Nov-94
16-Jan-94
12-Oct-98
14-Oct-96
31-Oct-96
19-Oct-95
23-Oct-94
03-Nov-94
15-Nov-94
30-Nov-95
29-Oct-98
04-0ct-94
29-Oct-98
O4-Oct-94
23-Oct-94
16-Sep-96
30-0ct-97
29-Oct-98
18~94
14-Jan-96
29-Dec-94
. 01-Nov-98
24-Oct-96
15-Oct-98
21-Oct-95
12-Oct-98
29-Oct-98
01-Feb-94
06-Jan-99
28-Nov-95
03-Nov-94
17-Oct-94
08-Dec-95
i4-Apr-96
O4-Oct-94
04-Nov-98
14-Jun-96
30-Nov-94
02-Nov-97
16-Jan-95
22-Dec-94
24-Jan-94
05-Nov-95
05-May-99
07-Aug-96
28-Oct-98
30-Nov-94
08-Sep-96
06-Nov-96
18-Mar-94
18-Oct-95
30-Oct-97
29-Oct-98
25-Apr-94

Legal kill second rifle season-47
Legal kill third rifle season-48
Unknown-suspect predation-30
Unknown-l l
Legal kill third rifle ~n-48
Wounding loss late rifle season-26
Legal kill first rifle season-46
Legal kill first rifle season-46
Wounding loss second rifle season-44
Wounding loss first rifle season-43
Legal kill second rifle season-47
Wounding loss second rifle season-44
Wounding loss second rifle season-44
Disappear first rifle season-40
Legal kill second rifle season-47
Legal kill archerylmuzzle season-27
Disappear second rifle season-41
Wounding loss archery/muzzle-24
Legal kill second rifle season-47
Legal kill muzzleloading season-34
Wounding loss second rifle season-44
Disappear second rifle season-41
Legal kill archery season-33
Legal kill late rifle season-29
Wounding loss late rifle season-26
Legal kill third rifle season-48
Legal kill second rifle season-47
Disappear [JISt rifle season-40
Legal kill second rifle season-47
Legal kill first rifle season-46
Wounding loss second rifle season-44
Mountain lion predation-3
Accident-irrigation ditch-If
Legal kill late rifle season-29
Wounding loss second rifle season-44
Legal kill first rifle season-46
Legal kill late rifle season-29
Unknown-11
Accident. birthinglca1ving-32
Legal kill third rifle season-48
Accident. birthinglca1ving-32
Disappear first rifle season-40
Legal kill third rifle season-48
Legal kill late rifle season-29
Wounding loss late rifle season-26
megal kill-7
Legal kill third rifle season-48
Malnutrition-6
Unknown-suspect predation-30
Wounding loss second rifle season-44
Disappear second rifle season-41
Legal kill archery season-33
Legal kill third rifle season-48
Mountain lion predation-3
Legal kill first rifle season-46
Disappear second rifle season-41
Disappear second rifle season-41 .
MaInutrition-6

---------------------------------------------------------------------------------------------

�187

Appendix I. (continued)
Frequency IDI
Trap
Year captured
Site Zone
173.000/94
173.010/93
173.041193
173.050/93
173.060/93
173.070/93
173.081193

173.090/93
173.100/93
173.120/93
173.140/93
173.160/93
173.171193

173.190/93
173.190/96
173.201193

173.210/93
173.210/96
173.219/93
173.219/96
. 173.232/93
173.232/96
173.262193

173.262/94
173.269/93
. .173.279/93
173.289/93
173.289/94
173.300/93
173.300/96
173.309/93
173.320/93
173.320/94
173.332/93
173.332/96
173.340/93
173.351193
173.351196

173.359/93
173.359/96
173.370/93
173.370/96
173.381196
173.390/93
173.402/93
173.410/93
173.410/96
173.420/93
173.429/93
173.439/93
173.450/93
173.461/93
173.461194
173.461196

173.469/93
173.469/94
173.479/93
173.479/96
173.492/93

HM
WM
GM
MH
MH
MH
FS
FS
FS
GM
PG
FS
FM
BC
BC
GR
GC
LM
BC
CG
BR
BC
BC
HM
MC
MC
MC
PR
GS
MC
HY
HY
HM
GH
BC
SG
SG
BG
AC
MC
MH
RG
RG
MG
MG
WM
EW
WM
MH
PG
PG
PG
CM
GM
FS
PR
FS
RG
FS

B
G
A
E
E
E
H
H
H
A
H
H
B
C
C
B
B
D
C
D
AMY
C
C
B
C
C
C
A
C
C
C
C
B
D
C
D
D
E
E
C
E
E
E
D
D
G
G
G
E
H
H
H
AMY
A
H
A
H
E
H

Death
Sex· Age
F
F
M
F
F
F
F
F
F
M
F
F
F
M
M
M
M
M
M
M

4
4
2
5
2
5
3
4
4
2
3
3
5
Y
2
2
2
2
2
2

M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M

2
C
2
2
3
C
2
2
2
Y
Y
2
2
2
4
2
2
2
2
2
C
C
2
2
2
1
2
2
2
2
C

M
M
M
M
M
M

2
C
2
2
2
2

Date
31-Oct-98
07-Jan-98
19-Oct-95
31-Oct-98
27-Dec-95
03-Mar-98
22-Oct-96
24-Oct-97
30-0ct-97
14-Oct-95
31-Oct-96
13-Nov-96
10-Oct-98
29-Oct-94
1O-Oct-98
30-Nov-95
19-Oct-95
30-Oct-97
06-Nov-95
21-Oct-98
15-Nov-94
31-Oct-98
18-Mar-94
12-Oct-96
06-Nov-95
12-Oct-96
22-Mar-94
18-Sep-96
24-Oct-95
10-Oct-98
30-Nov-94
20-Oct-94
14-Sep-96
12-Sep-95
10-Oct-98
20-Oct-97
05-Nov-95
27-Oct-98
06-Sep-95
09-Nov-98
08-Nov-95
08-Jan-97
19-Feb-97
30-Nov-95
18-Oct-95
02-Nov-95
29-Sep-98
24-Oct-95
14-Sep-95
30-Nov-95
15-Oct-95
07-Feb-94
19-5ep-95
22-Oct-98
25-Apr-94
20-Oct-96
1O-Sep-95
l7-Oct-98
03-Sep-95

Cause of death &amp; code number
Legalkill third rifle season-48
Accident-fell-l0
Legalkill first rifle season-46
Legalkill third rifle season-48
Legalkill late rifle season-29
Illegalkill-7
Legalkill secondrifle season-47
Legalkill secondrifle season-47
Legalkill secondrifle season-47
Legalkill first rifle season-46
WOWldinglosssecondrifleseason-44
Legalkill third rifle season-48
Legalkill first rifle season-46
megal kill secondrifle season-50
Legalkill first rifle season-46
Woundingloss third rifle season-45
Legalkill first rifle season-46
Illegalkill archery/muzz.season-8
Legalkill third rifle season-48
Legalkill secondrifle season-47
illegal kill secondrifle season-50
Legalkill third rifle season-48
Unknown-ll
Legalkill first rifle season-46
Legalkill third rifle season-48
Legalkill first rifle season-46
Unknown-ll
Legalkill muzzleloadingseason-34
Legalkill secondrifle season-47
Legalkill first rifle season-46
Illegalkill first rifle season-49
megal kill first rifle season-49
Legalkill archeryseason-33
Legalkill muzzleloadingseason-34
Legalkill first rifle season-46
Legalkill secondrifle season-47
Legalkill third rifle season-48
Legalkill secondrifle season-47
Legalkill archeryseason-33
Woundingloss third rifle season-45
Legalkill first rifle season-46
Mountainlion predation-3
Unknown-suspectpredation-30
Disappearfirst rifle season-40
Legalkill first rifle season-46
Woundingloss secondrifle season-44
Woundingloss archery/muzzleseasons-24
Legalkill secondrifle season-47
Legalkill archeryseason-33
Disappearfirst rifle season-40
Legalkill first rifle season-46
Malnutrition-6
Woundingloss archeryseason-50
Legalkill secondrifle season-47
Malnutrition-6
Legalkill secondrifle season-47
Legalkill archeryseason-33
Legalkill secondrifle season-47
Legalkill archeryseason-33

!~~~~~~]--------~~-----~-------~----]----7--]]~~~!:?~-~g~!~~E:~~~~:_~~~~

_

�188

Appendix I. (continued)
Frequency ID!
Year Captured

Trap.
Site Zone

Death
Sex
Age

173.510/93

FM
FM
FM

M
M
F
M
F
F
F
F
F
F
F
F

2
2
7
2
Y
3
Y
C
3
C
C
3

F
F
F
F
F
F
F
F
F
F
F
F
F
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M

4
2
2
4
4
4
C
3
2
4
4
2
C
Y
2
2
2
2
2
2
2
2
2
2
2
Y
2
3
2
Y
2

M
M

2
2

M
M
M
M
M
M
M
M

Y
2
2
C
2
2
Y
2

173.521193
173.530/94
173.540/94
173.549/94
173.569/94
173.580/94
173.589/94
173.610/94
173.640/94
173.640/96
173.649/94
173.659/94
173.679/94
173.689/94
173.719/96
173.739/94
173.750/94
173.760194
173.789/94
173.819/94
173.829/94
173.840/94
173.849194
173.859/94
173.870/94
173.919/94
173.929/94
173.939/94
173.959/94
173.970/94
173.981/94
173.990/94

174.001194
174.009194
174.019/94
174.039/94
174.049194
174.059/94
174.069/94
174.080/94
174.090/94
174.101/94
174.109/94

174.119/94
174.119/95
174.129/94
174.140194
174.140/95
174.150/94
174.160/94
174.170/94
174.170/96

174.181194
174.200/95
174.210/95
174.220/95
174.230/95

174.230/96

00

HM
PR
PR
00

BC
MC
GM
BC
MC
MP
BG
MC
BG
BG
MR
MR
MM
MM

MM
SM
SM
SM
BC
BC
BC
BC
MC
MP
BC
BG
BG
BG
MR
MM
MR
BG
MR
MR
MM
MM
MM
GB
MM
MM
GB
MM
MM
FM
MC
FM
MS
MS
MS
MS
EW

~~~~~~2~ ~

B
B
B
B
B
A
A
B
C
C
A
C
CF4
D
E
C
E
E
E
E
F
F
F
D
D
D
C
C
C
C
C
D
C
E
E
E
E
F
E
E
E
E
F
F
FMC
B
F
FMC
B
F
F
B
C
B
F
F
FMC
FMC
G

M

~

~

Date

Cause of Death &amp; Code Number

2

28-Aug-95
17-Oct-95
31-Oct-98
13-Oct-%
07-Sep-95
l6-Oct-97
21-Dec-95
01-Jun-95
14-Nov-97
30-Mar-95
16-Mar-97
1l-Oct-97
25-Oct-98
29-Oct-98
31-Oct-%
03-Nov-98
29-Oct-98
18-Oct-98
29-Oct-98
20-Mar-95
30-Oct-97
IO-Jan-97
29-Sep-98
20-Oct-98
23-Oct-96
21-Feb-95
02-Nov-95
l6-Oct-96
18-Sep-96
02-Nov-96
20-Oct-96
02-Nov-96
20-Oct-96
30-Nov-%
12-Oct-96
13-Nov-96
05-Sep-96
14-Sep-96
17-Oct-95
26-Sep-96
ll-Oct-97
20-Oct-96
24-May-96
19-Oct-96
01-Mar-95
30-Nov-97
14-Oct-96
14-Mar-95
30-Nov-96
14-Oct-96
15-Sep-96
25-Apr-95
10-Oct-98
30-Nov-96
18-Oct-96
ll-Oct-97
08-Apr-96
24-Apr-96
l3-Oct-98

Legal kill archeryseason-33
Legal kill first rifle season-46
Legal kill third rifle season-48
Legal kill first rifle season-46
Legal kill archeryseason-33
Woundingloss first rifle season-43
Unknown-ll
Unknown-suspectpredation-30
Woundingloss third rifle season-45
Unknown-suspectpredation-30
Malnutrition-6
Legal kill first rifle season-46
Legal kill secondrifle season-47
Woundingloss first rifle season-43
Legalkillfrrstrifleseason-46
Legal kill third rifle season-48
Woundingloss secondrifle season-44
. Legal kill secondrifle season-47
Disappear secondrifle season-41
Unknown-suspectmalnutrition-31
Legal kill secondrifle season-47
Legal kill late rifle season-29
Woundingloss archery/muzzleseasons-24
Legal kill secondrifle season-47
Legal kill secondrifle season-47
Mountain lion predation-3
illegal kill secondrifle season-50
Legal kill first rifle season-46
Legal kill archeryseason-33
Legal kill third rifle season-48
Legal kill secondrifle season-47
Legal kill third rifle season-48
Legal kill secondrifle season-47
Disappeararchery/muzzleseason-21
Legal kill first rifle season-47
illegaI kill rifle season-9
Legal kill archeryseason-33
Legal kill muzzleloadingseason-34
illegal kill first rifle season-49
Woundingloss archery/muzzle-24
Legal kill first rifle season-46
Legal kill secondrifle season-47
Unknown-suspectpredation-30
Legal kill secondrifle season-47
Mountain lion predation-3
Woundingloss rifle season-25
Legal kill first rifle season-46
Mountainlionpredation-3
llIegalkillthirdrifleseason-51
Legal kill first rifle season-46
Legal kill muzzleloadingseason-34
Mountain lion predation-3
Legal kill first rifle season-46
Disappear secondrifle season-41
llIegaIkill first rifle season-49
Legal kill first rifle season-46
Unknown-suspectmalnutrition-31
Mountain lion predation-3
Legal kill first rifle season-46

~

~I:~~~~~ ~~~~~~~~P!~~~:~

_

�189
AEEendix I. {continued}
Frequency ID!
Tral!
Site
Zone
Year caEtured
174.240/96
SR
B
MD
174.301195
E
MS
174.319/95
F
MD
174.329/95
E
MD
174.339/95
E
174.349/95
MD
E
174.360/95
MD
E
174.401/95
AP
D
174.420/95
AP
D
174.478/95
WD
e
174.491195
LB
e
174.500/95
LB
e
174.520/95
KR
B
174.520/96
GM
A
174.551/95
we
G
174.560/95
BL
A
174.609/95
GB
B
MD
174.629/95
E
174.639/95
MD
E
174.650/95
HG
E
174.679/95
HG
E
174.689/95
AP
D
174.689/96
EW
G
174.700/95
AP
D
174.710/95
AP
D
174.729/95
VM
D
174.740/95
VM
D
174.750/95
VM
D
174.760/95
VM
D
174.770/95
WD
e
174.780/95
WD
e
174.789/95
WD
e
174.789/96
EW
G
174.800/96
BG
E
WD
174.809/95
e
174.820/95
WD
e
174.830/95
LB
e
174.841195
LB
e
174.851195
LB
e
174.861195
KR
B
174.870/95
LB
e
174.880/95
KR
B
174.889/95
we
G
174.899/95
BL
A
174.910/96
LM
D
174.929/96
LM
D
174.959/96
LM
D
174.998/96
BG
E
175.059/96
Be
e
175.130196
GM
A
175.139/96
GM
A
175.149/96
SR
B
175.160/96
Be
e
175.170196
LM
D
175.189/96
RG
E
EW
175.199/96
G
175.209/96
MS
F
END

Death
Sex
Age
M
2
F
3
F
Y
F
Y
F
e
2
F
F
Y
F
2
F
2
2
F
2
F
e
F
F
Y
F
e
3
F
F
Y
e
F
2
M
M
2
M
3
M
Y
e
M
e
M
M
2
M
2
M
Y
M
2
M
2
M
3
M
2
2
M
e
M
2
M
M
e
y
M
2
M
M
2
3
M
M
2
Y
M
M
2
2
M
2
M
2
M
F
e
2
F
F
2
F
2
F
e
F
e
2
F
2
F
2
M
e
M
2
M
M
2
2
M

Date
12-Sep-98
20-Sep-98
02-Oct-%
03-Sep-96
27-Mar-96
l3-Oct-97
22-Apr-97
22-Sep-%
1l-Oct-97
13-Sep-97
10-Sep-97
16-Apr-96
21-Sep-96
25-Apr-97
14-Oct-98
14-May-97
15-Apr-96
11-Oct-97
21-Oct-97
14-Sep-98
13-Nov-96
05-Feb-96
14-May-97
16-Oct-97
15-Oct-97
17-Oct-%
08-Nov-97
05-Nov-97
15-Sep-98
16-Oct-97
II-Oct-97
22-May-96
28-Oct-98
09-Apr-97
22-Apr-97
14-Oct-97
l3-Oct-97
12-Sep-98
22-Oct-97
31-Oct-96
30-Oct-97
11-Oct-97
20-Oct-97
30-Oct-97
27-Feb-97
29-Oct-98
29-Oct-98
21-Oct-98
13-Feb-97
24-Mar-97
28-Oct-98
19-Oct-98
17-Sep-98
26-Mar-97
l3-Oct-98
29-Oct-98
24-Oct-98

Cause of death &amp; code number
Legal kill muzzleloading season-34
Legal kill archery season-33
Wounding loss archery season-52
Legal kill archery season-33
Unknown predator-S
Legal kill first rifle Season-46
Unknown-suspect predation-30
Legal kill muzzleloading season-34
Legal kill first rifle season-46
Legal kill muzzleloading season-34
Wounding loss archery season-52
Unknown-suspect predation-30
Legal kill muzzleloading season-34
Mountain lion predation-3
Legal kill first rifle season-46
Illegal kill-7
Unknown-suspect predation-30
Legal kill first rifle season-46
Legal kill second rifle season-47
Legal kill muzzleloading season-34
Illegal kill second rifle season-50
.Mountain lion predation-3
Unknown-suspect maInutrition-31
Wounding loss first rifle season-43
Legal kill first rifle season-46
Illegal kill first rifle season-49
Legal kill third rifle season-48
Legal kill third rifle season-48
Legal kill archery season-33
Disappear first rifle season-40
Legal kill first rifle season-46
Unknown-suspect predation-30
Wounding loss second rifle season-44
Mountain lion predation-S
Accident, fell-lO
Legal kill first rifle season-46
Legal kill first rifle season-46
Legal kill muzzleloading season-34
Illegal kill second rifle season-50
Illegal kill second rifle season-50
Wounding loss second rifle season-44
Legal kill first rifle season-46
Legal kill second rifle season-47
Wounding loss second rifle season-44
Unknown-suspect predation-30
Disappear second rifle season-41
Wounding loss second rifle season-44
Legal kill second rifle season-47
Unknown-l l
Mountain lion predation-3
Legal kill second rifle season-47
Legal kill second rifle season-47
Legal kill muzzleloading season-34
Unknown-suspect maInutrition-31
Legal kill first rifle season-46
Disappear second rifle season-41
Legal kill second rifle season-47

�190

Appendix Il, Abstract from paper presented at Western States and Provinces Elk and Mule Deer
Workshop, Salt Lake City, Utah, March 1999.

ESTIMATING ELK DENSITIES IN COLORADO: PROGRESS WITH PERPLEXITIES
DAVID J. FREDDY, Colorado Division of Wildlife, Research Center, 317 West Prospect Road,
Fort Collins, CO, USA 80526
DAVID C. BOWDEN, Department of Statistics, Colorado State University, Fort Collins, CO 80523 USA
GARY C. WIllTE, Department of Fishery and Wildlife Biology, Colorado State Univeristy, Fort Collins,
CO 80523 USA

Abstract: During winters 1994-1998, we evaluated helicopter survey methodologies to estimate elk
densities injuniper-pinyon (Juniperus osteosperma-Pinus edulis) and oakbrush-mountain shrub (Quercus
gambelii-Amelanchier alnifolia) habitats. We developed sighting bias correction models to correct for
groups of elk not observed when counting elk on 2.59-km2 (l-mf) quadrats. Within a 350-km2 area, we
compared elk densities obtained from a stratified random quadrat sampling system corrected for sighting
bias with independent estimates of densities obtained from mark-resight models using known numbers of
radio-collared elk (120-137 elk) within the quadrat survey area. Although observers detected about 80% of
the elk groups on quadrats during sighting bias trials and resulting sighting bias models increased estimated
elk densities on quadrats by 10-12%, quadrat densities were 2:,25%lower than mark-resight densities.
Estimated densities of elk ranged from 6-10 elk/krrr', We propose that errors in counting numbers of elk in
a group may contribute more to underestimating elk densities than errors in detecting groups of elk.

�239
Colorado Division of Wildlife
Wildlife Research Report
July 2000

JOB FINAL REPORT

Smreof

~C~m~o~rnrl~o~

_

Cost Center 3430

Project No.

W~-1=5=3__=-R:..:.-"""'1=_3
_

Manunals Research

Work Package

-=3...:::;0=02=--

_

Task No.

--=2'--

_

Elk Management
Estimating Survival Rates of Elk and Developing
Techniques to Estimate Population Size

Period Covered: July 1, 1999 - June 30,2000
Author: D. J. Freddy

\

)

Personnel: T. Beck, J. Broderick, G. Byrne, D. Crane, R Del Piccolo, J. Ellenberger, V. Graham, D.
Homan, R. Kahn, K. Madariaga, D. Masden, C. Mehaffy, P. Neil, J. alterman, P. Will, K. Wright, S.
Yamashita, D. Younkin, CDOW; D. Bowden, M. Conner, M. Kneeland, G. White, CSU; D. Ouren, D.
Schneider, T. Fancher, R. Waltermeir, USGS-BRD, BLM Glenwood Springs, CO, USFS Rifle, CO,
Rocky Mountain Elk Foundation, cooperating.

ABSTRACT
We monitored survival and movements of 112 previously radio-collared elk composed of 101 adult females
and 11 adult males from 1 July 1999 through 30 June 2000. Survival of adult females during summer-fall
was 0.89 ± 0.06 (n = 101) inclusive of hunting deaths and 1.00 (n = 90) with hunting deaths censored while
survival during winter-spring was 0.98 ± 0.03 (n = 88) inclusive of hunting "deaths and 0.99 ± 0.02 with
hunting deaths censored. The 1 non-hunting death of an adult female during winter-spring was attributed .
to mountain lion predation. Survival of adult males during summer-fall was 0.27 ± 0.30 (n = 11) inclusive
of hunting deaths and 1.00 (n = 3) with hunting deaths censored while survival during winter-spring was
1.00 (n = 3); With hunting deaths censored, annual survival rates during winter-spring were 2: 0.97 for
adult females and 2: 0.96 for adult males during 7 consecutive winters while annual survival rates during
summer-full were 2: 0.99 for both adult females and males during 6 consecutive summers. High adult
survival and high over-winter calf survival (0.89 ± 0.04) allow this population to potentially increase&gt; 15%
annually in the absence of hunting antlerless elk. Hunting related mortalities were the primary cause of
death for adult male and female elk. During 6 years, 98% of all adult male deaths and 89% of all adult
female deaths were related to hunting. Hunting annually removed 76% of the adult branch-antlered males
and 13% of the adult females. Annual wounding losses averaged 15% for adult males and 30% for adult
females while 11% of yearling spike-antlered males were illegally harvested. Sighting bias corrections for
counting elk on l-mf quadrats were developed and evaluated as a method to estimate elk densities. We
found counts of elk on quadrats corrected for sighting bias associated with detection of elk groups

.---.---ro rnvwLDL11i1llrilil~~llljilrnl
BDOW016789

�240
continued to under-estimate true numbers of elk present. Evidence indicates under-counting numbers of elk
in groups also contributes to underestimating true numbers of elk present. If a quadrat sampling system is
employed to estimate densities of elk, counts of elk would need to be increased by 1.3x to approximate true
numbers of elk present. Progress continues towards developing habitat use models to predict areas
important to managing elk Several manuscripts on elk survival rates, techniques to estimate population
size, and habitat use are progressing.

�241

ESTIMATING

SURVIVAL

JOB FINAL REPORT
RATES OF ELK AND DEVELOPING
ESTIMATE POPULATION SIZE

TECHNIQUES

TO

David J. Freddy

P. N. OBJECTIVE
Estimate survival rates of adult female, adult male, and calf elk and develop techniques to estimate
population size.
SEGMENT

OBJECTIVES

1. Analyze data concerning estimates of elk survival rates and experiments to estimate elk numbers.
2. Prepare Job Final Report
3. Prepare a manuscript for submission to a scientific journal which describes and summarizes research
results.
INTRODUCTION
Our objectives are to provide reliable estimates of survival rates for calves during winter and for adult
females and males throughout the year and to develop and test a system to estimate elk densities on winter
. ranges. Estimates of calf survival were obtained during winters 1993-94 through 1996-97 and summarized
in Freddy (1997). We continue to obtain estimates of survival for adult males and females. For adults, we
are interested in survival rates inclusive of hunting mortalities to document human-induced rates of survival
and exclusive of hunting mortalities to estimate natural rates of survival. We are evaluating a system for
estimating population size or density that incorporates estimates of sighting bias in conjunction with
random sampling of search quadrats as sample units. Our winter study area encompasses about 324 mi2
(839 knr') in the eastern half of Game Management Unit 42 south and east of Rifle, Colorado. This area is
part of the Grand Mesa Elk: Data Analysis Unit E-14. Elk winter habitats include juniper-pinyon woodland
(Juniperus osteosperma-Pinus edulis), oakbrush-mountain shrub (Quercus gambelii-Amelanchier
alnifolia), aspen (Populus tremuloides), sagebrush (Artemisia tridentata), and agricultural fields below
elevations of 9,800 ft. In summer, elk:use oakbrush-mountain shrub, aspen, and subalpine fir-Engelmann
spruce (Abies lasiocarpa-Picea engelmannii) meadow systems throughout the Grand Mesa region up to
elevations of 12,000 ft. (Freddy 1993).
METHODS
We placed radio collars (l72-176MHz) having mortality sensors on elk calves age 6 months and adults age
:::18 months during December 1993-1996 (Freddy 1997). Elk: were captured using helicopter net-gunning
and portable corral traps (Freddy 1997). During 1999-00, we monitored 112 adult elk, 101 females and 11
males, having functioning radios as of July 1999. Collars were white and had black identification symbols
on dorsal surfaces of collars to allow visual identification of individual elk.
Estimating Elk Survival Rates
During 1999-2000, we monitored survival of radioed elk with limited aerial surveys using a Cessna 185
and with opportunistic ground surveys. Extreme reductions in operating budgets during 1999-2000

�242
prevented following survey protocols used in previous years. Survival rates (S) of radioed elk were
calculated using the binomial estimator with a variance, VAR(S) = S( I-S)/n collars (White and Garrott
1990). Survival rates are expressed as the mean estimate ± the 95% confidence interval. Sample sizes
refer to numbers of individual radioed elk. Elk were censored if radios failed or if their life/death status
was unknown after an extended period of time
We defined 3 major time intervals for survival analyses: winter-spring was 1 December to 14 June,
summer-fall was 15 June to 30 November, and annual was 1 December to 30 November to coincide with
timing of capture and collaring. For adult elk during these time intervals, we calculated survival rates
inclusive of natural and hunting-related mortalities, exclusive of hunting mortalities, and exclusive of
natural mortalities. Excluding, or censoring hunting mortalities, provided estimates of natural survival
rates. Excluding natural mortalities but including hunting mortalities provided estimates of hunting
removal rates. Censoring elk associated with categories of mortalities reduced sample sizes used to estimate
survival rates ..
Archery, muzzleloading, and rifle hunting seasons occurred from about 1 September to 15 November each
year during the summer-fall time interval. Late-rifle seasons occurred in some years and restricted hunters
to taking only antlerless elk from about 25 November-31 January which included portions of the summerfall and winter-spring time intervals. Yearling spike-antlered males were generally not legal quarry in most
areas frequented by radioed elk. Male elk were legal quarry when branch-antlered usually at age 2 years.
Cause of death of radioed elk recovered in the field was estimated from presence or absence of gunshot
wounds or bite wounds on carcass, predator tracks or scat at carcass site, physical positioning of carcass
remains whether buried, covered, scattered, or consolidated (Wade and Browns 1982, Halfpenny and
Biesiot 1986), relative amount of internal fat and marrow fat if present with carcass, and results of
histopathology and marrow fat analyses. Fat content (percent dry matter) of bone marrow and estimates of
age based on dental cementum were obtained for dead elk by the Colorado Division of Wildlife Laboratory
while histopathology analyses were provided by the Colorado State University Veterinary Diagnostic
Laboratory. Photographs were taken of nearly all mortalities so that physical evidence could be reviewed
and judged by outside experts.
Population Estimation
Development of sighting bias corrections (Samuel et al. 1987) for aerial quadrat sampling systems to
estimate elk densities terminated after winter 1998. We have continued to analyze existing data to evaluate
and sources of negative bias associated with sighting.bias corrected counts of elk on quadrat sample units.
Elk Movements and Habitat Use Models
Aerial surveys to precisely locate radioed elk were terminated after June 1999 and development of habitat
use predictive models were hampered by reduced budgets in 1999-2000. However, we continued an
extensive process of database refinement and reduction. Using ArcInfo© and ArcVieW©, we linked all elk
locations to GIS coverages for elevation, slope, aspect (EW and NS), land ownership, private land density,
road density, hydrologic density, distance to private land, distance to roads, and distance to water. The
entire data set consisted of 5,164 elk locations representing 365 individual elk. For developing predictive
use models, we will use only data from elk that were randomly selected and systematically located during
years 1993-1999 which represented 2,900 locations representing 140 individual elk. All locations were
subset into groups by sex, age, (calf, yearling, adult) and season. Seasons were biologically defined as
spring (1 April- 30 May), summer (1 June- 31 August), fall (1 September - 30 November) and winter (1
December - 31 March).

�243
We also embarked on developing a supervised habitat type GIS coverage using ERDAS Imagine© and a
thematic mapper image from June 1993. We had anticipated obtaining this data from another source
during the last 3 years but such information did not become available.
RESUL TS AND DISCUSSION
Between 1 December 1993 and 14 June 2000, 256 radioed elk died of which 31 were calves 6-11 months
old and 225 were adults ~12 months old (fable 1, Appendix I). Calves died of natural causes (Freddy
1997) while hunting accounted for 93% of 225 adult deaths. Hunting caused 98% of 110 adult male
deaths and 89% of 115 adult female deaths.
Survival Estimates
Adult Females Summer-Fall
Survival during summer-fall 1999 for adult females all age ~24 months was 0.89 ± 0.06 (n = 101)
inclusive of hunting deaths and 1.00 (n = 90) with hunting deaths censored (fable 6). Survival rates for
adult females during summer-fall with hunting deaths censored remained &gt;0.99 during 6 consecutive years,
1994-1999 (fables 6-8) ..
Net summer-fall survival increased to 0.89 in 1999 from a low of 0.77 in 1998 (fable 6). An increase in
net survival was evident in nearly all cohorts of females (fables 2-8). Increased survival likely reflected
the return to using traditional limited antlerless permits during the 1999 hunting seasons compared to using
unlimited either-sex permits during portions of 1998 hunting seasons (Freddy 1999).
Adult Females Winter-Spring
Survival during winter-spring 1999-00 for adult females all age ~24 months was 0.98 ± 0.03 (n = 88)
inclusive of hunting deaths and 0.99 ± 0.02 (n = 87) with hunting deaths censored (fable 6). The 1 natural
death involved a female age 6 years that was killed by a mountain lion. Survival rates for adult females
during winter-spring with hunting deaths censored remained ~0.97 for 7 consecutive winters, 1993-941999-00 (fables 6-8).
Adult Females-Annual
Annual survival from 1 December 1998 to November 30 1999 was 0.83 ± 0.16 (n = 24) inclusive of
hunting deaths and 1.00 (n = 20) with hunting deaths censored for the 1993 cohort of radioed older adult
females (fable 9). Annual survival among years for this cohort ranged from 0.71 to 0.94 and from 0.92 to
1.00, inclusive and exclusive of hunting mortalities, respectively.
Adult Males Summer-Fall
Survival during summer-fall 1999 for adult males all age ~36 months was 0.27 ± 0.30 (n = 11) inclusive of
hunting deaths and 1.00 (n = 3) with hunting deaths censored (fable 11). With the unlimited branchantlered male hunting system used in the project area, the probability of a male living from age 6-months to
48-months was 5% (7 of 138 males, Tables 2-5).
Adult Males Winter-Spring
Survival during winter-spring 1999-00 for adult males all age ~42 months was 1.00 (n = 3)(fable 5).
There have been only 2 non-hunting deaths of males age ~12-months during 6 years and both occurred
during winter-spring and were attributed to an accidental fall and predation (fable 1).
Wounding Loss
Wounding loss during archery, muzzleloading, and rifle seasons in 1999 was 33% for adult males and 33%
for adult females. This compares to 1994-99 averages of 15% for adult males and 30% for adult females.
Wounding loss is defined as wounded / legal kill (Freddy 1997).

�244
Removal Rates
During the summer-fall period, hunting removal rates (1 - survival rate) averaged 0.76 for adult branchantlered males and 0.13 for adult females (Tables 10, 11). Peak removal rates of 0.92 for 24 month-old
males and 0.86 for all adult males occurred in 1996 while minimum removal rates of 0.64 and 0.65 for
these groups of males occurred in 1998. Peak removal rate of 0.23 occurred for adult females in 1998.
Removal rates in 1998 were associated with unlimited numbers of either-sex hunting permits during
portions of the 1998 seasons. These permits appeared to reduce hunting mortality on males and increase
hunting mortality on females. During those years when cohorts of yearling (12-17 months old) and adult
females (&gt;24 months old) were available, removal rates for yearling females tended to be lower than adult
females (Table 11).
Radio Collar Status
As of July 2000, 89 adult elk (3 males, 86 females) were alive with functioning radio collars and remained
in the project area. Many of these collars should be subject to electronic failure soon. Quality radio collars
(Lotek, Inc) with very low electronic failure rates allowed obtaining accurate survival rates on elk for 6.5
years. Collars having 1 D-celilithium battery remained functional for up to 78 consecutive months.
Population Estimation
Continuing analyses strongly indicate that under-counting numbers of elk in groups is an important source
of error, or negative bias, and may be equivalent in magnitude to negative bias associated with missing
entire groups of elk.. Thus, errors in detecting groups and in counting elk within groups contribute to
underestimates of true numbers of elk present. The assessment of negative bias was possible because of
independently obtained mark-resight estimates of elk numbers that provided robust estimates of true
numbers of elk.
Elk Movements and Habitat Models
Spatial plots of elk distribution, movements, and seasonal ranges were completed. All outputs were
prepared for color reproduction, and as such, are not suitable to reproduce in this report. Further statistical
assessment of predictive habitat use variables is ongoing. We anticipate completion and evaluation of the
habitat type coverage during Fall 2000. Once the vegetation coverage is completed, analyses of habitat use
can proceed towards completion.
Manuscripts
The following manuscripts are in various stages of progress.
ESTIMATING ERROR ASSOCIATED WITH AERIAL TELEMETRY LOCATIONS OF ELK ON
GRAND MESA, COLORADO. Projected outlet is CDOW technical series publication.
SPATIAL DISTRIBUTION OF ELK ON GRAND MESA, COLORADO. Projected outlet is CDOW
technical series publication in cooperation with USGS-BRD with financial support from the Rocky
Mountain Elk Foundation.
SURVNAL OF ELK CALVES DURING WINTER ON GRAND MESA, COLORADO.
outlet is Journal of Wildlife Management.
SURVNAL OF ADULT ELK ON GRAND MESA, COLORADO.
Management.

Projected

Projected outlet is Journal of Wildlife

ESTIMATING ELK DENSITIES ON GRAND MESA, COLORADO.
Wildlife Management.

Projected outlet is Journal of

�245
Additional publications regarding effects of helicopter net-gunning capture protocols on elk calves and
refinements to portable elk corral traps are planned.
CONCLUSIONS
With hunting deaths censored, annual survival rates during winter-spring were 2: 0.97 for adult females and
2: 0.96 for adult males during 7 consecutive winters while annual survival rates during summer-fall were 2:
0.99 for both adult females and males during 6 consecutive summers. High adult survival in conjunction
with high over-winter calf survival (0.89 ± 0.04) allows this population to potentially increase&gt; 15%
annually in the absence of hunting antlerless elk. Hunting related mortalities were the primary cause of
death for adult male and female elk. During 6 years, 98% of all adult male deaths and 89% of all adult
female deaths were related to hunting. Hunting annually removed 76% of the adult branch-antlered males
and 13% of the adult females. Wounding losses averaged 15% for adult males and 30% for adult females
while 11% of yearling spike-antlered males were illegally harvested. We found counts of elk on quadrats
corrected for sighting bias associated with detection of elk groups continued to under-estimate true numbers
of elk present. Evidence indicates under-counting numbers of elk in groups also contributes to
underestimating true numbers of elk present. If a quadrat sampling system is employed to estimate
densities of elk, counts of elk on quadrats would need to be increased by l.3x to approximate true numbers
of elk present.
LITERATURE

CITED

Freddy, D. J. 1993. Estimating survival rates of elk and developing techniques to estimate population size.
Colorado Division of Wildlife Game Research Report. July: 83-117 ..
Freddy, D. 1. 1997. Estimating survival rates of elk and developing techniques to estimate population size.
Colorado Division of Wildlife Game Research Report. July: 47-73.
Freddy, D. 1. 1999. Estimating survival rates of elk and developing techniques to estimate population size.
Colorado Division of Wildlife Game Research Report. July: In press ..
Halfpenny,1. C., and E. A Biesiot. 1986. A field guide to mammal tracking in North America. Johnson
Books, Boulder, Colorado, USA.
Samuel, M.D., RO. Garton, M.W. Schlegel, and RG. Carson. 1987. Visibility bias during aerial surveys
of elk in northcentral Idaho. journal of Wildlife Management 51 :622-630.
Wade, D. A, and J. E. Browns. 1982. Procedures for evaluating predation on livestock and wildlife.
Texas Agricultural. Experiment Station Publication B-1429.
White, G. C., and R A Garrott. 1990. Analysis of wildlife radio-tracking data. Academic Press, Inc.,
San Diego, California USA.

Prepared by

_
David 1. Freddy
Life/Science Researcher

�246
Table 1. Causes of death for radio-collared elk between I December 1993 and 14 June 2000. Calves (M=male,
F=female) were age 6-11 months and collared at age 6 months. Yearling males and females were age 12-17
months and juvenile males and females were age 18-23 months and all were collared at age 6 months. Adult
males and females were age &gt;24 months at time of death.
Elk Age/Sex Class at Death
Cause of Death
Calves
Yearling
Juvenile
Adult
Total
and -Code
All
M F
M
F
M
F
M
F
M
F
Natural Causes
Malnutrition-6
2 2
0
0
1
2
3
5
0
0
0
Unknown-Suspect
Malnutrition-31
0
0
3
4
3
1
0
0
0
1
0
O· 2
Predation-Lion- 3
8 4
0
0
8
6
14
0
0
Predation-Bear-35
0 0
0
0
0
0
0
0
0
0
0
Unknown Predator-5
0
1
0
1
0
0
0
0
1
0
0
Unknown-Suspect
Predation-30
2 5
0
3
8
0
1
1
2
11
0
Accident -Birthing- 32
0 0
0
0
2
2
0
0
0
0
2
Accident-FeU-I0
0
0
0
0
2
1
2
0
0
1
3
Unknown Cause-l l
2
0
2
4
1
0
0
0
1
2
6
Subtotals
17 14
19
27
46
Q 11
Q
Q
~
~
Legal Hunting
Archery-33
0 0
0
9
5
9
7
16
0
2
0
Muzzleloading-34
0 0
8
2
8
4
12
0
2
0
0
ArcherylMuzzle-27
0
0
0
0
0
1
0
1
1
0
0
Rifle-First-46
0
0
33
33
13
46
0
0
0
0
13
Rifle-Second-47
0
0
0
0
16
19
16
19
35
0
0
Rifle- Third-48
0
9
13
22
0
0
0
0
9
13
0
Rifle-Late-29
0 0
0
0
0
7
0
7
7
0
0
Rifle-Unk.Reg-28
0 0
0
0
0
0
0
1
1
1
0
Subtotals
75
75
65
61
140
Q Q
Q
Q
Q
1
I
Wound~Loss
Archery
uzzle-24
0 0
2
2
2
2
4
0
0
0
0
0 0
0
1
2
Archery-52
1
0
0
1
3
1
Rifle-Flrst-43
0 0
1
0
0
0
1
3
3
4
0
Rifle-Second-44
0
0
0
4
4
11
15
0
0
0
11
Riflc- Third-45
0 0
0
0
3
1
3
1
4
0
0
Rifle-Unk.Reg. -25
2
2
4
0 0
0
0
0
2
2
0
Rifle-Late-26
0
0
0
3
0
3
3
0
0
0
0
Subtotals
12
23
13
24
37
Q
Q Q
Q
!
!
Illegal Hunting
Rifle-First-49
0 0
0
5
5
0
0
0
0
5
0
Rifle-Second-50
6
0 0
5
0
0
1
0
0
6
0
Rifle- Third-51
0
0
0
0
0
0
1
0
1
1
0
Rifle-Unk.Reg, -9
0 0
0
0
1
0
1
0
1
0
0
Archery Season-S
0 0
0
0
0
0
1
0
1
0
1
Out -of-Season-?
0 0
0
0
2
0
3
3
0
0
1
Subtotals
12"
14
17
Q Q
Q
Q
!
~
~
2
Presumed Hunting"
Missing-ArchMuzz-21
0
0
0
0
1
0
1
0
1
0
0
Missing-Rifle Ist-40
0 0
3
3
3
6
0
0
0
0
3
Missing-Rifle 2nd-41
0 0
2
0
0
0
6
2
7
9
1
Missing-Rifle 3rd-42
0 0
0
0
0
0
0
0
0
0
0
Subtotals
0
16
.Q
.Q ...!.Q
Q Q
Q
Q
.2
!
Totals

17

14

13

6

2

3

95

106

127129

256

• These elk were illegally shot as spike-antlered yearling males: (173.190/93) (173.232/93) (173.309/93) (173.320/93) (173.919/94)
(174.059/94) (174.140/95) (174.200/95) (174.679/95) (174.729/95) (174.861/95) (173.210/96). (173.309/93) disappeared in 1994
during first rifle season when spike-antlered yearling males were not legal and was assumed to have been taken illegally. All other
illegal deaths were confirmed.
b These elk disappeared during hunting seasons and remained missing for several months and are assumed dead and legally harvested:
(172.207/93) (172.269/93) (172.308193) (172.498/93) (172.649193) (172.800/93) (172.961/93) (172.991193) (173.390/93)
(173.439/93) (173.760/94) (174.001194) (174.181/94) (174.770/95) (174.929/96) (175.199/96).

�247
Table 2. Survival rates, inclusive of non-hunting and hunting mortalities, for winter-spring (WS, 1 December-14
June) and summer-fall (SF, 15 June-30 November) time periods from 1 December 1993-14 June 2000 for the
cohort of calves age 6 months radio-collared in December 1993. Survival rate for male and female calves pooled
when age 6-11 months was 0.92 (95% CI 0.86-0.98, n~73). Survival rates (S) calculated as a mean estimate of
(alive)/(alive + dead) and variance S(1-S)/n collars.
Elk Age (months) and Time Period (WS or SF dates)
6-83
6-1l(mos) 12-17 18-23 24-29 30-35 36-41 42-47 48-53 54-59 60-65 66-71 72-77 78-83
SF
WS
SF
WS
SF
WS
SF
WS
SF
WS
SF
WS
ALL
WS
1993-94 1994 1994-95 1995 1995-96 1996 1996-97 1997 1997-98 1998 1998-99 1999 1999-00 1993-00
MALES
0.00
0.88 1.00
Survival
0.89
0.21 1.00
0.50 1.00
0.00
L95%CI
0.78
0.76
0.06 0.00
0.00
U95%CI
0.99
0.99
0.37 0.00
1.00
4
2f
33
32
28
n collars
36
28c
4
1&amp;
3"&amp;
o
0
Censored" 0
o
0
o
2"
22d
0
Died
4
33
4b
0
2
0
1
4
o
0
o
0
Nonhunt
4
o
0
o
29
4
Hunt
0
0
22
0
2
0
1
FEMALES
Survival
L 95%CI
U 95% CI
n collars
Censored"
Died
Nonhunt
Hunt

0.95
0.87
1.00
37
0

0.97
0.92
1.00
35

o

34
0

2

Ih

0

1

1

5

2
()

o

0
0

o

0

o

1

If

5

1

1.00

0.97
0.91
1.00
34

0.97
0.91
1.00
33

0.84
0.71
0.97
32

o

0

o

1.00

27
0
0
0
0

0.87
0.72
1.00
23

o

0.96
0.87
1.00
24
0
1
1

3

0

3

0.89
0.76
1.00
27

o
i

3

• Censored denotes collar failure and/or animal life/death status not known.
b Collar (173.309/93)
disappeared 1994 hunting seasons and assumed dead.
c Includes
(173.241193) collar failure August 1995 but seen January 1996.
• Collars (173.390/93),(173.439/93)
disappeared 1995 hunting seasons and assumed dead .
• Censored elk; (173.241/93) failed August 1995, (173.381/93) slipped collar December 1995.
f Includes (173.340/93)
alive May 1997.
, Censored elk: (173.249/93) slipped collar September 1997.
k Collar (172.800/93)
disappeared 1994 hunting seasons and assumed dead.
i Collar (172.961193) disappeared
1997 hunting seasons and assumed dead.
j Collar (172.991193) disappeared
1998 hunting seasons and assumed dead.
k Censored
elk: (172.849/93) failed May 1999, (173.151193) failed February 1999.

1.00

18

0.89
0.73
1.00
18

0.94
0.81
1.00
16

0.43
0.26
0.60
35

0

21;:

1

20
4
16

o

21;:

o

Ji

0

2

o

0
0

o

1

2

0

�248
Table 3. Survival rates, inclusive of non-hunting and hunting mortalities, for winter-spring (WS, 1 December-14
June) and summer-fall (SF, 15 June-30 November) time periods from 1 December 1994 -14 June 2000 for the
cohort of calves age 6 months radio-collared in December 1994. Survival rate fot male and female calves pooled
when age 6-11 months was 0.90 (95% CI 0.83-0.97, n=69). Survival rates (S) calculated as a mean estimate of
~alive2/~alive + dead2 and variance Sp-S2/n collars.
Elk Ase {months~and Time Period {WS or SF dates}
6-11(mos} 12-17 18-23 24-29 30-35
54-59
60-65 66-71
36-41 42-47 48-53
6-71
. SF
WS
ALL
SF
WS
WS
WS
WS
WS
SF
SF
SF
1994-95
1995 1995-96 1996 1996-97 1997 1997-98 1998 1998-99 1999 1999-00 1994-00
MALES
0.91
0.90
0.00
Survival
0.96
0.08
1.00
0.50
1.00
0.00
0.81
0.79
L 95%CI
0.88
0.00
0.00
1.00
U 95% CI
1.00
1.00
1.00
0.19
2d
n collars
33b
30b
31
26
25
2
1
0
2C.~
1c
1~
Censored'
0
0
0
0
0
0
3
3
31
Died
0
0
0
1
23
1
Nonhunt
3
0
0
4
1
0
0
0
0
0
3
27
HWlt
0
23
0
0
0
1
FEMALES
Survival
L 95% CI
U95%CI
n collars
Censored'
Died
Nonhunt
Hunt

0.89
0.78
0.99
36
0
4
4
0

0.97
0.91
1.00
32
0
1
0
1

0.97
0.90
1.00
30
1·
1
1
0

0.93
0.83
1.00
29
0
2
0
2 I

0.96
0.89
1.00
27
0
1
0

0.85
0.70
0.99
26
0
4
0
4

1.00

22
0
0
0
0

• Censored denotes collar failure and/or animal life/death status not known.
Includes (173.949/94) collar failure December 1994 but seen January 1996
• Censored elk (173.949/94) collar failure, which was killed in first rifle season 1996.
d Includes (174.030/94) alive June 1997.
• Censored elk (173.719/94) slipped collar May 1996.
f Collar (173.760/94) disappeared 1998 hunting seasons and assumed dead.
• Censored elk (174.030/94) slipped collar September 1998.
b Censored elk (173.799/94) collar failure February 2000.
b

0.64
0.42
0.85
22
0
8f
0
8

1.00

14
0
0
·0
0

0.86
0.66
1.00
14
0
2
0
2

0.91
0.72
1.00
11

Ih
1
0
1

0.29
0.14
0.45
34
2·,h
24
5
19

�249
Table 4. Survival rates, inclusive of non-hunting and hunting mortalities, for winter-spring (WS, 1 December-14
June) and summer-fall (SF, 15 June-30 November) time periods from 1 December 1995-14 June 2000 for the
cohort of calves age 6 months radio-collared in December 1995. Survival rate for male and female calves pooled
when age 6-11 months was 0.88 in 1995 (95% CI 0.81-0.96, n=69). Survival rates (S) calculated as a mean
estimate of ~alivel/~alive+deadl and variance of Sp-S2/n collars.
Elk Ag_e(months) and Time Period (WS or SF dates)
48-53
54-59
6-59
6-11 (mos)
12-17 18-23
30-35
36-41
42-47
24-29
ALL
SF
WS
WS
SF
SF
WS
SF
WS
WS
1995-96
1996 1996-97
1999 1999-00
1995-00
1997
1997-98
1998 1998-99
MALES
0.00
Survival
0.86
0.83
0.96
0.23
1.00
0.25
1.00
0.00
0.74
L 95%CI
0.68
0.87
0.04
0.00
0.98
U95%CI
0.97
1.00
0.41
0.86
n collars
35
32
29
24
22
4
4
1
1
5b,C,d,.
2b
Ie
Id
1·
0
0
0
0
Censored"
5
5
1
32
Died
1
17
0
3
0
5
6
Nonhunt
0
0
0
0
0
0
1
0
5
0
17
0
1
26
Hunt
0
3
FEMALES
Survival
L95%CI
U95%CI
n collars
Censored"
Died
Nonhunt
Hunt
• Censored
Censored
e Censored
d Censored
• Censored
t Censored
• Censored
b

0.91
0.81
1.00
34
0
3
3
0

0.87
0.75
0.99
31
0
4
0
4

0.93
0.82
1.00
27
0
2
1
1

I

0.83
0.66
0.99
23
2f

1.00

Ig

4
0
4

0
0
0

18

0.89
0.73
1.00
18
0
2
0
2

1.00

16
0
0
0
0

denotes collar failure and/or animallifeldeath
status not known.
elk (174.619/95) slipped collar May 1996, (174.800/95) capture mortality.
elk (174.660/95) slipped collar July 1996.
elk (174.671/95) likely collar failure July 1997.
elk (174.190/95) slipped collar May 1998.
elk (174.441/95) slipped collar August 1997 and (174.580/95) collar failure July 1997.
elk (174.470/95) collar failure December 1997.

0.88
0.70
1.00
16
0
2
0
2

1.00

14
0
0
0
0

0.36
0.18
0.53
31
3
17
4
13

�250
Table 5. Survival rates, inclusive of non-hunting and hunting mortalities, for winter-spring (WS, 1 December-14
June) and summer-fall (SF, 15 June-30 November) time periods from 1 December 1993-14 June 2000 for the
cohort of calves age 6 months radio-collared in December 1996. Survival rate for male and female calves pooled
when age 6-11 months was 0.86 (95% CI 0.81-0.96, n=69). Survival rates (S) calculated as a mean estimate of
~alive~/~alive+dead~ and variance of Sp-S~/n collars.
Elk A~e (months2 and Time Period (WS or SF dates)
6-47
6-11 (mos)
36-41
42-47
12-17
24-29
30-35
18-23
ALL
SF
SF
WS
WS
SF
WS
WS
1996-00
1999-00
1996-97
1997
1997-98
1998-99
1999
1998
MALES
1.00
0.09
0.85
0.97
1.00
0.30
Survival
1.00
0.36
0.00
L 95%CI
0.73
0.90
0.00
0.17
0.98
1.00
0.63
0.19
U 95% CI
0.54
n collars
34
10
3
34
29
28
28
10
1b
1b
Censored"
0
0
0
0
0
0

0

Died
Nonhunt
Hunt

5
5
0

1
0
1

0
0
0

18d
0
18

0
0
0

7
0
7

0
0

FEMALES
Survival
L 95% CI
U95%CI
n collars
Censored"
Died
Nonhunt
Hunt

0.86
0.74
0.98
35
0
5
5
0

1.00

1.00

1.00

1.00

1.00

30
0
0
0
0

30
0
0
0
0

0.80
0.65
0.95
30
0
6C
0
6

24
0
0
0
0

24
0
0
0
0

24
0
0
0
0

• Censored denotes collar failure and/or animallifeldeath
status not known.
b Censored
elk (174.619/96) capture mortality.
c Collar (174.929/96) disappeared 1998 hunting seasons and assumed dead.
d Collar (175.199196) disappeared
1998 hunting seasons and assumed dead.

31
5
26

0.69
0.53
0.85
35
0
11
5
6

�251
Table 6. Survival rates, inclusive of non-hunting and hunting mortalities, for winter-spring (WS 1 December-14
June) and summer-fall (SF, 15 June-30 November) time periods from 1 December 1993 - 14 June 2000 for all
radio-collared adult female elk age :::12 months. Survival rates (S) calculated as a mean estimate of (alive)/(alive +
dead2 and variance S{I-S2/n collars.
Elk A8e and Time Period (WS or SF dates 2
Adult Adult
Adult
Adult Adult Adult Adult Adult Adult Adult Adult Adult Adult
WS
WS
SF
WS
SF
WS
SF
WS
WS
WS
SF
SF
SF
1993-94 1994 1994-95 1995 1995-96 1996 1996-97 1997 1997-98 1998 1998-99 1999 1999-00
0.99
0.77
0.98
0.98
Survival
0.96
0.87
0.96
0.94
0.91
0.89
0.94
0.89
0.98
0.70
0.95
L95%CI
0.91
0.80
0.90
0.87
0.97
0.83
0.95
0.92
0.90
0.84
0.95
1.00
0.84
1.00
U95%CI
0.94
1.00
0.98
1.00
0.96
1.00
1.00
0.95
0.98
0.94
100b[ 95b&amp;
68b•
1431&lt; 1271 152m
ncollars
129bh ll~
138°
136q
103'
101ft
88v
2ft
2i
Censored"
IP
0
2'
0
2'"
0
0
0
0
0
0
c
4
Died
13
3
4
8
7
13
2
31r
2
11
2
16
3
Nonhunt
0
1
1
1
0
4
0
2
0
1
1
1
Hunt
13
2
12
8
31
0
11
1
3
3
15
2
• Censored denotes collar failure or life/death status unknown.
e Collars (172.800/93,172.649/93)
disappeared 1994 hunt seasons.
• Composed of6-18+ and 62-30+ months old females.
I Composed
of34-18+ and 61-30+ months old females.
; Composed of 30-18+ and 89-30+ months old females.
k Composed
of31-12+, 29-24+, and 83-36+ months old females.
• Composed of30-12+, 23-24+, and 99-36+ months old females.
• Censored elk: (174.441/95) slipped collar August 1997 and
(174.580/95) likely failure June 1997
P Censored elk: (174.470/95)
likely collar failure August 1997.
'Collars (172.269/93, 172.308/93, 172.498/93, 172.991/93,
173,760/94, 174.929/96) disappeared 1998 hunt seIjSOns
and assumed dead.
• Composed of 24-36+ and 77-48+ months old females
W Censored
elk: (172.418/93 April 2000, 173.799/94 Feb.2000)

Includes (172.011/93) collar failure April 1994, seen January 1996
Collar (172.207/93) disappeared 1995 hunt seasons, assumed dead.
f Composed
of35-12+, 6-24+, and 59-36+ months old females.
k Composed
of32-12+, 34-24+, and 63-36+ months old females.
j Censored
elk: (172.011/93) failure and (173.719/94) slipped collar.
I Composed of27-18+
and 100-30+ month old females.
b
d

o

Composed

of30-18+

and 108-30+ months old females.

Composed of30-24+ and 106-36+ months old females.
• Composed of 24-30+ and 81-42+ months old females.
q

I
V

Censored elk: (172.849/93, 173.151/93) failed collars.
Composed of24-42+ and 66-54+ months old females

�252
Table 7. Survival rates, inclusive of non-hunting and hunting mortalities, for winter-spring (WS 1 December-14
June) and summer-fall (SF, 15 June-30 November) time periods from 1 December 1993 - 14 June 2000 for radiocollared adult female elk age :::24 months. Survival rates (S) calculated as a mean estimate of (alive)/(alive + dead)
and variance S{l-S~/n collars.
Elk Ase and Time Period (WS or SF dates2
Adult Adult Adult Adult Adult Adult Adult Adult Adult Adult Adult Adult Adult
WS
WS
SF
WS
SF
WS
WS
SF
WS
SF
SF
WS
SF
1993-94 1994 1994-95 1995 1995-96 1996 1996-97 1997 1997-98 1998 1998-99 1999 1999-00
Survival
0.77
0.89
0.98
0.95
0.82
0.93
0.93
0.89
0.89
0.98
0.98
0.93
0.99
L 95%CI
0.72
0.84
0.70
0.95
0.83
0.95
0.90
0.87
0.88
0.84
0.96
0.88
0.97
0.84
1.00
U 95% CI
1.00
1.00
1.00
1.00
0.95
0.91
0.99
0.98
0.99
0.95
0.95
n collars
136
103
101
62
65
97
100
122
108
88
61
89
112
Ib
Id
2f
2&lt;
Censored"
2·
0
0
0
0
0
0
0
0
Died
3
12
7
31
11
4
6
12
13
2
2
2
1
Nonhunt
1
0
0
0
1
1
3
0
1
2
1
1
0
Hunt
2
11
7
13
31
3
3
11
1
0
11
1
1
• Censoreddenotescollarfailureor life/deathstatusunknown.
Censoredelk (174.441/95)(174.580/95)
e Censoredelk (172.849/93,173.151193)
e

Censoredelk (172.011/93)
Censoredelk (174.470195)
fCensored elk (172.418/93,173.799/94)
B
d

Table 8. Survival rates, inclusive of non-hunting and hunting mortalities, for winter-spring (WS, 1 December-14
June) and summer-fall (SF, 15 June-30 November) time periods from 1 December 1993 - 14 June 2000 for the
group of adult female elk age :::18 months when radio-collared in December 1993. Survival rates (S) calculated as
a mean estimate of (alive)/(alive + dead) an? variance S(l-S)/n collars.
Elk Ase and Time Period (WS or SF dates2
Adult Adult
Adult Adult Adult
Adult Adult
Adult Adult Adult Adult Adult Adult
SF
WS
WS
SF
WS
SF
WS
SF
WS
SF
WS
SF
WS
1993-94 1994 1994-95 1995 1995-96 1996 1996-97· 1997 1997-98 1998 1998-99 1999 1999-00
Survival
1.00
1.00
0.73
0.83
0.96
0.82
0.93
0.88
0.93
0.92
1.00
0.94
0.97
0.57
0.68
L95%CI
0.72
0.78
0.85
0.84
0.87
0.92
0.91
0.85
0.99
U95%CI
0.88
1.00
0.91
0.99
0.97
1.00
1.00
1.00
1.00
331:
II)l
241:
241
68b•
34i
3~
36i
36i
n collars
65bf
53bf
49bh 42h
o
o
Censored" 0
o
0
0
0
o
0
0
0
l'
12&lt;
Died
3
0
2
1
9
o
4
3
6d
4
3
o
o
Nonhunt
o
0
0
0
o
1
1
0
3
1
Hunt
9
o
4
2
11
6
3
0
2
1
3
0
• Censored denotes collar failure or Iifcldcalh status unknown
• CoDar (172.649/93) disappeared 1994 hunt seasons.
• Composed of 6-18+ and 62-30+ month old females.
• Censored (172.011/93) coDar failure Apri11994.
i Composed
of 100% females 48+ months old.
• Composed of 100% females 72+ months old
- Censored elk (172.418/93) collar failure Apri12000.

• Includes (172.011/93) collar failure Apri11994 but seen Jan. 1996.
• CoDar (172.207/93) disappeared 1995 hunt eeasons and assumed dead.
r Composed of l000A. females 24+ months old.
• Composed of 100% females 36+ months old.
; Composed of 100% females 60+ months old.
, Composed of l000A. females 84+ months old

�253
Table 9. Annual survival rates from 1 December-30 November each year 1993-94 - 1998-99 inclusive of nonhunting and hunting mortalities and overall survival through Novemeber 1999 for the group of adult female elk
age ~18 months when radio-collared in December 1993. Survival rates (S) calculated as a mean estimate of
(alive)/(alive+dead) and variance S(1-S)/n collars.
Elk Age and Time Period (dates)
Adult
Adult
Adult
Adult
Adult
Adult
Adult
19931994199519961997199819931994
1995
1996
1997
1998
1999
1999
Survival
0.78
0.84
0.86
0.94
0.71
0.83
0.30
L 95%CI
0.68
0.75
0.75
0.87
0.55
0.68
0.19
U 95% CI
0.88
0.93
0.97
1.00
0.86
0.99
0.41
68b,.
53b.f
34)
24k
n collars
42g
36i
67
Ib
Ib
Censored"
0
0
0
0
0
d
Died
15°
10
6
2
10
47
4
Nonhunt
2
1
3
0
0
6
0
Hunt
13
9
41
3
2
10
4
• Censored denotes collar failure or life/death status unknown
b Includes collar (172.011193)
failed 4/1994 seen alive 111996
d Collar (172.207/93)
disappeared 1995 hunt seasons, assumed dead.
t Composed of 100% females 24+ months old.
~ Censored (172.011193) failure 4/1996.
j Composed
of 60+ months old females.

c Collar (172.649/93)
disappeared 1994 hunt seasons
• Composed of 6-18+ and 62-30+ months old females
• Composed of36+ months old females
I Composed
of 48+ months old females
k Composed
of72+ months old females

Table 10. Survival rates for adult male elk during summer-fall, 15 June-30 November, 1995-1999. All deaths due
to hunting. Survival rates (S) calculated as 11 mean estimate of (alive)/(alive + dead) and variance S(I-S)/n collars.
Removal rate = (1-S). All males radio-collared as 6-month old calves in December 1993-1996.
Summer-Fall Time Period Year
All Years
1995
1999
1996
1997
1998
MALES (age 24-29 months)
Survival
0.21
0.22
0.08
0.23
0.35
L 95%CI
0.06
0.00
0.14
0.04
0.17
U95%CI
0.37
0.19
0.30
0.41
0.54
n collars
28
103
25
22
28
Died Hunting
80
22
23
17
18
Removal Rate
0.79
0.78
0.92
0.77
0.65
MALES (age 24-53 months)
Survival
0.21
L 95% CI
0.06
U95%CI
0.37
n collars
28
Died Hunting
22
Removal Rate
0.79

0.14
0.01
0.27
29
25
0.86

0.24
0.06
0.42
25
19
0.76

0.33
0.17
0.50
33
21
0.64

0.27
0.00
0.57
11
8
0.73

0.24
0.17
0.32
126
95
0.76

�254
Table 11. Survival rates for adult female elk during summer-fall, 15 June-30 November, 1994-1999. For adult
females, 2 natural deaths occurred during summer-fall in these 6 years and these 2 elk were censored from survival
calculations. All deaths shown were due to hunting. Survival rates (S) calculated as a mean estimate of (alive) /
(alive + dead) and variance of S(I-S) / n collars. Removal rate = (l -S). Females radio-collared as adults in 1993
or as 6-month calves in December 1993-1996.
Summer-Fall Time Period Year
1994
1999
1995
1996
1997
1998
All Years
FEMALES (age&gt; 24 months)
Survival
0.83
0.89
0.77
0.89
0.93
0.91
0.87
L 95% CI
0.73
0.70
0.83
0.88
0.85
0.84
0.84
U95%CI
0.92
0.98
0.95
0.84
0.95
0.89
0.96
n collars
64
110
122
136
99
628
97
Died Hunting
11
11
7
10
13
31
83
Removal Rate
0.17
0.11
0.07
0.09
0.11
0.23
0.13
FEMALES (age 12-17 months)
0.97
Survival
L95% CI
0.92
U95%CI
1.00
n collars
35
Died Hunting
1
Removal Rate
0.03

0.97
0.91
1.00
32
1
0.03

0.87
0.75
0.99
31
4
0.13

1.00

30
0
0.00

0.95
0.92
0.99
128
6
0.05

�255
Appendi x I. MortaLities of 256 radio-coLLared eLk from 1 December 1993 through 14 June 2000. Age is
aE2roximate a2e in ~ears of eLk at death: C=caLf a2e 6-11 months, Y=~earLin2 a2e 12-23 months.
Death
Frequency 101
Tra!;!
Cause of Death &amp; Code Number
Date
Age
Zone
Sex
Year Ca~tured Site
legaL kiLL second rifLe season-47
19-Oct-99
B
9
SR
F
172.019/93
legaL kiLL second rifLe season-47
27-Oct-95
5
BR
A
F
172.030/93
legaL kiLL third rifLe season-48
31-Oct-98
F
12
EG
B
172.050/93
Unknown-suspect predation-30
14-Jun-95
B
F
4
GR
172.039/93
Unknown-11
12-Feb-96
F
11
BR
A
172.070/93
legaL kiLL third rifLe season-48
05-Nov-94
6
GM
A
F
172.080/93
Wounding Loss late rifle season-26
16-Jan-94
F
11
GR
B
172.090/93
legaL kiLL first rifLe season-46
12-Oct-98
0
F
11
SM
172.090/94
legaL kiLL first rifLe season-46
14-Oct-96
8
B
F
172.101/93
SR
Wounding Loss second rifLe season-44
31-Oct-96
8
B
F
GC
172.128/93
Wounding loss first rifLe season-43
19-0ct-95
17
BC
C
F
172.139/93
legaL kiLL second rifLe season-47
23-0ct-94
C
F
3
CC
172.160/93
Wounding Loss second rifle season-44
03-Nov-94
3
MC
C
F
172.181/93
Wounding Loss second rifle season-44
15-Nov-94
3
GS
C
F
172.201/93
Disappear first rifle season-40
30-Nov-95
4
SG
0
F
172.207193
legaL kiLL rifle season-28
30-Nov-99
0
F
8
GH
172.219/93
legaL kiLL second rifle season-47
29-Oct-98
8
MC
C
F
172.229/93
legaL kiLL archery/muzzLe season-27
04-Oct-94
3
HY
C
F
172.258/93
Disappear second rifLe season-41
29-0ct-98
C
F
12
MC
172.269/93
Wounding loss archerY/muzzLe-24
04-Oct-94
3
GS
C
F
172.277/93
legal kiLL second rifle season-47
23-0ct-94
D
6
SG
F
172.290/93
legal kilL muzzleloading season-34
16-Sep-96
SM
D
F
4
172.290/94
Wounding loss second rifLe season-44
30-0ct-97
E
8
AC
F
172.300/93
Disappear second rifle season-41
29-Oct-98
8
GH
D
F
172.308/93
legal kiLL first rifle season-46
10-Oct-99
D
11
SG
F
172.330/93
legaL kiLL second rifle season-47
19-Oct-99
SG
D
F
11
172.358/93
legaL kiLL archery season-33
18-Sep-94
3
AC
E
F
172.369/93
legaL kiLL Late rifLe season-29
14-Jan-96
FM
B
F
4
172.369/94
Wounding Loss Late rifLe season-26
29-Dec-94
8
AC
E
F
172.409/93
legaL kiLL third rifle season-48
01-Nov-98
MH
E
F
172.448/93
I12
legaL kiLL second rifle season-47
24-0ct-96
E
8
MH
F
172.459/93
Disappear first rifle season-40
15-0ct-98
12
FS
H
F
172.498/93
legaL kiLL second rifle season-47
21-0ct-95
3
FS
H
F
172.509/93
legaL kiLL first rifLe season-46
12-0ct-98
6
FS
H
F
172.519/93
Wounding Loss second rifLe season-44
29-Oct-98
8
FS
H
F
172.530/93
Mountain lion predation-3
01-Feb-94
6
FS
H
F
172.542193
Accident-irrigation ditch-10
06-Jan-99
15
FM
B
F
172.542/94
legaL kill late rifle season-29
28-Nov-95
7
PG
H
F
172.549/93
Wounding loss second rifle season-44
03-Nov-94
16
PG
H
F
172.570/93
legaL kiLL first rifLe season-46
17-Oct-94
PG
H
F
3
172.581/93
legal kill late rifle season-29
08-Dec-95
3
FM
B
F
172.581/94
Unknown-11
24-Apr-96
5
PG
H
F
172.590/93
Accident, birthing/calving-32
04-0ct-94
PG
F
3
H
172.610/93
legaL kiLL third rifLe season-48
04-Nov-98
H
F
5
PG
172.620/93
Accident, birthing/calving-32
14-Jun-96
16
PG
H
F
172.639/93
Disappear first rifle season-40
30-Nov-94
H
F
2
172.649/93
PG
legal kiLL third rifle season-48
02-Nov-97
H
F
5
PG
172.658/93
legal kiLL late rifle season-29
16-Jan-95
4
PG
H
F
172.670/93
Wounding loss late rifle season-26
22-Dec-94
PG
H
F
9
1'72.678/93
Illegal kit l-7
24-Jan-94
B
F
8
172.690/93
FM
legaL kiLL third rifLe season-48
05-Nov-95
B
7
FM
F
172.699/93
MaLnutrition-6
05-May-99
19
lS
H
F
172.730/95
Unknown-suspect predation-30
07-Aug-96
lS
H
F
11
172.749/95
Wounding Loss second rifLe season-44
28-Oct-98
15
lS
H
F
172.758/95
Wounding Loss second rifLe season-44
16-Oct-99
F
6
lS
H
172.769/95
Mountain Lion predation-3
31-Dec-99
6
SR
B
F
172.790/93
Disappear second rifLe season-41
30-Nov-94
SR
B
F
Y
172.800/93
legal kilL archery season-33
05-Sep-99
6
EG
B
F
172.810/93
legaL kilL archery season-33
08-S.ep-96
3
EG
B
F
172.821/93
legaL kilL third rifLe season-48
Q6-Nov-96
3
BC
C
F
172.890/93
Mountain Lion predation-3
18-Mar-94
BC
C
F
C
172.899/93
legaL kiLL first rifLe season-46
18-0ct-95
GH
D
F
2
172.950/93
Disappear 'second rifLe season-41
30-Oct-97
MG
D
F
4
172.961/93
Disappear second rifLe season-41
29-0ct-98
D
5
SG
F
172.991/93
Malnutrition-6
25-Apr-94
WM
C
173.000/93
G
F
legaL kill third rifLe season-48
31-Oct-98
F
4
173.000/94
HM
B
Accident-feLL-10
07-Jan-98
WM
4
G
F
173.010/93
legal kiLL first rifLe season-46
19-Oct-95
2
GM
A
M
173.041/93

�256
Appendix 1. (continued)
Frequency ID/
Tral2
Year Captured Site
Zone
173.050/93
MH
E
173.060/93
MH
E
173.070/93
E
MH
173.081/93
FS
H
173.090/93
FS
H
173.100/93
FS
H
173.120/93
GM
A
173.140/93
PG
H
173.160/93
FS
H
173.180/93
PG
H
173.171/93
FM
B
173.190/93
BC
C
173.190/96
BC
C
173.201/93
GR
B
173.210/93
GC
B
173.210/96
LM
D
173.219/93
BC
C
173.219/96
CG
D
173.232/93
BR
A
173.232196
BC
C
173.262/93
BC
C
173.262/94
HM
B
173.269/93
MC
C
173.279/93
C
MC
173.289/93
MC
C
173.289/94
PR
A
173.300/93
C
GS
173.300/96
MC
C
173.309/93
HY
C
173.320/93
HY
C
173.320/94
HM
B
173.332/93
GH
D
173.332/96
BC
C
173.340/93
SG
D
173.351/93
SG
D
173.351/96
BG
E
173.359/93
AC
E
173.359/96
C
MC
173.370/93
MH
E
173.370/96
RG
E
RG'
173.381/96
E
173.390/93
MG
D
173.402/93
MG
D
173.410/93
WM
G
173.410/96
EW
G
173.420/93
WM
G
173.429/93
MH
E
173.429/96
G
EW
173.439/93
PG
H
173.450/93
PG
H
173.450/96
EW
G
173.461/93
PG
H
173.461/94
CM
A
173.461/96
GM
A
173.469/93
FS
H
173.469/94
PR
A
173.479/93
FS
H
173.479/96
RG
E
173.492/93
FS
H
173.492196
GM
A
173.502/93
FS
H
173.510/93
FM
B
173.521/93
FM
B
173.530/94
FM
B
173.540/94
OG
B
173.549/94
B
HM
173.559/94
PR
A
173.569/94
PR
A
173.580/94
PR
A

Death
Sex
F
F
F
F
F
F
M
F
F
F
F
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
F
M
F
F
F
F

Age
5
2
5
3
4
4
2
3
3
6
5
Y
2
2
2
2
2
2
Y
2
C
2
2
3
C
2
2
2
Y
Y
,2
2
2
4
2
2
2
2
2
C
C
2
2
2
1
2
2
3
2
2
3
C
Y
2
C
2
2
2
2
3
3
2
2
7
2
Y
5
3
Y

Date
31-Oct·98
27-Dec-95
03-Mar-98
22-OCt-96
24-Oct-97
30-Oct-97
14-OCt-95
31-Oct-96
13-Noy-96
10-OCt-99
10-OCt-98
29-OCt-94
10-OCt-98
30-Noy-95
19-0ct-95
30-OCt-97
06-Noy-95
21-Oct-98
15-Noy-94
31-OCt-98
18-Mar-94
12-Oct-96
06-Noy-95
12-Oct-96
22-Mar-94
18-Sep-96
24-Oct-95
10-OCt-98
30-Noy-94
20-Oct-94
14-Sep-96
12-Sep-95
10-0ct-98
20-0ct-97
05-Noy-95
27-Oct-98
06-Sep-95
09-Noy-98
08-Noy-95
08-Jan-97
19-Feb-97
30-Noy-95
18-0ct-95
02-Noy-95
29-Sep-98
24-0ct-95
14-Sep-95
10-0ct-99
30-Noy-95
15-Oct-95
21-Oct-99
07-Feb-94
19-5ep-95
22-OCt-98
25-Apr-94
20-OCt-96
10-Sep-95
17-0ct-98
03-Sep-95
11-0ct-99
13-Noy-96
28-Aug-95
17-0ct-95
31-OCt-98
13-0ct-96
07-Sep-95
30-Oct-99
16-Oct-97
21-Dec-95

Cause of Death &amp; Code Number
Legal kill third rifle season-48
Legal kill late rifle season-29
Illegal kill-7
Legal kill second rifle season-47
Legal kill second rifle season-47
Legal kill second rifle season-47
Legal kill first rifle season-46
Wounding loss second rifle season-44
Legal kill third rifle season-48
Legal kill first rifle season-46
Legal kill first rifle season-46
Illegal kill second rifle season-50
Legal kill first rifle season-46
Wounding loss third rifle season-45
Legal kill first rifle season-46
Illegal kill archery/muzz. season-8
Legal kill third rifle season-48
Legal kill second rifle season-47
Illegal kill second rifle season-50
Legal kill third rifle season-48
Unknown-11
Legal ki II first rifle season-46
Legal k i II third rifLe season-48
LegaL kill first rifLe season-46
Unknown-11
LegaL kiLL muzzLeLoading season-34
LegaL kill second rifLe season-47
LegaL kiLL first rifle season-46
ILlegal kiLL first rifle season-49
Illegal kill first rifle season-49
LegaL kill archery season-33
LegaL kill muzzleloading season-34
Legal kiLL first rifle season-46
LegaL kill second rifLe season-47
Legal kill third rifle season-48
Legal kill second rifle season-47
Legal kill archery season-33
Wounding loss third rifle season-45
Legal kill first rifLe season-46
Mountain lion predation-3
Unknown-suspect predation-30
Disappear first rifle season-40
Legal kill first rifle season-46
Wounding (oss second rifle season-44
Wounding Loss archery/muzzle seasons-24
Legal kill second rifle season-47
Legal kill archery season-33
Legal kill first rifLe season-46
Disappear first rifLe season-40
Legal kill first rifle season-46
Legal kill second rifle season-47
Malnutrition-6
Wounding loss archery season-50
LegaL kill second rifLe season-47
MaLnutrition-6
Legal kill second rifle season-47
Legal kill archery season-33
LegaL kill second rifle season-47
Legal kiLL archery season-33
Legal kill first rifle season-46
LegaL kill third rifLe season-48
Legal kill archery season-33
LegaL kill first rifle season-46
Legal kill third rifle season-48
Legal kill first rifle season-46
Legal kill archery season-33
Legal kill third rifle season-48
Wounding loss first rifle season-43
Unknown-11

�257
A~ndix
I. (continued)
Frequency 10/
Tra!:!
Zone
Year Ca~tured Site
173.589/94
OG
B
173.610/94
C
BC
173.640/94
C
MC
173.640/96
GM
A
173.649/94
BC
C
173.659/94
C
MC
173.679/94
MP
D
173.689/94
BG
E
173.699/94
E
BG
173.719/96
MC
C
173.739/94
BG
E
173.750/94
E
BG
173.760/94
E
MR
173.779/94
MR
E
173.789/94
MR
E
173.819/94
MM
F
173.829/94
MM
F
173.840/94
MM
F
173.849/94
SM
D
173.859/94
SM
D
173.870/94
SM
D
173.919/94
BC
C
C
173.929/94
BC
173.939/94
C
BC
173.959/94
BC
C
173.970/94
MC
C
173.981/94
D
MP
173.990/94
C
BC
174.001/94
BG
E
174.009/94
BG
E
174.019/94
E
BG
174.039/94
MR
E
174.049/94
F
MM
174.059/94
E
MR
174.069/94
BG
E
174.080/94
E
MR
174.090/94
MR
E
174.101/94
MM
F
174.101/96
E~
G
174.109/94
MM
F
174.119/94
MM
F
174.119/95
GB
B
174.129/94
MM
F
174.140/94
F
MM
174.140/95
GB
B
174.150/94
MM
F
174.160/94
MM
F
174.170/94
FM
B
174.170/96
C
MC
174.181/94
FM
B
174.200/95
MS
F
174.210/95
MS
F
174.220/95
MS
F
174.220/96
F
MS
174.230/95
MS
F
174.230/96
G
E~
174.240/95
E
MD
174.240/96
SR
B
174.301/95
MD
E
174.319/95
MS
F
174.329/95
E
MD
174.339/95
MD
E
174.349/95
E
MD
174.360/95
MD
E
174.370/95
HG
E
174.380/95
AP
D
174.401/95
AP
D
174.420/95
AP
D
174.478/95
W
C

Death
Sex
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
M

M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
F
F
F
F
F
F
F
F
F
F
F

Age
C
3
C
C
3
4
it

2
5
2
4
4
4
5
C
3
2
4
4
2
C
Y
2
2
2
2
2
2
2
2
12
2
2
Y
2
3
2
Y
3
2
C
2
2
C
Y
2
2
C
2
2
Y
2
C
3
C
2
C
2
3
Y
Y
C
2
Y
4
4
2
2
2

Date
01-Jun-95
14-Nov-97
30-Mar-95
16-Mar-97
11-0ct-97
25-0ct-98
29-Oct-98
31-Oct-96
30-Nov-99
03-Nov-98
29-Oct-98
18-Oct-98
29-Oct-98
31-Dec-99
20-Mar-95
30-Oct-97
10-Jan-97
29-Sep-98
20-Oct-98
23-0ct-96
21-Feb-95
02-Nov-95
16-Oct-96
18-Sep-96
02-Nov-96
20-Oct-96
02-Nov-96
20-Oct-96
30-Nov-96
12-0ct-96
13-Nov-96
05-Sep-96
14-Sep-96
17-0ct-95
26-Sep-96
11-0ct-97
20-Oct-96
24-May-96
10-0ct-99
19-Oct-96
01-Mar-95
30-Nov-97
14-0ct-96
14-Mar-95
30-Nov-96
14-0ct-96
15-Sep-96
25-Apr-95
10-0ct-98
30-Nov-96
18-0ct-96
11-0ct-97
08-Apr-96
11-0ct-99
24-Apr-96
13-0ct-98
17-Apr-96
12-Sep-98
20-Sep-98
02-Oct-96
03-Sep-96
27-Mar-96
13-Oct-97
22-Apr-97
30-Nov-99
30-Aug-99
22-Sep-96
11-Oct-97
13-Sep-97

Cause of Death &amp; Code Number
Unknown-suspect predation-30
~ounding loss third rifle season-45
Unknown-suspect predation-30
Malnutrition-6
legal kill first rifle season-46
legal kill second rifle season-47
Wounding loss first rifle season-43
legal kill first rifle season-46
~ounding loss rifle season-25
legal kill thi~d rifle season-48
~ounding loss second rifle season-44
legal kill second rifle season-47
Disappear second rifle season-41
legal kill late rifle season-29
Unknown-suspect malnutrition-31
legal kill second rifle season-47
legal kill late rifle season-29
~ounding loss archery/muzzle seasons-24
legal kill second rifle season-47
legal kill second rifle season-47
Mountain lion predation-3
Illegal kill second rifle season-50
legal kill first rifle season-46
legal kill archery season-33
legal kill third rifle season-48
legal kill second rifle season-47
legal kill third rifle season-48
legal kill second rifle season-47
Disappear archery/muzzle season-21
legal kill first rifle season-47
Illegal kill rifle season-9
legal kill archery season-33
legal kill muzzleloading season-34
Illegal kill first rifle season-49
~ounding loss archery/muzzle-24
legal kill first rifle season-46
legal kill second rifle season-47
Unknown-suspect predation-30
legal kill first rifle season-46
legal kill second rifle season-47
Mountain lion predation-3
~ounding loss rifle season-25
legal .ki ll first rifle season-46
Mountain lion predation-3
Illegal kill third rifle season-51
legal kill first rifle season-46
legal kill muzzleloading season-34
Mountain lion predation-3
legal kill first rifle season-46
Disappear second rifle season-41
Illegal kill first rifle season-49
legal kill first rifle season-46
Unknown-suspect malnutrition-31
legal kill first rifle season-46
Mountain lion predation-3
legal kill first rifle season-46
Mountain lion predation-3
legal kill muzzleloading season-34
legal kill archery season-33
~ounding loss archery season-52
legal kill archery season-33
Unknown predator-5
legal kill first rifle season-46
Unknown-suspect predation-30
~ounding loss rifle season-25
legal kill archery season-33
legal kill muzzleloading season-34
legal kill first rifle season-46
legal kill muzzleloading season-34

�258
Apeendix I. (continued)
Frequency 10/
Tral;!
Year Captured Site Zone
174.491/95
lB
e
174.500/95
e
lB
174.520/95
KR
B
174.520/96
A
GM
174.551/95
\Ie
G
174.560/95
A
Bl
174.609/95
GB
B
174.629/95
E
MD
174.639/95
MD
E
174.650/95
HG
E
174.660/96
B
SR
174.679/95
E
HG
174.689/95
D
AP
174.689/96
G
EW
174.700/95
0
AP
174.710/95
0
AP
174.719/95
VM
0
174.729/95
D
VM
174.740/95
D
VM
174.750/95
D
VM
174.760/95
VM
D
174.770/95
e
W
174.780/95
e
W
174.789/95
e
W
174.789/96
G
EW
174.800/96
E
BG
174.809/95
W
C
174.820/95
W
C
174.830/95
lB
e
174.841/95
e
LB
174.851/95
e
lB
174.861/95
KR
B
174.870/95
e
lB
174.880/95
B
KR
174.889/95
G
we
174.899/95
Bl
A
174.910/96
LM
D
174.929/96
D
lM
174.959/96
lM
0
174.998/96
BG
E
175.059/96
BC
C
175.130/96
GM
A
175.139/96
GM
A
175.149/96
SR
B
175.160/96
c
Be
175.170/96
0
lM
175.180/96
E
RG
175.189/96
RG
E
175.199/96
EW
G
175.209/96
MS
F

Oeath
Sex
F
F
F
F
F
F
F
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
M
F
F
F
F
F
F
F
F
M
M
M
M
M
M

Age
2
e
Y
e
3
Y
e
2
2
3
3
Y
e
e
2
2
4
Y
2
2
3
2
2
e
2
e
Y
2
2
3
12
Y
2
2
2
2
e
2
2
2
C
C

2
2
2
C
3
2
2
2

Oate
10-Sep-97
16-Apr-96
21-Sep-96
25-Apr-97
14-Oct-98
14-May-97
15-Apr-96
11-Oct-97
21-0ct-97
14-Sep-98
07-Nov-99
13-Nov-96
05-Feb-96
14-May-97
16-Oct-97
15-0ct-97
10-0ct-99
17-0ct-96
08-Nov-97
05-Nov-97
15-Sep-98
16-Oct-97
11-0ct-97
22-May-96
28-0ct-98
09-Apr-97
22-Apr-97
14-Oct-97
13-0ct-97
12-Sep-98
22-0ct-97
31-0ct-96
30-0ct-97
11-0ct-97
20-0ct-97
30-0ct-97
27-Feb-97
29-Oct-98
29-0ct-98
21-0ct-98
13-Feb-97
24-Mar-97
28-0ct-98
19-0ct-98
17-Sep-98
26-Mar-97
30-Nov-99
13-0ct-98
29-0ct-98
24-0ct-98

Cause of Oeath &amp; Code Number
Wounding loss archery season-52
Unknown-suspect predation-30
legal kilL IlUzzleloading season-34
Mountain lion predation-3
legal kill first rifle season-46
Illegal kill-7
Unknown-suspect predation-30
legal kill first rifle season-46
legal kill second rifle season-47
legal kill IlUzzleloading season-34
Wounding loss third rifle season-45
Illegal kill second rifle season-50
Mountain lion predation-3
Unknown-suspect malnutrition-31
Wounding loss first rifle season-43
legal kill first rifle season-46
Legal kill first rifle season-46
Illegal kill first rifle season-49
Legal kill third rifle season-48
legal kill third rifle season-48
Legal kill archery season-33
Disapeear first rifle season-40
legal kill first rifle season-46
Unknown-suspect predation-30
Wounding loss second rifle season-44
Mountain lion predation-3
Accident, fell-10
legal kill first rifle season-46
legal kill first rifle season-46
Legal kill IlUzzleloading season-34
Illegal kill second rifle season-50
Illegal k ill second rifle season-50
Wounding loss second rifle season-44
legal kill first rifle season-46
legal kill second rifle season-47
Wounding loss second rifle season-44
Unknown-suspect predation-30
Disapeear second rifle season-41
Wounding loss second rifle season-44
legal kill second rifle season-47
Unknown-11
Mountain lion predation-3
legal kill second rifle season-47
legal kill second rifle season-47
legal kill IlUzzleloading season-34
Unknown-suspect malnutrition-31
Wounding loss rifle season-25 .
legal kill first rifle season-46
Oisapeear second rifle season-41
Legal kill second rifle season-47

�</text>
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                  <text>207
Colorado Division of Wildlife
Wildlife Research Report
July 1998
Job Progress Report

State of

Colorado

Cost center 3430

Project No.

W-153-R-11

Mammals Program

Project No.

3002

Elk conservation

Work Program No. - - ~ L - - - - - - -

Elk Movements in Response to Early

season Hunting in the White River Area
Period Covered:

July 1, 1997 - June 30, 1998

Author:

Mary Conner

Personnel:

Dave Freddy, Gary White, Rick Kahn, John Ellenberger, Jim
Lipscomb, Bruce Gill, Jeff Madison

ABSTRACT
The effects of early hunting seasons on the movements and distribution of elk
remains controversial. Those who hunt the regular rifle seasons claim that
archery and muzzle loading rifle seasons drive elk off of public lands and
onto private land refuges before the regular rifle season begins, making them
unavailable to most who hunt in the regular rifle season.· Landowners complain
that elk responses to early hunting seasons cause elk to spend longer periods
on private property at the expense of the landowner. Beginning in 1996, the
Colorado Division of Wildlife sponsored a management experiment designed to
test the effects of early hunting on the movements and distribution of elk
residing in and around the White River plateau.
Four primary conclusions emerged from a preliminary analysis of 2 years of
data:
(1) In both 1996 and 1997, between 22-37% of the elk were on private land
before mid-July. By mid-October, between 65-85% of the elk were on private
land. The proportion of elk on private land was positively correlated with
date; there was a 28-60% increase of elk on private land during the study
period.
(2-) The mean date of movement from public (non-refuge) to private land was not
significantly different between treatments in the crossover analysis. Mean
date of movement was different between treatments for 1997 but not for 1996.
Mean date of movement was different between treatments for elk on the north
half of the study area, but not found different for elk on the south half.
The difference between late minus early date of movement was 6 days for elk
receiving both treatments.

�208

(3) Differences between elk on the north area and elk on the south area showed
in responses of mean date of movement and proportion of elk on refuge areas.
Mean date of movement between treatments was significantly different for elk
on the north area but not for elk on the south area. The difference in
proportion of elk on refuge areas between treatments was greater for elk on
the north area than for elk on the south area.

(4) Although all elk were captured on national forest land, some elk
immediately moved to private land in 1996, and some elk were never located on
public land during 1997 flights. "Manageable" elk include only those elk that
are on public land within a month of early-season opening date.
"Unmanageable• elk are those not on public land within a month of early-season
opening date and are, therefore, not likely to be affected by changes in
hunting patterns on public land. Between 39-64% of elk on public land one
month before early-season opening date (unmanageable elk) moved to private
land, and the mean date of movement including opening date in 3 of 4 cases.
However, the elk that moved represent 31-41% of the entire herd (unmanageable
and manageable elk). Therefore, any management decisions regarding hunter
numbers is likely to affect at most 41%, and possibly less, of the White River
elk.

�209
ELK MOVEMENT IN RESPONSE TO EARLY SEASON
IIUHTING IN THE WHITE RIVER AREA
Mary Conner

P.H. OBJECTIVE
Test whether early-season hunting season causes movement of elk from areas of
heavy hunting pressure to areas of lighter hunting pressure.

SEGMENT OBJECTIVES
1.

Estimate the mean date of movement of elk from non-refuge to refuge
areas, and determine whether the timing is equivalent to the opening of
archery season.

2.

Evaluate alternative hypotheses about causes of elk movement such as
livestock grazing, woodcutting, recreationalists, weather, or forage
quality.

3.

Publish analyses of elk movement in response to archery hunting in peerreviewed scientific journals. Preparation of manuscripts will begin
during 1997-98.

METHODS ARD MATERIALS
Methods and materials used in this investigation are described in the detailed
study plan reported in Conner 1996.

RESULTS ARD DISCUSSIQH
Preliminary analyses, results and conclusions of the 2-year study of the
effects of early hunting seasons on the movements and distribution of elk in
the White River area are summarized in Attachment 1 to this report.

LITERATURE CITED
Conner, M. 1996. Elk movements in response to early season hunting in the
White River area. Colorado Division of Wildlife. Wildlife Research
Report. July 1996 Part 1. Pp. 43-86.

Prepared by
Graduate Research Assistant

��211

Attachment 1
ELK MOVEMENTS IN RESPONSE TO EARLY-SEASON HUNTING IN 11IE WlilTE RIVER AREA:
1997 PRELIMINARY RESULTS

Mary Conner

March 31, 1998

EXECUTIVE SUMMARY
This year was the second and final year of an experiment designed to determine if elk movements in
the White River area were caused by early-season (archery and muzzleloading) hunting. The goal of this
report is to present 1997 results in a timely manner. This interim report provides information for those
involved with the White River elk to make relevant management decisions. Analyses that are more extensive
will be included in my dissertation, which will be completed late spring or early summer 1998.
Three main conclusions emerged from preliminary analyses of data from both years: (1) the
proportion of elk located on private land (refuge) increased between July 15th - October 13th, (2) the timing of
these movements weakly corresponded to the opening date of archery season, (3) elk on the north area had a
stronger response to changes in archery-season opening date than elk on the south area, and (4) it is not clear
how many elk in the White River area would be affected by management actions such as a reduction of
archery hunting licenses.
Conclusion (1): In both 1996 and 1997 between 22-37% of the elk were on private land before midJuly. By mid-October, between 65-85% of the elk were on private land. The proportion of elk on private
land was positively correlated with date; there was a 28-60% increase of elk on private land during the study
period.
Conclusion (2): The mean date of movement from public (non-refuge) to private land was not
significantly different between treatments in the crossover analysis. Mean date of movement was different
between treatments for 1997 but not for 1996. Mean date of movement was different between treatments for
elk on the north half of the study area but not found different for the south half elk. The difference between
late minus early date of movement was 6 days for elk receiving both treatments.
Conclusion (3): Differences between elk on the north area and elk on the south area showed in
responses of mean date of movement and proportion of elk on refuge areas. Mean date of movement between
treatments was significantly different for elk on the north area but not for elk on the south area. The
difference in proportion of elk on refuge areas between treatments was greater for elk on the north area than
for elk on the south area.
Conclusion (4): Although all elk were captured on national forest land, some elk immediately moved
to private land in 1996, and some elk were never located on public land during the 1997 flights.
"Manageable" elk include only those elk that are on public land within a month of early-season opening date.
"Unmanageable" elk are those elk not on public land within a month of early-season opening date and
t rtherefore, not likely to be affected by changes in hunting patterns on public land. Between 39-64% of elk
on public land a month before early-season opening date (manageable elk) moved to private land, and the
mean date of movement included opening date in 3 of 4 cases. However, the elk that moved represent 3141 % of the entire herd (manageable and unmanageable elk). Therefore, any management decisions regarding
hunter nwnbers are likely to affect at most 41 %, and possibly less, of the White River elk.

INTRODUCTION
As with the 1996 analyses, the treatment was difference in opening date of archery season and the
primary response variables were mean date of movement and proportion of elk that move from public to
private land I repeated all 1996 analyses for area x year to evaluate effects of archery hunting on elk that
were on public land within a month of opening date and to compare to pilot study results (Appendix A:
Methods). Because there are now 2 years of data, overall analyses including year and area effects were done
to evaluate effects of changes in opening date of archery hunting. To evaluate treatment effects on mean date
of movement, I did the crossover analysis described in my study plan (Appendix A: Methods). To evaluate

�212

treatment effects on proportion of elk moving to refuge areas, I included area and year effects in the logistic
regression model used in 1996 to predict the proportion of elk on refuge areas (Appendix A: Methods). Data
from the entire 3-month study period were used in the crossover and logistic regression analyses.
PRELIMINARY RESULTS
Area x Year Analyses
The timing of elk movements from non-refuge to refuge areas on the early- and late-opening
treatments is presented for 1996 and 1997 (Fig. IA, B). Only elk moving within a month of opening date
were used for within-treatment analyses to represent effects on manageable elk.Figure 1. Histograms of
number of elk moving from public (non-refuge) to private (refuge) land with respect to archery-season
opening date on the early-opening (A) and late opening (B) treatments; White River elk herd, 1996 and 1997.

B

A
1996 south side

1996 north side

4

4

Mun date of
movemant8/26

CD

Hlstortcal
opening data

.E 3
~

~3

E

E

.:.=:

='GI 2

::,

0

!E

1

::,

1

z

z

0

0

IIIIIIIIIIIIIIIII
Early opening: 8/24

§

1997 north side
Mun Date
of MovenwntB/18

1997 south side

Hlstortcal
opening data

4-r-----------------,

3

.:.=:
'ii

2

!E

1

0
1

::,

z

Historical
opening date

CD
C

1
::,

IIII~ IIIIIIIIIIII
Late opening: 9/14

4 -r-----------------,

!E

Historical
opening date

~2

0

!E

Mean Date
of Movement: 1115

CD

C

Mean Data
of Movemant 916

z

~ ; IIt IIIIIIIIIIII
Early opening: 8/23

I

; IIi IIIIIII IIIIIII
Late opening 9/13

For elk moving from non-refuge to refuge areas, mean date of movement was tested under the null
hypothesis that the mean date of movement was not different from opening date (Table 1). Between 39-64%
of elk on non-refuge areas one month before opening date moved to refuge areas within a month of opening
date (Table 2).
The probability that classifications are independent of opening date (Table 2) evaluated the effect
archery hunting has on elk location by testing whether movements between classifications occurred
independently before and after opening of archery hunting.

�213

Table 1. Mean dates of movement of elk moving from non-refuge to refuge areas. opening dates of archery
season, and P-values from a t-test for differences between opening date and mean date of movement for earlyand late-opening treatments; White River study area. 1996 and 1997.
Early opening

Late opening

Mean date of movement
95% Confidence interval

26 August
17 August-

18 August
11 August-

5 September
30 August-

6 September
26 August-

Opening date of early-season

24 August

23 August

14 September

13 September

P = 0.578

P = 0.178

P = 0.014

P = 0.131

-

Ho: d _ = onenin2' date

Table 2. Movements ofradio-collared elk between refuge and non-refuge areas with respect to opening date.
early-and late opening treatments; White River study area. 1996 and 1997.
Movement Combinations:

Early opening

Late opening

Pre-opening -&gt; post-opening

YEAR 1 - South

YEAR 2 - North

YEAR 1 - North

YEAR 2 - South

Refuge -&gt; refuge

11

8

4

11

Refuge -&gt; non-refuge

5

0

2

2

Non-refuge-&gt; refuge

12

18

15

14

Non-refuge -&gt; non-refuge

19

10

20

15

Sample size

47

36

41

42

P= 0.047

P= 0.280

P=0.027

Probability movement combinations P=0.051

Overall Analyses on Mean Date of Movement
The time frame for between-treatment analyses is the 3-month study period of July 15 th - October
th
13 . Results from the crossover analysis on mean date of movement indicated no area (P = 0.138) or year
effect (P = 0.644); however, there was a significant random effect of elk in area (P = 0.025). There was not a
significant treatment effect (P = 0.159) on the mean date of elk movement from non-refuge to refuge areas
(Table 3). Sequence effect refers to the fact that each elk received either a late-early or early-late sequence of
treatments. Elk on the north half received the late-early treatment sequence. while elk on the south half
received the early-late treatment sequence. Area effects and sequence effects were confounded. That is. it is
impossible to determine if a sequence effect is really a difference due to the fact that the north side is different
from the south side because of location of private-land refuges, topogQlphy, etc., or due to the fact that elk
getting a late-opening treatment the first year followed by an early-opening treatment the second year will
behave differently than elk getting the early-late sequence. I will refer to an area effect for clarity in the
remainder of the paper.
There appeared to be a treatment x year and treatment x area interaction in the crossover analysis that
clouded the results. In a post hoc analysis, I found that there was a difference in mean date of movement
between treatments for elk moving from non-refuge to refuge areas in 1997 but not in 1996 (Fig. 2 and Table
4).

�214

Table 3. Least square mean differences in days between mean dates of movement for effects specified in the
crossover analysis with their 95% confidence intervals; White River elk herd 1996 and 1997.
No. of days difference

No. of days difference

No. of days difference

between areas: ok

between treatments: a;

between years: Pi

7±9

2±7

6±8

Figure 2. Mean date of movement, 95% confidence interval, and archery opening date for elk on early-and
late opening treatments, 1996 (A) and 1997 (B), White River elk herd.
A

1996

Early open: South
Mean date of movement:

Late open: North

Aug 26 Aug 31

Sept14

Aug 24

Opening Date:
B

1997

Late open: South

Early open: North
Mean date of movement: Aug 18

Sept3

~ IIII
Aug 23

Opening Date:

I

Sept 13

Table 4. Differences between opening dates and mean dates of movement between early- and late-treatments,
95% confidence interval, and P-value for test of differences between mean opening dates 1996 and 1997;
White River elk herd
Year

Days between

..
1996
1997

.

dates
20
20

Days between mean

p

dates of movement
5± 11
16± 12

0.371
0.010

�215

I also did a post-hoc analysis to evaluate the treabnent effect by area, as it appeared that elk on the
north area were moving to private land more readily than elk on the south area. There was a difference in
mean date of movement between treabnents for elk on the north area but not for elk on the south area (Table
5).

Table.5. Differences between opening dates and mean dates of movement between early- and late-treabnents
for north- and south-side elk, 95% confidence interval, and P-value for test of differences between mean
opening dates; White River elk herd 1996 and 1997.
Area

Days between

Days between mean dates

p

North side

ooenine: dates
20

of movement
13 ± 10

0.009

20

8 ± 14

0.267

(late-early treabnent)
South side
(earlv-late treabnent)

I then analyzed date of movement only for individual elk that received both the early and late
treabnent. Only 16 elk received both treabnents because some elk were not on public land for one year and
some changed side of study area between years. For the elk getting both treabnents, I subtracted their early
date of movement from their late date of movement to account for the fact that this was a repeated
measurement on the elk. I tested the hull hypothesis that:
Ho: Difference in date of movement for late treabnent • early treabnent = 0
Ha: Difference in date of movement for late treabnent - early treabnent &gt; 0 .
The difference in mean date of movement was 6 ± 7 days (p = 0.065). The distribution of differences in date
of movement was not normal (Fig. 3); 12 of the 16 elk had a positive difference for date of movement. If
movements were random, then there would be an equal number of positive and neg~tive differences. There
was a greater count of positive differences than expected if date of movement was random with respect to
treabnent (p = 0.038).
Overall Analyses on Proportion of elk on Refuge

Akaike's Information Criteria (AIC) was used to choose a model to predict the proportion of elk on
refuge areas from a combination oftreabnent, area, year, and date effects (Fig. 4A, B). All models accounted
for the repeated measurements taken on individual elk between treabnents. For the lowest AIC model, the
logistic regression parameters for treabnent (P = 0.032), area (P &lt; 0.001), year (P &lt; 0.001), date (P &lt; 0.001),
and area x date (P &lt; 0.00 I) were significantly different from z.ero. When these factors were controlled for
there was a treabnent x date (P &lt; 0.082) effect (Table 6). The borderline treabnent x date effect indicated that
the slope, or rate of change in proportion of elk on refuge areas, was different for the 2 treabnent areas (Fig.
5). The significance of the area~ date parameter indicates that the slope, or rate of change in proportion of
elk on refuge areas, was greater for elk on the north side (late-early sequence) compared to elk on the south
side (early-late sequence; Fig. 6). Elk on the north area showed a greater response in proportion of elk on
refuge area by treabnent compared to elk on the south area (Fig. 7A, B). The fitted proportion of elk on
refuge for each area x year category and the corresponding predicted proportion of elk on refuge for the
opposite treabnent was calculated to evaluate the effect of changing archery season opening date (Fig 8A, B,
C,D).

�216

Figure 3. Distribution of differences in date of movement between late and early treatments for elk
experiencing both treatments; White River elk herd 1996 and 1997.

ntlQUDiCT

7

6

4

3

2

1

-35

-25

-15

-5

5

15

Di t f•r•nce aovea•nt d.a.t•

25

35

(Late-early)

Figure 4. Proportion of elk on refuge areas with respect to archery-season opening date, on early- and lateopening treatments for 1996 (A) and 1997 (B); White River elk herd.

1996

A
Q)

-

0.9

O&gt;

:::, 0.8
Q)
L.

C

0

~

0.7
0.6

Q)

0.5

0

0.4

... , ,. ...

C

0
:.::;
0L.

0.2

0L.

0.1

a.

Cl..

Late treatment
North side

0.0
(D
0)

io
..r--

--

~

N
C:!
r--

(D

e?
0)

C:!
r--

~

!Q
a:)

~

(D

~

(D
0)

(D

~

(D
0)

(D
0)

(D
0)

-- t;
..... C:! ~ -- .....
----'
date:
Early opening date: Late opening
N
.....

CD

e?
0)

(0

CD

CD

Aug24

O&gt;

e?
0)
O&gt;

(0

O&gt;

Sept 14

C'5
C:!
O&gt;

0

(')

O&gt;

0

�217

Figure 4. (Continued)

1997

B
Cl)

0.9 - . - - - - - - - - - - - - - - - - - - - - - - - - - ,

g&gt; 0.8

e 0.1

~

oC 0.6

~

"a; 0.5
O

C

0.4

j

0.3

[

0.2

0
(l'.
0.1

...

...

,, ,, 'Early treatment
North side

0.0 +---r-,........,,.......,.---,---,---,--,--.-it-r--.,....-..--,........,--,--t,---,---,---,-~-,--....-....--1

i

~

....

~ ~ ~.... Si....;:::
co co
~

....
~
~

....
e....
55

Early opening date:
Aug23

....

I

....
~
....
a;

....
..,~ e....
~

c3
....

I....

Late opening date:
Sept 13

Table 6. Parameter estimates for logistic regression model used to predict the proportion of elk on refuge
areas; White River elk herd 1996 and 1997.
INTERCEPT
SEQUENCE
TREAT
JULDAY

YR
JULDAY*TREAT

-7.2244
4.2030
1.2382
0.0305
-0.2395
-0.0041

0.5082
0.5757
0.5684
0.0021
0.0606
0.0023

0.0001
0.0001
0.0323
0.0001
0.0001
0.0821

�218

Figure 5. Treatment r date effect for elk on early- and late-opening treatments 1996 and 1997; White River
elk herd.
Treatment Effect
Q)
C)

.2
!
C

0

~

Q)

'5
C

0

:e0

a.

e
a.

0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0

•• • ••
Early opening ~ • • •

••• •

•
I

•

•

•

•
•

• •

•

• . •
•

~

•

• • •

•

•
• • •
•••

Late opening
• Early opening
Late opening

■

7/8

7/22

8/5

8/19

9/2
Date

9/16

9/30 10/14

Figure 6. Area x date effect for elk given the early-late or the late-early treatment sequence during 1996 and
1997; White River elk herd.

Area Effect
Q)
C)

:::,

!

C

0

~

Q)

0

C

0

:e0

a.

e

a.

0.9
0.8

early-late treatment

0.7
0.6
0.5
0.4
0.3

•

•• • ••

South side elk

• •

•
•

•

•

0.2
0.1
0

■.

late-early treatment

7/8

7/22

8/5

8/19

9/2
Date

■

•

South-side elk

• North-side elk

9/16

9/30 10/14

�219

Figure 7. Fitted curves of proportion of elk on refuge areas by treatment from logistic regression analysis for
elk on the north area (A) and elk on the south area (B); White River elk herd 1996 and 1997.
(A)

North Area: Elk movement to refuge by treatment

0.9
a,
C&gt;

0.8

.2

0.7

C

0.6

e

0

-a;

~

-

0.5

0

0.4

:e0

0.3

e

0.2

C

0

C.

a.

-North ear1y opening -fitted cutve

0.1

-

North late opening - fitted cuive

0.0
7/8

7/28

9/6.

8/17

9/26

10/16

Date

(B)

South Area: Elk movement to refuge by treatment

0.9
a,
C&gt;

0.8

.2

0.7

C

0.6

!

~-

0

~

-

0.5

:e0

0.3

e

0.2

a,
0

C
0

C.

a.

~

0.4

-South ear1y opening- fitted cuive

0.1

-

South late opening - fitted cutve

0.0
7/8

7/28

9/6 ,.

8/17
Date

9/26

10/16

�220

Figure 8. Fitted curves and predicted curves for reversed treatments, early treatment on south area 1996 (A),
late treatment on north area 1996 (B), early treatment on north area 1997 (C), and late treatment on south
area 1997 (D); White River elk herd.
(A)

(C)
South Side - early treatmert 1996

North Side - early treatmert 1997

0.9

0.9

., 0.8
a,

0.8

,2

0.7

§,

0.7

C

0.6

l!

0.6

.&gt;t!

0.5

.&gt;t!

I!!
0

.;
0

15

0.5

0.4

a;
'5

0.4

.Q
t:

0.3

-~

0.3

e

0.2

C

8.

n.

J
l===~I

0.1
0.0
718

7/28

8117

9/6

9/26

0.2
1-Filled early
- Predicted late

0.1
0.0
718

10/16

7/28

8/17

Date

C

0

.&gt;t!

., 0.8

0.7

,2

0.6

C

1-Filled late

I

a,

I!!
0

0.7
0.6

.&gt;t!

0.5

0
C

0.4

.Q
t:

0.3

8.

0.9

0.8

.;

e
n.

10/16

South Side - late treatment 1997

0.9

I!!

9/26

(D)
North Side - late treatment 1996

,2

9/6
Date

(B)

.,a,

I

.;

0
C

.Q
t:

8.

0.2

e
n.

-Fitted late

0.1

-

Predicted earty

0.0

0.5
0.4
0.3
0.2
0.1

-

Predicted ea~y

0.0
718

7/28

8117

9/6

9/26

Date

10/16

718

7128

8/17

9/6

9/26

10/16

Date

DISCUSSION AND FUTURE WORK
Although all elk were captured on national forest land, some elk moved to private land early in the
summer before the ±1 month time frame used for within-half analyses, and some elk were never located on
public land during the 1997 flights. "Manageable" elk are the proportion of the herd on public land within a
month of early-season opening date. "Unmanageable" elk are the proportion of the herd not on public land
within a month of early-season opening date and are, therefore, not likely to be affected by changes in hunting
patterns on public land. In determining effects of archery hunting activity on elk movement, two types of
effects were examined; the effects on manageable elk, and the effects on total herd (manageable plus
unmanageable elk).
Between 39-64% of the manageable elk moved to private land within a month of archery-season
opening date. For the manageable elk, confidence intervals on mean date of movement included opening date
in 3 of 4 cases, and movements of elk between refuge and non-refuge areas was not independent of opening
date in 3 of 4 cases. North-side elk experiencing the late-opening treatment were the exception in the tests,
possibly due to several early movers that attenuated the treatment effect. In general, it appears that early
season hunting activity has an effect on the manageable elk.

�221

The effects of the manipulation of archery-season opening date on elk movements on the entire herd
was evaluated by responses in mean date of movement and proportion of elk on refuge. The strongest test is
the crossover analysis because it controls for external sources of variation when testing for treatment effects.
The lack of a treatment effect in the crossover analysis is evidence that early-season hunting is not affecting
the timing of elk movements from refuge to non-refuge areas. However, because there appeared to be
interactions between treatment x area and treatment x year, post hoc analyses were done which reveled several
pieces of evidence indicating that early-season hunting activity altered elk movements: (I) mean date of
movement was different between treatments for elk on the north area, (2) mean date of movement was
different between treatments for 1997, (3) for elk getting late and early treatments, there was a 6 day
difference in late minus early date of movement, and (4) there was a significantly greater count of positive
late minus early date of movement differences than expected if date of movement was random with respect to
treatment. Also, from the logistic regression analysis of proportion of elk on refuge, the rate at which elk
move from public land to private land refuge areas was borderline different for early- and late-opening
treatments.
Part of the ambiguity in evaluating the effects of archery hunting on elk movements may result from
differences in movement patterns of elk on the north side versus elk on the south side of the study area. The
steeper slope, or faster gain in proportion of elk on refuge areas over time for the north-side elk (Fig. 6)
suggests that north-side elk move to private land more readily than south-side elk. This was surprising as
south-side elk, which experienced the early-opening treatment the first year, were expected to move more
readily the second year. Similarly, north-side elk, which experienced the late-opening treatment the first year
would be taken by surprise by an early opening the second year, and were expected to move less readily. In
addition to moving more readily, elk on the north area were more responsive to changes in opening of archery
season. The timing of the movements of north-side elk was affected by archery season opening date, as
indicated by the significant difference in mean date of movement betw~n treatments. South-side elk did not
have as wide a spread in their mean date of movement between treatments and there was not a significant
difference in mean date of movement between treatments. Also, the proportion of elk on refuge was greater
during the early treatment compared to the late treatment for elk on the north area (Fig. 7A). For elk on the
south area, the proportion of elk on refuges was similar for early and late treatments (Fig. 7B). It may be that
the north-side elk move more readily due to the presence of a large private-land refuge adjacent to national
forest land.
Between 39-64% of the manageable elk moved to private land within a month of early-season
opening date. However, the elk that moved represent 31-41 % of the entire herd. Hence, any management
decisions regarding hunter numbers are likely to affect at most 41 %, and possibly less, of the White River
elk. The question remains as to what percentage of the manageable elk would still move if hunting were
reduced or eliminated.
These results are not complete; I still need to analyre 1997 hunter survey data, test for elk avoidance
of livestock, and calculate daily distances moved and elevational shifts with respect to early-season hunting
activity. Additionally, I need to reclassify refuge areas; there needs to be a third land classification for habitat
refuges. Habitat refuges will be defined as topographically steep areas where changes in elevation per linear
distance are greater than some threshold (to be determined). Elk locations will be reclassified as public,
private, or habitat refuge, and reanalyred in a multinomial model. Although it appears that north-side elk
move more readily than south-side elk, results may change when habitat refuge areas are included in analyses.
South-side elk may not need to move to private land because they move into habitat refuges. It may be that
elk with available habitat refuges are of little management concern with respect to private-land problems.
These results will be incorporated and discussed in my dissertation.

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APPENDIX A
Methods

METHODS
The study area was split roughly east-west by the White River and North Fork of the White River
into 2 halves for application of early- or late-opening treatments during 1996 and 1997. Game Management
Unit (GMU) 12 and part of GMUs 23 and 24 comprised the north half, while GMU 33 and part of GMUs 23
and 24 comprised the south half. There was a 3-week difference in opening dates; archery hunting opened
early, August 24th, on the south half, and late, September 14th, on the north half during 1996. Treatments
were reversed in 1997; archery hunting opened late, September 13th on the north half, and early, August 23 rd ,
on the south half. Although data were collected on each elk from July 15 - October 13 for both years, withintreatment analyses were restricted to locations collected within a month of opening date (i.e. July 23 September 24 for early-opening treatment, and August 13 - October 13 for the late-opening treatment). The
±I-month interval allows evaluation of treatment effect on manageable elk and allowed for comparison to
pilot study results. All other analyses were done over the 3-month study period for valid comparison of
between-treatments effects on the entire herd (manageable plus unmanageable elk).
The primary response variables were mean date of movement and proportion of elk that change
classification (non-refuge -&gt;refuge/ public -&gt;private). All locations were labeled as either refuge or nonrefuge based on land ownership or management, and not on topographical considerations. That is, the Flat
Tops Wilderness Area and all private land were labeled as refuge, while all National Forest, State Wildlife,
and BLM lands were labeled as non-refuge.
Area x Year Analyses

This is a geographically nested design. with 2 levels of analysis. One level of analysis is within half,
where the treatment is location on non-refuge or refuge areas. The time frame for within treatment analyses is
±1 month of opening date. The ±1 month interval allows evaluation of treatment effect on manageable elk.
If hunting has no effect on elk movements, then elk movements from hunted non-refuge areas should not
correlate with opening date. The primary hypothesis tested were:
1. Ho: Mean date of movement from non-refuge to refuge areas = opening date.
Ha: Mean date of movement from non-refuge to refuge areas * opening date.
2. Ho: Location of elk on non-refuge and refuge areas was independent of the opening of archery
hunting.
Ha: Location of elk on non-refuge and refuge areas was not independent of the opening of archery
hunting.
These were the same hypotheses tested for the 1992,..1995 pilot study data; they were tested separately for
both north and south halves of the study area. Differences in time of movement were tested with a one
sample t-test. •Hypothesis 2 evaluated the effect archery hunting had on elk movements by testing whether
changes in classifications (refuge-&gt;refuge, refuge-&gt;non-refuge, non-refuge-&gt;refuge, and non-refuge-&gt;nonrefuge) were independent of the presence of archery hunting. If archery hunting had no effect, then there
should be no difference in elk locations before or after the opening of archery season. A chi-square test was
used to evaluate if movement of elk between non-refuge and refuge areas was independent of being before or
after opening date.

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Overall Analyses on Mean Date of Movement
The experimental unit is north or south half of the study area, the sampling unit is individual elk, and
the treatment is early or late opening of archery season in this 2-period crossover design. The time frame for
all overall analyses is the 3-month study period of July 15th -October 15th; the 3-month interval allows valid
comparison between treatments for the entire herd (manageable and unmanageable elk). The crossover
analysis used data from both years of the study to test the effects of early-season hunting on the mean date of
elk movement from non-refuge to refuge areas (see methods: Elk movements in response to early-season
hunting in the White River area: study plan). If hunting had no effect on elk movements, then there should be
no difference between the mean date of movement to refuge areas between treatments. To test for a treatment
effect on mean date of movement, the area (sequence) in which the treatments were applied,-the year, and the
random effect of the individual sample elk must be accounted for. The corresponding analysis of variance
model is:
YiJ1d = µ + O.t + "1(1c) + (X; + A + &amp;i11d,
where:
yij1d
µ

= date of movement for the fl' elk, in area k, treatment i, and year j
= overall mean date of movement (for all elk, both years)

bi

= fixed effects due to area k (either north or south)
= random effects due individual elk / in area k
= fixed effects due to treatment i (early or late opening)
= fixed effects due to year j (year I or year 2).

tri(k)
a;
/3j

Specific questions tested in the crossover ANOVA model were:
1. Mean date of movement for north-side elk (early-late treatment sequence)= mean date of
movement for south-side elk (late-early treatment sequence), Ok= 0.
2. Elk randomly chosen from the south side (early-late sequence) were the same as elk randomly
chosen from the north side (late-early sequence); 7rJ(k)-= 0.
3. Mean date of elk movement for early- opening treatment = mean date of elk movement for late
opening treatment; a; = 0.
4. Mean date of elk movement of elk for year I of experiment= mean date of elk movement of elk
for year 2; Pj = 0.
Hypothesis 3 is the experimental hypothesis; hypotheses 1, 2, and 4 are needed to account for other sources
of variation.
Overall Analyses on Proportion of elk on Refuge
The logistic regression model used in 1996 to test for treatment and date effects on the proportion of
elk located on refuge areas (p):
logit(p) =Po + P1(date)+ P2 (treatment)+ P3 (treatmentx.date) + e,
was expanded to include area and year effects. Various combinations of treatment, area, year, and date were
modeled. Akaike's Information Criterion (AIC) was used to select the best model given the precision and
bias tradeoff. The DSCALE option was used in this analysis to account for the repeated measures on the
individual elk and allow for inference to the entire herd. The model with the lowest AIC was:
logit(p) = Po + P1 (area)+ P2 (year)+ p 3 (date)+ P4 (treatmemt) + Ps (treatment xdate)
+ P6 (areaxdate) + e.

�225

From this model the following hypotheses were tested:
1:
2:
3:
4:
5:
6:

Proportion of elk on refuges was independent of the area, given date, treatment, and year
differences were controlled for; p, = 0.
Proportion of elk on refuge areas was independent of year, given date, treatment, and area
differences were controlled for; P2 = 0.
Proportion of elk on refuge areas was independent of date, given area, year, and treatment
differences were controlled for; P1 = 0.
Proportion of elk on refuge areas was independent of treatment, given area, year, and date
· differences were controlled for; p,;= 0.
Early and late treatment had the same slope, that is, elk moved from non-refuge to refuge
areas at the same rate on early- and late-treatment areas; PJ= 0.
The south and north side had the same slope, that is, elk moved to refuge areas at the same
rate whether they were on the south side (early-late treatment sequence) or on the north side
(late-early treatment sequence); p6= 0.

Hypotheses 5 is the experimental hypotheses. Hypothesis 5 was a test of proportion on refuge and timing of
movement to refuge; that is, if archery hunting had no effect, then elk would be expected to move to refuge
areas at the same rate for early- or late-opening treatments. A likelihood ratio test of the area x date effect
(/J,) was an overall test of archery effects, given that elk would move the same on the 2 areas otherwise.
Hypotheses 1-4 allow for accounting of additional sources of variation. Hypothesis 6 tested whether the rate
of movement to refuge areas was different by area. This test was more biologically interesting than testing
for a difference in the proportion of elk on refuge between areas. For example, a difference between areas
may only indicate that more elk happened to begin on refuge areas on the north or south side, which is
irrelevant to archery hunting activity. However, if elk on the south side receiving the early-treatment the first
year were more wary the second year, then the south side elk should show a greater rate of movement than the
north side (late-early sequence) elk. This effect was tested by the inclusion of the area x date interaction term
in the logistic model.

��191

Colorado Division of Wildlife
Wildlife Research Report
July 1999

JOB FINAL REPORT

State of _ _ _ _--=C...,o=lo=r=ad=o,.___ _ _ __
Project No. ------=-W_,__-..:;.1=53=--=R=--=-=12=-----Work Package _~3-0~02~-----Task No.
2

------'-------------

Cost Center 3430
Mammals Research
Elk Conservation
Elk Movements in Response to Early-season
Hunting in the White River Area

• Period Covered: July 1, 1998 - June 30, 1999
Author: M. M. Conner
Personnel: G. White, D. Freddy, R Kahn, J. Maddison, J. Ellenberger

ABSTRACT
Understanding causes of elk movement to private land is important to wildlife managers who use
hunting on public land as a population management tool. In the White River area of northwest
Colorado, late-summer elk movements onto private lands made it difficult to harvest enough elk to
maintain specified population levels. I conducted a 2-year field experiment to determine if early-season
hunting (archery and muzzleloading) caused elk movement to private land during late summer. The
study area was split into north and south treatment areas: each area received both an early- and lateopening treatment. Early-opening treatment was archery season that opened 1 week earlier than the
historical opening, and late-opening treatment was an archery season that opened 2 weeks later,
yielding a 23-week difference in opening dates. The 80-88 adult female elk used in this study were
captured from random locations throughout the study area I relocated radiocollared elk approximately
2 times per week for a 3-month period surrounding early- and late-opening dates each year. Using a
Geographical Information System (GIS) generated map, I classified each elk location as being on
public or private land.
Elk receiving the late-opening treatment moved 10 days later than elk receiving the early
treatment (P = 0.013, one sided ANOVA). Because there appeared to be an interaction between area
and treatment, I performed a post hoc analysis separately by area In the north area, elk receiving the
late-opening treatment moved 14 days later than elk receiving the early treatment (P + 0.006), one
sided t-test), compared to a 6-day difference for elk in the south area (P = 0.218). Approximately
twice as many radiocollared elk moved to private land on the north area (44%) compared to the south
area (23%). The experimental effect on the number of elk directly influenced by early-season hunting
can be estimated by the abrupt increase in the proportion of elk moving to private land when hunting
opened. Proportion of elk on private land increased 8-18% at the opening of early season.
The greater response of elk to hunter activity on the north area may be due to topographical and
migration differences between areas. The south area had densely forested canyons and cliffs,
inaccessible to motor vehicles, which provided elk good refuge from hunters on public land. In

�192

contrast, the north area offered less shelter on public land, but had refuge in large private-land tracts
that bordered the area During the study period, elk moving to private land in the north were just
beginning their fall migration, whereas elk in the south area were completing their migration by moving
to private land. Elk on the north area that move onto private land do not risk depleting their winter
forage, while elk on the south area may degrade their winter range by grazing an extra couple of
months on their wintering grounds.
Colorado Division of Wildlife.surveyed 34% and 37% of hunters using the study area during a
post-hunt telephone survey in 1996 and 1997 to estimate the number of hunters afield per day with a
maximum 95% CI of ±150 hunters. Daily use varied between 115-1,130 hunters per treatment area,
with corresponding hunter densities of0.006-0.51 hunters/km2. The proportion of elk on private land
was not strongly affected by hunter density.
•
Domestic sheep were accused of causing elk movements to private land during early-season
hunting. I collected a location for at least one band of sheep per flight. From this data, I used nonparametric statistics and bootstrapping techniques to calculate the probability that elk avoided sheep at
3 spatial scales. Locations of elk were random with respect to sheep when all elk were used in
analyses (P &gt; 0.342), and when only elk within 1 km of a sheep band were used (P &gt; 0.912). Although
elk may avoid sheep at &lt;l km, it is unlikely that they avoid sheep at large enou.gh distances to cause
widespread elk movements to private land.
Although early-season opening may not be the sole cause of elk movements to private land, the
experimental results show that early-season hunting caused some elk to move to private land,
especially on the north area The increase of elk on private land directly attributable_ to opening of
hunting was 8-18%. Hence, the CDOW can reduce, at most, approximately 20% of elk movement to
private land by manipulating early-season hunting. However, if elk movements are concentrated in
problem areas, then manipulation of opening date may result in a proportionally higher reduction of elk
movements in those areas. Managers concerned with reducing elk movement to private land should
consider the public and private land refuges available to elk, as well as historical elk migration patterns.

�193

ELK MOVEMENT IN RESPONSE TO EARLY-SEASON HUNTING
IN THE WHITE RIVER AREA

Mary M. Conner

P. N. OBJECTIVES

I.

Test whether early-season hunting causes movement of elk from areas of heavy hunting pressure
to areas of lower hunting pressure.
SEGMENT NARRATIVES

I.

Estimate the mean date of movement of elk from non-refuge areas, and determine whether the
timing is equivalent to the opening of archery season.

2.

Evaluate alternative hypotheses about causes of elk movement such as livestock grazing,
woodcutting, recreationalists, weather or forage quality.
••

3.

Publish analyses of elk movement in response to archery hunting in peer-reviewed scientific
journals.
INTRODUCTION

Following is the most recent available draft of the Ph.D. Thesis summarizing results of research
activities directed toward accomplishment of Program Narrative and Segment Narrative Objectives.

��195

DISSERTATION

ELK MOVEMENT IN RESPONSE TO EARLY-SEASON HUNTING IN THE
WHITE RIVER AREA, COLORADO

Submitted by
Mary M. Conner
Department of Fishery and Wildlife Biology

In partial fulfillment of the requirements
for the Degree of Doctor of Philosophy
Colorado State University
Fort Collins, Colorado
Fall 1999

�196

COLORADO STAIB UNIVERSITY

June 28, 1999

WE HEREBY RECOMMEND THAT THE DISSERTATION PREPARED UNDER OUR SUPERVISION
BY MARY M. CONNER ENTITLED ELK MOVEMENTS IN RESPONSE TO EARLY-SEASON HUNTING IN
THE WHITE RIVER AREA BE ACCEPIBD AS FULFILLING IN PART REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHIT.,OSOPHY.

Committee on Graduate Work

Advisor

Department Head

�197
ABSTRACT OF DISSERTATION

ELK MOVEMENT IN RESPONSE TO EARLY-SEASON HUNTING IN THE

WHITE RIVER AREA, COLORADO

Understanding causes of elk movement to private land is important to wildlife managers who use hunting
on public land as a population management tool. During the 1980s, late-summer elk movements onto private land
in the White River area of northwest Colorado made it difficult to harvest enough elk to maintain specified
population levels. I conducted a 2-year field experiment to determine if early-season hunting (archery and
muzzleloading) caused elk movement to private land during late summer. The study area was split into north and
south treatment areas; each area received both an early- and late-opening treatment. Early-opening treatment was
an archery season that opened 1 week earlier than the historical opening, and late-opening treatment was an
archery season that opened 2 weeks later, yielding a 3-week difference in opening dates. The 80-88 adult female
elk used in this study were captured from random locations throughout the study area. I relocated radiocollared elk
approximately 2 times per week for a 3-month period surrounding early- and late-opening dates each year. Using a
Geographical Information System (GIS) generated map, I classified each elk location as being on public or private
land.
Elk receiving the late-opening treatment moved 10 days later than elk receiving the early treatment
(P = 0.013, one-sided ANOVA). Because elk on the north area appeared to respond differently to treatment than
elk on the south area, I performed a post hoc analysis separately by area. In the north area, elk receiving the lateopening treatment moved 14 days later than elk receiving the early treatment (P = 0.006, one-sided I-test),
compared to a 6-day difference for elk in the south area (P = 0.218). Approximately twice as many radiocollared
elk moved to private land on the north area (44%) compared to the south area (23%). The experimental effect on
the number of elk directly influenced by early-season hunting can be estimated by the abrupt increase in the
proportion of elk moving to private land when hunting opened. Proportion of elk on private land increased 8-18%
at the opening of early season.
The greater response of elk to hunter activity on the north area may be due to topographical and migration
differences between areas. The south area had densely forested canyons and cliffs, inaccessible to motor vehicles,
which provided elk good refuge from hunters on public land. In contrast, the north area offered less shelter on
public land, but had refuge in large private-land tracts that bordered the area. During the study period, elk moving
to private land in the north area were just beginning their fall migration, whereas elk in the south area were
completing their migration by moving to private land. Elk on the north area that move onto private land do not
risk depleting their winter forage, while elk on the south area may degrade their winter range by grazing an extra
couple months on their wintering grounds.
Colorado Division of Wildlife surveyed 34% and 37% of early-season hunters using the study area during
a post-hunt telephone survey in 1996 and 1997. The goal was to survey enough hunters to estimate, during the
study period, the number of hunters afield per day with a maximum width 95% CI of ±150 hunters. Daily use
varied between 115-1, 130 hunters per treatment area, with corresponding hunter densities of 0.06-0.51
hunters/km2• The proportion of elk on private land was not affected by hunter density. Elk in the White River area
responded more to the opening of hunting season than to hunter density. It may be that hunter density must
surpass or drop below a threshold before elk begin to respond directly to hunters, and hunter densities did not cross
any threshold during the study. If hunter density continues to be a suspected cause of increased elk movement to
private land, then an experiment manipulating hunter density should be conducted.
Domestic sheep also were considered to cause elk movements to pmrate land ,dwing early-season hunting.
I collected a location for at least one band of sheep per flight. From these data, I used non-parametric statistics and
randomization techniques to calculate the probability that elk avoided sheep at 3 spatial scales. Locations of elk
were random with respect to sheep when all elk were used in analyses (P= 0.737 in 1996, P = 0.199 in 1997),
when only elk within 5 km of a sheep band were used (P = 0.342 in 1996, P = 0.990 in 1997), and when only elk
within I km ofa sheep band were used (P&gt; 0.969 in 1996, P= 0.912 in 1997). Although elk may avoid sheep at

�198
&lt; I km, it is unlikely that they avoid sheep at large enough distances to cause widespread elk movements to private
land.
Although early-season opening may not be the sole cause of elk movements to private land, the
experimental results show that early-season hunting caused some elk to move to private land, especially on the
north area. The direct effect of hunting season is reflected in the 8-18% increase in proportion of elk on private
land that occurred on opening day. Hence, in the White River area, the CDOW can reduce, at most, approximately
20% of elk movement to private land by manipulating early-season hunting. However, if elk movements are
concentrated in problem areas, then manipulation of opening date may result in a proportionally higher reduction
of elk movements in those areas. The elk not affected by opening of hunting season may be elk for which private
land is enroute to their wintering area. Late summer movement onto private land may have become part of a
learned migration behavior, changing hunt season opening and/or hunter density may have little effect on these
elk. Future experiments and management actions should consider an early hunting season on private land, where
problems occur, to retain elk on public land during late summer.

Mazy M. Conner
Department of Fishery and Wildlife Biology
Colorado State University
Fort Collins, CO 80523
Fall 1999

�199

TABLE OF CONTENTS

ABSTRACT OF DISSERTATION ........................................................ .
ACKN"OWLEDGMENTS ............................................................... .
INTRODUCTION ..................................................................... .
ELK MOVEMENTS IN RESPONSE TO DISTURBANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Elk Movement in Response to Human Activities , ........................................... .
Elk Movement in Response to Hunting ................................................... .
PROJECT OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FIGURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CHAPTER 1: ELK MOVEMENT IN RESPONSE TO EARLY-SEASON HUNTING IN NORTHWEST
COLORADO ......................................................................... .
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
STUDY AREA ......................................................................... .
METIIODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Experimental design ................................................................. .
Data collection .................................................. ;· .................. .
Data analysis ...................................................................... .
REsULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MANAGEMENT IMPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CHAPTER 2: EFFECT OF HUNTER DENSITY ON ELK MOVEMENT TO PRIVATE LAND IN
NORTHWEST COLORADO ............................................................ .
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
STUDY AREA ......................................................................... .
METIIODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Radio-telemetry Data Collection ........................................................ .
Hunter Survey Data Collection ......................................................... .
Estimating Number ofHunters ......................................................... .
Estimating Number ofHunters Afield per Day . ............................................. .
Estimating Mean Number ofDays per Hunter and Hunter-days ................................ .
Elk Movement versus Hunter Density .................................................... .
RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Hunter Survey Data .................................................................. .
Elk Movement versus Hunter Density .................................................... .
DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MANAGEMENT IMPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
,.

CHAPTER 3: ELK LOCATIONS IN RELATION TO DOMESTIC SHEEP BANDS AND A METHOD TO
TESTFORAVOIDANCE OR ATTRACTION BETWEEN ANIMALS ........................... .
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
STUDY AREA ......................................................................... .
METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Data Collection ..................................................................... .
Data Analysis ...................................................................... .

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RESULTS
DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Experimental Results ................................................................. .
Methodology for Determining Attraction and Avoidance ...................................... .
MANAGEMENT IMPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

APPENDIX 1: SAMPLE SIZE CALCULATION FOR HUNTER SURVEY ....................... .
APPENDIX 2: STANDARD ERRORS FOR DAILY GMUESTIMATES OF HUNTERS AND ATVS AFIELD
APPENDIX 3: MAPS OF ELK AND DOMESTIC SHEEP LOCATIONS ON SELECTED FLIGHTS ...

ACKNOWLEDGMENTS

ri

.:1:

Funding was provided by Colorado Division of Wildlife (CDOW). Colorado Habitat Partners Program in
the Northwest Region provided funding for flights to collect elk locations. I greatly appreciate the financial support.
From the CDOW, I would like to extend a special thanks to Dave Freddy for his insightful elk discussions, reviews,
and helping to procure financial support. A second special thanks to Dick Bartmann; without his help,
organization, funding procurement, and common sense I would have struggled with all the logistics of collaring and
tracking over 80 elk. Also from the CDOW, thanks to Jeff Madison for all his help with obtaining funding from
Colorado Habitat Partners Program.
My major professor, Dr. Gary White, has been quite an inspiration to me. What can I say, he is one of the
smartest people I know and I have been lucky to study with such an adept thinker. My committee member, Dr. Ken
Burnham, has always been a great help with statistical and mathematical issues that were difficult for me, and never
missed a detail in my dissertation work. His help greatly improved my dissertation. Dr. Bill Alldredge always had
the common elk-sense aspect and practical questions. Without him, I might have forgotten the most important
issues about elk in their natural environment Finally, Dr. Bruce Wunder provided me with the interesting big
picture questions that I would not have considered with out him. Thank you to all my committee; I enjoyed and
benefitted from your input and help tremendously.
The proximate reasons that I was able to complete this academic endeavor were excellent academic
advising and a good funding source, but the ultimate reason is the relationships that have nourished me since •
childhood. Primarily, my parents are the reason I have been able to start and complete my doctorate. My mother,
who importuned me to ''finish what you begin", and my dear father, with his natural Buddhist nature, both allowed
me and encouraged me to do whatever it is to which I set out. Additionally, their financial support during graduate
school kept me out of the poorhouse and kept my car out of the junkyard. I must thank my sister, who rolled her
eyes and told me to "get a grip" many times during my graduate studies. I then thank my extended family, the cast
of characters to whom I am related. They make me laugh and somehow think that I could do anything if that's the
stock from which I originate. To my long time friends who work hard, but certainly expect to vacation well, and
have little tolerance of any stupid, wimpy PhD excuses, thank you. My friends M. Kiuchi, P. Kurz, M. Zimmer, E.
Soderstrom, A. Peet, D. Yonenaka, N. Larsen, M. Riker, T. Howe, A. Bruno, and T. Weller deserve special
acknowledgements. Of the mentors from my academic career, I would like to thank and acknowledge Sister Rita
Basta, Dr. Mike Jaeger, Dr. Dale McCullough, and Dr. Wayne Getz. Wayne, a special thanks to you, although you
will never know how much you inspired me. I would also like to thank and acknowledge the iny:riad of graduate
students who have made my life bright and graduate school stimulating.
Most importantly, infinite thanks to my dear husband, John Shivik. He has been a stalwart support, fellow
adventurer, paper reviewer, research partner, coffeemaker, cocktail alchemist, bad joke teller, and all round husband
extrodinaire. Thank you, thank you, thank you all. I hope you like what you've been so instrumental in producing
-this one's for you.

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INTRODUCTION
ELK MOVEMENTS IN RESPONSE TO DISTURBANCE

Migration between high-elevation summer range and low-elevation winter range is common among Rocky
Mountain elk (Cervus e/aphus ne/soni) in mountainous regions (Adams 1982). High-elevation ranges provide high
levels of nutrition during the summer, but snow makes forage inaccessible during the winter. Fall migrations
typically take place before the snow becomes too deep for animals to forage. In the White River area of Colorado,
elk migrate between summer range, located in high-elevation national forest and wilderness areas, and lowelevation wintering grounds, located as near as the base of the summer range or as far as 80 km away. Historically,
fall elk migration took place in December (Boyd 1970), but since the 1980s, fall movements have apparently
advanced into August and September (Gray et al. 1994). During the development of the 1994 elk management plan
for the White River herd, early elk movement from summer ranges onto public land was the most common
complaint (Gray et al. 1994). In response to complaints. Colorado Division of Wildlife (CDOW) conducted a pilot
study on 20 radiocollared cow elk from 1992-1995 to determine if and when elk were moving onto private land.
Results from the pilot study indicated a correlation between early-season hunting activity and elk
movement to private lands. However, it did not establish a causal relationship. Before instituting any management
changes, COOW needed an experiment to determine whether early-season hunting activity was causing latesummer elk movements. I designed and conducted such an experiment in 1996-1997, and that experiment is the
topic of my dissertation. In this introduction, I present background material on elk responses to an array of human
activities in general and to hunting in particular. I intend this background material to provide a framework for
understanding my experiment to determine the cause oflate-summer elk movements in the White River area.
Elk Movement in Response to Human Activities
Elk responses to recreational activities such as hiking, cross-counl:Iy skiing, and automobile driving depend
on habituation to humans and on the presence of hunting. In Rocky Mountain National Park, where elk were
accustomed to people and were not hunted, elk showed little response to approaches of people in automobiles or on
foot, day or night (Schultz and Bailey 1978). In a study of another unhunted elk population in Yellowstone
National Park, elk response to cross-counl:Iy skiers depended on how accustomed elk were to people. In areas of low
human activity during the winter, elk responded with flight distances of 125-1,700 m, while in an area of high
human activity, the flight distance was considerably shorter, ranging from Oto 300 m (Cassirer et al. 1992).
Interestingly, elk in the area of high human activity showed a three-fold increase in flight distance when they were
disturbed outside the area where people were present 24 hours a day (Cassirer et al. 1992). Thus, even habituated
elk appear to flee human activity in areas where they do not expect such activity.
Besides habituating to humans, elk may learn to differentiate between dangerous and benign situations
with respect to road avoidance. In Rocky Mountain National Park, where elk were not hunted and traffic volume
was high, Schultz and Bailey (1978) found that none of their 14 delineated elk behaviors changed with traffic
volume, and there was little or no avoidance of the roads in winter. In contrast, in Roosevelt National Forest, which
is adjacent to Rocky Mountain National Park, Rost (1975) found that a population of hunted elk avoided roads in
winter. Wright (1983) found that mean distance ofradiocollared elk to jeep trails more than doubled, increasing
from 800 m to 2, I 00 m when hunting season opened.
In addition to danger level, the level of road activity also affected elk movements. After roads were closed
in an experimental treatment, Cole et al. (1997) found a reduction in daily movement, home range size, and core
area, all measures of elk movement Czech (1991) found a significant increase in mean elk distances to a road after
it was opened to the general public with a corresponding increase in traffic. Elk also cross heavily traveled roads
less often than lightly traveled roads (Hershey and Legee 1982).
A third factor, cover, may also determine the degree,of elk response to disturbance. Logging disturbances
changed normal elk movements (Edge and Marcun'i 1985): elk moved significantly longer distances away from
logging areas than toward them. But both distance from disturbances, and areas of high elk use, were correlated to
the amount of cover in the area (Edge and Marcum 1985). Similarly, Czech (1991) found that elk tolerance of
logging operations was correlated positively with proximity to hiding cover. In one of the few manipulative
experiments on elk movements. elk calves subjected to simulated surface-mining activities sought coniferous forest
significantly more often than undisturbed calves (Kuck et al. 1985). Oil drilling has the same effect as mining: elk
increased their use of forested habitats during drilling and post-drilling periods, compared with pre-drilling periods
(Van Dyke and Klein 1996). Collectively, these disturbance experiments build a strong case for a relationship
between elk movement and availability of cover.

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All studies that evaluated elk movements after the disturbance ended found displacement to be a temporary
condition in most situations. The Yellowstone elk displaced by cross-country skiers typically returned close to their
original locations after people left the area (Cassirer et al. 1992). Road proximity resumed pre-hunting distances
after hunting season closed (Wright 1983), and mean distance to roads decreased soon after the roads were closed
for the season (Hershey and Legee 1982). During weekends, and immediately following the end oflogging
activities, elk moved back into logged areas (Ward 1976, Edge and Marcum 1985).

;;a,

Elk Movement in Response to Hunting
Documented responses of elk to hunting include movement away from hunters or heavily hunted areas,
increased movement, movement to thick cover, shifts in circadian patterns, and elevation shifts. Most responses
seem to occur before winter migration, but some studies attribute changes in migration patterns to hunting
pressures. For example, Knight (1970) and Morgantini and Hudson (1979) found a reversal of the normal
downward autumn migration of elk, coinciding with the opening of the hunting season.
Responses of elk to hunting activity may depend on the amount, location and quality of hiding cover, as
well as the topography of the area. Altmann (1956) described an evasive "migration" of elk hunted adjacent to
Yellowstone National Park. With the opening of hunting season, movements of these elk became relatively long (513 km), and the elk ceased long movements only when they reached the sanctuary of the Park. Similarly, Martinka
( 1969) found that 12 marked elk, which were in the National Elk Refuge just prior to hunting season, moved
between 8 and 22 Ian, to areas closed to hunting in Grand Teton National Park. Other studies have found lessdramatic movement to refuge areas. With opening of hunting season, elk moved to densely forested (Irwin and
Peek 1979) or shrubby (Morgantini and Hudson 1979) areas adjacent to their typical areas of activity, which
provided refuge from hunting. Unpublished data for 1992-1995 from a pilot study on elk in the White River area
(M. M. Conner, Colorado State University, unpublished data) found that distance moved around opening date(± 1
week from opening date) differed depending on habitat cover in the vicinity. Elk located in rugged and relatively
inaccessible areas with access to thick timber and rough terrain (n = 11) moved an average of858 m/day (95% CI=
602, 1113). In contrast, elk located in road-accessible areas (n = 15), with little access to vegetative and
topographic cover, moved an average of 1258 m/day (95% CI= 1011, 1505) to refuge on private land. Thus, elk
without access to nearby habitat refuges moved significantly farther (401 m/day: 95% CI= 45, 756) than elk with
access (P = 0.014, I-sided). Areas of rough topography and dense timber may serve as refuge; if such refuge is
available, elk may not move far even when subject to high hunting pressure.
Elk may respond to hunting method or density of hunters. Wright (1983) examined elk response to
different hunting seasons: archery and muzzleloading, rifle-special elk, rifle-special deer, and deer and elk rifle.
The greatest density of elk hunters was during the rifle-special elk season, and distances traveled by elk were also
greatest during that season. Elk traveled three to four times farther during this season than during archery and
muzzleloading season. Wright (1983) concluded that archery and muzzleloading hunters did not change the
behavior of radiocollared cow elk. However, this result might be explained by low hunter densities (0.13 archery
and muzzleloading hunters/km2, compared to 1.42 rifle hunterslkm2) rather than by the hunting method. In a 1985
study in the White River area, Consolidation Coal Company radiocollared 23 elk to evaluate their movement onto
the company's protected land during early-season hunting. Eighty-seven percent of the elk were still found on
National Forest lands midway through archery and muzzleloading seasons (Camp Dresser and McKee, Inc. 1986).
But the lack of movement may be explained by a 63% reduction in archery hunters from 1984 to 1985, due to a
change in hunting regulations (Gray et al. 1994). z.abn (1974), Lemke (1975), and Hershey and Legee (1982)
noticed an increase in movements during the first 10-12 days of hunting season, followed by normal movement
during the remainder of the season. These authors noted that hunting pressure was heavy during the first 10-12
days of hunting and relatively light for the remainder of the season. These studies of hunting suggest that elk
behavior may change only when the density of hunters reaches a critical threshold.
While some elk appear to have learned to move to refuge areas, elk already in refuges may learn to remain
there in response to hunting pressure. In Jackson Hole, both resident and migratory elk use the National Elk Refuge
for their winter range (Martinka 1969). Of the 183 marked elk in the study, resident elk were defined as elk found
at any time from July through August within 15 km of the winter range, while migratory elk were defined as all
other elk. In the fall, both resident and migratory elk had to cross hunting areas to move to their winter range in the
National Elk Refuge. Resident elk were sensitive to hunter presence and tended to hang back in areas closed to
hunting, while migratory elk were less hesitant to move through hunting areas to the winter range. These studies of
elk moving to, or staying in, refuge areas support the theory that elk are responding, possibly with learned behavior,
to hunting pressure.

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Other studies found evidence to indicate that elk are not responding to hunting pressure, but are being
differentially removed from heavily hunted areas. In Wyoming, hunting pressure focused on a resident population
of elk just east of Yellowstone National Park, drastically reducing their numbers (Rudd et al. 1983 ). Like the
Jackson Hole herd, migratory elk that summered in protected areas of Yellowstone National Park wintered with
resident elk in unprotected range just outside of the park. Hunting in the unprotected range occurred before the
migratory elk arrived from the park, drastically reducing the herd of resident elk (Rudd et al. 1983). The proportion
of migratory to resident elk increased in the unprotected range, apparently due to hunting itself and not to huntinginduced shifts in elk behavior. Boyce (1991) noted that migration of elk wintering in the National Elk Preseive in
Jackson Hole changed dramatically between the 1950s and 1980s. The primary migration routes shifted from openhunting national forest lands to routes through Grand Teton National Park, where hunting was more restricted.
Between 1950 and 1954, 22% of the migrating elk were estimated to have moved through Grand Teton National
Parle; by 1980-1984 the figure was 51%. Boyce (1991) hypothesized that this change maybe due to differential
haIVest of the migrating animals and not due to shifts in elk behavior. However, there has been no experiment to
test whether the cause of migration changes is differential removal or learned response.
Similar to results from non-lethal disturbance studies, z.ahn (1974), Lemke (1975), and Hershey and Legee
(1982) found that elk response to hunter disturbance was short-lived. These studies noted that elk movements
return to normal after the initial 10-12 days of opening day, and that hunting is most intense during those initial
days. Elk not only discontinued their erratic and increased movements, but also returned to their pre-season activity
areas, indicating that hunting activity was a temporary disturbance.
In conclusion, elk show highly plastic responses to human activity, habituating to people in areas where
there is no hunting, but actively avoiding hunters. Elk response to human activity depends on the amount of, and
the danger of, contact with humans. For example, avoidance of roads varies with the amount of human use and the
danger level. The presence of dense cover for hiding seems to attenuate responses to human activity. Finally, elk
responses to human activity do not seem to persist after the activity subsides. All studies of elk responses to hunting
have been obseivational and any causal relationship between hunting and elk movements remains untested.
PROJECT OVERVIEW

Game Management Units (GMUs) 12, 23, 24, and 33 in northwestern Colorado compose the majority of
the area of the White River elk herd. The White River herd has been one of the most heavily hunted, managed, and
documented elk herds in Colorado (Boyd 1970, Freddy 1987, Gray et al. 1994). Like all elk herds in Colorado, the
White River herd was decimated during the late 1800s, eventually being reduced to a few hundred elk (Bryant and
Maser 1982). Since regulated hunting began in 1929, the population has been growing and was estimated to be
31,000 in 1993, the upper bound for COOW management objectives (Gray et al. 1994). The number of hunters
using the area has grown along with the elk herd, with especially significant increases in the number of early-season
hunters (archery and muzzleloading) between 1984 and 1992 (Fig. I.I).
In the White River area, summer range is high-elevation public forest, and winter range is lower-elevation
private land. Historically, the main White River elk migration from summer to winter ranges took place between
late November and early January (Boyd 1970). However, Freddy (1987) noted that elk were beginning to be found
in lower elevations, characteristically winter range, during the September and October hunting seasons, which was
uncommon in the 1960s. Furthermore, there is now evidence that elk are moving in August and early September,
during early-season archery hunting (Gray et al. 1994). Typically, early-season hunters did not hunt private lands;
thus, private lands provided elk a refuge during early-season hunts. Late-summer elk movements to private land
have led to complaints by local private landowners and resource managers (Gray et al. 1994). For private
landowners, complaints focused on crop damage. For COOW, the primacy problem is herd size: because hunters
have limited access to private lands, it is difficult for COOW to maintain or reduce herd size via haIVest (J. Madison
and C. Reichert, COOW, personal communication). Hunter equity is a third issue: if a large proportion of elk are
on private land, then the best hunting will be monopolized by those with enough money to buy trespass pennits (J.
Madison and C. Reichert, COOW;' personal communication).
Complaints about late-summer elk movement during the mid- to late-1980s prompted the CDOW to
conduct a prelimiruuy study on late-summer elk movement to private land in the White River area. In 1992 the
COOW trapped and radiocollared 20 adult female elk. A 4-year pilot study from 1992 to 1995 was conducted on 14
to 20 of these radiocollared elk from GMUs 12, 23, 24, and 33. During the study, 70-100% ofradiocollared elk
located on public land areas moved to private or wilderness areas, and the mean day of movement was not different
from opening day of early-season hunting. For elk moving from public to private land (n = 29) during the 4- year
pilot study, the mean date of movement was 3 days (95% CI= -4, 11) from opening date (M. Conner, Colorado

�204
State University, unpublished data). Although it did not establish a causal relationship, this study provided strong
evidence of a correlation between elk movements and the opening of early-season hunting.
To determine if archery and muzzleloading hunting caused elk movements in the White River area in the
White River area, I conducted a 2-year experiment. In the White River area, other factors that may contribute to elk
movement include historical movement patterns, long-term, learned movement responses, recreational activity,
wood cutting, and livestock activity. Any or all of these factors may contribute to elk movement from July through
October. However, because the pilot study identified archery hunting as the prime suspect for late-summer
movements, and because the CDOW was interested in manageable rather than academic issues, this study focused
on the effects of archery hunting on elk movement. In Chapter 1, I report on the field experiment designed to
determine whether archery hunting causes elk movement: this experiment compares the timing of elk movements,
and the proportion of elk on or moving to private land, with the opening date of archery season. In Chapter 2, I
estimate daily hunter densities and compare elk movement to private lands with hunter density. In Chapter 3, I
discuss the impact of domestic sheep grazing on elk movement. Each chapter is written to stand alone for
publication and follows manuscript guidelines for The Journal of Wildlife Management.
LITERATURE CITED

Adams, A. W. 1982. Migration. Pages 301-321 in J. W. Thomas and D.E. Toweill, editors. Elk of North
America: ecology and management. Stackpole Books, Harrisburg, Pennsylvania, USA.
Altmann, M 1956. Patterns of herd behavior in free-ranging elk of Wyoming, Cervus_canadensis ne/soni.
Zoologica 41:65-71.
Boyce, M S. 1991. Migratory behavior and management of elk (Cervus e/aphus). Applied Animal Behaviour
Science 29:239-250.
Boyd, R J. 1970. Elk of the White River Plateau, Colorado. Colorado Division of Game, Fish and Parks Technical
Publication 25, Fort Collins, Colorado, USA.
Bryant, L. D., and C. Maser. 1982. Classification and Distribution. Pages 1-59 in J. W. Thomas and D.E. Toweill,
editors. Elk of North America: ecology and management. Stackpole Books, Harrisburg, Pennsylvania, USA.
Camp Dresser and McKee, Inc. 1986. Meeker PRLA elk migration study: monitoring report, volume 2. Prepared
for Consolidation Coal Company. Camp Dresser and McKee, Inc., Denver, Colorado, USA.
Cassirer, E. F., D. J. Freddy, and E. D. Ables. 1992. Elk responses to distwbances by cross-country skiers in
Yellowstone National Park. Wildlife Society Bulletin 20:375-381.
Cole, E. K., MD. Pope, and R G. Anthony. 1997. Effects of road management on movement and survival of
Roosevelt elk. Journal of Wildlife Management 61: 1115-1126.
Craighead, J. J., G. Atwell, and B. W. O'Gara. 1972. Elk migrations in and near Yellowstone National Park.
Wildlife Monographs 29.
Czech, B. 1991. Elk behavior in response to human distwbance at Mount St. Helens National Volcanic
Monument. Applied Animal Behaviour Science 29:269-277.
Edge, W. D., and C. L. Marcum. 1985. Movements of elk in reaction to logging distwbances. Journal of Wildlife
Management 49:926-930.
Freddy, D. J. 1987. The White River elk herd: A perspective, 1960-85. Colorado Division of Wildlife Technical
Publication 37 Fort Collins, Colorado, USA.
Gray, J. P., G. Byrne, and J. Madison. 1994. White River elk data analysis unit plan: game management units:
11,211,12,13,131,231,23,24,25,26,33. Colorado Division of Wildlife Internal Report, Grand Junction,
Colorado, USA.
Hershey, T. J., and T. A. Leege. 1982. Elk movements and habitat use on a managed forest in north-central Idaho.
Idaho Department of Fish and Game Wildlife Bulletin 10, Boise, Idaho, USA.
Irwin, L. L., and J. M. Peek. 1979. Relationships between road closures and elk behavior in northern Idaho. Pages
199-204 in M. S. Boyce and L. D. Hayden-Wing, editors. North American elk: ecology, behavior, and
'management University of Wyoming, Laramie, Wyoming, USA.
it
Knight, RR 1970. The Sun River elk herd Wildlife Monographs 23.
Kuck, L., G. L. Hompland, and E. H. Merrill. 1985. Elk calf response to simulated distwbance in southeast Idaho.
Journal of Wildlife Management 49:751-757.
Lemke, T. 0. 1975. Movement and seasonal ranges of the Burdette Creek elk herd, and an investigation of sport
hunting. Montana Fish and Game Department Job Final Report 32.01, Job No. BG-3.15, Missoula, Montana,
USA.

�205

Martinka. C. J. 1969. Population ecology of summer resident elk in Jackson Hole, Wyoming. Journal of Wildlife
Management 33:465-481.
Morgantini, L. E., and R J. Hudson. 1979. Human distribution and habitat selection by elk. Pages l32-l39 in M.
S. Boyce and L. D. Hayden-Wing, editors. North American elk: ecology, behavior, and management.
University of Wyoming, Laramie, Wyoming, USA
Rost, G. R 1975. Responses of deer and elk to roads. Thesis, Colorado State University, Fort Collins, Colorado,
USA.
Rudd, W. J., AL. Ward, and L. L. Irwin. 1983. Do split hunting seasons influence elk migrations from
Yellowstone National Park? Wildlife Society Bulletin 11:328-331.
Schultz, R D., and J. A. Bailey. 1978. Responses of national park elk to human activity. Journal of Wildlife
Management 42:91-100.
Van Dyke, F., and W. C. Klein. 1996. Response of elk to installation of oil wells. Journal ofManunalogy
77:1028-1041.
Ward, A L. 1976. Elk behavior in relation to timber harvest operations and traffic on Medicine Bow Range in
south-central Wyoming. Pages 32-43 in S. Hieb, editor. Proceedings of the Elk-Logging-Roads Symposium.
University ofldaho, Moscow, Idaho, USA
Wright, K. L. 1983. Elk movements, habitat use, and the effects of hunting activity on elk behavior near Gunnison,
Colorado. Thesis, Colorado State University, Fort Collins, Colorado, USA.
z.abn, H. M. 1974. Seasonal movements of the Burdette Creek elk herd. Montana Fish and Game Department Job
Final Report 32.01, Job BG-3.13, Missoula, Montana, USA

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Figure I. 1. Number of archery and muzzleloading hunters using GMUs 12, 23, 24, and 33 in northwest
Colorado, 1984-1994. Data from Deer, Elk, and Antelope Management (DEAMAN) database and software,
Colorado Division of Wildlife, unpublished data.

�206

�207

CHAPTER 1: ELK MOVEMENT IN RESPONSE TO EARLY-SEASON HUNTING IN NORTHWEST
COLORADO
INTRODUCTION

Since the early 1900s, Rocky Mountain elk (Cervus elaphus nelsoni) populations have expanded their
range from remote areas to much of the Rocky Mountain States (Bryant and Maser 1982). As elk range
expanded, so too did elk contact with humans and human disturbances. Elk responses to hunting, road traffic,
hikers, cross country skiers, snowmobiles, logging, mining, and oil drilling have been studied in order to reduce
elk-human conflicts. Problems with elk responding to hunting center around elk moving onto hunting refuges,
which are areas with no or low levels of hunting such as private land, national parks, or densely forested areas.
Documented responses of elk to hunting include movement away from hunters or heavily hunted areas (Altmann
1956, Martinka 1969, Wright 1983), increased movement (Zahn 1974, Lemke 1975, Hershey and Legee 1982,
Wright 1983), movement to dense vegetative cover (Irwin and Peek 1979, Morgantini and Hudson 1979),
movement to private land (Wright 1983) or national parks (Altmann 1956, Martinka 1969), shifts in circadian
patterns (Strohmeyer and Peek 1996), and elevation shifts in migration patterns (Knight 1970, Morgantini and
Hudson 1979). Most responses to hunting occur before migration to winter range, but some studies have noted
changes in migration patterns that were attributed to hunting pressures (Martinka 1969, Boyce 1991). All
previous studies of elk responses to hunting have been observational, there have been·no experiments designed to
test whether hunting activity causes elk movements.
Elk inhabiting the White River area of northwest Colorado are no exception to the pattern of increased
range expansion and increased conflict with humans. Prior to 1960, the fall migration of White River elk from
high elevation public land, summer range, to lower elevation private land, winter range, (Fig 1.1) occurred during
the month of December (Boyd 1970). However, Freddy (1987) noted that elk were beginning to be found in
lower elevations during the September and October hunting seasons, which was an uncommon occurrence in the
1960s. Since the 1980s, fall movements have apparently advanced into August and September (Gray et al. 1994).
Archery and muzzleloading hunting (early-season hunting) opens on the third Saturday of August in the White
River area; around the time of the alleged elk movements onto private land. Since the 1960s, the number of earlyseason hunters using the White River area has grown, with especially significant increases between 1984 and
1992 (Fig. 1.2).
Typically, archery hunters did not hunt private lands; thus, private lands provided elk a refuge during
early-season hunts. As archery and muzzleloading hunter numbers increased, so too did complaints about early
elk movements onto private land. For the private landowner, complaints about early elk movements focused on
crop damage. For the Colorado Division of Wildlife (CDOW), the primary problem was herd size: it was
difficult for CDOW to maintain or reduce herd size via harvest because hunters have limited access to private
lands, (J. Madison and C. Reichert, Colorado Division of Wildlife, personal communication). Because of
complaints during the mid- to late 1980s, CDOW conducted a preliminary study on late summer elk movement to
private land in the White River area. From 1992 to 1995, 20 radiocollared elk were intensively monitored during
August and September, approximately one month before and one month after opening day of archery hunting.
Although the proportion and date of elk moving indicated a correlation between elk movement and opening of
early-season hunting, a causal relationship was not established. Before instituting any management changes, the
CDOW required. an experiment to determine if early-season hunting activity was causing late summer elk
movements.
My objective was to determine if archery hunting caused elk movement to private land during late
summer. Specifically, I conducted a 2-year field experiment in :which_opening date of archery hunting was
manipulated in a crossover design. The study area was split into 2 treatment areas; each area received an earlyand late-opening treatment. I tested the null hypotheses that; (1) the mean date of movement to private land was
not different between early and late treatments, and (2) the proportion of elk on private land was not affected by
the opening of archery hunting.

�208
STUDY AREA

The White River area of northwestern Colorado covered approximately 4,540 km2 and was composed of
Game Management Units (GMUs) 12, 23, 24, and 33. In Colorado, GMUs were delineated to distribute hunters
through allocation of hunting licenses. White River area land ownership was 34% private land and 66% public
land (Fig 1.1), with 82% of public land being United States Forest Service (USFS). USFS land was mostly at
high elevation and toward the center of the study area, with some Bureau of Land Management (BLM) areas at
lower elevations in the southern sections of the study area. Private land was lower in elevation and comprised
mainly ranches and coal mines.
Topography, climate, and vegetation varied widely throughout the study area. Elevation ranged from
1,629 to 3,700 m. The central part of the study area was high elevation public land, split by the White River
valley. The high elevation areas dropped off to lower elevations to the north, south, and western edges of the
study area. Higher elevations had severe winters with heavy snowfall, while lower elevations had comparatively
mild winters. Mean annual precipitation at 3,000 m in the National Forest areas was about 100 cm, compared
with about 30 cm at lower elevations of &lt;2,000 m. Vegetation types at elevations &gt;2,600 m were in the
montane/subalpine zone and included groves of aspen (Popu/us tremu/oides), Engelmann spruce (Picea
enge/manni), and alpine fir (Abies /asiocarpa) interspersed with grassy meadows. Middle elevations (1,9802,600 m) were a transitional zone that consisted primarily of pinion pine (Pinus edu/is),jumper (Juniperus
scopulorum), and big sagebrush (Artemisia tridentata). Lower elevations (&lt;2,000 m) in the southern and
northern parts of the study area were in the Great Basin zone with sage grasslands. Oakbrush patches were found
at the middle and lower elevations with major shrubs that included Gambel's oak (Quercus gambe/ii),
serviceberry (Amelanchier alnifo/ia), mountain mahogany (Cercocarpus montanus), chokecherry (Prunus
virginiana), snowberry (Symphoricarpos utahensis), bitterbrush (Purshia tridentata), and rabbitbrush
(Chrysothamnus nauseosus). Higher and middle elevation areas provided summer and fall forage for elk, while
lower elevations were typically used by elk during winter. Boyd (1970) provides a detailed description of the
study area.
Hunting for elk was economically important to local residents in the study area (Gray et al. 1994).
Guides, outfitters, local service sectors, and private landowners (who sell trespass permits) made a large
proportion of their annual income during the elk and deer hunting seasons, with most hunting revenues accrued
during rifle hunting seasons.
MEmODS

Experimental design
The White River and North Fork of the White River divided the study area roughly east-west into 2
halves (Fig. 1.3). GMU 12 and parts of GMUs 23 and 24 composed the north treatment area, while GMU 33 and
parts of GMUs 23 and 24 composed the south treatment area. Because only 2 elk moved from one side of the
White River to the other within a year during the 4-year pilot study (M. Conner, Colorado State University,
unpublished data), I felt there would be little interchange between treatment areas. Two treatments were applied:
an archery season that opened 1 week earlier, and another that opened 2 weeks later than normal, yielding a 3week difference in opening dates. During the first year of the study, the early-opening treatment was randomly
assigned to the south treatment area. Treatments were reversed the second year of the study. Thus, in 1996,
archery hunting opened early, 24 August, in the south area, and late, 14 September, in the north area. When
treatments were reversed in 1997, archery hunting opened early, 23 August, in the north area, and late, 13
September, in the south area The number of archery and muzzleloading licenses issued for elk and deer during
the study,:'were based on the mean number per year calculated for 1990-1994 (4,985; Colorado Division of
,· •1
Wildlife unpublished data), with licenses allocated approximately 50% per treatment area. Restricting licenses
kept hunter density consistent during the study and consistent with years of high elk movement complaints.
Sample size for number of collared elk was based on the primary response variable, mean date of
movement, for the following parameters; Cl= 0.05, ~ = 90%, effect siz.e = 7-day difference in mean date of
movement between treatments, and estimated variance = 22. 7 days. The variance was based on pilot study data
(M. Conner, Colorado State University, unpublished data). For these parameters, 36 cows per treatment area

•

�209
were required. To allow for some telemetry failures or erratic elk movements off the study area, extra cows were
collared. Thus, 40 cows per treatment area were collared for the study.
Elk capture locations were randomly picked from a uniform distribution by a computer. Random
Universal Transverse Mercator (UTM) coordinates were generated until 80 points lay within the study area's
national forest boundaries. Elk were captured by helicopter netgunning (Barrett et al. 1982) during mid-July in
1996 and 1997. Elk were captured on their summer range to assure a random sample for the July-October study
period. The helicopter pilot flew to each randomly selected location and captured the first adult female elk found
near that location. Although it was not practical to capture exactly as dictated by a random number algorithm,
due to constraints on private land access and time, a reasonably representative sample was obtained with 2 elk
being captured at some locations (Fig. 1.3). In addition to the 80 elk captured in 1996, 8 radiocollared elk from
the pilot study were used in 1996 analyses. In 1997, 10 additional elk were captured to replace animals that died,
bringing the total number of collared animals back to 80, with 40 per treatment area. Colorado State University
Institutional Animal Care and Use Committee approved the capture and handling methods (protocol 95-180A-0l).
Each elk was fitted with a 148-152 MHz radio collar with a mortality sensor. A high percentage of bulls
are lost to hunting, which could reduce sample size below levels required to maintain the power of the hypothesis
tests. Because this study was to take place during a hunting season, when bulls are desirable game, I wished to
collar only adult females to minimize loss of sample size. During fall rutting season, August-October, there is a
high degree of association (97%) between male and female elk (Franklin and Lieb 1979). I collared only adult
female elk to represent the movement patterns of both sexes and maintain the power of the hypothesis tests.

Data collection
The relevant time frame for determining elk movement in response to archery hunting was defined as ±1
month of opening day. Because early treatment opening was 23-24 August and late treatment opening was 13-14
September, I collected locations 20 July- IO October. The study period ended slightly less than a month after late
treatment opening date to avoid confounding elk movements due to archery hunting with effects due to rifle
hunting, which opened 13-14 October. All analyses were done on data collected over the entire 3-month study
period.
I relocated radiocollared elk between 0700-1500 hr using a Cessna 182 or 185 fixed-wing aircraft with a
2-element Yagi antenna mounted to each strut of the airplane. For each elk relocation, UTM coordinates were
recorded with a Global Positioning System that was not differentially corrected. I collected elk locations 2 times
a week with 2-4 days between collections. A Geographical Information System (GIS) map was used to record elk
locations, land ownership, and treatment boundaries. The GIS map was digitized from a United States Geological
Survey map at a scale of 1:100,000. For each location of a telemetered cow, a 0 was assigned if the location was
on public land (e.g. Flat Tops Wilderness Area, USFS, State Wildlife, and BLM lands) and a I was assigned if
the location was on private land.
Because I was interested in gross classifications of elk locations (public land versus private land), I did
not do a formal check of the telemetry error. However, I did a cursory check of telemetry error when picking up
collars from a different study in the area. The mean error on the collars I collected was 333 m (n = 24, 95% CI=
265, 40 I), with a range of 117-683 m.

Data analysis
The primary response variables were mean date of movement for elk that changed classification
(occupying public and moving to private land) and proportion of elk on private land. I calculated th~ date of
movement for each elk using logistic regression oflocation on public (y = 0) and private land (y = 1) versus date.
The date of movement was defined as the date at which the logistic curve crossed 0.5 on the y-axis, indicating an
equal probability of being on public or private land. Only dates of movement from public to private land during
the study period were included in analyses of mean date of movement.
If hunting had no effect on elk movements, then there should be no difference between the mean date of
movement to private land between early- and late-opening date treatments. To test for a treatment effect on mean
date of movement, I accounted for treatment, area, and year effects. The corresponding ANOVA model was:

�210

where:
yyu = date of movement for the ff' radiocollared elk, receiving treatment i, in year j and in area k,
µ = overall mean date of movement (for all elk, both years),
a., = fixed effects due to treatment i (early or late opening),
131 = fixed effects due to yearj (year 1 or year 2),
ok = fixed effects due to area k (either north or south), and
&amp;yu = random error for the /'1' radiocollared elk.
Specific hypotheses tested were:

Ho 1: Mean date of elk movement for early-opening treatment = mean date of elk movement for late-opening
treatment; a., ~ 0;
HA1: Mean date of elk movement for early-opening treatment &lt; mean date of elk movement for late-opening
treatment; a., &lt; 0;

ffm: Mean date of elk movement for year 1 of experiment = mean date of elk movement for year 2; f31 = 0;
HA2: Mean date of elk movement for year 1 of experiment :t:. mean date of elk movement for year 2; 131 -:#- 0;

Hen: Mean date of movement for north-area elk = mean date of movement for south-area elk, ok= 0;
HAJ: Mean date of movement for north-area elk mean date of movement for south-area elk, ok:t:. 0.

*

Hypothesis l was the experimental hypothesis; hypotheses 2 and 3 accounted for other sources of variation. I
used PROC GLM (SAS Institute 1990) to estimate and test differences in mean date of movement by area,
treatment, and year. Type m sum of squares were used for hypothesis tests.
To determine whether elk receiving both early and late treatments on public land, regardless of area or
year, were affected by opening date, I used a paired I-test blocked on individual elk. This individual blocking
reduced confounding effects and better accounted for repeated measures taken on animals receiving both
treatments; thus, the analysis was limited to those individuals that received both early- and late-opening date
treatments. Fewer elk received both treatments than received a single treatment because some elk died after the
first study period, some elk were on public land only one year (they stayed on private land the other year), and
some changed treatment areas between years. For the elk getting both treatments, I subtracted their early date of
movement from their late date of movement to account for the fact that this was a repeated measurement on the
elk. I tested the null hypothesis:

Ho: Difference in date of movement for late treatment - early treatment &lt;= 0;
HA: Difference in date of movement for late treatment - early treatment&gt; 0.
I used logistic regression models to predict the proportion of elk on private land on day i (j, i) from elk
location data (public or private land). Models included date as a covariate, and hunting season, area and year
effects as categorical variables. Julian date was used to model date effects so that year effects could be considered
separately from study period date. Hunting season referred to the period before opening of archery season (hunting
season= 0) and after opening (hunting season= 1). I began with a global model, which included date, hunting
season, area, year, plus all 2-, 3- and 4-way interactions of date, hunting season, area, and year (fable 1.1, Model
1). I then developed 9 additional a priori hypothetical models for proportion of elk on private land (fable 1.1,
Models 2-10). After analyzing the a priori models, I built 3 additional models to see if a better model could be built
(fable 1.1, Models 11-13).

�211
I followed the methodology of Burnham and Anderson ( 1998) to select an appropriate model. I used
Akaike's Information Criterion (Akaike 1973), adjusted for overdispersion and corrected for small sample bias
(QAICc), as the basis for objectively ranking models and selecting an appropriate "best approximating" model
(Burnham et al. 1995). QAICc was defined as:
QAICc =- 2{lni) +2K + 2K(K +I)
n-K -l '

c

where In .e is the natural logarithm of the likelihood function evaluated at the maximum likelihood estimates for a

c

given model, K is the number of estimable parameters from that model, n is sample size, and is the estimated
overdispersion factor. QAICc was used instead of AICc because repeated measurements were taken on
radiocollared elk. Lack of independence in the data, in this case repeated measures on elk, may lead to
overdispersion or "extra-binomial variation" (Burnham and Anderson 1988). I estimated the overdispersion
parameter ( c) from the global model, and then used this estimate to adjust (inflate) the variance estimates of model
parameters and predicted values, and to calculate QAICc for all models (Burnham and Anderson 1998). Parameter
estimates, c, and QAICc values were calculated using PROC GENMOD (SAS Institute 1993). The sample size, n,
was the number of elk locations collected during the study period.
The best approximating model was selected based on minimum QAICc. Models were ranked and
compared using DQSAICc (Leberton et al. 1992, Burnham and Anderson 1998) and normalized QAICc weights
(Buckland et al. 1997, Burnham and Anderson 1998). For the suite of models being compared, AQAICc was
computed for each model as:
AQAICc,,, = QAICc,,, - QAICc.,,n ,
where QAICc,,, was the QAICc value for the mth model and QAICc.,,n was the minimum QAICc among the suite
models being compared. Essentially, AQAICc,., is an estimate of the distance between the best approximating model
and model m. Normalized AICc weights (w.,) were estimated for each mth model:
_ _!.~QAICc

w m-

e 2

~&gt;
R

"'

l
--~QAICc

2

,
r

r=l

where R refers to the R models chosen for evaluation. AQAICc and normalized QAICc weights were used to
address model selection uncertainty. Generally, models within 1-2 QAICc units of the selected model were
considered competing models for explaining elk movements to private land.
Another element of uncertainty in estimates of model precision is selection of the appropriate model
(Buckland et al. 1997). If several sets of data, generated from the same underlying process, were evaluated using
AICc, there would be some variation in the selected best model (Burnham and Anderson 1998). Estimates of
precision from any one best model do not include model selection variance and may be biased low. Therefore,
after model selection, I used model averaging to better estimate the precision of the estimates of daily proportion
of elk on private land from all the models I developed. Average estimates of the daily proportion of elk on private
land were calculated for each day i across all models considered. Because all models were logit models, modelaveraged daily proportion of elk on public land, P;, and var(p;) were calculated in the logit scale and backtransformed to calculate the appropriate confidence interval, which was slightly asymmetric. The transfomation
used was:
logit(J\) = 1n[ I

-

R

!fa;].

logit(p;) = L Wm logit(P;m), and
m=l

�212

where wm is the normalized AICc weight. The variance of the model-averaged estimates, which included
conditional sampling variance and model uncertainty was estimated:

where M,,, is the mth model. The 95% confidence interval for the daily estimated proportion of elk on private land
was calculated as:

+95%CI(p;)

e +9S%Cl~ogit(fa1)]
- - - - - - - , and
I +e +9S%CI~ogit(fa,)]

-95%Cl(p;)=

e -9S%CI[logit(fa1)]
_
I +e -9S%CI~ogit(j,1)]

To estimate the effect of hunting season on the proportion of elk on private land, I estimated the
difference between the proportion of elk on private land immediately before and after opening date:

e logit(fab)
l +elogit(j,b) '

pa

p

where
and b are the model-averaged proportion of elk on private land after and before opening date. The
variance in estimated proportion of elk on private land before and after opening of archery hunting was calculated:

�213

Procedures for estimating covariance of model-averaged values are in the development stage and untested (K.
Burnham, Colorado Cooperative Fish and Wildlife Research Unit, personal communication). Thus, I assumed the
covariance to be z.ero. This omission may result in a slightly inflated variance, and a possibility of not detecting a
true effect of hunting season. The variance of the model-averaged estimated proportion of elk on private land was
calculated using the delta method (Seber 1982):

~i,

Let u =logit(pa), then var(pa) =v:J

and

"l1+e"

A

•

~

2

du
du
du
=-=viir(u )-=- =(-=-) viir(u) =[
A

viir(p a)

dfaa

dfaa

dfaa

]2

e"

A

A

(l+e")

2

viir(u) •

Substituting logit(p a) back in for u:

2

_

elogit(it&gt;

var(_p a) =

_

_

[

2

( 1+ elogit(faa))

_

_

var[logit(p a)]= [fa a (l - pa)

f var[logit(pa)].
-

1

The var(pb) was calculated similarly. The 95% CI was calculated:

-

-

-

-

I\_

95%Cl(p0 - Pb)~ (Pa - fib)± l.96se(p0 - Pb)·

Because previous studies used changes in daily distances moved and elevation shifts to evaluate elk
responses to disturbance, I calculated these metrics for comparison. Mean daily distances moved and mean daily
elevations during the study period were calculated from the 80-radiocollared elk. Distances were calculated from
consecutive UTM locations for each elk as straight-line distances. Because elk were not located at fixed time

�214

intervals, distances between locations were expressed per day by dividing the distances moved by the number of
days between locations. Daily distances were not absolute measures of distance moved, rather they were indices
of movement. Elevations for each elk location came from a statewide I: l 00,000-scale elevation map.
RESULTS

Results from the ANOVA on mean date of elk movement indicated a treatment effect (P = 0.013, one
sided), but no area or year effects (P &gt; 0.100; Table 1.2). However, north- and south-area elk showed different
responses to opening of archery hunting. To evaluate this apparent difference, I preformed a post hoc analysis
separately by area. This analysis revealed a 14-day difference (P = 0.006, one sided) in mean date of movement
between treatments for elk in the north area, versus a 6-day difference (P = 0.218, one sided) between treatments
for elk in the south area (Table 1.3).
Area and year were confounded within sequence of treatments this study. That is, elk in the north area
received the late-early treatment sequence, while elk in the south area received the early-late treatment sequence.
Thus, it was impossible to determine whether a sequence effect was really a difference resulting from (1) a
difference between treatment areas because oflocation of private-land refuges, topography, etc., or (2) elk
receiving a late-opening treatment the first year followed by an early-opening treatment the second year behave
differently than elk receiving the early-late sequence. I reference this confounded effect as an area effect, which I
will discuss later.
Sixteen of the 80-radiocollared elk received both early and late treatments and moved from public to
private land during the study period. That is, there were 32 paired movements (16 elk receiving 2 treatments and
moving form public to private both years) compared to 60 unpaired movements (elk receiving treatments and
moving from public to private land at least 1 year). Some elk moved to private land immediately after capture in
1996, and some elk never returned to public land in 1997, thus fewer than 80 elk were available for treatment
each year. The difference between the paired and unpaired movements occurred because 4 elk moved the first
year but died before the second year, 3 elk were collared in 1997 and moved only the second year, 11 elk only
moved one year because they were on public land one year and private land the other year, 1 elk changed
treatment areas and received late-late treatments (counting as 2 unpaired movements), and 8 elk moved from
public to private land one year only. The difference in mean date of movement for the 16 elk receiving both early
and late treatments was 5 days (95% CI= -3, 13; P = 0.091 one sided).
Using model-averaged values, I generated predicted curves of proportion of elk on private land versus
Julian day, hunt season, area, and year (Fig. 1.4 and 1.5). All logistic models to estimate the daily proportion of
elk on private land had a significant positive date effect indicating that proportion of elk on private land increased
from 19 July-10 October both years of the study (Fig. 1.4 and 1.5). The logistic regression model with the lowest
AICc (Table 1. 1, model 13) was:
logit(f,;) = --4.715-1.294(area) +4.987(hunt season)+ 0.015(Julian day)+ 0.009(area x Julian day)
-0.018(hunt season xJulian day) ,
where f,; is the predicted proportion of elk on private land on Julian day i. The top 2 models, both post hoc
models, (Table 1.1, models 13 and 12) were 1.85 AICc units from each other, while the remaining 11 models
were over 3 AICc units greater than model 13 (Table 1.4). Hence, I considered models 13 and 12 as competing
models. Model 12, the second model, was identical to model 13 except for an additional area x hunt season
interaction. Thus, area, hunt season, Julian date,,;u-ea x Julian day, hunt season x Julian day, and area x hunt
season may be important predictors of the proportion of elk on private land. The area effect arose from a higher
proportion of elk on private land, in general, on the north area versus the south area, the hunt season effect arose
from a higher proportion of elk on private land after hunting opened versus before, and the Julian date effect arose
from the increase in elk on private land through time (the study period). The area x Julian day interaction arose
from the steeper slope for the north area versus the south area, and the hunt season x Julian day interaction arose
from the steeper slope before hunting season opened versus after it opened.

�215

The experimental effect on the number of elk directly influenced by early-season hunting can be
estimated by the abrupt increase in proportion of elk moving to private land when hunting opened. I used the
difference in the model-averaged predicted proportion of elk on private land immediately before and immediately
after opening day to estimate the direct effect of opening of hunting. Elk on private land increased 8-18% at the
opening of early-season hunting (Table 1.5). During the study period, a significantly higher proportion of
radiocollared elk moved to private land in the north treatment area compared to south area (P = 0.035; Table 1.6).
On average, elk moved 613 m/day (95% CI= 594,632). The mean daily distance moved by elk before
hunting season opened was 651 m/day (95% CI= 619, 683) and 575 m/day (95% CI= 540,610) after opening
(Fig. 1.6 and 1. 7). During the study, the mean elevation of elk changed by -2.1 m/day (95% CI = -2.3, -1.9).
Elk moved down in elevation an average of-2.4 m/day (95% CI= -2.9, -1.9) before hunting season opened and
down -0.7 m/day (95% CI= -1.2, -0.2) after opening (Fig. 1.8 and 1.9).
DISCUSSION

Experimental ResulJs
Although elk movements in the White River area may not be solely caused by archery hunting activity,
the experimental results show that archery hunting activity has an effect on elk movements despite other factors,
especially in the northern treatment area. The strength of a 2 x 2 crossover design is that it blocks or controls for
two sources of external variation, allowing for much stronger inference of cause and effect than the same design
without a strict crossover (Ratti and Garton 1994). The crossover is also more efficient than a randomiz.ed design
(Ott 1993); that is, a randomiz.ed design requires a larger sample size. In this experiment, area and year were the
external sources of variation controlled for by the crossover design, and opening date of archery hunting was the
treatment Any factor that occurred on both halves of the study area, such as recreational activity, grazing,
weather, forage phenology etc., that also caused elk to move, would lessen detection of an effect due to hunting
activity. For example, if recreational activity caused some elk movement during the study period, then these
recreationally induced movements would be unaffected by opening date of archery hunting and would serve to
attenuate detection of archery hunting effects. If no elk were responding to archery hunting activity, either
because they moved in response to another factor or they did not move at all, then I would fail to reject the null
hypothesis and would conclude that archery hunting was not affecting elk movement. In the White River elk
population, some elk may move regardless of what happens with archery hunting, because their movement was a
response to some other factor; some elk may not move; and some elk may move due to changes in archery hunting
activity. In the north treatment area, elk receiving the early treatment moved 14 days earlier than elk receiving
the late treatment, indicating that some elk moved in response to archery season.
Similarly, the effects of archery hunting on the daily proportion of elk on private land can also be
distinguished from other effects. The positive slope for proportion of elk on private land resulted from steady
movement of elk to private land during the study period and suggested that factors other than archery hunting may
have affected elk movements. However, some of the movement to private land was directly attributable to
hunting. That is, 23-44% of the radiocollared elk moved to private land during the study period, and 8-18% of
this movement occurred at the opening of archery season. The significant jump in proportion of elk on private
land at archery opening, beyond the steady increase, indicates that archery hunting activity did affect movement
beyond that caused by other factors on both the north and south treatment areas.
Sequence or carry-over effects can dilute detection of treatment effects in this type of study. A carryover effect occurs when the sequence of treatments affects responses to treatments (Ott 1993). In the case of
White River elk, a carry-over effect would exist if south-area elk, receiving the early-opening treatment the first
year, moved early the second year, before the late-opening date. A carry-over effect would be manifest on the
north area if elk receiving the late-opening treatment the first year, moved late the second year, after the earlyopening date. In this experiment, elk on the north area moved slightly before opening date both years, while elk
on the south area moved in accordance with opening date. Thus, I concluded that there was no carry-over effect
due to the sequence of the treatments. I attributed differences in movements to area rather than sequence effects.
A post hoc analyses on mean date of movement and daily proportion of elk on private land revealed that
treatment effects were greater in the north area. When designing the study, I assumed that the north and south

�216
areas were similar and would serve as controls for each other. Alleged elk movements to private land were
perceived to be similar problem on both areas. The differences may have occurred because habitat, cover,
topography, or any other area factors important to elk movement were different on the two treatment areas.
Fortunately, each area received both treatments, so I could look at each area as its own control and evaluate each
area separately.
In the north treatment area there was a significant 14-day difference in mean date of movement between
early and late treatments, while in the south treatment area there was a non-significant 6-day difference. In the
north treatment area, about twice as many elk moved to private land ( 44%) compared to elk in the south area
(23%). The difference in treatment response in the north and south areas may be due to cover and refuge
configuration. In general, animals must balance the tradeoff between feeding and danger (Krebs and Davies
1993); elk may reduce use of open areas and use cover more frequently in times of perceived or real danger. Elk
calves subjected to simulated surface-mining activities used coniferous forest significantly more often compared
to undisturbed calves (Kuck et al. 1985). Similarly, elk subjected to oil drilling significantly increased use of
forested habitats during drilling and post drilling periods, compared with the pre-drilling period (Van Dyke and
Klein 1996). Where logging activities disturbed elk, areas of high elk use were negatively correlated to the
amount of cover in the area (Edge and Marcum 1985, Edge et al. 1985, Czech 1991). In the White River area,
the north area was rolling, with open parks interspersed with a few high peaks, while the higher elevation south
area was essentially a plateau cut by steep narrow canyons and with steep, densely forested cliffs defining the
plateau. These densely forested canyons and cliffs, inaccessible to motor vehicles, offered good refuge from
hunters on public land. In contrast, the north area offered less shelter on public land, but had refuge in large
private-land tracts that bordered the area. The south treatment area had less private land adjacent to public land,
as BLM land was abundant at lower elevations. It may be that elk in the south area moved into forest refuges on
public land after archery hunting opened, while elk in the north area moved to private-land refuges.
More generally, elk movements during hunting seem to depend on location and quality of hiding cover.
Elk decreased their daily movements after attaining sanctuary from hunting in national parks (Altmann 1956,
Martinka 1969) or thick vegetation inaccessible to most hunters (Lemke 1975, Irwin and Peek 1979, Morgantini
and Hudson 1979). I found a similar general pattern; elk on the north and south areas reduced their daily
movements an average of 76 m/day after hunting season opened and they attained refuge from hunting on private
land or in thick vegetation.

a

Scale Issues
Three main issues became evident during the course of the study that fall under the rubric of large-scale
field experiments: (1) a difference between movement responses for elk in the north and south areas, (2) a
difference in the experimental results compared to pilot study results, and (3) failure of many elk to receive both
treatments. As discussed, I think the difference in treatment responses between north and south elk were due to
proximity of cover and private land hunting sanctuary. Additionally, I speculate that differences in wintering
grounds and migration routes between the two treatment areas also affected movement responses. In the south
treatment area, wintering grounds were at the south end of the study area. Southern elk were impaired from
migrating beyond the study area by barriers created by Interstate 70 and the Colorado River. In the north
treatment area, although private-land refuge was adjacent to the study area, wintering grounds were 30-80 km
west of the study area During the study period, elk moving to private land in the north area were just beginning
their fall migration, whereas elk in the south area were completing their migration by moving to private land. It
may be that there was no energetic cost to northern elk to move to private land in late summer, while southern elk
would risk depleting their winter forage by moving to private land in late summer.
There was less movement during..the ex~ent than I expected based on pilot study data. During the
experiment, 21-48% of elk moved to private land compared to 70-100% during the pilot study. I think this
disparity arose because the pilot study lacked a random sample from the entire area. Pilot study animals were
collared primarily in areas with perceived movement problems. When the spatial scope of sampling expanded
such that the entire study area was randomly sampled, many elk were collared in areas with no previous record of
movement Corresponding to the increased spatial variability in elk capture location was an increased variability
in elk movement responses: elk in some areas did not move. The pilot study animals were not representatives of
the entire study area, rather they represented areas with movement problems.

�217

I designed this experiment with the intent that it be a crossover experiment, which used a crossover
AN OVA model to test whether the mean date of elk movement from public land to private land was different
between treatments. Exposure by each animal to both treatments was a requirement of the crossover analysis,
and this requirement was impossible to implement in this large-scale field experiment. I did not have the control
to ensure that each animal received both treatments; therefore, I analyzed the data as paired and unpaired data.
Interpretation of mean date of movement results would have been more robust if all elk received both treatments.
Mean date of movement between treatments was less dramatic for the paired analysis (5 days) compared to the
unpaired analysis (10 days), though the difference was not significant. This difference may represent sampling
variance; the small size of the paired sample makes this possibility likely.
MANAGEMENT IMPLICATIONS

Although there was a statistically significant effect of archery hunting on timing and number of elk
moving to private land in the north treatment area, the question remains as to whether this effect was significant to
elk management. The experimental effect on number of elk moving can be estimated by the abrupt increase in
proportion of elk moving to private land when hunting opened. This jump was 8-18%; hence, the CDOW can
reduce, at most, approximately 20% of the elk movement to private lands by manipulating archery hunting
activity. However, 20% of a herd may represent a large enough number of animals to make management changes
worthwhile. Additionally, if elk movements are concentrated in problem areas, then manipulation of opening date
may result in a proportionally higher reduction of elk movements in those areas. Managers must decide whether
the contribution of archery hunting activity to elk movement is large enough to warrant management action.
Elk responded to archery hunting activity differently in north and south treatment areas; I concluded that
archery hunting activity had little or no effect in the south area, but had a statistically significant effect on timing
and proportion moving in the north area. Thus, managers concerned with elk movement need to be cautious if
citing White River results as a reason for management actions; elk movement was dependent on the habitat and
topography of an area, and these factors must be considered in any plan to reduce elk movements. Furthermore,
because this study manipulated opening date of hunting activity but kept hunter numbers constant, the question
remains of what percentage of the elk would still move if hunting were reduced or eliminated.
Managers may also want to consider the time needed to make permanent changes in elk movement
patterns. Elk responses to disturbance may be long- or short-lived depending on the type of disturbance and the
type of elk response. For example, studies that evaluated elk movements after disturbances ceased found that
displacement appears to be temporary in most situations. Elk displaced by cross-country skiers returned to their
original locations after people left the area (Cassirer et al. 1992). During weekends, and immediately following
the end oflogging activities, elk moved back into logged areas (Ward 1976, Edge and Marcum 1985). Even for
more potentially lethal hunting disturbances, mean distances to roads returned to pre-hunting distances after
hunting season closed (Hershey and Legee 1982, Wright 1983). Zahn (1974), Lemke (1975), and Hershey and
Legee (1982) also found that elk response to hunter disturbance was short-lived. In the White River area, this
short-lived response seems to characterize south-area elk. In 1996, hunting season opened early, 24 August, in
the south area, and closed 14 September. A drop in the proportion of elk on private land occurred after closing
date (Fig. 1.4a), indicating that some elk moved back to public land after hunting season closed. This was also
seen in elevation shifts of south-area elk: after hunting season closed in 1996, mean daily elevations increased
(Fig 1.9a), indicating that elk moved back up to public land after the disturbance ended. Elk in the south
treatment area seem to exhibit a short-term response to hunting disturbances.
On the other hand, if the elk response to disturbance was a migration shift, then the movement response
may last longer. Elk that have learned to move to unhunted refuges and choose migration routes through lightly
hunted areas (Altmann 1956, Martinka 1969) may continue these patterns ifno cost was incurred by the change. In
the north area, the steady movement may be only partially a direct effect of hunting season. Some elk may learn to
move to private land as a conditioned response to avoid hunting danger, and this movement may have become
paired with some unconditioned stimuli, such as shortening day length. Because movement in the north area is the
beginning of migration, and because timing of migration is thought to be stimulated by daylight cues (Krebs and
Davies 1993), north-area elk may now move when the days begin to shorten in addition to the stimulus of hunter
activity. As older cow elk have been found to assume leadership roles within a group (Franklin and Lieb 1979),

�218
social learning may pass on this pattern to future generations. Thus, elk on the north area may move to private land
in response to direct cues of hunter activity and indirect cues of day length.
When considering elk movements in response to hunting activity, wildlife managers should consider the
type of movements being exhibited by the elk as well as the refuge configuration in the area. Although reducing
hunter numbers may reduce movement where elk responses to disturbance are short lived (probably short
movements to habitat refuges), different management practices may be needed where migration patterns have
become a fixed behavior. If elk have established a migration pattern onto private land, private land hunts, on
lands to which elk move, may be a good solution to break the migration pattern and deter early elk movements
onto private land.
LITERATURE CITED

Akaike, H. 1973. Information theory and an extension of the maximum likelihood principle. Pages 267-281 in B.
N. Petran and F. Csak:i, editors. International symposium on information theory. Second edition. Akademiai
Kiadi, Budapest, Hungary.
Altmann, M. 1956. Patterns of herd behavior in free-ranging elk of Wyoming, Cervus canadensis ne/soni.
Zoologica 41 :65-71.
Barrett, M. W., J. W. Nolan, and L. D. Roy. 1982. Evaluation of a hand-held net gun to capture large mammals.
Wildlife Society Bulletin 10:108-114.
..
Boyce, M S. 1991. Migratory behavior and management of elk (Cervus elaphus). Applied Animal Behavioral
Science 29:239-250.
Boyd, R J. 1970. Elk of the White River Plateau, Colorado. Colorado Division of Game, Fish and Parks Technical
Publication 25, Fort Collins, Colorado, USA.
Buckland, S. T., K.. P. Burnham, and N. H. Augustin. 1997. Model selection: an integral part of inference.
Biometrics 53:603-618.
Burnham, K.. P., D. R Anderson, and G. C. White. 1995. Model selection strategy in the analysis ofcapturerecapture data. Biometrics 51 :888-898.
Burnham, K.. P., and D. R Anderson. 1998. Model selection and inference: a practical information-theoretic
approach. Springer-Verlag, New York, New Yorlc, USA.
Bryant, L. D., and C. Maser. 1982. Classification and Distribution. Pages 1-59 in J. W. Thomas and D. E.
Toweill, editors. Elk of North America: ecology and management Stackpole Books, Harrisburg,
Pennsylvania, USA.
Cassirer, E. F., D. J. Freddy, and E. D. Ables. 1992. Elk responses to disturbances by cross-country skiers in
Yellowstone National Park. Wildlife Society Bulletin 20:375-381.
Czech, B. 1991. Elk behavior in response to human disturbance at Mount St Helens National Volcanic
Monument. Applied Animal Behavioral Science 29:269-277.
Edge, W. D., and C. L. Marcum. 1985. Movements of elk in reaction to logging disturbances. Journal of Wildlife
Management 49:926-930.
Edge, W. D., C. L. Marcum, and S. L. Olson. 1985. Effects oflogging activities on home-range fidelity of elk.
Journal of Wildlife Management 49:741-744.
Franklin, W. L., and J. W. Lieb. 1979. The social organization ofa sedentary population of North American elk: a
model for understanding other populations. Pages 185-198 in M. S. Boyce and L. D. Hayden-Wing editors.
North American elk: ecology, behavior, and management. University of Wyoming, Laramie, Wyoming, USA.
Freddy, D. J. 1987. The White River elk herd: A perspective, 1960-85. Colorado Division of Wildlife Technical
Publication 37, Fort Collins, Colorado, USA.
Gray, J.P., G. Byrne, and J. Madison. 1994. White River elk data analysis unit plan: game management units:
ll,211,12,13,i31,231,23,24,25,26,33. Colorado Division of Wildlife Internal Report, Grand Junction,
Colorado, USA.
..
Hershey, T. J., and T. A. Leege. 1982. Elk movements and habitat use on a managed forest in north-central Idaho.
Idaho Department of Fish and Game Wildlife Bulletin 10, Boise, Idaho, USA.
Irwin, L. L., and J.M. Peek. 1979. Relationships between road closures and elk behavior in northern Idaho. Pages
199-204 in M. S. Boyce and L. D. Hayden-Wing editors. North American elk: ecology, behavior, and
management. University of Wyoming, Laramie, Wyoming, USA.
Knight, RR 1970. The Sun River elk herd. Wildlife Monographs 23.
Krebs, J. R, and N. B. Davies. 1993. An introduction to behavioural ecology. Third edition. Blackwell Science
Ltd., Oxford, England.

�219
Kuck, L., G. L. Hompland, and E. H. Merrill. 1985. Elk calf response to simulated disturbance in southeast Idaho.
Journal of Wildlife Management 49:751-757.
Leberton, J-D., K. P. Burnham, J. Clobert, and D. R Anderson. 1992. Modeling survival and testing biological
hypotheses using marked animals: a unified approach with case studies. Ecological Monographs 62:67-118.
Lemke, T. 0. 1975. Movement and seasonal ranges of the Burdette Creek elk herd, and an investigation of sport
hunting. Montana Fish and Game Department Final Report 32.01, Job Number BG-3.15, Missoula, Montana,
USA.
Martinka, C. J. 1969. Population ecology of summer resident elk in Jackson Hole, Wyoming. Journal of Wildlife
Management 33:465-481.
Morgantini, L. E., and R J. Hudson. 1979. Human distribution and habitat selection by elk. Pages 132-139 in M.
S. Boyce and L. D. Hayden-Wing editors. North American elk: ecology, behavior, and management.
University of Wyoming, Laramie, Wyoming, USA.
Ott, R L. 1993. An introduction to statistical methods and data analysis. Fourth edition. Wadsworth, Inc.,
Belmont, California, USA.
Ratti, J. T., and E. 0. Garton. 1994. Research and experimental design. Pages 1-23 in S. Hieb, editor. Research
and management techniques for wildlife and habitats. Fifth edition. The Wildlife Society, Bethesda,
Maryland, USA.
SAS Institute. 1990. SAS/STAT® user's guide, version 6.0. Fourth edition. SAS Institute, Inc., Cacy, North
Carolina, USA.
SAS Institute. 1993. SAS/STAT® software: The GENMOD procedure, release 6.09. SAS® Technical ReportP243, SAS Institute, Inc., Cacy, North Carolina, USA.
..
Seber, G. A. F. 1982. The estimation of animal abundance and related parameters. Second edition. Edward
Arnold, London, England.
Strohmeyer, D. C., and J. M Peek. 1996. Wapiti home range and movement patterns in a sagebrush desert.
Northwest Science 70:79-87.
Van Dyke, F., and W. C. Klein. 1996. Response of elk to installation of oil wells. Journal ofMammalogy
77:1028-1041.
Ward, A. L. 1976. Elk behavior in relation to timber harvest operations and traffic on Medicine Bow Range in
south-central Wyoming. Pages 32-43 in S. Hieb, editor. Proceedings of the Elk-Logging-Roads Symposium.
University of Idaho, Moscow, Idaho, USA.
Wright, K. L. 1983. Elk movements, habitat use, and the effects of hunting activity on elk behavior near Gunnison,
Colorado. Thesis, Colorado State University, Fort Collins, Colorado, USA.
Zahn, ll M. 1974. Seasonal movements of the Burdette Creek elk herd. Montana Fish and Game Department
Final Report 32.01, Job Number BG-3.13, Missoula, Montana, USA.

�220
Table 1.1. Description and representation of a priori (models 1-12) and post hoc (models 11-13) models relating
effects of year, area. opening of archery hunting season. and Julian date to daily proportion of radiocollared elk
found on private land (p,) from 20 July to 10 October in the White River area. Colorado, 1996-1997.
1.

HyPOthesis
Global model: year, area. opening of archery
hunting, Julian day, and all possible interactions

2.

No year x date interactions

3.

No year x main effects (A and S) interactions

4.

No year effects

5.

No area x date interactions

6.

No area x main effects (Y and S) interactions

7.

No area effects

8.

No hunt season x date interactions

9.

No hunt season x main effects (A and Y)
interactions
10. No hunt season effects

11. Only hunt season effects
12. Only hunt season and area effects
13. Only hunt season and area effects with no S x A
interaction

Model structure •
f3o+f31 (Y)+f32(A)+f3iS)+f3iD)+f3s(YxA)+f36(YxS)
+f37CY xD )+f3s(Ax S)+f39(AxD)+f3 10(SxD)
+f3 11 (YxAxS)+f3 12(YxAxD)+f3 13(YxSxD)
+f3 14(AxSxD)+f3 15(YxAxSxD)
f3o+f31 (Y)+f3iA)+f3 3(S)+f3iD)+f35(YxA)+f36(Y xS)
+f3i{AxS)+f3s(AxD)+f39(SxD)+f3 10(YxAxS)
+f3 11 (AxSxD)
f3o+f31(Y)+f32(A)+f33(S)+f3iD)+f3 5(YxD)
+f36(AxS)+f3i{AxD)+f3s(SxD)+f39(AxSxD)
f3o+f3,(A)+f32(S)+f3iD)+f3 4(AxS)+f35(AxD)
+f3iSxD)+f3i{AxSxD)
f3o+f31 (Y)+f32(A)+f3iS)+f3iD)+f3s(YxA)+f36(YxS)
+f37CY"xD)+f3s(AxS)+f3 9(SxD)
+f3 10(YxAxS)+f3 11 (YxSxD) ..
f3o+f31(Y)+f32(A)+f33(S)+f34(D)+f3 5(YxS)+f3~xD)
+f3i{AxD)+f3s(SxD)+f39(YxSxD)
f3o+f3,(Y)+f32(S)+f33(D)+f34(YxS)+f3 5(YxD)
+f3iSxD)+f37CYxHxD)
f3o+f3, (Y)+f32(A)+f3iS)+f34(D)+f3s(YxA)+f36(Y xS)
+f37CY'xD)+f38(AxS)+f3 9(AxD)+f3 10(YxAxS)
+f3 11 (YxAxD)
f3o+f3,(Y)+f32(A)+f33(S)+f34(D)+f3s(YxA)+f36(YxD)
+f3i{AxD )+f3s(SxD)+f39(YxAxD)
f3o+f3,(A)+f32(Y)+f33(D)+f3iAxY)+f3 5(AxD)
+f36(YxD)+f3i{Ax YxD)
f3o+f3,(S)+f32(D)+f3iSxD)
f3 0+f3 1(A)+f3iS)+f33(D)+f3iAxS)+f3 5(AxD)+f36(SxD)
f30+f3 1(A)+f3 2(S)+f33(D)+f3 4(AxD)+f3 5(SxD)

• Y represents year with 1996 = 0 and 1997 = 1, A represents treatment area with south area = 0 and north area =
I, S represents archery hunting season with O= before opening and 1 = after opening, and D represents the
covariate date, which is Julian day. The dependent variable (p,) was in logit scale.

�221
Table 1.2. Days between opening dates, least-square mean differences with ±95% CI, and P-value for the null
hypothesis of no difference between mean date of movement by treatment, year, and area for radiocollared elk in
the White River study area, Colorado 1996-1997.
Days between
opening dates
Treatment effect: (late treatment - early treatment)
Year effect: (1997 - 1996)
Area effect: (south area - north area)

Days between mean
dates of movement

p

20

10±9

1
0

4±9
7±8

0.013•
0.346
0.100

• One-sided test

Table 1.3. Differences between opening dates, least square mean differences with ±95% CI. and one-sided P-value
for the null hypothesis of no difference between mean date of movement for radiocollared elk in the White River
study area, Colorado 1996-1997.
Treatment area
North
South

Days between
Opening dates
20
20

Days between mean dates of movement
(late treatment - early treatment)

p

14 ± 10
6 ± 15

0.006
0.218

�222
Table 1.4. Ranking of a priori (models 1-12) and post hoc (models 11-13) hypothesized models relating effects of
year, area, opening of archery hunting season, and Julian day to daily proportion of radiocollared elk found on
private land (p,) from 20 July to 10 October in the White River area, Colorado, 1996-1997. Models were ranked by
QAICc values and normalized QAICc weights ( wm ).
Model number b

Kc

QAICc

AQAICc

Wm

13o+13,(A)+l3i(S)+l3iD)+l3iAxD)+l3lSxD)

13

6

4718.68

0.00

0.495

13o+l31(A)+l32(S)+l3J(D)+l3iAxS)+l3£AxD) +l3 6(SxD)

12

7

4720.53

1.85

0.196

13o+l31(Y)+l3i(A)+l3J(S)+l3iD)+l3£YxA)
+l3 6(YxD)+l3-;(AxD)+l3s(SxD)+l3g(YxAxD)

9

10

4721.92

3.24

0.098

13o+l3i(A)+l3i(S)+l33(D)+l3iAxS)+l3lAxD)+l3iSxD)
+l3-;(AxSxD)

4

8

4722.42

3.74

0.076

13o+l31(Y)+l3i(A)+l3iS)+l34(D)+l3£YxS)
+l3 6(YxD)+l3-;(AxD)+l3s(SxD)+l39 (YxSxD)

6

10

4723.37

4.69

0.048

13o+l3,(Y)+l3i(A)+l3iS)+l34(D)+l3£YxA)
+l3 6(YxS)+l3-;(AxS)+l3s(AxD)+l3g(SxD)
+l3 10(YxAxS)+l3 11 (AxSxD)

2

12

4723.57

4.90

0.043

13o+l3,(Y)+l3i(A)+l3iS)+l34(D)+l3iYxD)
+l3iAxS)+l3-;(AxD)+l3 8(SxD)+l3lAxSxD)

3

10

4724.11

5.43

0.033

13o+l3,(Y)+l3i(A)+l3iS)+l34(D)+l35(YxA)+l3 6(YxS)
+l3-;(YxD)+l3s(AxS)+l3g(SxD)+l3 10(Y xAxS)
+l3 11 (YxSxD)

5

12

4726.6

7.92

0.009

1
13o+l31(Y)+l3i(A)+l3JCS)+l34(D)+l35(YxA)+l3 6(YxS)
+l3-;(YxD)+l3s(AxS)+l3iAxD)+l3 10(SxD)+l3 11 (YxAxS)
+l3 12(YxAxD)+l3 13(Y xSxD)+l3,◄&lt;AxSxD)
+l3 15(YxAxSxD)
8
130+131 (Y)+f3i(A)+l3J(S)+l34(D)+l3 5(YxA)+l3 6(Y x S)
+l3-;(YxD)+l3s(AxS)+l3iAxD)+l3 10(Y xAx S)
+l3 11 (YxAxD)

16

4730.41

11.74

0.001

12

4733.36

14.68

0.000

Model structure •

130+131 (A)+l32(Y)+f3 3(D)+13 i Ax Y)+l3£AxD)
+l3 6(YxD)+l3-;(Ax Y xD)

10

8

4745.57

26.89

0.000

13o+l31(Y)+f3i(S)+l33(D)+l34(YxS)+l3 5(Y xD)+l3 6 (SxD)
+l3-;(SxYxD)

7

8

4845.74

127.07

0.000

4855.07 136.39
11
4
0.000
13o+l3i(S)+l32(D)+l3J(SxD)
• Y represents year with 1996 = 0 and 1997 = 1, A represents treatment area with south area= 0 and north area=
1, S represents archery hunting season with 0 = before opening and 1 = after opening, and D represents the
covariate date, which is Julian day. The dependent variable (p,) was in logit scale.
b Numbers correspond to those in Table 1.1
c Number of estimable parameters.

�223
Table 1.5. Model-averaged estimates of hunt season effect represented by the difference of proportion of
radiocollared elk on private land immediately before and after opening day and 95% confidence intervals; White
River area, Colorado, 1996-1997.
rrreatment Area
1997: North -early
1996: North - late
1996: South - early
1997: South - late

Estimated oronortion of elk on orivate land
Immediately
Immediately
Difference
95%CI
after oneninv;
of difference
before oneninv;
0.095-0.257
0.408
0.584
0.176
-0.001-0.158
0.542
0.621
0.078
0.089-0.231
0.256
0.416
0.160
0.317
0.416
0.099
0.028-0.170

Table 1.6. Mean proportion ofradiocollared elk on private land during 1996-1997 for each treatment area in the
White River area, Colorado, at the beginning (19 July) and end (10 October) of the stud.y period.
Mean proportion of elk on private land 1996-1997
Treatment area
North
South

July 19
0.200
0.161

October 10
0.636
0.393

Change
0.436
0.232

95% CI of change
0.296-0.577
0.105-0.360

�224

t
N

km
0

.~

ra........
.

... I

10

20

BLM Land
Flat Tops Wilderness

GMU Boundaries

J$ State Wildlife Land

D study Area Boundary
II Forest Service Land
White River

.•

Towns

Colorado

Figure 1.1. Alleged elk movements from high elevation public land to lower elevation private land, and land
ownership in the White River study area, Colorado.

7000

-

6000

C

5000

~

(I)

C

,,. - . -....

:::,

.c
0

'

u,

cu
(1)

u,

4000

I

&gt;,

"C

cu

3000

0

2000

(1)

L..

(1)

.a

§ 1000
z
0
1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994

Year

* Variance estimates not available 1984-1987.
Figure 1.2. Number of archery and muzzleloading hunters using GMUs 12, 23, 24, and 33 in northwest Colorado,
1984-1994. Data from Deer, Elk, and Antelope Management (DEAMAN) database and software, Colorado
Division of Wildlife, unpublished data.

�225

t
N

.I! BLM Land
fiffl Flat Tops WIiderness

~ State WIidiife Land

D Study Area Boundary

km
0

10

20

■· Forest Service Land
•

Elk Capture Locations

•·

Towns

Figure 1.3. North and south treabnent areas and July 1996 elk capture locations in the White River study area,
Colorado.

�226

Early Opening

Late Opening

a

C

0.9

0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0

"'C
C

ca

Q.)

ca

&gt;
·c:

'J••--- •• ! -~- ·······-···

.'!.------------- ♦----- •.•.

South 96
&lt;X)
~

;:::

C.
C

!12

Opening date

0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0

Opening date

~ ~ cc ~

North 97
Cl)

II)

~

;::::

0

~

Q)

0

C

0

:e0

C.

e
a..

b

d
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0

0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0

Opening date

North 96
Cl)

Opening dale

------♦-- .........

-----·-•-·-•··
South 97
Cl)

I()

I()

;:::: ~
~

i:: ~

♦

Raw data
Predicted

--•95%CI

Figure 1.4. Model averaged predicted values, 95% CI, and raw data of proportion ofradiocollared elk on private
land versus date for (a) early treatment on the south area 1996, (b) early treatment on the north area 1997, (c) late
treatment on the north area 1996, and (d) late treatment on the south area 1997, July-October in the White River
study area, Colorado.

�227

0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0

a
Earl!' opening filled curve\

■

•••• ■ ~

•

■

•

I .I:. ■

•••• •

■ ■ •■ ~- -■••

•
-■

■ ■

■

ii Late opening
• Early opening

Late opening fitted curv

----CX)

IC)

T""

CX)

IC)

T""

N

CX)

CX)

T""

...... ......

0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0

CX)

N

---

0)

~

~

CX)

CX)

IC)

N

0)

T""

T""

0)

0)

co

0)

-

&lt;-&gt;

0

0

~

0)

T""

0

T""

T""

Date

b
■ Late opening
• Early opening

Early opening fitted curve

■

•
CX)

IC)

T""

~

j::::

•
• •••
■

•

■

••
■

..

- T""

CX)

CX)

a&gt;

IC)
T""

CX)

■

N

••
■

- --

■

■

■

•

■

■ - -■ -

••

■

\

Late opening filled curve

0)

!!?
0)

~ ~
Date

-N

0)

T""

T""

0)

0)

co

~

0)

&lt;-&gt;

0

T""

0

T""

0

T""

Figure 1.5. Model averaged predicted values and raw data of proportion of radiocollared elk on private land versus
date for (a) north-treatment area and (b) south-treatment area during July-October 1996-1997 in the White River
study area, Colorado.
1600 ~ - - - - - - - - - - - - - - - - - - - ~
-Soulh early 1996
Early opening Late opening
-c. ._as 1400 --North early 1997
E
·-····· South late 1997
&gt;-

-c

1200

CD

~ 1000

(I)

g 800
(ti
..,

-~

"'C

~

'iii
"'C
C
(ti
(I)

600
400
200

:::E

0
co
.....
.....
,..._

I()
('.I

.....
,..._

.....
.....
co

co
.....
co

I()
.....
.....
co

as

('.I

.....

oi

0)
.....
.....
0)

(0

~

~

0

.....

0

.....

0
.....

Date

Figure l.6. Mean distance moved per day by radiocollared elk during July-October 1996-1997 in the White River
study area, Colorado.

�230

�231
CHAPTER 2: EFFECT OF HUNTER DENSITY ON ELK MOVEMENT TO PRIVATE LAND IN
NORTHWEST COLORADO
INTRODUCTION

Animals may modulate their response to stimuli depending on the quality, quantity, context, and
intensity of the stimuli. Prey species, such as elk (Cervus elaphus), may show responses to varying densities of
predators, such as hunters. Elk may increase their use of a refuge to avoid hunters; that is, as the density of
predators increases, so too does the probability that elk are found in a refuge area. Or, elk may ignore hunters at
low densities, and move to refuge areas only when hunter densities increase above some tolerance and danger
threshold. To avoid hunters, elk have moved to refuges in national parks (Altmann 1956, Martinka 1969),
private land (Wright 1983, Chapter 1), or densely vegetated areas (Irwin and Peek 1979, Morgantini and
Hudson 1979) adjacent to their typical areas of activity. However, little research as been done on general elk
responses to differing levels of hunter pressure, and no research has directly evaluated the effects of hunter
density on elk use of refuge.
Since the 1960s, the number of early-season (archery and muzzleloading) hunters using the White River
area of northwest Colorado has grown, with especially significant increases between 1984 and 1992 (Fig. 2.1,
DEAMAN, Colorado Division of Wildlife, unpublished data). Typically, archery hunters did not hunt private
lands; thus, private lands provided elk a refuge during early-season hunts. As archery and muzzleloading hunter
numbers increased, so too did complaints about early elk movements onto private land. For the Colorado
Division of Wildlife (CDOW), the primary problem was herd size: it was difficult for CDOW to maintain or
reduce herd size via harvest because hunters have limited access to private lands, (J. Madison and C. Reichert,
Colorado Division of Wildlife, personal communication). Managers hypothesized that reduction of early-season
hunter pressure, achievable through limiting licenses, would reduce movement onto private land.
As part of an experiment about elk movement in response to early-season hunting activity, CDOW
conducted an intensive hunter survey in the fall of 1996 and 1997. The study area was split into 2 treatment
areas. A telephone survey of early-season hunters was conducted to estimate the daily number of hunters using
each treatment area with a 95% confidence interval of ±150 hunters (total confidence interval of300 hunters). I
used these data, along with elk location data, to determine how the density of early-season hunters affected elk
movement to private land.
My objectives were to: (1) summarize hunter survey data and provide estimates of hunter numbers,
hunter-days, and mean days hunted per hunter by treatment area, Game Management Unit (GMU), hunt code,
and day, (2) compute these estimates for hunters using ATVs, and (3) evaluate the relationship between hunter
density and elk movement to private land. I used logistic regression and Akaike's Information Criteria (AIC)
model selection (Burnham and Anderson 1998) to evaluate the relationship between hunter density and elk
movement to private land.
STUDY.AREA

The White River area of northwestern Colorado covered approximately 4,540 km2 and was composed of
Game Management Units (GMUs) 12, 23, 24, and 33. In Colorado, GMUs were delineated to distribute hunters
through allocation of hunting licenses. White River area land ownership was 34% private land and 66% public
land (Fig 2.2), with 82% of public land being United States Forest Service (USFS). USFS land was mostly at
high elevation and toward the center of the study area, with some Bureau of Land Management (BLM) areas at
lower elevations in the southern sections of the study area. Private land was lower in elevation and comprised
mainly ranches and coal mines.
Topography, climate, and vegetation varied widely throughout the study area. Elevation ranged from
1,629 to 3,700 m. The central part of the study area was high elevation public land, split by the White River
valley. The high elevation areas dropped off to lower elevations to the north, south, and western edges of the
study area. Higher elevations had severe winters with heavy snowfall, while lower elevations had comparatively
mild winters. Mean annual precipitation at 3,000 min the National Forest areas was about 100 cm, compared

�232

with about 30 cm at lower elevations of &lt;2,000 m. Vegetation types at elevations &gt;2,600 m were in the
montane/subalpine zone and included groves of aspen (Populus tremuloides), Engelmann spruce (Picea
engelmanni), and alpine fir (Abies lasiocarpa) interspersed with grassy meadows. Middle elevations (1,9802,600 m) were a transitional zone that consisted primarily of pinion pine (Pinus edu/is),juniper (Juniperos
scopu/orum), and big sagebrush (Artemisia tridentata). Lower elevations (&lt;2,000 m) in the southern and
northern parts of the study area were in the Great Basin zone with sage grasslands. Oakbrush patches were
found at the middle and lower elevations with major shrubs that included Gambel's oak (Quercus gambelii),
servicebeny (Amelanchier alnifolia), mountain mahogany (Cercocarpus montanus), chokecherry (Prunus
virginiana), snowberry (Symphoricarpos utahensis), bitterbrush (Purshia tridentata), and rabbitbrush
(Chrysothamnus nauseosus). Higher and middle elevation areas provided summer and fall forage for elk, while
lower elevations were typically used by elk during winter. Boyd (1970) provides a detailed description of the
study area
Hunting for large game was economically important to local residents in the study area (Gray et al.
1994). Guides, outfitters, local service sectors, and private landowners (who sell trespass perm.its) made a large
proportion of their annual income during the elk and deer hunting seasons, with most hunting revenues accrued
during rifle hunting season
METHODS

Radio-telemetry Data Collection

As part of a study on effects of early-season opening date on elk movements to private land, the study
area was divided roughly east-west into 2 halves along the White River and North Fork of the White River (Fig.
2.2). GMU 12 and parts of GMUs 23 and 24 composed the north treatment area, while GMU 33 and parts of
GMUs 23 and 24 composed the south treatment area. Two treatments were applied: an archery season that
opened 1 week earlier, and another that opened 2 weeks later than normal, yielding a 3-week difference in
opening dates. Each area received both an early- and late-opening treatment During the first year of the study,
the early-opening treatment was randomly assigned to the south treatment area. Treatments were reversed the
second year of the study. Thus, in 1996, archery hunting opened early, 24 August, in the south area, and late, 14
September, in the north area. When treatments were reversed in 1997, archery hunting opened early, 23 August,
in the north area, and late, 13 September, in the south area. Archery season was 4 weeks long during the earlyopening treatment and 3 weeks long during the late-opening treatment. Muzzleloading season was 1 week long
and nested within archery season. Opening of muzzleloading season coincided with opening of archery season
for the late-opening treatment, and occurred on the third weekend during the early-opening treatment.
The 80 adult female elk used in this study were captured from random locations throughout the study
area. Chapter 1 describes capture and collaring procedures in detail. Elk locations were collected 20 July-10
October 1996-1997. I relocated radiocollared elk between 0700-1500 hr using a Cessna 182 or 185 fixed-wing
aircraft with a 2-element Yagi antenna mounted to each strut of the airplane. For each elk relocation, Universal
Transverse Mercator (UTM) coordinates were recorded with a Global Positioning System that was not
differentially corrected. During the early-season hunt, I collected elk locations 2 times a week with 2-4 days
between collections. A Geographical Information System (GIS) map was used to record elk locations, land
ownership, and treatment boundaries. The GIS map was digitized from a United States Geological Survey map
at a scale of 1:100,000. For each location of a telemetered cow, a Owas assigned if the location was on public
land (e.g. Flat Tops Wilderness Area, USFS, State Wildlife, and BLM lands) and a 1 was assigned if the
location was on private land.
Hunter Survey Data Collection

Number of archery and muzzleloading hunting licenses for elk and deer in 1996 were based on the mean
number calculated from 1990 - 1994 (4,985; Colorado Division of Wildlife unpublished data). Restricting
licenses kept hunter density consistent during the study and consistent with years of high elk movement
complaints. In the fall of 1996 and 1997, after archery and muzzleloading season ended, CDOW conducted a

�233
telephone survey with a goal of sampling enough hunters to estimate the number of hunters afield on any day
with a 95% confidence interval of ±150 hunters (total confidence interval width= 300 hunters; Appendix 1).
Sample size was based on the binomial distribution and was conservative. That is, the maximum variance
occurs when 50% of the license holders hunt, and enough license holders were surveyed to meet the ±150
hunters confidence interval under this condition.
CDOW conducted the telephone survey following protocols typically used to collect hunter data. The
sample was a simple random sample. The initial sample size was larger than required, with an expectation that
70-90% of hunters called will respond with a complete survey. If this requirement was not met, then additional
hunters were again randomly chosen from those not sampled the first time. The survey began as soon as the
hunting season closed, and continued for approximately 4 months. Telephone surveys have been found to
provide valid estimates of harvest and days hunted (White 1993, Steinert et al. 1994). Hunt codes:
D-E-012-01-A
E-E-012-01-A
E-F-012-01-M
E-M-012-01-M
D-M-012-01-M
D-E-033-01-A
E-E-033-01-A
E-F-033-01-M
E-M-033-01-M
D-M-033-01-M

- archery deer, either sex, on north area,
- archery elk, either sex, on north area,
- muzzleloading elk, cow, on north area,
- muzzleloading elk, bull, on north area,
- muzzleloading deer, buck, on north area,
- archery deer, either sex, on south area,
- archery elk, either sex, on south area,
- muzzleloading elk, cow, on south area,
- muzzleloading elk, bull, on south area, and
- muzzleloading deer, buck, on south area,

were surveyed. Hunters that purchased two licenses on the same treatment half (e.g. D-E-012-01-A and E-E012-01-A) were counted as one hunter and were proportionally assigned to hunt-code groups. The number of
individuals purchasing licenses was the size of the statistical population sampled for estimates, and was used in
all estimates of hunter number, hunter-days, and average days/hunter. Hunters were asked:
1.
2.
3.
4.
5.
6.
7.

License identification number,
Hunt code;
If they hunted or did not hunt;
In which GMUs they hunted;
How many days they hunted per unit;
If they hunted on day I, on day 2, on day 3, etc. of the 7season; and
If they used an ATV.

From these data, 3 categories of information were estimated for hunt-code group, treatment area, and GMU:
Number of hunters that hunted and number of hunters that used ATVs;
Number of hunters afield per day, and number of hunters with ATVs afield per day; and
Number of hunter-days and average number of days in the field per hunter and per hunter using an ATV.
The following notation is used in estimator formulas, with i, j, k, /, and m indexing the group for which the
estimator is being used:
i .. .., .
j

k
I
m

-

-

day (day I is opening day, day 2 is 2nd day of the season etc.),
"."'
hunt code group (north treatment area contained hunt code groups: DE01201A, DM01201M,
EE01201A, EF01201M, EM01201M; south treatment area contained hunt code groups:
DE03301A, DM03301M, EE03301A, EF03301M, EM03301M),
GMU (12, 23, 24, or 33),
individual hunter, and
treatment area (north or south half of study area).

�234

For example, H;m is the estimated number of hunters afield on day i in treatment m, H;1cm is the estimated
number of hunters afield on day i in GMU k, treatment area m, H1an is the estimated number of hunters that
hunted in GMU k, treatment area m, etc. Additional notation is:
N

-

N' -

n

I

n -

a

-

Number of individuals purchasing licenses,
Number of licenses sold,
Number of license holders surveyed who responded with at least partial infonnation,
Number of license holders surveyed who reported hunting,

fr -

Number of license holders surveyed who reported hunting with an ATV,
Estimated number of hunters,
Estimated number of hunters using ATVs,
Number of hunter-days reported for surveyed hunters,
Number of hunter-days reported for surveyed hunters using ATVs,
Number of hunter-days reported for surveyed hunters in a particular GMU,
Estimated
number of hunter-days,
..
.
Estimated number of hunter-days for hunters using A TVs,

d
f
p

-

Mean number of days afield per hunter,
Mean number of days afield per_ hunter using an A TV.
Estimated probability that a license holder hunted, and

r

-

Estimated probability that a license holder hunted with an A TV.

H A d
f
u

-

D -

Day i, hunter/, and A TV use were entere~ as~ or I. For example,. if a surveyed license holder hunted, then
a I was entered, or, if they did not hunt, then a 0 was entered. Similarly, if a hunter hunted on.day i, then a
I was entered, or, if the hunter did not hunt, then a 0 was entered for that day. If a hunter used an ATV
.
.
..
then a I was entered, and the hunter was assumed to use the A TV every day hunting. The finite correction
fact?r, (N~~ n) , was used for all estimates. N~te that N' was used in the finite correction because each

-

license, and not individual, was randomly sampled. Thus, a license holder purchasing 2 licenses could be
interviewed for 0, I, or 2 of the licenses. The number of licenses sold varied between I 50-1,219 by hunt
code and the finite correction factor varied between 0.45-0.72 (Table 2.4 and 2.5). The 95% confidence
intervals were constructed similarly for all variables, e.g.:

ii ±t.96.Jvar&lt;.il&gt; ,
or, where sample sizes were &lt;100, the appropriate t-statistic was used in lieu of 1.96:

Estimating Number of Hunters
Estimates of number of hunters (if) and their associated variances were calculated for each hunt
code group (J) separately, then summed over hunt~ode groups{/) for treatment (m) or GMU (k). The
number of hunters from hunt code group (j) that hunted in treatment area (m) was estimated:

�235

5

ii m = L ii J , and
J=I

5

var(ilm) = L var(il1).
J=I

Similarly, the number of hunters using ATVs (A) from hunt code group (J) that hunted treatment area (m)
was estimated:

.~pf;·&gt;=
""'' 1

(N'- -n-) r-(l-r-)
J
J
J
J
N'
'

ni

J

5

Am= 2..,A1, and
J=l

5

var(Am) = 2.., var(AJ).
J=l

The number of hunters (ii) from hunt code (J) that hunted in GMU (k) and treatment area (m) was
estimated:
"

n'.k
J

PJk = - ,

ni

:;...1·

Va,.\Pjk

)

=

(N'-J -n J·) p" J·k(l-p"J-k)

,

N1

5

ii km = "I.., ii Jk , and
J=I

n1

�236

s

L var(H jk).

var(H km)=

j=I

Similarly, the number of hunters with AlVs (A) from hunt code (j) that hunted in GMU (k) and treatment
area (m) was estimated:

:;.~A

Vcu\rjk

)

=

(N'-J -nJ·) r-k(l-r-k)
J
J
I

Nj

nj

s
A1an = LAjk , and
j=I

var(Akm) =

s

L var(A jk).

j=I

Estimating Number of Hunters Afield per Day

Estimates of total number of hunters (if) afield per day(,) and their associated daily variances were
calculated for each hunt code group(/) separately, then summed over hunt code groups (j) for treatment (m)
.
.
.
.
or GMU (k). The number of hunters afield on day (,) within treatment (m) was estimated:

A

s

A

H;m = LHij, and
j=I

var(H;m) =

s

L va.r(H ij).
j=I

Similarly, the number of hunters afield using AlVs ( A ) on day(,) within treatment area (m) was
estimated:

�237

a-I]
r.--=1]
,
A

nj

var(r--) =

(N'- -n -) r--(1-r--)
J

~

J

I]

N'-

IJ

J

I]

nJ

5 ~

Aim= LAij ,and
j=l

5

var(A;m) =}:: var(Aij).
j=l

The number of hunters(/) afield (ii) on day(,) in GMU (k), treatment area (m) was estimated:

n.::..

i:.Pijkl
l=l

Pijk = - ' - - - - ' - - nj

var(H ijk) = var(N j Pijk) = NJ var(Pijk),
~

5

~

Hil,m = L Hijk, and
j=l

5

var(Hikm) = L var(H ijk).
j=l

Similarly, the number of hunters (l) using ATVs ( A ) afield on day (I) in GMU (k), treatment area (m) was
estimated:

�238

A

A;1cm =

5

L Aiik , and
A

j=l

s

var(A;km) =

L var(Aijk) j=l

Estimating Mean Number ofDays per Hunter and Hunter-days
-

A

Estimates of mean days afield per hunter ( d ) and total hunter-days ( D ), and their associated variances
were calculated for each hunt code group (j) separately. For each hunt code group (J), mean days afjeld per
hunter ( J ) was assumed to be independent of the proportion of license holders that hunted ( p). Estimates
of mean days afield per hunter by treatment and GMU were calculated directly, and associated variances
were summed over hunt code groups (j) for treatment (m) or GMU (k). The mean days afield per hunter
and total number of hunter-days were estimated for hunters (l) from hunt code group (j) that hunted
treatment area (m):

nm

Ldml
-dm_-l=l
--,-,
nm

-

var(d m) =

Ls var(d- j),
J=l

�239

5

A

A

Dm=L,Dj,and
j=l

5

r, var(i&gt; j).

var(i&gt;m) =

j=l

Similarly, for each hunt code group (j), mean days afield per hunter using an ATV ( j) was assumed to be
independent of the proportion of license holders that hunted (; ). The mean days afield per hunter using an
ATV ( j ) and total number of hunter-days with ATVs (ft) were estimated for hunters ({) from hunt code
group (J) that hunted treatment area (m):

F'_j =Ajfj =N/j/j,
var(Fj) = var(N j1'j

-

var(/m) =

7j) = NJ f/ var{] j)+ 7/ var(rj )-(var(rj)var(/ ))],

L5 var(/- j) ,
j=I

A

5

A

Fm= LFj ,and
j=l

5

var(Fm) =

L var(Fj) .
j=l

For each hunt code group (J), mean days afield per hunter ( d ) was assumed to be independent of the
proportion of license holders that hunted ( p ). Mean days afield per hunter ( d) and total number of
hunter-days ( D) were estimated for hunters ({) from hunt code group (J) that hunted GMU (k) and
treatment area (m):

�240

-

5

~

var(d Jan)=}: var(djk),
j=I

5
D1an = I, b jk , and
j=I

5

var(D1an) =

L var(D jk).
j=I

Similarly, for each hunt code group(/), mean days afield per hunter using an ATV(]) was assumed to be
independent of the proportion of license holders that hunted ( r ). Mean days afield per hunter([) using an
A TV ( J) and number of hunter-days using ATVs (fr) were estimated for hunters that hunted GMU (k)
and treabnent area (m):
ijk/ = fjl Pk/,

�241

5

A

Ljjkajk
j=I

~

f1an=--s-"'iajk
j=I

s

A

var&lt;}Jan)=

A

L var&lt;}jk) ·
j=I

s

F1an = Iftjk , and
j=I

s
var(F1cm)= Ivar&lt;ftjk)j=I

�242

Elk Movement versus Hunter Density

I used logistic regression models to evaluate the effects of hunter density on elk movement to private
land. The response variable representing elk movement to private land, proportion of elk on private land on day ;
(v;), was calculated from elk location data (each elk location was classified as public or private land). Hunter
density was the estimated density of hunters afield on day;, in hunters/km2 . Hunter density was not an exact
measurement, rather it was an estimate with an error term. Typically, using a predictor variable with an error
term results in the regression coefficient biased toward z.ero (Fuller 1987). That is, I would be less likely to
detect an effect of hunter density than actually existed. However, if the variance of the predictor variable (hunter
density) is large compared to the variance of the estimates, then the effect of the error in the predictor variable
can be effectively ignored during regression analysis (Draper and Smith 1966). The variance of hunter density
(0.0098) was large compared to the variance of the estimates (maximum variance= 0.0002); hence I ignored the
error in hunter density. Because this experiment was not designed to manipulate hunter density, I used model
selection to evaluate the effect of hunter density beyond other possible confounding factors.
I previously built an extensive suite of models to evaluate the effects of hunt season opening on elk
movement to private land (Chapter 1, Table 1.1 ). Instead of generating another long list of models, I began with
the 2 best models from the existing set (Chapter 1, Table 1.4, Models 12 and 13); these 2 models were &lt;2
QAICc units from each other and were competing models (Table 2.1, Models 1 and 2). My main goal was to
evaluate the effect of hunter density on elk movement to private land, and compare this effect to hunt season
opening. I replaced Julian day with hunter density to evaluate whether hunter density was a better predictor of
elk on private land on day i than Julian day (Table 2.1, Models 3 and 4). To evaluate the importance of hunt
season opening compared to hunter density, I first removed hunt season from Model 3, and then removed hunter
density (Table 2.1, Models 5 and 6). Although treatment models did not work well predicting the proportion of
elk on private land in the study manipulating opening date, I hypothesized that treatment may provide more
information when hunter density was included in a model because hunter density patterns varied between earlyand late-opening treatments. To evaluate this idea, I added treatment to the best model that included hunter
density (Table 2.1, Model 7), and replaced area with treatment (Table 2.1, Model 8). Finally, evaluate whether
the cumulative interaction with hunters caused elk to move to private land, I replaced hunter density with
cumulative hunter density in the best model that included hunter density (Table 2.1, Model 9). Note that none of
these models were strictly a priori because I began with previously run best models and built from these best
models.
I followed the methodology of Burnham and Anderson (1998) to select an appropriate model. I used
Akaike's Information Criterion (Akaike 1973), adjusted for overdispersion and corrected for small sample bias
(QAICc), as the basis for objectively ranking models and selecting an appropria~l'best approximating" model
(Burnham and Anderson 1998). QAICc was defined as:

QAICc =- 2~l) + 2K + 2K(K +1),
c

n-K-1

where In l is the natural logarithm of the likelihood function evaluated at the maximum likelihood estimates for
a given model, K is the number of estimable parameters from that model, n is sample siz.e, and cis the estimated
overdispersion factor. QAICc was used instead of AICc because repeated measurements were taken on
radiocollared elk. Lack of independence in the data, in this case repeated measures on elk, may lead to
rr.,, overdispersion or "extra-binomial variation" (Burnham and Anderson 1988). I estimated the overdispel'$.ion
,, ,~
parameter ( c) from the global model, and then used this estimate to adjust (inflate) the variance estimates of
model parameters and predicted values, and to calculate QAICc for all the models (Burnham and Anderson
1998). Parameter estimates, c, and QAICc values were calculated using PROC GENMOD (SAS Institute
1993). The sample siz.e, n, was the number of elk locations collected during the study period.

�243

The best approximating model was selected based on minimum QAIO::. Models were ranked and
compared using AQAIO:: (Leberton et al. 1992, Burnham and Anderson 1998) and normaliz.ed QAIO:: weights
(Buckland et al. 1997, Burnham and Anderson 1998). For the suite of models being compared, AQAIO:: was
computed for each model as:
AQAICc., = QAICc., - QAICc.,,n .

where QAIO::. was the QAIO:: value for the mth model and QAIO::""" was the minimum QAIO:: among the suite
models being compared. Essentially, AQAIO::,.. is an estimate of the distance between the best approximating
model and model m. Normaliz.ed QAIO:: weights (w.) were estimated for each mth model:
__!_ An AICc
A

e 2"""'&lt;

-

Wm = - - - 1- - - ,

R --AQAICc
I;e
2
r
r=l

where R refers to the R models chosen for evaluation. AQAIO:: and normaliz.ed QAICc weights were used to·
address model selection uncertainty. Generally, models within l-2 QAIO:: units of the selected model were
considered competing models for explaining elk movements to private land.
RESULTS

Hunter Survey Data
CDOW surveyed 35-36% of early-season hunters using the study area in 1996 and 1997. Early-season
hunters were 77% archers and 23% muzzleloaders. Estimates of hunter use with and without ATVs are
provided by treatment (fable 2.2) and GMU (fable 2.3). Estimates are provided by hunt code for 1996 (fable
2.4) and 1997 (fable 2.5). The estimated number of hunters afield per day and number of hunters using ATVs
are shown with their 95% confidence intervals by treatment (Fig. 2.3) and GMU (Fig. 2.4). In 1996, daily
information was collected for 23 days for each hunter, although hunting season extended 30 days during the
early-opening treatment Therefore, 1996 graphs of the south area, where hunting opened early, show only the
first 23 days of the season. In 1997, the survey was changed to collect information on hunter use for the entire
30-day season. Appendix 2 contains confidence intervals for daily GMU data.

Elle Movement versus Hunter Density
The best logistic regression model with the lowest QAIO:: value (fable 2.6, Model 1) was:

This was the best model from the manipulative experiment and did not have a hunter density covariate. In fact,
the first model with a hunter density covariate was 35.2 QAIO:: units from the top model (fable 2.6, Model .9),
and the hunter density regression coefficient was not significantly different than zero in any of the models in
which it was included. Model 9, with cumulative hunter density preformed similarly (AQAIO:: &lt; 2) to its
counterpart, Model 6 with straight hunter density (Table 2.6). Model 5, with hunter density, preformed poorly
(AQAIO:: &gt;&gt; 2) compared to its counterpart, Model 6, with hunt season replacing hunter density (fable 2.6).

�244

DISCUSSION

By design, hunter use of the study area was constant from year to year and between treabnent areas.
However, the daily pattern of use was different for early- and late-opening treabnents. When hunting opened
early, hunter use was relatively constant. There were several small peaks coinciding with each weekend during
the season, and one larger peak coinciding with the opening of muzzleloading season. When hunting opened
late, there was a large peak on opening weekend, partially because muzzleloading season opened with archery
season. The late treabnent peaked at higher densities of hunters (0.44-0.50 hunters/km2) compared to the early
treabnent (0.28-0.36 hunters/km2).
Several hunting studies indirectly provide insight about elk responses to different levels of hunting
pressure. Wright (1983) examined elk response to different hunting seasons: archery and muzzleloading, versus
3 different types of rifle hunting seasons. Distances traveled by elk increased with hunter density, and were
lowest during archery and muzzleloading season when hunter densities were the lowest. Although hunting
method and hunter density were confounded, elk response to hunter density remains a possible explanation for
increased elk movements. An earlier study in the White River area, designed to evaluate elk movement onto a
coal company's protected land during early-season hunting, found that 13% of the radiocollared elk were on
private lands midway through archery and muzzleloading seasons (Camp Dresser and McKee, Inc. 1986).
During this study, 50% and 53% of the radiocollared elk were on private land on the same day during 1996 and
1997 respectively. The lack of movement onto private land in the earlier study may be explained by a 63%
reduction in archery hunters for that year because of a change in hunting regulations (Gray et al. 1994). Thus,
elk movement to private land may decrease when hunting pressure drops. Finally, Zahn (1974), Lemke (1975),
and Hershey and Legee (1982) noticed an increase in distances moved by elk during the first 10-12 days of
hunting season, followed by normal movement during the remainder of the season. These authors noted that
hunting pressure was heavy during the initial 10-12 day of hunting, and relatively light for the remainder of the
season. Although all these hunting studies are observational, taken together a pattern emerges; at high hunter
densities elk increase their movements to refuge, and at low densities they decrease their movements to refuge.
However, there is a confounding between the effects of hunter density and the opening of hunting season
opening. That is, the increase in distances moved by elk during the initial 10-12 days of hunting season (Zahn
1974, Lemke 1975, Legee 1982) could be due to high densities of hunters or to the opening of hunting season
itself. Elk in the White River area seemed to respond more to the opening of hunting season than to hunter
density. That is, models that included a hunt season effect did significantly better than models without hunt
season effect (Chapter 1). In contrast, models with a Julian day covariate (fable 2.6, Models 1 and 2)
preformed far better than models with a hunter density covariate (fable 2.6, Models 3-5 and Models 7-9). In
fact, hunter density can not be considered as a predictor of proportion of elk on private land because models with
hunter density were a minimum of35.2 AQAICc units from the top model. Additionally, at the opening of earlyseason hunting, 8-18% of the study elk moved to private land (Chapter 1), while after opening, elk movement to
private land was not related to hunter density (Fig. 2.5). Thus, hunter density had no effect on elk movements to
private land in the White River area. It may be that hunter density must exceed a threshold before elk begin to
respond directly to hunters, and hunter densities did not surpass this threshold during the study.
MANAGEMENT IMPLICATIONS

If hunter density continues to be a suspected cause of increased elk movement to private land, then an
experiment manipulating hunter density should be conducted. Managers concerned with reducing elk movements
to private land have an opportunity to evaluate effects of hunting pressure when setting license numbers for a
particular area. Additionally, increasing hunter density on private land where problems are occurring may be the
most direct strategy to retain elk on public land during late summer. Whatever the management strategy,
manipulation of hunter density offers managers a good opportunity to conduct an adaptive management
experiment to increase information regarding the management of elk movements to private land.

�245
LITERATURE CITED

Akaike, H. 1973. Information theory and an extension of the maximum likelihood principle. Pages 267-281 in
B. N. Petran and F. Csaki, editors. International symposium on information theory. Second edition.
Akademiai Kiadi, Budapest, Hungary.
Altmann, M. 1956. Patterns of herd behavior in free-ranging elk of Wyoming, Cervus canadensis nelsoni.
Zoologica 41 :65-71.
Boyd, R J. 1970. Elk of the White River Plateau, Colorado. Colorado Division of Game, Fish and Parks
Technical Publication 25, Fort Collins, Colorado, USA
Buckland, S. T., K. P. Burnham, and N. H. Augustin. 1997. Model selection: an integral part of inference.
Biometrics 53:603-618.
Burnham, K. P., and D. R Anderson. 1998. Model selection and inference: a practical information-theoretic
approach. Springer-Verlag, New York, New York, USA
Camp Dresser and McKee, Inc. 1986. Meeker PRLA elk migration study: monitoring report, volume 2.
Prepared for Consolidation Coal Company. Camp Dresser and McKee, Inc., Denver, Colorado, USA.
Draper, N. Rand H. Smith Jr. 1966. Applied regression analysis. Second edition. John Wiley and Sons, New
York, New York, USA
Fuller, W. A 1987. Measurement error models. John Wiley and Sons, New York, New York, USA
Gray, J.P.; G. Byrne, and J. Madison. 1994. White River elk data analysis unit plan: game management units:
l l,21 l,12,13,13 l,231,23,24,25,26,33. Colorado Division of Wildlife Internal Report, Grand Junction,
Colorado, USA
Hershey, T. J., and T. A Leege. 1982. Elk movements and habitat use on a managed forest in north-central
Idaho. Idaho Department of Fish and Game Wildlife Bulletin 10, Boise; Idaho, USA
Irwin, L. L., and J.M. Peek. 1979. Relationships between road closures and elk behavior in northern Idaho.
Pages 199-204 in M. S. Boyce and L. D. Hayden-Wing, editors. North American elk: ecology, behavior,
and management. University of Wyoming, Laramie, Wyoming, USA
Leberton, J-D., K. P. Burnham, J. Clobert, and D. R Anderson. 1992. Modeling survival and testing biological
hypotheses using marked animals: a unified approach with case studies. Ecological Monographs 62:67118.
Lemke, T. 0. 1975. Movement and seasonal ranges of the Burdette Creek elk herd, and an investigation of
sport hunting. Montana Fish and Game Department Job Final Report 32.01, Job Number BG-3.15,
Missoula, Montana, USA
Martinka, C. J. 1969. Population ecology of summer resident elk in Jackson Hole, Wyoming. Journal of
Wildlife Management 33:465-481.
Morgantini, L. E., and R J. Hudson. 1979. Human distribution and habitat selection by elk. Pages 132-139 in
M. S. Boyce and L. D. Hayden-Wing, editors. North American elk: ecology, behavior, and management.
University of Wyoming, Laramie, Wyoming, USA
SAS Institute. 1993. SAS/STAT® software: The GENMOD procedure, release 6.09. SAS® Technical Report
P-243, SAS Institute, Inc., Caty, North Carolina, USA
Steinert, S. F., H. D. Riffel, and G. C. White. 1994. Comparisons of big game harvest estimates from check
stations and telephone surveys. Journal of Wildlife Management 58:335-340.
White, G. C. 1993. Precision of harvest estimates obtained from incomplete responses. Journal of Wildlife
Management 57:129-134.
Wright, K. L. 1983. Elk movements, habitat use, and the effects of hunting activity on elk behavior near
Gunnison, Colorado. Thesis, Colorado State University, Fort Collins, Colorado, USA.
Zahn, H. M. 1974. Seasonal movements of the Burdette Creek elk herd. Montana Fish and Game Department
Job Final Report 32.01, Job BG-3.13, Missoula, Montana, USA.

�246

Table 2.1. Description and representation of models relating effects of area, treatment, hunt season opening,
hunter density, and Julian date to daily proportion ofradiocollared elk found on private land (v,) from 20 July-10
October in the White River area, Colorado, 1996-1997.
Hypothesis
Model structure •
I. Lowest AICc model from the experimental manipulation of
early-season opening date b
2. Second lowest AICc model from the experimental
f3 0+f3 1 (A)+f32(S)+f3iD)+f3◄(AxD)+f3 5 (SxD)
manipulation of early-season opening date b
+f3iAxS)
3. Hunter density is a better predictor than Julian day - Model f3o+f3 1(A)+f3 2(S)+f3J(H)+f3.(AxH)
I with hunter density replacing the Julian day covariate •
4. Hunter density is a better predictor than Julian day - Model f3o+f3 1 (A)+f32(S)+f3 3(H)+f3◄(AxH)+f3s(AxS)
2 with hunter density replacing the Julian day covariate •
5. Hunter density is a better predictor than hunt season hunter density and area effects only
6. Hunt season is a better predictor than hunter density - hunt
season and area effects only
7. Treatment is an important effect when hunter density is a
covariate - add treatment to best model with hunter density
8. Treatment is an important effect when hunter density is a
covariate - replace area with treatment
9. Cumulative hunter density better predicts elk movement to
private land - use best model that includes hunter density
and replace the hunter density covariate with a cumulative
hunter density covariate
• A represents treatment area with south area= 0 and north area = I, S represents archery hunting season with O =
before opening and I = after opening, D represents the covariate date, which is Julian day, and H represents the
covariate hunter density on day i in hunters/km2• The dependent variable (v,) was in logit scale.
b See Chapter I, Table 1.4.
• SxH cannot be estimated because hunter density= 0 before hunt season opening.

�247
Table 2.2. Number of licenses sold (N), percent surveyed (s), estimates of hunter numbers ( ii ), hunter-days ( f&gt; ),
mean days hunted/hunter ( J ), hunters using ATVs (A), hunter-days with ATVs (ft), and mean number of
days/hunter using an ATV ( ] ), by treatment area during archery and muzzleloading season in the White River
area l 996-1997. The half-width of the 95% confidence interval is shown for all estimates.
fl b

Dc

37.2
36.9

1,362 ± 25
1,786 ± 20

8,999 ± 390
10, 716 ±426

6.4 ± I.I
6.0 ±0.8

35.1

1,715 ± 30

10,920 ±455

6.2 ± 1.0

Area

Year

N•

s

North

1996
1997

1,711
2,170

1996

2,253

South

d

A

F

209 ± 34

1,555 ± 314

7.2 ±4.1

329 ± 45

2,134 ±392

6.4 ± 2.1

f

300 ±40 2,205 ± 380
7.1 ±2.8
1997 2,090 33.2
1,679 ± 26 11,128 ± 419 6.4 ± 0.9 258 ±40
2,083 ±408
7.6 ± 2.5
• Because some individuals purchased 2 licenses, the number of individuals purchasing licenses, which was used in all
estimates, was slightly less than the number of licenses sold.
b The estimated number of hunters is lower than the number oflicenses sold because some hunters purchasing licenses did
not hunt and because some hunters purchased 2 licenses.
c Estimated number of hunter-days and hunter-days with AlVs are sums of estimated hunter-days by hunt code (fables 2.4
and 2.5), and not the direct product of estimated number of hwiters x mean number of days/hunter.

Table 2.3. Estimates of hunter numbers (fl), hunter-days (D ), mean days hunted/hunter (d), hunters using
ATVs (A), hunter-days with ATVs (F), and mean number of days/hunter using an ATV(]), by GMU during
archery and muzzleloading season in the White River area 1996-1997. The half-width of the 95% confidence
interval is shown for all estimates.
fl•
Db
F
Year
Area
GMU
J
A

Jc

North

12
22
23

773 ±48
1,014 ± 58
437 ± 44
533 ± 52
291 ± 38
426 ±49

4,842 ± 441
6,295 ±484
2,653 ± 355
3,274 ± 483
1,504 ± 277
2,425 ± 401

6.0± 1.8
6.0± 1.2
5.8± 2.0
5.9± 2.2
5.0±2.5
5.3 ± 1.8

74 ±22
117 ± 30
104 ± 25
162 ± 33
75 ±21
102 ± 26

480 ± 181
571 ± 173
676 ±212
1,092 ±333
399 ± 154
643 ±296

6.3 ±7.1
5.0 ±3.1
6.3 ±4.7
6.3 ±3.5
5.3 ±7.5
5.8 ±3.9

1996
3,893 ±409
151 ± 30
890 ±235
5.7 ±3.6
715 ± 53
5.3± 1.8
1997
700 ±201
6.0 ±2.6
494 ± 51
2,770 ±358
5.5 ± 1.9
111 ±28
4.5 ±4.5
23
1996
342 ± 170
3,272 ± 375
5.4± 2.0
75 ±21
600 ± 51
1997
8.5 ± 7.4
577 ± 53
3,514 ±417
5.9±2.4
21 ± 12
195 ± 308
1996
5.7±2.0
132 ± 28
974 ±287
6.9 ±4.8
33
638 ± 52
3,735 ±456
1997
143 ± 31 1,188 ±302
8.0 ±3.1
746 ± 56
4,843 ±452
6.3± 1.4
• All GMU estimates are slightly greater than treatment or hunt code estimates because some hunters hunted in more than
oneGMU.
b Estimated number of hunter-days and hunter-days with AlVs are sums of estimated hunter-days by hunt code, and not
the direct product of estimated number ofhunters x mean number of days/hunter.
c Because of the small sample sizes, a log-based confidence interval should be used in some cases so that values for the
95% CI of ] are &gt;O.
South

22

1996
1997
1996
1997
1996
1997

�Table 2.4. Estimates of hunter numbers (H ), hunter-days (D ), mean days hunted/hunter (d ), hunters using ATVs (A), hunter-days with ATVs (fr), and
mean number of day0iunter using an ATV (] ), by hunt code during archery and muzzleloading season in the White River area 1996. The half-width of the
95% confidence interval is shown for all estimates.
Percent of
Number of
NORTH AREA
fr
b
H
d
A
f
licenses sold • hunters surveyed
241
32.0
D-E-012-01-A
663 ± 83
94 ±7
7.1 ± 0.7
18±8
139 ±67
7.6 ±2.0
32.5
E-E-012-01-A
973
874 ± 22
6,368 ± 367
7.3 ± 0.4
149 ± 31
1,198 ± 302
8.1 ± 1.1
51.5
165
E-F-012-01-M
647 ± 69
5.1 ± 0.4
126 ± 8
12 ±6
66±43
5.3 ±2.7
178
48.9
E-M-012-01-M
808 ± 61
4.8 ± 0.4
167 ± 3
21 ±9
103 ± 48
4.8 ± 1.3
46.8
D-M-012-01-M
154
513 ± 59
101 ± 7
5.1±0.4
8±5
50 ±38
6.0 ± 3.2
SOUTH AREA
30.6
526
380 ± 128
D-E-033-01-A
292 ± 13
1,849 ± 187
6.3 ±0.6
59 ± 16
6.4 ± 1.3
1,219
32.0
7,184
±
400
E-E-33-01-A
1,056 ± 23
6.8 ± 0.4
194 ± 35
1,579 ± 352
8.1 ± 1.1
49.3
150
581 ± 55
16 ±7
E-F-033-01-M
4.8 ± 0.4
86 ±41
5.3 ± 1.0
122 ± 6
47.5
160
5,8 ± 0.4
E-M-033-01-M,
140 ±6
817 ± 70
16±8
93 ±50
5.9 ± 1.6
45.5
198
490 ±77
4.7 ±0.5
14±7
4.9 ± 1.9
D-M-033-01-M
105 ± 12
68±41
• Because some individuals purchases 2 licenses, the number of individual purchasing licenses was slightly less the number of licenses sold. The number of individuals
purchasing licenses was used for all estimates.
Table 2.5. Estimates of hunter numbers (H ), hunter-days (D ), mean days hunted/hunter (d ), hunters using ATVs (A), hunter-days with ATVs (fr), and
mean number of days/hunter using an ATV (] ), by hunt code during archery and muzzleloading season in the White River area 1997. The half-width of the
95% confidence interval is shown for all estimates.
Percent of
Number of
NORTH AREA
fr
b
H
"J
A
]
licenses sold • hunters surveyed
402
54.7
D-E-012-01-A
1,243 ± 63
205 ±5
6.1 ± 0.3
41 ±8
253 ± 57
6.3 ±0.8
1,277
27.9
E-E-012-01-A
1,193±16
7,456 ± 407
6.3 ± 0.3
1,540 ± 377
233 ± 42
6.6 ± 1.1
166
43.4
E-F-012-01-M
134 ± 8
686 ± 70
5.1 ± 0.4
31 ± 11
193 ± 73
6.1±1.0
180
48.3
E-M-012-01-M
850 ± 63
5;3 ± 0.4
160 ± 5
21 ±9
131 ± 60
6.2 ± 1.4
145
45.5
D-M-012-01-M
480 ± 53
94 ±6
5.1 ± 0.5
16 ± 17
5.0 ±0.0
3±3
SOUTH AREA
30.0
D-E-033-01-A
416
223±7
1,503 ± 119
6.8±0.5
43 ± 13
330 ± 118
7.7 ± 1.4
28.4
1,185
E-E-33-01-A
1,058 ±23
7,640 ± 388
7.2±0.3
166 ± 34
1,516 ± 386
7.1±1.2
147
48.3
E-F-033-01-M
121 ±6
584±56
4.8 ±0.4
17 ±7
73 ±34
4.3 ±0.6
155
49.0
E-M-033-01-M
139±4
711 ±57
5.1 ±0.4
55 ± 34
11 ±6
4.8 ± 1.6
D-M-033-01-M
187
46.0
138 ±7
689 ± 63
5,0·± 0,4
21 ±8
109 ±4 9
5, 1 ± 1.2
• Because some individuals purchases 2 licenses, the number of individual purchasing licenses was slightly less the number of licenses sold. The number of individuals
purchasing licenses was used for all estimates.

N

+'-

00

�249
Table 2.6. Ranking of models relating effects of area, treatment, hunt season opening, hunter density, cumulative
hunter density, and Julian day to daily proportion ofradiocollared elk found on private land (v,) from 20 July-10
October in the White River area, Colorado, 1996-1997. Models were ranked by QAICc values and normalized
QAICc weights ( ww ).
Model number b Kc

QAICc

AQAICc

wm

f3 0+f3 1(A)+f3 2(S)+f33(D)+f3.(AxD)+f3s(SxD) +f3iAxS)

1
2

6
7

3760.28
3762.26

0.00
1.97

0.729
0.271

f3o+f31(A)+f32(S)+f3iC)+f3.(AxC) +f3s(AxS)

9

6

3795.45

35.17

f3o+f31(A)+f32(S)+f33(Ax S)
f3o+f31(A)+f32(S)+f3iH)+f3.(AxH) +f3s(AxS)

6
4
3
7

4
6

3796.29
3798.59

36.01
38.31
40.13

0.000
0.000
0.000

Model structure •

f3 0+f3 1(A)+f3 2(S)+f3 3(D)+f3.(AxD)+f3s(SxD)

5
3800.41
0.000
3802.34
8
42.06
0.000
4
5
3867.39
107.11
0.000
f3o+f31(A)+f32(D)+f3 3(Ax D)
3897.96
8
6
137.68
0.000
f3o+f31m+f32(S)+f33(H}+f34(fxH) +f3s(fxS)
• A represents treabnent area with south area= 0 and north area= 1, S represents archeiy hunting season opening with
before opening= 0 and after opening= 1, T represents treabnent with early opening= 0 and late opening= 1, D represents
the covariate date, which is Julian day, H represents the covariate hunter density on day i in hunters/km2, and C represents
the covariate cumulative hunter density on day i in hunters/km2. The dependent variable (v,) was in logit scale.
b Numbers correspond to those in Table 2.1
c Number of estimable parameters.
f3o+f3.(A)+f32(S)+f3iH)+f3.(AxH)
f3o+f31(A)+f3 2(S)+f3iH)+f3 4(f)+f3s(AxH) +f3iAxS) +(3-ifxH)

-

7000

f!
Q)

______ ,

C 6000

.

~

.c.
C
0

5000

U)

co
Q)
C{)

4000

&gt;,

1a 3000
Q)

0 2000
L-

Q)

.c
~

z

1000
0
1984 1985 1986 1987 1988 1989 1990 199119921993 1994
Year

* Variance estimates not available 1984-1987.
Figure 2.1. Number of archery and muzzleloading hwiters using GMUs 12, 23, 24, and 33 in Colorado, 19841994. Data from Deer, Elk, and Antelope Management (DEAMAN) database and software, Colorado Division
of Wildlife wipublished data.

�250

11· BLMLand

llJ: Flat Tops Wilderness

a.

0

10

State Wildlife Area

□ Treatment Area Boundary

Km
20

-II Forest Service Land

Figure 2.2. North and south treatment areas and land ownership in the White River study area, Colorado.

�251

a

C

Early Opening

1,200

Late Opening

1,200
Opening of muzzleloading

End of muzzleloading

1,000

1,000

800 --

"'C

ai
ii:
cu

600

800

South 1996

1

~

600

400

~

400

Cl)

.c

200

:::s

0

E

C
"'C

scu

...,.
~

m

....

~

....a;...,.

~

0

....
a1

b

.. _ -- -- -- -- --

....
a1

....a;...,.

m

a1

....~

,.._

a....

d
1,200

1,000

1,000

w

-- - - . -

200

•- ---- ·-·- ·------- --••••·- ::::::::::-- -- = - = , , ~

E 1,200

.....u,
·-

North 1996

800

..
600

800

North 1997

600

400

400

200

200

------ ---- ---· ··-- ---- ·-

0
C')

N

cc

"'• •'"' ••

••

------

-- ·· -- ....a;

C')

....a;

C')

0

a1

0

a1

a1

Date
LEGEND
Hunters
Hunters using A TVs
•••••••••••• 95%CI
Figure 2.3. Estimated daily number of hunters and hunters using A TVs in the (a) south treatment area
1996, (b) north treatment area 1997, ( c) north treatment area 1996, and (d} south treatment area 1997,
during archery and muzzleloading season in the White River area, Colorado. The first date is opening
date. Each date shown represents a Saturday.
1 There is a break in estimates for the south area in 1996 because survey data were only collected for 23

out of the 3'0 days of the early treatment. The survey was extended to 30 days in 1997.

,.":

�252

a
1,000

1.000

"O

B 1

A

800

co
ii=

1997

C

1996

600

600

400

400

.0

200

200

::l

0

...cu
(1)

E
C

- ... - -

.....

~

~

Cl)

"O

.....

I:::

oi

0

-

Cl)

!!!

~

~

CJI

C

B

C

~

d
1,000

A

B 1

C

A

800

I

I

600

400

400

200

200

0

B

0

a,

E

600

..,
~

a

Jg b
cu 1,000
800

A

800

C

·-

... --.... :.-:, ··--•.• ···~-~-::,...

-.r
CJI

0
a,

~

"'
0

..,
~

---- ..
a
t!
ID

Date
LEGEND

-GMU12
......... GMU 23
--GMU24
-GMU33
A
Opening date of archery season on early-treatment
B
Opening date of muzzleloading season and archery season on late treatment.
C
Closing date of muzzleloading season.

Figure 2.4. Estimated daily number of (a) hunters 1996, (b) hunters using ATVs in 1996, (c) hunters
1997, and (d) hunters using A TVs 1997, during archery and muzzleloading season in the White River
area, Colorado. Each date shown represents a ~aturday.
1

There is a break in estimates for GMU 23, 24, and 33 in 1996 because survey data were only collected

for 23 out of the 30 days of the early treatment. The survey was extended to 30 days in 1997.

�253

CHAPTER 3: ELK LOCATIONS IN RELATION TO DOMESTIC SHEEP BANDS AND A METHOD TO
TEST FOR AVOIDANCE OR ATTRACTION BE1WEEN ANIMALS

INTRODUCTION

Hearsay, accusation, tall tales, and rumor dominate the discussion about Rocky Mountain elk (Cervus
elaphus nelsoni) movements in response to domestic sheep (Ovis aries). Elk movement responses to sheep are a
concern of hunters, who feel that livestock grazing on public land is a disturbance that elk avoid Hunters claim
that domestic sheep force elk away from public hunting areas and onto private land, but there is little
documentation of elk responses to domestic sheep. In one study of elk and livestock grazing, Clegg (1994) found
that elk densities decreased rapidly after introduction of sheep, herders, and dogs. However, the distance of
impact was not recorded making it difficult to assess whether sheep could move elk away from public hunting
areas. Most studies of elk and sheep have originated from livestock concerns and concentrated on dietary
overlaps and forage competition (Pickford and Reid 1943, Nichols 1957, Stevens 1966, Olsen and Hansen 1977,
MacCracken and Hansen 1981, Beck et al. 1996).
In the White River area, elk and domestic sheep graz.e high mountain meadows. Approximately 26
bands of domestic sheep used the study area between May and October. Early-season hunting (archery and
muzzleloading), which occurs between late August and mid-October, overlaps with sheep grazing. During
meetings about elk movements in response to early-season hunting, archery hunters expressed concern that
domestic sheep cause elk to move off public land to private land during the early season. As part of the
stakeholder process, CDOW agreed to collect locations of sheep bands in the area when collecting locations of
80 radiocollared elk for an archery hunting study.
My objectives were to (1) determine if elk avoided sheep at several spatial scales and (2) develop a
methodology applicable to radio-telemetry data to evaluate attraction or avoidance between animals. I used
location data from radiocollared elk and visual locations of sheep bands from the summer and fall of 1996 and
1997. The null hypothesis was that elk locations were random with respect to sheep locations. I used
nonparametric statistics and randomization techniques to calculate, under the null hypothesis, the probability that
elk avoided sheep.
STUDY .AREA

The White River area of northwestern Colorado covered approximately 4,540 km2 and was composed of
Game Management Units (GMUs) 12, 23, 24, and 33. In Colorado, GMUs were delineated to distribute hunters
through allocation of hunting licenses. White River area land ownership was 34% private land and 66% public
land (Fig. 3.1), with 82% of public land being United States Forest Service (USFS). USFS land was mostly at
high elevation and toward the center of the study area, with some Bureau of Land Management (BLM) areas at
lower elevations in the southern sections of the study area. Private land was lower in elevation and comprised
mainly ranches and coal mines.
Topography, climate, and vegetation varied widely throughout the study area. Elevation ranged from
1,629 to 3,700 m. The central part of the study area was high elevation public land, split by the White River
valley. The high elevation areas dropped off to lower elevations to the north, south, and western edges of the
study area. Higher elevations had severe winters with heavy snowfall, while lower elevations had comparatively
mild winters. Mean annual precipitation at 3,000 min the National Forest areas was about 100 cm, compared
with about 30 cm at lower elevations of &lt;2,000 m. Vegetation types at elevations &gt;2,600 m were in the
montane/subalpine zone and included groves of aspen (Popu/us tremuloides), Engelmann spruce (Picea
enge/manni), and alpine fir (Abies lasiocarpa) interspersed with grassy meadows. Middle elevations (l,9802,600 m) were a transitional zone that consisted primarily of pinion pine (Pinus edu/is),juniper (Juniperus
scopulorom), and big sagebrush (Artemisia tridentata). Lower elevations (&lt;2,000 m) in the southern and
northern parts of the study area were in the Great Basin zone with sage grasslands. Oak.brush patches were
found at the middle and lower elevations with major shrubs that included Gambel's oak (Quercus gambelii),
serviceberry (Amelanchier alnifo/ia), mountain mahogany (Cercocarpus montanus), chokecherry (Prunus

�254

virginiana), snowbcrry (Symphoricarpos utahensis), bittcrbrush (Purshia tridentata), and rabbitbrush
(Chrysothamnus nauseosus). Higher and middle elevation areas provided summer and fall forage for elk, while
lower elevations were typically used by elk during winter. Boyd (1970) provides a detailed description of the
study area.
USFS issued permits for sheep grazing on national forest lands on the study area. During the study
period, approximately 26 bands of domestic sheep used the study area. Each band was assigned to a particular
area called an allotment. Bands ranged in size from 750-1,350 sheep, and averaged approximately 1,043 sheep
(95% CI= 981, 1,106; USFS unpublished data from 1992-1995). Band sizes are approximate because actual
numbers were often less than permitted numbers (Mary Massey, United States Forest Service, Meeker Colorado,
personal communication). Sheep arrived on the study area 16 June-I I July, and left 10 September-15 October.
Herders and dogs stayed with the sheep bands and moved them through their allotment area.
METHODS

Data Collection

The adult female elk used in this study were captured from randomly selected locations throughout the
study area. Capture and collaring procedures are descried in detail in Chapter 1. Elk and sheep locations were
collected 20 July-10 October 1996-1997. I relocated radiocollared elk between 0700-1~00 hr using a fixed-wing
aircraft with a 2-element Yagi antenna mounted to each strut of the airplane. For each elk relocation, Universal
Transverse Mercator (U1M) coordinates were recorded with a Global Positioning System. I collected elk locations
2 times a week with 2-4 days between collections. During each flight, the position of at least 1 sheep band was
recorded. Because elk-sheep interactions were not the focus of the study, locations of sheep bands were
opportunistically chosen. That is, I typically recorded the location of only one band of sheep seen and did not
record any other bands, although up to 3 bands per day were sometimes seen. Thus, each band location was a
sample of the population of 26 bands. Because I did not collect locations in a specific route each flight, the daily
sample of sheep bands was fairly random (Fig. 3.1). Once a sheep band was seen, I flew over the band and
recorded lITM coordinates at the approximate center of the band
Data Analysis

·r

r·

All analyses were computed separately for each year. Distances between elk and sheep bands were
calculated from UTM coordinates as straight-line distances. For each day a sheep band was located, I calculated
the distance between the band and every radiocollared elk located that day. I called these paired distances
because they were paired in time (same day). I then calculated the distance between the location of the sheep
band, located that day, and the locations of each radiocollared elk located every other day. I called these
unpaired distances because they were temporally unpaired During the study period, 20-23 locations were
collected on each elk per year. Thus, for each elk, there was I paired distance and 19-22 unpaired distances for
each day locations were collected. Note that there was no way to compute the variance on I measurement; hence
paired and unpaired distances could not be compared using parametric methods. However, a rank representing
the paired distance compared to the unpaired distances, between 1 elk and I sheep band, represents I sample.
Thus, I used a ranking method to evaluate avoidance between elk and sheep bands. For each elk and each day
locations were collected, I ordered distances, paired and unpaired, from smallest to largest, and assigned a
ranking to each distance. That is, the smallest distance between a sheep band and an elk was assigned a 1, the
next smallest distance a 2 and so on. Thus, for each elk and each day data were collected, there was a ranking of
I to number of distances collected on that elk (Fig. 3.2).
If elk were located randomly with respect to sheep bands, then paired distances·would be equal to
unpaired distances, and the mean rank of paired distances would be equal to the mean rank unpaired rankings. If
elk avoided sheep, then paired distances would be farther from sheep, on average, than unpaired distances, and
the mean rank of paired distances would be significantly greater than the mean rank of unpaired rankings.
Conversely, if elk were attracted to the sheep, then paired distances would be closer to sheep, on average, than
unpaired distances, and the mean rank of paired distances would be significantly less than the mean rank of
unpaired rankings (Fig. 3.3). This assumes that elk do not avoid an area where sheep were located after the
sheep leave the area.

�255

For each year, I extracted the rank of the paired distances for each elk and day that both the elk and
sheep band were located, and calculated the mean ranking of the paired distances. The statistical expressions of
the null and alternative hypothesis were:

Ho: The mean rank of paired distances = the expected mean rank of unpaired ranks, and
HA: The mean rank of paired distances&gt; the expected mean rank of unpaired ranks,
which tested the study hypothesis:

Ho: Locations of elk were random with respect to locations of sheep; elk did not avoid sheep, and
HA: Locations of elk were father to sheep than expected at random; elk avoided sheep.
Note that it was possible that elk were attracted to sheep because sheep are graz.ed in areas preferred by elk for
grazing, but this was not the question of interest.
In order to evaluate the probability of the observed paired rank, I generated the distribution of paired
ranks under the null hypothesis that elk and sheep were located randomly with respect to each other. To develop
the null distribution, I randomiz.ed on sheep bands. That is, I randomly assigned a day to each sheep band. For
example, a sheep band located on day 2, may be randomly assigned to day 6. After randomly assigning a day to
each sheep band, paired and unpaired distances were calculated as described for the observed data. From each
sample, I extracted the ranks of the randomly "paired" rank. From the collection of samples via the
randomization procedure, I generated the distribution of mean ranks for paired elk and sheep locations that were
random, and created a null distribution representing no avoidance (or attraction) between elk and sheep. For
each randomiz.ed sample, the mean rank was saved and the randomization was re-run until there were 999 mean
rankings. The mean of the 999 randomiz.ed mean ranks was the expected mean rank. The observed mean rank
was merged with the randomiz.ed mean ranks, and the mean ranks were ordered from largest to smallest. The
percentile of the observed sample was the P-value of the hypothesis test; that is, the probability of observing the
rank of the sample or a larger rank under the null hypothesis that elk are located randomly with respect to sheep
(Mooney and Duval 1993).
Spatial scale may influence the ability to detect avoidance or attraction between animals (Doncaster
1990, Turchin 1998). That is, 'if elk were&gt; 10 km from a particular sheep band, then it was not likely that there
was any interaction between those elk and the sheep band. To include only elk close enough to interact with the
sheep bands, I repeated this analysis at 2 other spatial scales. First, I re-analyz.ed the data using elk and sheep
bands that were &lt;5 km from each other on any day. Finally, I re-analyz.ed the data using elk and sheep bands
that were &lt; l km of each other. I did not examine closer spatial scales because sample sizes became too small.
RESULTS

The observed ranks were distributed without any apparent attraction or avoidance for 1996 (Fig. 3.4) and
1997 (Fig. 3.5). For all elk, elk &lt;5 km from a sheep band, and elk &lt;1 km ofa sheep band, the observed mean rank
was not significantly greater than the expected mean rank under the null hypothesis that locations of elk were
random with respect to sheep (Table 3.1). Thus, elk did not avoid sheep at the 3 spatial scales examined.
For all spatial scales, the randomized mean rank remained constant (Table 3.1). In 1996, when
approximately 22 locations were collected per elk, the randomized mean rank was 11.48-11.49 for the 3 spatial
scales. In 1997, when approximately 23 locations were collected per elk, the randomized mean rank was 11.9311. 97 for the 3 spatial scales. Maps of elk and domestic sheep locations on several flights are presented in
Appendix 3.
DISUCSSION

Experimental Results

Elk did not appear to avoid sheep at any of the spatial scales I examined. Elk may avoid sheep at &lt;l
km, but I lacked sample sires needed for finer scale detection of avoidance. However, because elk did not avoid

�256
sheep at &gt; I km, it is extremely unlikely that domestic sheep caused any large scale movements of elk from public
to private lands. Additionally, it may be that elk avoided the area used by sheep following sheep occupation. If
this effect lasted for a long period of time, then the rank method used would be biased because would not detect
this avoidance. If there is concern about elk avoidance of sheep at &lt;l km, or elk avoidance of an area after
sheep occupation, then a study designed to answer these questions is needed.
Although there is little documentation of elk response to domestic sheep disturbances, studies have been
conducted on other, similar, non-lethal disturbances. Elk responses to recreationalists, cross country skiers,
cattle, and roads may illuminate possible elk responses to domestic sheep. In areas of continuous human
presence, such as Rocky Mountain Park, elk showed little response to approaches of people in automobiles or on
foot, day or night (Schultz and Bailey 1978). However, in the less intensely used Medicine Bow National
Forest, Ward et al. (1973) found that elk avoided recreationalists (campers, fishermen, and picnickers) at &lt;800
m. Elk Response to cross country skiers depended on the habituation of elk; in areas of high human activity elk
moved short distances away from skiers, while in areas of low human activity, elk movement away from skiers
was over 3 times greater than that of habituated elk (Cassirer et al. 1992). With respect to cattle, elk showed no
movement responses to cattle grazing at&gt; 100 m (Ward et al. 1973, Clegg 1994). In addition to habituating to
non-lethal disturbances, elk may learn to distinguish between dangerous and harmless disturbances. In Rocky
M01mtain National Parle, where elk were not hunted, Schultz and Bailey (1978) found no avoidance of roads in
winter. In contrast, in Roosevelt National Forest, which is adjacent to Rocky Mo1D1tain National Parle, Rost
(1975) found that a population ofh1D1ted elk avoided roads in winter. Wright (1983).found that mean distance to
dirt roads more than doubled when hunting season opened. In the White River area, where sheep have been
grazed for the past l 00 years, elk may have learned that sheep pose no threat, and like elk exposed to other nonlethal human activities, the White River elk may have habituated to sheep activities and ceased to avoid sheep.
Methodology for Determining Attraction and Avoidance

One of the difficulties in studying behavioral interactions between animals with radio telemetry data is
lack of quantitative methods to determine if one animal's movements or locations are related to another animal's
(White and Garrott 1990). Historically, radio-telemetry location data has been used to descn"be the size and shape
of an animal's home range. Most studies collecting these type of data do not take into account the temporal
information available in the telemetry data (White and Garrott 1990). This temporal information can be used to
describe social interactions, such as avoidance or attraction, between animals. Two general approaches have been
used to descn"be animal interaction. The first, static territorial overlap, describes the overlap of home ranges
(Webster and Brooks 1981, Minta 1992) as an indication of attraction or avoidance. The second method, temporal
or dynamic interactions, uses distance expectations based on expected home range use to test for attraction or
avoidance (Dunn 1979, Macdonald et al. 1980, Doncaster 1990, Minta 1992).
Both static and parametric temporal methods of testing for avoidance between animals require
knowledge of home range siz.e or use. There are difficulties in estimating the mean area and variance of a home
range, even if estimation procedures are accurate (Worton 1987). Additionally, home range statistics vary
depending on the method of estimation (White and Garrott 1990). Parametric methods that test for temporal
interaction assume that home range use follows a bivariate normal distribution (Jennrich and Turner 1969, Dunn
1979). It is unlikely that animals use space in a bivariate normal manner because resources, mates, and cover
are all likely to be clumped and non-normal in distribution. To combat unlikely representations of home range
siz.e of use, Doncaster (1990) suggests a nonparametric approach based on differences between observed and
theoretical distributions of separation distances between 2 animals. All temporally paired distances and unpaired
distances between 2 animals are calculated, and a critical distance is chosen for analysis of temporal interaction.
Using this distance, data can be placed in a 2 x 2 contingency table showing frequen_cies of Pa.ii"~ and unpaired
distances closer and farther than this critical distance. If distances are closer than expected, then the animals are
attracted to each other; if distances are farther than expected, then the animals are avoiding each other.
The rank method presented here is similar to Doncaster's (1990) nonparametric test for attractions and
avoidance. Both methods have the advantage of not requiring assumptions about home range size or use
compared to the static and parametric dynamic methods. However, there are 2 main advantages of the rank
method over Doncaster's (1990) nonparametric approach. First, the rank method requires no arbitrary critical
distance to evaluate attraction or avoidance. Although it may appear that the various spatial scales I used are
similar to a critical distance, they are not. This study was not originally designed to test for attraction and

�257

avoidance between elk and sheep, and the spatial scale over which I collected data (4,540 lan.2) was too large for
accurate testing of attraction and avoidance between animals. Because of the large scale, I examined various
spatial scales to subset out animals close enough to sense each other. Studies designed to test for avoidance or
attraction interactions would not be at such a large scale and would not need to subset out animals close to each
other. Additionally, at any scale examined, I did not set any critical distance at which attraction or avoidance
was to occur. Second, Doncaster's (1990) method uses a chi-square test statistic, which works best when
expected cell counts are ~5. The chi-square would not have worked well in this study because there was only 1
paired distance, which results in a count of 1 and O in cells containing the number of paired distances closer and
farther than the critical distance. The chi-square test may not work well for any study with low sample sizes or
unbalanced data (more locations on one animal than another). However, this problem is attenuated if a Fisher's
exact test is used to evaluate the 2-way contingency table of paired and unpaired distances.
MANAGEMENT IMPLICATIONS

This study suggests that elk do not avoid domestic sheep at distances great enough to cause elk
movements off public hunting grounds to private land. If concern about elk avoidance of sheep at distances of
&lt;1 km becomes serious, a more complete study, with radiocollared sheep from each band and a design tailored to
the avoidance question, should be performed. The rank method used to test for elk avoidance of sheep could be
used in many radio-telemetry data sets to evaluate attraction or avoidance between animals. The rank method,
using a randomization procedure to generate the null distribution, is a flexible, powerful, and assumption reduced
approach to test for attraction or avoidance behaviors between animals. The main requirement of the method is
that simultaneous locations are taken on all animals in the study.
LITERATURE CITED

Beck, J. L., J. T. Flinders, D. R Nelson, and C. L. Clyde. 1996. Dietary overlap and preference of elk and
domestic sheep in aspen-dominated habitats in north-central Utah. Pages 81-85 in K. E. Evans, compiler.
Sharing common ground on western rangeland: proceedings of a livestock/big game symposium. U.S.
Forest Service, Intermountain Research Station, Ogden, Utah, USA.
Boyd, R J. 1970. Elk of the White River Plateau, Colorado. Colorado Division of Game, Fish and Parks
Technical Publication 25, Fort Collins, Colorado, USA.
Cassirer, E. F., D. J. Freddy, and E. D. Ables. 1992. Elk responses to disturbances by cross-country skiers in
Yellowstone National Park. Wildlife Society Bulletin 20:375-381.
Clegg, K. 1994. Density and feeding habits of elk and deer in relation to livestock disturbance. Thesis, Utah
State University, Logan, Utah, USA.
Doncaster, C. P. 1990. Nonparametric estimates of interaction from radio-tracking data. Journal of Theoretical
Biology 143:431-443.
Dunn, J.E. 1979. A complete test for dynamic territorial interaction. Pages 159-169 in F. M. Long, editor.
Proceedings for the second international conference on wildlife biotelemetry. University of Wyoming,
Laramie, Wyoming, USA.
Jennrich, RI., and F. B. Turner. 1969. Measurement of non-circular home range. Journal of Theoretical
Biology 22:227-237.
MacCracken, J. G., and R M. Hansen. 1981. Diets of domestic sheep and other large herbivores in south
central Colorado. Journal of Range Management 34:242-243.
Macdonald, D. W., F. G. Ball, and N. G. Hough. J:980. The e¥aluation of home range size and configuration
using radio tracking data. Pages 405-424 in C. J. Amlaner, Jr. and D. W. Macdonald, editors. A
handbook on biotelemetry and radio tracking. Pergamon Press, Oxford, England.
Minta, S. C. 1992. Tests of spatial and temporal interaction among animals. Ecological Applications 2:178204.
Mooney, C. Z., and RD. Duval. 1993. Bootstrapping: a nonparametric approach to statistical inference. Sage
Publishing Inc., Newbury Park, California, USA.

�258
Nichols, L. Jr. 1957. Forage utilization by elk and domestic sheep in the White River National Forest. Thesis,
Colorado State University, Fort Collins, Colorado, USA.
Olsen, F. W., and R. M. Hansen. 1977. Food relationships of wild free-roaming horses to livestock and big
game, Red Desert, Wyoming. Journal of Range Management 30: 17-20.
Pickford, G. D. and E. H. Reid. 1943. Competition of elk and domestic livestock for summer range forage.
Journal of Range Management 7:328-332.
Rost, G. R. 1975. Responses of deer and elk to roads. Thesis, Colorado State University, Fort Collins,
Colorado, USA.
Schultz, R. D., and J. A. Bailey. 1978. Responses of national park elk to human activity. Journal of Wildlife
Management 42:91-100.
Stevens, D. R. 1966. Range relationships of elk and livestock, Crow Creek drainage, Montana. Journal of
Wildlife Management 30:349-363.
Turchin, P. 1998. Quantitative analysis of movement: measuring and modeling population redistribution in
animals and plants. Sinauer, Sunderland, Massachusetts, USA.
Ward, A. L., J. J. Cupel, A. L. Lea, C. Z. Oakeley, and R. W. Weeks. 1973. Elk behavior in relation to cattle
grazing, forest recreation, and traffic. Transcripts from the 38th American Wildlife Natural Resource
Conference 38:327-337.
Webster, B. A, and R. J. Brooks. 1981. Social behavior ofMicrotus pennsylvanicus in relation to seasonal
changes in demography. Journal ofMammalogy 64:738-751,
White, G. C., and R. A. Garrott. 1990. Analysis of radio-tracking data. Academic Press, San Diego,
California, USA
Wright, K. L. 1983. Elk movements, habitat use, and the effects of hunting activity on elk behavior near
Gunnison, Colorado. Thesis, Colorado State University, Fort Collins, Colorado, USA
Worton, B. J. 1987. A review of models of home range for animal movement Ecological Modeling 38:277298.

Table 3.1. Paired mean rank, randomiz.edmean rank, 95% confidence interval of the randomu:ed mean rank,
and the probability of observing the sample rank or greater under the null hypothesis that elk locations are
random with respect to sheep locations. Paired mean rank is the observed rank of temporally paired
observations, and randomized mean rank is the expected rank of the temporally paired observations if elk are
located randomly with respect to sheep.
Num.berof
observed rankings

Paired
mean rank

Randomi7.ed
meanraok

Randomu:ed
95%CI

11.34
12.14

11.48
11.97

[11.47, 11.49]
[11.96, 11.98]

0.737
0.199

11.71
10.59

11.48
11.93

[11.45, 11.52]
[11.89, 11.96]

0.342
0.990.:.

9.09
9.84

11.49
12.00

[11.41, 11.57]
[I 1.90, 12.10)

0.969
0.912

All elk
1,844
1996
1997
1,790
All e//c &lt;5 km ofa sheep band on any day
1996
150
124'
1997
All elk &lt;l km of a sheep band on any day
1996
34
1997
19

�259

t
N

Meeker

Glenwood Springs

•

Rifle
km

0

10

20

BLM Land
Flat Tops Wilderness
State Wildlife Land
Study Area Boundary
Forest Service Land
Sheep Locations 1996
Sheep Locations 1997
Towns

a
~
..lo.

*
■

Figure 3.1. Sheep bands located during flights 20 July-IO October 1996-1997, and land ownership in the White
River Area, Colorado. Note that all white area (blank area) is private land.

�260
Elk

Day

Sheep
Band

i
2
3

Temporally paired and
unpaired distances
PAIRED
unpaired
unpaired

Rank

21
4

11

22

1

2

1

3

PAIRED
unpaired

17
1

22

unpaired

3

Unpalied

2

.

2

unpaired

3

unpaired

21
15
7

PAIRED

20

I

1

22

2

i

PAIRED

I

2
2

2

21

3

unpaired
oopalred

2
2

22

unpaired

2

2

9
15
7

2

3

2

.

22

uupalied

.j

1

.

PAIRED
unpaired

21

22

• unpaired

2

2
2

2

unpaired
unpaired

22
4

2

22

22

PAIRED

11

88
88

1

1

3

PAIRED
unpaired
unpaired

18

2

88

2

.

3

.

88
88
88

22

88

88

1
7

oopalred

2

Ot'
l' e&lt;l
p .fl'RED

8
21

3

unpaired

1

22

unpaired

3

I

2

2

Figure 3.2. Representation of temporally paired and unpaired distances between elk and sheep. Only I sheep
band was l~ted per day, therefore sheep band I was located on day 1, sheep band 2 was located on day 2 9tf.
Ranks were randomly assigned as an example. Ranks of the temporally paired distances were extracted to •
calculate the paired mean rank for a given year and spatial scale.

�261

a
-----·------------

Paired mean rank= 7.1

200

Expected mean rank= 5.5
&gt;- 150
u

C

GI

6- 100
e

u.

1

2

3

4

5 6
Rank

7

8

9

10

b
200

Paired mean rank= 3.9
Expected mean rank = 5.5

&gt;- 150
u

C

GI

6- 100
e
u.
50

I

0 ..µ,....._.....,......_,....u1•..,....11.,,l~'~r.....,L,-.
1

2

3

4

5 6
Rank

7

8

9.

10

9

10

C

Paired mean rank= 5.5

200

Expected mean rank= 5.5
&gt;-150
u
.
C
a,
::,

ec-100

u.

50

0
1

2

3

4

5
6
Rank

7

8

Figure 3.3. Theoretical distribution of paired ranks and paired mean rank under the expectation that (a) elk avoid
domestic sheep, (b) elk are attracted to domestic sheep, or (c) elk are located rando!llly with respect to domestic
sheep. Paired mean rank is the observed rank of temporally paired observations, and expected mean rank is the
mean rank of all observations (temporally paired and unpaired) if elk are located randomly with respect to sheep.

�262

a
120 - r - - - - - - - - - - - - : - - - - : - : - = - : - - - - - - - - ,
Paired mean rank= 11.34
100
Expected mean rank= 11.48

~80

C
CD

5-60
Kt40

20
0 ---..-.--..-.--..-.
1 3 5 7 9 11 13 15 17 19 21 23

Rank

b
15 - r - - - - - - - - - - - - - - - - ,
Paired mean rank-= 11.71
Expected mean rank"" 11.48

&gt;40

-CJ
C
CD

::s

CJ"

f5
IL

1

3

5

7

9 11 13 15 17 19 21 23
Rank

C

&amp;~-------------------,
5

Paired mean rank= 9.09
Expected mean rank= 11.49

1
0 - . - . . - - -........-...---.......-.--.-...........,-,.-----1
1 3 5 7 9 11 13 15 17 19 21 23
Rank

Figure 3.4. Observed distribution of paired ranks and paired mean rank for (a) all elk, (b) elk &lt;5 km of a sheep
band, and (c) elk &lt;I km ofa sheep band, 20 July-IO October 1996 in the White River area, Colorado. Paired mean
rank was the observed rank of temporally paired observations. Expected mean rank was the mean rank of all
observations (temporally paired and unpaired) if elk were located randomly with respect to sheep, and was
calculated from 999 samples that randomized on locations of sheep bands~

�263
a
120 ~ - - - -Paired
- -mean
- -rank
- -c -----,
12.14
100

Expected mean rank = 11.97

('; 80
C

~ 60

O"
Cl)

~ 40

20
0 -flil,,...,....,....-,...,...,..,-,..,.....-,.,..,...,..,..,....,..,-.,.....,...,_,-i
1 3 5 7 9 11 13 15 17 19 21 23

Rank
b
15 ~ - - - - - - - - - - - - - - - - - .
Paired mean rank-= 10.69

Expected mean rank c 11.93

~10
C

G&gt;

::s

er

e

u. 5

1

3

5

7

9 11 13 15 17 19 21 23

Rank
C

6~---------------~
Paired mean rank .. 9.84

5·

Expected mean rank .. 12.00

1
0 -t-.,-,..-.-'r-T-.-...-,--.-,---+--,-..,-,--......,......-.........~

1

3

5

7

9 11 13 15 17 19 21 23

Rank
Figure 3.5. Observed distribution of paired ranks and paired mean rank for (a) all elk, (b) elk &lt;5 km ofa sheep
band, and (c) elk &lt;l km ofa sheep band, 20 July-IO October 1997 in the White River area, Colorado. Paired mean
rank was the observed rank of temporally paired observations. Expected mean rank was t;he mean rank of all
observations (temporally paired and unpaired) if elk were located randomly with respect to sheep, and was
calculated from 999 samples that randomized on locations of sheep bands.

�264

�265
APPENDIX 1: SAMPLE SIZE CALCULATION FOR HUNTER SURVEY

Note, G. White (Colorado State University, personal communication) derived this sample siz.e calculation.
Hunt codes D-E-012-01-A. E-E-012-01-A. E-F-012-01-M, E-M-012-01-M, D-M-012-01-M, D-E-033-01-A. E-E033-01-A. E-F-033-01-M, E-M-033-01-M, and D-M-033-01-M used the study area during the study. To estimate
total number of hunters on any day with a 95% confidence interval within ±150 hunters, the binomial distribution
and proportion of licenses holders was used to derive the number of license holder to be surveyed, where:
N

Number of licenses holders (number of individuals purchasing licenses),

p

Estimated proportion of hunters hunting,

n

Number of licenses holders sampled/surveyed,

H

Estimated num.ber of hunters hunting,

N-n
N

Finite population correction factor,

H=pN,and
N -n
~rt A)_ N -n N2 p(l- p)
vaAr(HA)- - N2 v...
\p - - -------'--.
N
N
n

The maximum variance will occur if 50% of the license holders hunt (i.e., p = 0.5), with the variance
decreasing for larger or smaller percentages. For N license holders, the sample size (n) required to obtain a 95%
confidence interval of ±150 with a= 0.05 and p = 0.5 is:

On most days, the confidence interval will be less than ±150 because not exactly 50% of the hunters will be
hunting. For example, if80% oflicense holders are hunting, then the variance of p is reduced from 0.25/n to
0.16/n (without the finite population correction factor). Thus, the confidence interval will be considerably smaller
than ±150 hunters.

�266

�267
APPENDIX 2: STANDARD ERRORS FOR DAILY GMU ESTIMATES OF HUNTERS AND ATVS AFIELD
Estimated number of hunters afield per day by GMU and standard enors of the estimates for 1996.
Stanoaro error of estimates

Est1matoo fiunters af1elo
DATE

8!:M/96
8/25/96
8/26/96
8/27/96
8/28/96
8/29/96
8/30/96
8/31/96
9/1/96
9/2/96
9/3/96
9/4/96
9/5196

9/6/96
9nl96

9/8/96
919196

9/10/96
9/11/96
9/12/96
9/13/96
9/14/96
9/15/96
9/16/96
9/17/96
9/18/96
9/19/96
9/20/96
9/21/96
9/22/96
9/23/96
9/24/96
9/25/96
9/26/96
9/27/96
9/28/96
9/29/96
9130196

10/1/96
10/2/96
10/3/96
10/4/96
10/5/96
10/6/96

Rl2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
568
551
498
460
410
362
314
282
209
155
124
111
91
80
80
74
73
70
64
61
63
66
51

H23
210
211
176
157
151
122
124
154
150
118
109
112
106
116
161
147
120
115
113
109
103
526
531
381
343
296
241
211
186
113
77
72

62
50

43
75
64
37
33
33
38
39
46
42

R2:il

127
135
129
119
106
85
84
121
132
126
105
105
94
88
119
118
116
114
113
112
113
421
400
265
243
197
163
133
117
47
30
32
25
22
28
36
33
26
29
3"1
31
25
19
21

R:33
218
226
185
176
152
129
130
177
175
151
133
119
112
118
163
146
74
69
65
71
74
211
213
94
78
52
43
39
34
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

Rl2SE
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
23
23
23
22
21
21
20
19
18
16
14
14
12
12
12
11
11
11
11
10
11
11
10

1-12:JSE
17
17
16
15
·15
14
14
15
15
14
13
13
13
14
16
15
14
14

H24SE
14
14
14
14
13
II
11
14
14
14
13
13
13
12
14
14
14
14

14
13
13
25
25
20
20
19
17
16
15
13
II
II
IO
9
9

13

II

11
8
8
8
8
8
9

9

14
14
22
22
16
16
15
14
13
12
9
7
7
6
6
7
8
7
7
7
7
7
7
6
6

H33SE
18
18
17
16
15
14
14
16
16
15
15
14
13
14
16
15
11
11
10
11
11
16
16
8
8
6
6
6
5

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

Note: H12 represents estimated number of hunter afield in GMU 12, H23 represents estimated number of hunter
afield in GMU 23, etc. Hl2SE represents the standard error of the estimated number of hunters in GMUI2,
Hl2SE represents the standard error of the estimated number of hunters in GMU23, etc.

�268
Estimated number of hunters using ATVs afield per day by GMU and standard errors of the estimates for 1996.

DATE
8724796
8/25/96

8/26/96
8/27/96
8/28/96

8/29/96
8/30/96
8/31/96
9/1/96

9/2/96
9/3/96
9/4/96
9/5/96
9/6/96

9nt96
9/8/96
9/9/96
9/10/96
9/11/96
9/12/96

9/13/96
9/14/96
9/15/96

9/16/96
9/17/96
9/18/96
9/19/96

9/20/96
9/21/96
9/22/96
9/23/96
9/24/96

9/25/96
9/26/96
9/27/96
9/28/96

9/29/96
9/30/96
10/1/96
10/2/96
10/3/96
10/4/96
10/5/96
10/6/96

Stanaaro error of estimates
Esf1matea liunters usmg A I Qs af1elo
HA12
HA23
HA24
HA'.33 HAl2SE HA23SE HA24SE HADSE
48
0
2o
0
9
6
51
9
6"
0
47
20
52
0
9
9
44
0
41
17
0
8
5
9
0
41
16
43
0
8
5
9
4
0
40
13
41
0
8
8
4
0
36
12
41
0
8
8
4
0
36
12
36
8
0
8
0
29
7
4
13
55
0
IO
4
7
0
26
13
51
0
9
17
5
0
11
50
0
4
IO
0
17
14
47
5
5
0
9
0
17
5
14
36
0
5
8
0
16
8
5
3
35
0
8
0
32
7
8
33
0
3
8
0
49
7
57
9
3
0
IO
0
46
6
48
0
9
3
9
0
40
8
6
26
0
3
7
0
8
39
7
23
3
0
7
0
8
39
7
23
0
3
7
0
33
8
2
5
18
0
6
28
7
0
11
4
15
0
5
14
50
139
77
45
9
IO
8
50
136
14
77
42
9
IO
8
47
90
II
59
13
9
9
3
46
85
11
8
12
9
55
3
37
77
46
12
8
IO
8
3
36
56
39
8
8
9
7
2
35
50
34
6
8
9
7
2
40
33
27
6
8
7
6
2
31
20
9
7
6
4
0
0
22
16
2
0
6
1
5
0
17
17
4
6
2
0
6
0
15
12
4
0
5
4
2
0
12
12
4
4
0
4
2
0
9
15
7
0
4
5
3
0
9
24
9
4
0
7
4
0
6
19
9
0
4
3
6
0
2
IO
8
0
I
4
4
0
2
4
8
0
0
3
4
2
4
8
0
0
3
4
4
2
8
0
0
4
3
0
7
6
0
0
0
3
3
3
10
0
2
0
0
4
0
3
7
0
0
0
2
3
0

Note: Hl2 represents estimated number of hunter afield in GMU 12, H23 represents estimated number of hunter
afield in GMU 23, etc. Hl2SE represents the standard error of the estimated number of hunters in GMU12,
Hl2SE represents the standard error of the estimated number of hunters in GMU23, etc.

�269
Estimated number of hunters afield per day by GMU and standard errors of the estimates for 1997.
Stanaara error of estimates
H23SE
H24SE
H12SE

DATE

Eshmatoo liunfers af1ela
H23
RI2
R24

H33

8723797

328

178

124

0

23

17

15

0

8/24/97
8/25/97
8/26/97
8/27/97
8/28/97
8/29/97
8/30/97
8/31/97
9/1/97
9/2/97
9/3/97
9/4/97
9/5/97
9/6/97
9nl97
9/8/97
9/9/97
9/10/97
9/11/97
9/12/97
9/13/97
9/14/97
9/15/97
9/16/97
9/17/97
9/18/97
9/19/97
9/20/97
9/21/97
9/22/97
9/23/97
9/24/97
9/25/97
9/26/97
9/27/97
9/28/97
9/29/97
9/30/97
10/1/97
10/2/97
10/3/97
10/4/97
10/5/97

314
282
252
226
206
191
220
211
191
151
139
115
107
130

168

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

23
22
21
20
19
19
20
20
19
17
17
15
15
16
17
·11

17
15
14
14
13
13
14
14
14
13
13
13
12.
14
13
11
12
12

15
15
14
13
12
11
11
II
12
12
10
10
10
11
11
12
12
12

0
0
0
0
0
0
0
0
0
0
0
0
0
0

0
483
477
401
403
379.
317
249
275
240

17
23
22
21
21
20

161
148

0
0
-0
0
0
0
0
0
0
0
0
0
0
0

141
132
120
112
122
142
416
391
364
345
300
205
172
160
112
0
0
0
0
0
0
0
0
0
0
0
0
0
0

98

119
117
109
100
82
66
67
64
81
77
56

96

49

87

51
62
61
63
66
67
60
61
477
470
462
409
399
307
242
224
207
135
123
115
114
105
81
73
75
72
71
67
51
34
24

138
123
115
109
92
115
110
119
97

IOI

87
65
67

68
68
71

484
483
449
442
404
309
275.
223
149
57
50
53
52
50
46
50
44
50
39
37
37
40
45

.o

127
126
130
142
137
79
77
87
91
98
111
105

16
15
16

18
17
16

14

ii

11

11
26
26
25
25
24
22
21
19
16
10
10
10
10
10
9
IO
IO
IO
8
8
8
9
9

12
26
26
26
24
24
22
20
20
19
16
15
15
15
14
13
12
12
12
12
12
10
8
7

H33SE

()

0
0
0
0
0
25
25
23
23
23
22
20
21
20

18
17
15
15
16
16
16
13
12
13
14
14
15
14

Note: Hl2 represents estimated number of hunter afield in GMU 12, H23 represents estimated number of hunter
afield in GMU 23, etc. HI 2SE represents the standard error of the estimated number of hunters in GMU 12,
Hl2SE represents the standard error of the estimated number of hunters in GMU23, etc.

�270
Estimated number of hunters using ATVs afield per day by GMU and standard errors of the estimates for 1997.

DATE

8723797
8/24/97
8(25/97
8(26/97
8f27/97
8(28/97
8/29/97
8/30/97
8/3 l/97
9/1/97
9f2/97
9/3/97
9/4/97
9/5/97
9/6/97
9nl91

9/8/97
9/9/97
9/10/97
9/l l/97
9/12/97
9/13/97
9/14/97
9/15/97
9/16/97
9/17/97
9/18/97
9/19/97
9f10l91
9fll/91

9(22/97
9(23/97
9f24/97
9f15l97
9f16l91

9(27/97
9(18/97

9/29/97
9/30/97
10/1/97
I0/2/97
10/3/97
I0/4/97
10/5/97

Estimatea nunters af1ela
HA[2
HA23
HA24
43
70
34
39
36
70
32.
56
39
35
30
48
30
48
40
45
30
33
25
30
26
21
27
30
28
18
27
24
31
16
18
36
18
18
36
12
15
33
12
8
29
9
7
IO
34
5
30
8
12
30
8
30
8
5
2
8
30
28
3
5
7
21
5
110
29
50
32
110
50
112
51
30
20
113
48
22
106
48
81
ll
39
IO
77
33
52
7
30
7
19
35
14
0
7
0
14
7
0
8
7
8
0
7
0
8
7
0
15
3
0
19
3
0
19
3
0
19
3
0
19
3
0
19
3
0
19
3
0
12
3
0
12
3

HA33

0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
99
IOI
94
85
78
63
56
64
58
54
40
37
35
42
48
39
29
22
24
22
34
34
34

Stanaara error of estimates
HAl2SE HA23SE HA24SE HA33SE
12
8
9
0
12
9
8
0
IO
9
8
0
9
8
0
8
9
9
8
0
8
8
9
0
8
7
0
7
7
8
8
0
8
6
0
8
8
5
7
0
8
6
6
0
8
6
5
0
8
5
5
0
7
3
4
0
8
3
4
0
8
4
3
0
8
4
5
0
8
4
3
0
8
4
0
8
3
0
3
4
7
3
0
8
14
13
7
14
8
13
8
8
13
14
8
8
12
14
6
14
8
12
6
12
8
11
5
12
8
10
4
8
11
3
IO
6
11
3
8
4
11
6
0
0
6
4
9
4
0
4
9
4
0
4
9
4
4
9
0
6
3
IO
0
0
6
3
9
8
6
3
0
7
6
3
0
7
6
3
0
7
6
3
0
9
3
0
6
9
3
0
5
9
0
5
3

Note: Hl2 represents estimated number of hunter afield in GMU 12, H23 represents estimated number of hunter
afield in GMU 23, etc. Hl2SE represents the standard error of the estimated number of hunters in GMUI2,
H 12SE represents the standard error of the estimated number of hunters in GMU23, etc.

�:.!__;
l

White River Elk Movement Study

White River Elk Movement Study

Elk and Shee~ Locations on July 19, 1996

Elk and Sheep Locations on July 24, 1996

Hamilton

Km
20

z

t:I

~
!-:I

Hamilton

0

~
~

l'1!j

~

40

en
0

',ij
l'1!j

~
~
t:I
t:I

0

~

l'1!j

en
-i

~

n

en

=
l'1!j
l'1!j
~

I:""

0

n

&gt;
-i

Rio Blanco

~

0

z

en
0

z

en

LEGEND
BLM Land
Flat Tops WIiderness
State Wildlife Land
Study Area Boundary
White River National Forest

Springs
■

*
A

■

...,

White River
Elk Location
Sheep Location
Towns

l'1!j

I:""
l'1!j

n

-i

Springs
■

l'1!j

t:I
',ij

I:""
~

(;')

=

-i
en

N

-.J

�White River Elk Movement Study

White River Elk Movement Study

Elk and Sheep Locations on July 31, 1996

Elk and Sheep Locations on August 4, 1996

Hamilton

Hamilton

Krn
0

20

40

LEGEND
Springs

•

.BLM Land
Flat Tops WIiderness
State Wildlife Land
Study Area Boundary
White River National Forest
- White River
• Elk Location
Sheep Location
■ Towns

!*

--------

Springs ■

�White River Elk Movement Study

White River Elk Movement Study

Elk and Sheep Locations on August 14, 1996

Elk and Sheep Locations on August 28, 1996

Hamilton

Hamilton

Km
0

20

40

Rio 81anco

LEGEND
Springs
■

*
•

■

BLM Land
Flat Tops Wilderness
State Wildlife Land
Study Area Boundary
White River National Forest
White River
Elk Location
Sheep Location
Towns

ts)

...J
\.,.)

�N
-.I

White River Elk Movement Study

White River Elk Movement Study

Elk and Sheep Locations on August 20, 1997

Elk and Sheep Locations on September 6, 1997

Hamilton

Hamilton

Km
20

0

LEGEND
BLM Land
Flat Tops WIiderness
State Wildlife Land
Study Area Boundary
White River National Forest

!*

- White River
•

■

Elk Location
Sheep Location
Towns

40

00

�White River Elk Movement Study

White River Elk Movement Study

Elk and Sheep Locations on September 17, 1997

Elk and Sheep Locations on Septermber 24, 1997

Hamilton

Km
0

20

40

LEGEND
BLM Land
Flat Tops Wilderness
State Wildlife Land
Study Area Boundary
White River National Forest
- White River
• Elk Location
Sheep Location.
■ Towns

!*

N

--.J

'°

�White River Elk Movement Study

White River Elk Movement Study

~:~ c:-:c S:;ee:::: ~oc:::~:o~s 0:1 Cctober 1,

~ 997

Elk and '":,he::&gt;~, Lr;r,rJ;:r:;n~: on October 5, 1997
Hamilton

Hamilton

Km
0

• 20

LEGEND
BLM Land
Flat Tops Wilderness Area
State Wildlife Area
Study Area Boundary
White River National Forest
- White River
• Elk Location
Sheep Location
■ Towns

!*

40

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                  <text>227
Colorado Division of Wildlife
Wildlife Research Report
July 1998
JOB PROGRESS REPORT

State of

Colorado

cost center 3430

Project No.

W-153-R-11

Mammals Program

Work Package No. ___3_0_0-2______
Task No. _______.._______

Elk conservation
:

Monitoring and Managing-Chronic

wasting Disease in Elk
Period Covered: July 1, 1997 - June 30, 1998

w. Miller

Authors:

M.

Personnel:

s. Berry, K. Larsen, K. I. O'Rourke, T. R. Spraker,
Wheeler, M.A. Wild, and E. S. Williams

s. Tracy, E.

ABSTRACT
Elk from throughout Colorado were examined for occurrence of chronic wasting
disease using a combination of targeted surveys and harvest or road-kill
surveys. We continued to develop and modify a statewide targeted surveillance
program for acquiring, examining, and reporting on CWD suspects submitted from
Colorado. Between June 1997 and May 1998, 2 chronic wasting disease (CWD)
cases were diagnosed among 6 •suspect• elk submitted from endemic game
management units (GMUs) in northeastern Colorado; CWD was not diagnosed in any
of 6 additional "suspect• elk submitted from elsewhere in Colorado.
Harvest surveys were used to estimate CWD prevalence in enzootic management
units. About 0.21 of elk harvested in Larimer County data analysis units
(DAUs) (E4 or E9) tested positive for CWD via immunostaining; CWD was not
detected in any of the harvested elk submitted from outside Larimer county.
Requiring hunters to participate in harvest surveys continued to increase the
number of samples submitted for CWD examination.
Data from both targeted surveillance and surveys indicate that Larimer county
remains the only focus of CWD in Colorado elk, although some undetected
natural spread may be occurring. Compared to deer, however, CWD is a
relatively rare disease in free-ranging elk in northcentral Colorado. Targeted
surveillance of clinical suspects appears to be the most sensitive approach
for initially detecting CWD in elk populations throughout Colorado, and will
be continued statewide. Based on low prevalence detected in 1995-1997
surveys, future harvest and road-kill surveys will be conducted at about 5-yr
intervals to estimate prevalence, monitor trends, and compare rates among
endemic elk DAUS.

��229
MONITORING ARD MANAGING CHRONIC WASTING DISEASE IN ELK
M.w. Miller

P, H, OBJECTIVES
(1) Design, conduct, and report results of:
(a) targeted surveillance to estimate and detect changes in distribution
of chronic wasting disease (CWD) in free-ranging elk populations; and
(b) harvest or road-kill surveys to estimate and detect changes in
prevalence of CWD in enzootic elk populations.
(2) Design, conduct, and report results of experimental studies using
captive elk naturally or experimentally infected with CWD.

SEGMEHT OBJECTIVES
(1)

Conduct and report results of targeted surveillance to estimate and
detect changes in distribution of CWD in free-ranging elk populations
statewide.

(2)

Conduct and report results of harvest surveys to estimate prevalence
of CWD in DAUS E4 and E9.

(3)

Observe epizootiological features of naturally-occurring CWD in captive
elk.

IHTRQDUCTIQH
Chronic wasting disease (CWD) is a disease of native deer and elk
characterized by behavioral changes and progressive loss of body condition
that invariably lead to the death of affected animals (Williams and Young
1992). Neither the causative agent nor its mode of transmission have been
identified. There are no tests currently available for diagnosing CWD in live
animals, and postmortem tests require microscopic examination of brain tissue.
There are no known treatments for CWD. Previous attempts to eradicate CWD
from research facilities failed on at least 2 occasions (Williams and Young
1992). Although similar in some respects to other transmissible spongiform
encephalopathies that affect domestic sheep (scrapie) and cattle (bovine
spongiform encephalopathy; BSE; "mad cow disease"), there is no evidence
suggesting CWD can be naturally transmitted to domestic livestock, or that
scrapie or BSE can be transmitted to native cervids. Moreover, there is no
evidence suggesting that CWD presents a threat toLhuman health.
"Chronic wasting disease" was first recognized by biologists in the 1960's as
a disease syndrome of captive deer held in wildlife research facilities in Ft.
Collins, co, and was subsequently recognized in captive deer, and later in
captive elk, in wildlife research facilities near Ft. Collins, Kremmling, and
Meeker, co and Wheatland, WY (Williams and Young 1980, 1982). Since 1981, 74
cases of CWD have also been diagnosed in free-ranging mule deer, white-tailed
deer, and elk from northeastern Colorado; most of these diagnoses have been
made since 1990 (Spraker et al. 1997; M. w. Miller, unpubl. data). At
present, the known world-wide distribution of CWD in wild cervids appears to

�230
be limited to northeastern Colorado and southeastern Wyoming. Although CWD
was first diagnosed in captive cervids, the original source of CWD in either
captive cervids or free-ranging cervids is unknown; whether CWD in captive
cervids really preceded CWD in wild cervids, or vice versa, is equally
uncertain (Spraker et al. 1997).
In Colorado, free-ranging CWD cases in elk have all originated from along the
northern Front Range. Game Management Units (GMUs) yielding infected elk
include 7, 9, 19, 191, and 20. All clinical elk cases have come from two Data
Analysis Units (DAUs)(E4, E9). To date, examinations of elk from other parts
of Colorado have not detected CWD. Preliminary data from hunter-killed deer
indicate that even in enzootic areas CWD is relatively rare: it probably
affects $l.5% of the elk in E4 and E9. No real trend in prevalence
(increasing or decreasing) can be discerned from data available to date.
In
the absence of historical (20-30 years ago) prevalence data or reliable
estimates of transmission rates, it is also unclear whether incidence of CWD
in northcentral Colorado DAUs is stable or increasing, or whether short-term
observations can accurately forecast long-term trends.
The significance of CWD and its impacts on native elk populations are unclear.
Preliminary results of simulation modeling to predict dynamics and impacts of
CWD on affected deer populations suggest that, sustained at current prevalence
(about 6.5% in deer), CWD could impact wild deer herds and lead to population
declines (M. w. Miller and c. w. McCarty, unpubl. data). Although CWD
prevalence is lower in elk than in deer in enzootic DAUs, it is conceivable
that impacts could occur if prevalence were allowed to increase. Clearly,
reliable estimates of CWD prevalence in wild elk populations are needed to
guide policy decisions and monitor efficacy of management efforts.
In the absence of data to the contrary, and considering the difficulties
inherent in eliminating CWD from captive or wild cervid populations once
established, it seems most prudent to assume CWD could adversely affect native
deer or elk populations and manage to reduce its occurrence and prevent its
further spread. Consequently, the Colorado Division of Wildlife needs to
undertake a variety of actions to further understanding about CWD and its
management through surveillance and experimental research in order to reduce
the occurrence of CWD and minimize the risk of its spread to other native deer
or elk populations in Colorado.

MATERIALS AND METHODS
Surveillance
We monitored elk populations throughout Colorado for occurrence of CWD using a
combination of targeted surveillance and harvest or road-kill surveys. These
were organized and conducted as follows:

Targeted(= clinical disease) surveillance: Elk showing clinical signs
consist~nt with those seen in chronic wasting disease were collected by field
personnel statewide and brain tissues examined for evidence of spongiform
encephalopathy. The "suspect casen profile was defined as follows:
•
•
•

Species:
Age:
Signs:

elk
~

18 months
emaciated and
abnormal behavior &amp;/or
indifference to human activity &amp;/or

�231
increased salivation &amp;/or
tremor, stumbling, incoordination &amp;/or
difficulty or inefficiency in chewing/swallowing
&amp;/or increased drinking and urination
Where possible, submissions were subjected to complete necropsy; in some
situations, only heads were available for examination and sampling.
In all
cases, histopathology of brain tissue (Williams and Young 1993) was used to
diagnose CWD; in some cases, immunohistochemistry or other ancillary tests
were used to confirm or support diagnoses.

Harvest surveys: In order to obtain reliable estimates of CWD prevalence that
will serve as a basis for monitoring responses to management interventions, we
continued conducting harvest surveys on select deer populations. During the
1997-1998 hunting seasons, fresh brain and select lymphatic tissues were
collected from endemic and nonendemic GMUs. Brain tissues were examined at
the Colorado State University Diagnostic Laboratory for histopathological
lesions (Williams and Young, 1993)or anti-PrP immunostaining reactions
(O'Rourke et al., 1998) consistent with CWD infection. Because sample sizes
for most individual GMUs were too small to provide reliable prevalence
estimates by GMO, we pooled data by DAU for comparisons within and among
species. Small sample sizes also precluded meaningful analysis of data from
deer or elk harvested outside known enzootic areas.
Epizootiological Studies

cwo

Epidemiology of naturally-occurring
in captive elk (Miller and Wild): we
observed captive adult elk (n = 19) held at CDOW's Foothills Wildlife Research
Facility for clinical signs of CWD and submitted all mortalities for complete
necropsy and histopathological examination. A manuscript describing CWD
epidemiology in captive elk (Miller et al., 1998) was revised and accepted for
publication.
RESULTS AND DISCUSSION
Surveillance

Targeted(= clinical disease) surveillance:

Between June 1997 and May 1998, 2
chronic wasting disease (CWD) cases were diagnosed among 6 "suspect" elk
submitted from endemic game management units (GMUs) in northeastern Colorado;
CWD was not diagnosed in any of 6 additional "suspect" elk submitted from
elsewhere in Colorado.

Harvest surveys; During the 1997-1998 hunting seasons, fresh brain and select
lymphatic tissues were collected from 653 elk harvested in enzootic GMUs •
(Table l); 103 elk harvested or culled in other GMUs throughout Colorado were
also sampled as negative controls. Estimated prevalence among harvested elk
did not differ (P = 1.0) between E4 (0.2%) and E9 (0%). As in 1996, overall
CWD prevalence among elk harvested in Larimer County was lower (P &lt; 0.009)
than in sympatric deer populations (see Miller, 1998).
Even the foregoing prevalence estimates may be somewhat liberal because the
definition of "positive" included subclinical cases where either
histopathological lesions or anti-PrP immunostaining reactions in brain tissue
were observed. The elk case identified in 1997, as well as all 4 elk cases in
1996, were classified as positive solely on the basis of immunostaining
reactions. Although no known "false positives" were identified among the 103
elk examined from outside known enzootic DAUs in 1997, further evaluation of

�232
both sensitivity and specificity of existing diagnostic techniques still
appears warranted.
During the 1997-1998 rifle seasons, harvest survey participation was required
of successful elk hunters in both E4 and E9. In E4, 454 successful elk
hunters submitted heads in 1997, compared to only 81 voluntary submissions in
1996. These observations reemphasize previous observations (Miller, 1997) that
compelling participation in harvest surveys via regulation is the single most
effective method for increasing sample sizes.
Data from both targeted surveillance and surveys indicate that Larimer County
remains the only focus of CWD in Colorado elk, although some undetected
natural spread may be occurring. Compared to deer, however, CWD is a
relatively rare disease in free-ranging elk in northcentral Colorado. Targeted
surveillance of clinical suspects appears to be the most sensitive approach
for initially detecting CWD in elk populations throughout Colorado, and will
be continued statewide. Based on low prevalence detected in 1995-1997
surveys, future harvest and road-kill surveys will be conducted at about 5-yr
intervals to estimate prevalence, monitor trends, and compare rates among
endemic elk DAUs.
Epizootiological Studies

Epidemiology of naturally-occurring cwp in captive elk (Miller and Wild): None
of the 19 captive adult elk held at CDOW's Foothills Wildlife Research
Facility developed clinical CWD during June 1997-May 1998; one female (G86)
that died showed no histological evidence of ewe. We will continue to monitor
this naturally-infected captive herd and examine all mortalities for evidence
of ewe.
A manuscript describing CWD epidemiology in captive elk (Miller et al., 1998)
was accepted for publication. Judging from requests for prepublication
copies, this manuscript appears to be of considerable interest to those
investigating and managing recently recognized foci of CWD in privately-owned
captive elk throughout the us and Canada.

ACKHQWLEDGMEHTS
The statewide CWD monitoring and surveillance program described here relies
heavily on efforts of dedicated field personnel throughout the Colorado
Division of Wildlife, and truly represents a division-wide effort to improve
our understanding and management of this important disease problems. In
addition to those specifically listed, we collectively thank all of those
regional and area biologists, district and area wildlife managers, volunteers,
deer and elk hunters, and others who assisted by submitting suspect cases,
harvested animals, or road-killed animals throughout the year.

LITERATURE CITED
Miller, M. w. 1997. Monitoring and managing wildlife chronic wasting disease
in Colorado. in Wildlife Research Report, Mammals Research, Federal Aid
Projects, Job Progress Report, Project W-153-R-10, WP2, Jl7. Colorado
Division of Wildlife, Fort Collins, Colorado, USA, pp. 37-46.

�233
1998. Monitoring and managing wildlife chronic wasting disease in
deer. in Wildlife Research Report, Mammals Research, Federal Aid
Projects, Job Progress Report, Project W-153-R-11, WP3001, T3. Colorado
Division of Wildlife, Fort Collins, Colorado, USA, in press.

___ ,M.A. Wild, and E. s. Williams. 1998. Epizootiology of chronic
wasting disease in captive Rocky Montain elk. J. Wildl. Dis. 34: 532538.
O'Rourke, K. I., T. v. Baszler, J.M. Miller, T. R. Spraker, I. SadlerRiggleman, and D. P. Knowles. 1998. Monoclonal antibody F89/160.1.5
defines a conserved epitope on the ruminant prion protein. J. Clin.
Microbiol. 36: 1750-1755.
Spraker, T. R., M. W. Miller, E. S. Williams, D. M. Getzy, W. J. Adrian, G. G.
Schoonveld, R. A. Spowart, K. I. O'Rourke, J.M. Miller, and P.A. Merz.
1997. Spongiform encephalopathy in free-ranging mule deer (Odocoileus
hemionus), white-tailed deer (Odocoileus virginianus), and Rocky Mountain
elk (Cervus ·elaphus nelsoni) in northcentral Colorado. J. Wildl. Dis.
33:1-6.
Williams, E. s., ands. Young. 1980. Chronic Wasting disease of captive mule
deer: A spongiform encephalopathy. Journal of Wildlife Diseases 16: 8998.
___ ,and___
1982. Spongiform encephalopathy of Rocky Mountain elk.
Journal of Wildlife Diseases 18: 465-471.
___ ,and___
1992. Spongiform encephalopathies in Cervidae. Revue
Scientifique et Technique Office International des Epizooties 11: 551567.
___ ,and___
1993. Neuropathology of chronic wasting disease in mule
deer (Odocoileus hemionus) and elk (Cervus elaphus nelsoni). Veterinary
Pathology 30: 36-45.

C

Wildlife Research Veterinarian

�234

Table 1. Results of 1997 CWD harvest surveys -- archery, muzzleloader, &amp; rifle seasons.

ELK
DAU

GMU

# Examined

# Positive

E4

7

104

0

8

184

0

191

30

0

9

9

0

19

127

1

Total

454

1

20

199

0

Total

199

0

E9

Prevalence

(95% Cl)

0.002

(0.0001-0.012)

0

(0-0.019)

�281

Colorado Division of Wildlife
Wildlife Research Report
July 1999

JOB PROGRESS REPORT
State of - - - - ~ " ' " " "Colorado
-"'""""''-=-------Project No. _ _ _. . _W.:. . --=1=5;:;.. 3--=-R-=--=12;___ _ _ __
Work Package No. -~3....0___0=2_ _ _ _ _ __
Task No. _ _ _ _ _........;::3;,.____ _ _ _ __

Cost Center 3430
Mammals Program
Elk Management
Monitoring and Managing Chronic Wasting
Disease in Elk

Period Covered: July 1, 1998 -June 30, 1999
Authors: M. W. Miller and C. T. Larsen
Personnel: K. I. O'Rourke, T. R Spraker, E. Wheeler, M.A. Wild, and E. S. Williams

ABSTRACT
Elk from throughout Colorado were examined for occurrence of chronic wasting disease using targeted
surveillance. Between June 1998 and May 1999, 7 chronic wasting disease (CWD) cases were diagnosed
. from among 12 "suspect" elk submitted from endemic game management units (GMUs) in northeastern
Colorado. CWD was not diagnosed in any of 4 additional "suspect" elk submitted from elsewhere in
Colorado.
No cases ofCWD occurred among 23 adult elk held at CDOW's Foothills Wildlife Research Facility.

�282

�283

MONITORING AND MANAGING CHRONIC WASTING DISEASE IN ELK
M. W. Miller and C. T. Larsen

P. N. OBJECTIVES
(I)

Design, conduct, and report results of:
(a) targeted surveillance to estimate and detect changes in distribution of chronic wasting disease
(CWD) in free-ranging elk populations; and
(b) harvest or road-kill surveys to estimate and detect changes in prevalence of CWD in enzootic
elk populations.

(2)

Design, conduct, and report results of experimental studies using captive elk naturally or
experimentally infected with CWD.
AGREEMENT OBJECTIVES

(1)

Conduct and report results of targeted surveillance to estimate and detect changes in distribution of
CWD in free-ranging elk populations statewide.

( 2 ) Observe epizootiological features of naturally-occurring CWD in captive elk.

MATERIALS AND METHODS
Surveillance
We monitored elk populations throughout Colorado for occurrence of CWD using a combination of
targeted surveillance and harvest or road-kill surveys. These were organized and conducted as follows:

Targeted(= clinical disease) surveillance: Elk showing clinical signs consistent with those seen in chronic
wasting disease were collected by field personnel statewide and brain tissues examined for evidence of
spongiform encephalopathy. Toe "suspect case" profile was defined as follows:
• Species:

elk

• Age:

2: 18 months

• Signs:

emaciated and
abnormal behavior &amp;/or
indifference to human activity &amp;/or
increased salivation &amp;/or
tremor, stumbling, incoordination &amp;/or
difficulty or inefficiency in chewing/swallowing
&amp;/or increased drinking and urination

Where possible, submissions were subjected to complete necropsy; in some situations, only heads
were available for examination and sampling. In all cases, histopathology of brain tissue (W"tlliams

�284

and Young 1993) was used to diagnose CWD; in some cases, immunohistochemistry (O'Rourke
et al., 1998) or other ancillary tests were used to confirm or support diagnoses.
Harvest surveys: No elk harvest surveys were planned for this segment.

Epizootiological Studies
Epidemiology of naturally-occurring CWD in captive elk (Miller and Wild): We observed captive
adult elk (n = 23) held at CDOW's Foothills Wildlife Research Facility for clinical signs ofCWD
and submitted all mortalities for complete necropsy and histopathological examination.

RESULTS AND DISCUSSION
Surveillance
Targeted(= clinical disease) surveillance: Between June 1998 and May 1999, 7 chronic wasting
disease (CWD) cases were diagnosed among 12 "suspect" elk submitted from endemic game
management units (GMUs) in northeastern Colorado; CWD was not diagnosed in any of 4
additional "suspect" elk submitted from elsewhere in Colorado. Since 1981, 23 clinical CWD
cases have been diagnosed in elk from Larimer County GMUs (Fig. I).
Harvest surveys: No elk harvest surveys were conducted in this segment, and none are planned
for 1999-2000.

Epizootiological Studies
Epidemiology of naturally-occurring CWD in captive elk (Miller and Wild): None of the 23
captive adult elk held at CDOW's Foothills Wildlife Research Facility developed clinical CWD
during June 1998-May 1999; 3 female elk that died during that period were not infected. We will
continue to monitor this naturally-infected captive herd and examine all mortalities for evidence of
CWD.
A manuscript describing CWD epidemiology in captive elk during 1986-1997 was published in
July (Miller et al., 1998).

ACKNOWLEDGMENTS
The statewide CWD monitoring and surveillance program described here relies heavily on efforts
of dedicated field personnel throughout the Colorado Division of Wildlife, and truly represents a
division-wide effort to improve our understanding and management of this important disease
problems. In addition to those specifically listed, we collectively thank all of those regional and
area biologists, district and area wildlife managers, volunteers, elk hlfflters, and .others 'Who
assisted by submitting suspect cases, harvested animals, or road-killed animals throughout the
year.

�285

LITERATURE CITED
Miller, M. W., M. A. Wild, and E. S. Williams. 1998. Epizootiology of chronic wasting disease in captive
Rocky Montain elk. J. Wildl. Dis. 34: 532-538.
O'Rourke, K. I., T. V. Baszler, J. M. Miller, T. R. Spraker, I. Sadler-Riggleman, and D. P. Knowles.
1998. Monoclonal antibody F89/160.1.5 defines a conserved epitope on the ruminant prion protein. J.
Clin. Microbiol. 36: 1750-1755.
Williams, E. S., and S. Young. 1993. Neuropathology of chronic wasting disease in mule deer
(Odocoileus hemionus) and elk (Cervus elaphus nelsoni). Veterinary Pathology 30: 36-45.

Prepared by _ _ _ _ _ _ _ _ _ _ __
Michael W. Miller
Wildlife Research Veterinarian

oCheyenne:

South Platte
River
River
50

100

_ ___.__ _...____ km

Figure 1. Between March 1981 and June 1999, 23 clinical CWD cases have been diagnosed in elk from
GMUs in Larimer County, Colorado.

�286

�233

L

Colorado Division of Wildlife
Wild)ife Research Report
July 2000

JOB PROGRESS REPORT
Stateof _ _ _ _ _ _C=o=l=orad==o_ _ _ __

Cost Center 3430

Project No. _ _ _ _ _W~-1=5___3___
-R___-=13=------

Mammals Program

Work Package No. _____3---00=2.___ _ __

Elk Management

Task No.

1
----------------

Monitoring and Managing Chronic Wasting
Disease in Elk

Period Covered: July 1, 1999 - June 30, 2000
Authors: M. W. Miller and C. T. Larsen
Personnel: K. I. O'Rourke, T. R Spraker, E. Wheeler, M.A. Wild, and E. S. Williams
\

.

)

ABSTRACT
Elk from throughout Colorado were examined for occurrence of chronic wasting disease using targeted
surveillance. Between June 1999 and May 2000, 5 chronic wasting disease (CWD) suspect elk were
submitted from endemic game management units (GMUs) in northeastern Colorado; none of those suspects
were infected :with CWD. In addition, CWD was not diagnosed in any of 7 other suspect elk submitted
from elsewhere in Colorado. Locoism was diagnosed in 5 suspect elk (all from Jefferson County), and
cause of emaciation could not be determined in 5 cases (including 4 from endemic GMUs).
One case ofCWD occurred among 23 adult elk held at CDOW's Foothills Wildlife Research Facility. The
last case in this herd occurred nearly 5 years ago. Exposure to run-off from pens holding CWD-infected
deer was the most likely source of infection.

BDOW016787

��235

MONITORING AND MANAGING CHRONIC WASTING DISEASE IN ELK
M. W. Miller and C. T. Larsen

P. N. OBJECTIVES
(I) Design, conduct, and report results of:
(a) targeted surveillance to estimate and detect changes in distribution of chronic wasting disease
(CWD) in free-ranging elk populations; and
(b) harvest or road-kill surveys to estimate and detect changes in prevalence of CWD in enzootic elk
populations.
(2) Design, conduct, and report results of experimental studies using captive elk naturally or
experimentally infected with CWD.

AGREEMENT OBJECTIVES
(I) Conduct and report results of targeted surveillance to estimate and detect changes in distribution of
CWD in free-ranging elk populations statewide.
f

(2) Observe epizootiological features of naturally-occurring CWD in captive elk.

MATERIALS AND METHODS
Surveillance
We monitored elk populations throughout Colorado for occurrence of CWD using a combination of
targeted surveillance and harvest or road-kill surveys. These were organized and conducted as follows:
Targeted(= clinical disease) surveillance: Elk showing clinical signs consistent with those seen in chronic
wasting disease were collected by field personnel statewide and brain tissues examined for evidence of
spongiform encephalopathy. The "suspect case" profile was defined as follows:
• Species:

elk

• Age:

::::, 18 months

• Signs:

emaciated and
abnormal behavior &amp;/or
indifference to human activity &amp;/or
increased salivation &amp;/or
tremor, stumbling, incoordination &amp;/or
difficulty or inefficiency in chewing/swallowing
&amp;/or increased drinking and urination

�236

Where possible, submissions were subjected to complete necropsy; in some situations, only heads were
available for examination and sampling. In all cases, histopathology of brain tissue (Williams and Young
1993) was used to diagnose CWD; in some cases, immunohistochemistry (O'Rourke et al., 1998) or other
ancillary tests were used to confirm or support diagnoses.
Harvest surveys: No elk harvest surveys were planned for this segment.
Epizootiological Studies
Epidemiology of naturally-occurring CWD in captive elk (Miller and Wild): We observed captive adult elk
(n = 23) held at CDOW's Foothills Wildlife Research Facility for clinical signs ofCWD and submitted all
mortalities for complete necropsy and histopathological examination.

RESULTS AND DISCUSSION
Surveillance
Targeted(= clinical disease) surveillance: Between June 1999 and May 2000, no chronic wasting disease
(CWD) cases were diagnosed among 5 "suspect" elk submitted from endemic game management units
(GMUs) in northeastern Colorado; CWD was not diagnosed in any of 7 additional "suspect" elk submitted
from elsewhere in Colorado. Since 1981, 23 clinical CWD cases have been diagnosed in elk from Larimer
County GMUs (Fig. I).

Harvest surveys: No elk harvest surveys were conducted in this segment, and none are planned for 20002001.
Epizootiological Studies
Epidemiology of naturally-occurring CWD in captive elk (Miller and Wild): One of the 23 captive adult elk
held at CDOW's Foothills Wildlife Research Facility developed clinical CWD during June 1999-May
2000. The last case in this herd had occurred nearly 5 years earlier (February, 1995; Miller et al. 1998).
Exposure to run-off from pens holding CWD-infected deer was the most likely source of infection. We will
continue to monitor this naturally-infected captive herd and examine all mortalities for evidence of CWD.

ACKNOWLEDGMENTS

The statewide CWD monitoring and surveillance program described here relies heavily on efforts of
dedicated field personnel throughout the Colorado Division of Wildlife, and truly represents a division-wide
effort to improve our understanding and management of this important disease problems. In addition to
those specifically listed, we collectively thank all of those regional and area biologists, district and area
wildlife managers, volunteers, elk hunters, and others who assisted by submitting suspect cases, harvested
animals, or road-killed animals throughout the year.

�237

Number of cllnlcal cases per MU In elk

I

Lara
RI

River

Cache la Pou
River
50

100

- ~ ~ ~1~ - k m

Figure 1. Between March 1981 and May 2000, 23 clinical CWD cases have been
diagnosed in elk from GMUs in Larimer County, Colorado. Cases reported in
Wyoming are also shown to provide context on overall geographic distribution of
CWD in free-ranging elk. Figure modified from Miller et al. (2000).

LITERATURE CITED
Miller, M. W., M. A. Wild, and E. S. Williams. 1998. Epizootiology of chronic wasting disease in captive
Rocky Montain elk. J. Wildl. Dis. 34: 532-538.
Miller, M. W., E. S. Williams, C. W. McCarty, T. R. Spraker, T. J. Kreeger, C. T. Larsen, and E. T.
Thome. 2000. Epizootiology of chronic wasting disease in free-ranging cervids in Colorado and
Wyoming. Journal of Wildlife Diseases 38: 676-690.
O'Rourke, K. I., T. V. Baszler, J.M. Miller, T. R. Spraker, I. Sadler-Riggleman, and D. P. Knowles.
1998. Monoclonal antibody F89/160.1.5 defines a conserved epitope on the ruminant prion protein.
J. Clin. Microbiol. 36: 1750-1755.
Williams, E. S., and S. Young. 1993. Neuropathology of chronic wasting disease in mule deer
(Odocoileus hemionus) and elk (Cervus elaphus nelsoni). Veterinary Pathology 30: 36-45.

Prepared by _ _ _ _ _ _ _ _ _ _ _ __
Michael W. Miller
Wildlife Research Veterinarian

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                  <text>273

Colorado Division of Wildlife
Wildlife Research Report
July2000

JOB PROGRESS REPORT

State of

Colorado

Cost Center 3430

Project No.

W-153-R-13

Mammals Research Program

Work Package No. ----"'3--=-0.a.;03"---------

Carnivorous Mammals Conservation

Study No.

1

Black bear muscle physiology

Period Covered: July 1, 1999-June 30, 2000
Author: T.D.I. Beck
Personnel: T. Beck, R. Firth, CDOW; H. Harlow, M. Hooker, T. Lohuis, L. Willmarth, U. of Wyoming

\

)

ABSTRACT

In 1999 10 black bears were captured in Grand County for studies on muscle disuse atrophy. Fat and
muscle biopsies and blood samples were obtained from all ten bears. No direct in vivo measurements of
hind limb muscle strength were obtained because of problems with electrical and computer equipment.
Eight radio-collared bears were selected for study in December 1999. Direct muscle strength
measurements, fat biopsies, muscle biopsies and blood samples were obtained from all. Six of these 8
bears were re-sampled successfully during the late-den period (March 2000). The other 2 bolted from their
dens early and were not captured. Five of the bears handled in March 2000 were equipped with knockdown collars to facilitate recapture in June 2000. None of these collars worked as designed and could not
be triggered to inject the immobilizing drug. Conventional trapping produced 6 bears for the comparative
summer sample. Two of the ATS knock-down collars have been·retrieved and were submitted for
examination to determine cause of failure. Data summary and analyses are still being conducted by U. of
Wyoming personnel as the,major part of a Ph.D. dissertation. Final reports will be in the next segment.

)

�275

BLACK BEAR MUSCLE PHYSIOLOGY
Thomas D. I. Beck

SEGMENT OBJECTIVES

I. Obtain early-denning and late-denning comparative measurements of muscle strength, morphology, and
protein metabolism in order to accurately describe the lack of muscle disuse atrophy.

METHODS AND MATERIALS

Black bears (Ursus americanus) were captured in cage traps throughout Grand County, Colorado during
July 1999 and June 2000. All bears estimated to be adults were instrumented with standard VHF radio
transmitter collars. Bears were located by aerial telemetry during the early-denning period ofmidNovember to December. Ground-based telemetry confirmed den entry. The early-season den work was
begun as soon as all study bears had denned. Aerial tracking was used in early March to determine if bears
had changed dens. All late-denning season work began in mid-March. The primary purpose of this project
was to provide study bears for physiological research that is being funded through the Univ. of Wyoming
under a National Science Foundation grant. This collaboration has been a joint undertaking since 1993.
During den handlings, all bears were initially immobilized with Telazol administered by jab stick at the
dosage rate of 7 mg/kg. Following imrilobiliz.ation, bears were removed from the den and placed on a
foam pad which was on a tarp for insulation. When precipitation seemed likely, an overhead tarp was
erected to keep rain/snow off bear. A sterile opthalmic ointment was placed in each eye and a stocking
mask placed on the bear to shield the eyes. Each bear was then weighed. Whole body fat content was
measured using bioelectrical impedence (Baumgartner et al. 1990).
In vivo muscle strength of the hind limb was measured using a force transducer apparatus modified from a
design used for human clinical research by one of the project collaborators (P. Iazzo, U. of Minn.).
Electrical stimulation of the perinea! nerve caused the tibialis anterior to contract. This contraction was
measured on a force plate. Using sterile surgical techniques, a 1-2 gm muscle biopsy was removed from
the vastus Iateralis of the quadraceps. This sample was equally divided into 3 subsamples for later
analyses for total protein content, total nitrogen content, RNA content, DNA content, muscle morphometry
and fiber type, ubiquitin concentration, and in vitro muscle strength. A small fat sample was also removed
from subcutaneous fat reserves for identification of fatty acid profiles. A 15-ml blood sample was obtained
by venipuncture in the inguinal region. Blood samples were analyzed for key amino acid levels of activity,
ubiquitin messenger RNA, and a general chemistry screen. All of the surgical procedures and laboratory
-analyses were conducted by Dr. Henry Harlow and graduate student Tom Lohuis of the Univ. of Wyoming
under a joint NSF grant.
During the early-denning sample period, all biopsies were taken from the left hind limb while during the
late-denning sample period the right hind limb was used. The in vivo muscle strength measurements were
taken on the left hind limb in both periods. Following the work-up, all bears were placed back in their dens
and the den entrances covered.
In addition, 5 of the black bears handled in March 2000 were instrumented with knock-down collars
manufactured by Advanced Telemetry Systems. These collars held syringes loaded with ketamine/xylazine

�276
which could be activated by radio transmitter. The plan was to obtain the same data as collected in winter
during the summer from the identical study bears. As a back-up to this system, traditional trapping
protocols with cage traps would be implemented if needed to obtain a summer cohort of bears. Bears
captured in June 2000 for this project were not radio instrumented and radio collars were removed from .
any bears handled in June 2000.

RESULTS AND DISCUSSION
During July 1999 IO black bears were captured and collared. In vivo strength measurements were not
obtained on any of these bears because of problems in both software and electrical hardware needed. The
equipment had been modified to reduce the weight and volume of equipment. Bench tests of the equipment
had been successful but we were unable to make the needed corrections once the field problems occurred
during July 1999. The equipment was corrected before the den seasons. However, muscle and fat biopsies
were obtained from all ten (9 males, 1 female) bears.
During the early denning period (Nov-Dec 1999) 7 of these bears were located as well as 8 bears collared
in previous years. From this group, a subset of 8 (7 females, 1 male) were selected for denning studies.
Criteria for selection were primarily gender (females move less than males) and ease of den access based on
topography, avalanche danger, and land ownership. Muscle and fat biopsies, blood samples, and in vivo
muscle strength measurements were obtained for all 8 bears.
Sampling was repeated in March 2000 on 6 of these 8 bears. All samples and measurements were
successfully obtained on these six. One 1female black bear exited her den unusually early (early March) and
did not return while another female exited her den upon the approach of the field crew. Neither of these
bears re-denned so could not be captured. Five of these bears (4 females, 1 male) were fitted with the ATS
knock-down collars while the remainder had a conventional radio collar.
During June 2000, 4 of the 5 bears equipped with ATS knock-down collars were located via aerial and
ground telemetry. Numerous attempts were made to activate the syringes on the collars for each of the 4
bears. None worked. Conventional trapping resulted in a total of 6 bears captured. One recapture had an
ATS knock-down collar on while another recapture had a conventional collar. Additionally, a male
equipped with the ATS knock-down collar was struck by a vehicle and killed. Thus we obtained 2 of the
collars for analysis of the malfunctions. The 6 bears captured in June 2000 (5 males, 1 female) provided
muscle biopsies, blood samples, and measurements of muscle strength.
All laboratory analyses have been conducted by collaborators at University of Wyoming. However, data
analysis has not been completed but should be in final form and will be the major portion of the Ph.D.
dissertation of Tom Lohuis (expected completion Spring 2001). All surgical incisions were carefully
examined during subsequent handlings. All healed without problems. No further data will be collected for
these studies in the next segment. Analyses will be completed and an effort will be made in December 2000
to locate collared bears and remove as many collars as is feasible.

LITERATURE CITED

Baumgartner, R. N., W. C. Chumlea, and A. F. Roche. 1990. Bioelectrical impedance for body
composition. Exercise and Sport Reviews 18:193-224.

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                  <text>235
Colorado Divison of Wildlife
Wildlife Research Report
July 1998

JOB FIHAL REPORT

state of

Colorado

cost center 3430

Project No.

W-153-R-11

Mammals Program

Work Package No. _ _,,3~P~P~3_ _ _ __

Predatory Mammals Management

Task No.

Use of Sport Hunting to Reduce

Puma Depredation on sheep
Period Covered: July 1, 1997 - June 30, 1998
Author: Thomas D. I. Beck
Personnel: T. Beck, J. Madison, J. Wallace; CDOW

ABSTRACT
A puma density sampling protocol was prepared based on probability sampling
along line transects. A prototype sampling unit was designated. However, the
appropriate snow conditions did not occur in Jan.-Mar., 1998 to allow for
sampling. An evaluation of the logistical constraints on the technique, along
with loss of management authority, resulted in the termination of the study.

�237
Use of Sport Bunting to Reduce Puma Depredation to Sheep

P.H. objectives
1.

Evaluate the efficacy of liberal sport hunting quotas to reduce
the density of puma.

2.

Investigate the relationship of puma density to depredation levels
on domestic sheep.

segment Objectives
1.

Compile historic data on sport kill of puma and puma depredation
on sheep in DAU L-7.

2.

Prepare detailed protocol on transect sampling and puma density
estimation.

3.

Conduct puma density estimation transects on 2 study areas.

METHODS AND MATERIALS
Kill of puma (.E.e.l..i.a. concolor) by hunters was tabulated from mandatory check
files for the years 1988-1997 for DAU L-7. The frequency distribution of kill
by time was calculated in one-week intervals in hopes of identifying periods
where sampling would have minimal impact on hunting activities. Based on
location of historic kills and terrain considerations, a pilot study site of
approximately 400 Jan2 was delineated in the Piceance creek drainage. A
detailed sampling protocol was prepared based on the techniques described by
Becker (1991) and Van Sickle and Lindsey (1991).

RESULTS AND DISCUSSION
Hunter kill of puma increased from 12 in 1988 to 80 in 1997 in DAU L-7. The
marked increase in kill began in 1993 and was the result of greater quotas
allocated in hopes of reducing puma depredation on domestic sheep. During the
period 1995-1997 a total of 209 puma were taken by hunters and an additional
30 were taken by either landowners or predator control agents in DAU L-7.
Game damage payments for puma depredation statewide varied from $46,000 to
$60,000 per year during 1988-1991. Since 1992 the annual payments have varied
from $93,000-$132,000. The relative importance of possible causative factors
is unknown. Approximately 50% of the statewide puma damage payments are made
in DAU L-7.
A detailed sampling protocol was prepared (Appendix A) but never implemented.
During the January-March 1998 sampling period adequate snow cover did not
exist in the sampling block. In trying to implement the sampling scheme
several serious logistical impediments became apparent. Scheduling of
helicopter time was problematic because of restrictions with state contracts
and the higher priority status of ungulate census and survival work. The puma
census would have to compete with other on-going work for both helicopter and
personnel time.

�238
The logistical impediments, along with the changed management status of puma
in Colorado (shared authority with Colorado Dept. of Agriculture), make the
successful completion of this job improbable. Thus it was decided by
participants to cease the effort at density estimation for future years.

�239
Appendix A
PROTOCOL FOR PROBABILITY SAMPLING OF PUMA DEIISITY

SAMPLING AREA: Area should be a rectangle of at least 390 km 2 , and must be at
least 13 km wide on the shortest axis (baseline axis). The long axis
(transect axis, 30 km) should be perpendicular to the majority of the major
drainages in the area. You must delineate a specific rectangular area in
order to make inclusion judgments.
TRANSECTS: At least 3 transects should be flown in a straight line along the
long axis for the entire 30 km length. Transect 1 should be randomly selected
to start within the first 3 kms of the baseline axis. The remaining transects
should be spaced 4 km distant (Example: Transect 1 begins at baseline point
of 2 km, No. 2 at 6 km, No. 3 at 10 km). Flight time will be about 60 minutes
to fly a 30 km transect plus about 10 minutes of search time per puma track
set.
MODIFICATIONS: If a 30 km transect cannot be fitted into the areas of
concern, the long axis can be shortened. However, total area should remain at
least 400 km2 and transects should be separated by at least 4 km. Thus a
20X20 km area would have 5 transects flown, of 20 km each. Long (30 km)
transects are more efficient in terms of flight time.
SURVEY PERIOD: The helicopter surveys should be flown 2-3 days following a
snowfall which is sufficiently deep as to not melt out within 48 hours and
completely cover old tracks (about 8 cm). Very deep snows (&gt;20 cm) restrict
puma movement and are to be avoided. Optimum snow depth would be 8-12 cm.
There must be at least one complete night for movement following the snow. A
2-night period is better unless very high winds are occurring; however, more
than 2 nights creates difficulty because of other animal tracks and wind-blown
snow.
PROCEDURE: Surveys should be conducted by a crew consisting of a trained
observer and a navigator. The navigator should have detailed knowledge of the
terrain. While biologists may be excellent observers, we should try to
utilize experienced puma hunters for observers as they will more easily detect
the track patterns of puma. All locations should be recorded by UTM. Fly a
straight line along Transect 1 until a puma track is encountered. Record
location. Fly the backtrack until you find where puma started moving
following snowfall; record the location of the point where the track is
farthest from the transect. Fly the front track until you locate puma (often
you will not see animal but will see where tracks end in heavy cover); record
location of the point where the track is farthest from the transect. Because
of the non-linear nature of travel, the beginning and ending points may not be
the farthest distance traveled parallel to the baseline axis. Record the
extreme distances from the transect. Return to original transect line at the
point where track was located. Continue along the line until the next puma
track is encountered. Repeat the process to estimate travel distance for each
set of tracks. The objective is to obtain a straight-line distance of travel
parallel to the base-transect. At the end of transect 1, move 4 Jans along the
baseline and return along transect 2, which parallels transect 1.
Multiple puma tracks traveling together (female w/kittens or male-female pair)
should only be counted as 1 track set. However, make a notation of the group
size. There are separate analysis procedures which can be used if this is a
common occurrence.

�240

Do not count kitten tracks traveling separate from the mother. This is an
unlikely occurrence and distinguishing from bobcat tracks while airborne is
quite problematic.
Kill sites will be characterized by lots of tracks in the near vicinity of the
kill. Estimate the diameter of the circle which would include all the tracks.
This diameter will be used as the travel distance.
Most straight-line travel distances will be less than 3 km. However, in the
event that a puma track crosses 2 transects, it should be separately recorded
for each transect.
Data to be recorded:
location of each puma track along each transect;
location of farthest points of travel of puma perpendicular to the transect;
all in UTM's.
Data to be calculated: straight-line distance parallel to baseline moved by
each puma, in km's.
Data for any puma where &gt;50% of the travel distance was outside the designated
rectangular survey area will not be used in the calculations.
ANALYSIS: Population size is estimated from the following equations, from
Becker (1991) and Van Sickle and Lindzey (1991):

P;=x/(D/q)

½=L (lip;)
where Pi= probability that the ith puma i
sample; xi= distance, parallel to the baseltoetatnedeledtb~ Yhb aystpmaalcD =
length of baseline; q = number of transects per systematic sample; and Tj =
population estimate for the jth systmatic sample.
since we will not be flying replicate samples for an area, variance of the
estimate will be estimated using jackknife procedures and dividing the
transects into segments (McDonald and Manly 1989). This will be done by a
contract statistician. While replication is the preferred methodology,
helicopter costs make this prohibitive.
ASSUMPTIONS FOR PROBABILITY SAMPLING PROCEDURE:
1.
2.
3.
4.
5.
6.
7.
8.

All animals move during the survey period.
Puma tracks are readily recognizable.
All animal tracks are continuous.
Animal movements are independent of the sampling process.
Post-snowstorm tracks can be distinguished.
All puma tracks crossing a transect will be observed.
Study area is rectangular in shape.
All the transects are oriented perpendicular to the baseline axis.
LITERATURE CITED

Becker, E. F. 1991. A terrestrial furbearer estimator based on probability
sampling. J. Wildl. Manage. 55(4):730-737.
Van Sickle, w. D. and F. G. Lindzey. 1991. Evaluation of a cougar population
estimator based on probability sampling. J. Wildl. Manage. 55(4):738743.

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                  <text>245
Colorado Division of Wildlife
Wildlife Research Report
July 1998
JOB PROGRESS REPORT

State of

Colorado

cost center 3430

Project No.

W-153-R-ll

Mammals Program

Work Plan No.

3004

Management of other ungulates

Task No.

Strategies for Managing
Pasteurellosis in Mountain Sheep

Populations
Period Covered:

July 1, 1997 - June 30, 1998

Authors:

M. W. Miller and H.J. McNeil

Personnel:

s. Berry, J. George, K. Larsen, J. Vayhinger, T. Verry

ABSTRACT
We continued investigations of multivalent Pasteurella haemolytica supernatant
vaccines in captive bighorn sheep (Ovis canadensis). A vaccine lot(PhSV lot
#970520) that combined bighorn and domestic strains appears to contain
antigenicity comparable to that of the original multivalent vaccine, and was
selected for use in future laboratory and field studies.
To evaluate vaccine delivery options, 30 captive bighorns were divided into 3
groups of 10 based on vaccine history and baseline P. haemolytica leukotoxin
neutralizing antibody titers; treatment groups included hand injection,
biobullet implantation and oral gavage of PhSV. Serum leukotoxin-neutralizing
antibody titers differed among delivery treatments (P = 0.009). Neutralizing
titers were highest among hand-injected bighorns; no serum antibody response
was detected among bighorns vaccinated orally. Although neutralizing titers
were lower among implanted bighorns than in the hand injected controls (P &lt;
0.021), seroconversion rates did not differ (implantation= 6/10, hand
injection= 9/10; P = 0.303). Although our data demonstrated that handinjection elicits higher absolute titers than either biobullet implantation or
oral vaccination, biobullet implantation may also stimulate effective antibody
responses to P. haemolytica supernatant vaccines. Further evaluation of
biobullet vaccination against pneumonic pasteurellosis in free-ranging
populations of wild bighorn sheep appears warranted.
A total of 110 free-ranging bighorn sheep from 4 different herd units. in
central Colorado were vaccinated with PhSV during January-March 1998. No
adverse reactions or mortalities were detected among vaccinated bighorns
through June 1998. Ongoing monitoring in the Tarryall-Kenosha herd complex
will provide additional data on efficacy of vaccination to protect freeranging bighorns from pasteurellosis under field conditions.

�247
EXPERIMENTS TO IDENTIFY AND MANAGE STRESS
IN MOUNTAIN SHEEP POPULATIONS

M. W. Miller and H.J. McNeil

P, H, OBJECTIVES
1.

Design, conduct, and report on experiments evaluating Pasteurella
haemolytica vaccines and vaccine delivery systems and identify those
with potential application in managing free-ranging bighorn populations.

2.

Design, conduct, and report on field experiments evaluating management
strategies for preventing pasteurellosis epizootics in bighorn
populations

SEGMENT OBJECTIVES
1.

Conduct and report results of an experiment evaluating options for
delivering a multivalent Pasteurella haemolytica supernatant vaccine to
bighorn sheep.

2.

Provide multivalent Pasteurella haemolytica supernatant vaccine for use
in select bighorn sheep management activities statewide.

STRATEGIES FOR MANAGING PASTEURELLOSIS
IN MOUNTAIN SHEEP POPULATIONS
Inability to control infectious disease outbreaks and subsequent mortality in
mountain sheep populations represents a significant obstacle to long-term
success in their management. Although the "bighorn pneumonia complex" has
been studied intensively for over 3 decades, little is known about many
aspects of its etiology and epizootiology. Moreover, management interventions
recommended for preventing or controlling this problem remain untested.
Although viral, bacterial, and parasitic agents have all been incriminated in
these outbreaks, Pasteurella spp. are perhaps the most common pathogens
associated with bronchopneumonia in bighorns. Two species, P. haemolytica and
P. multocida, and several biotypes and/or serotypes within those species, have
been isolated from bighorns during epizootics. Unfortunately, despite
extensive diagnostic and experimental investigation, the epizootiology of
pasteurellosis in wild bighorn populations is poorly understood.
In the
absence of knowledge about the epizootiology of pasteurellosis, effective
strategies for managing pneumonia in bighorn populations have not emerged.
Here, we report on a series of ongoing research studies designed to improve
knowledge about various aspects of pasteurellosis epizootiology and management
in bighorn sheep.

METHODS ARD MATERIALS

Refinement of experimental Pasteurella haemolytica supernatant vaccine
(McNeil, Miller, and Shewen): A rabbit study was previously conducted with
Pasteurella haemolytica supernatant vaccine (PhSV) lot #970520 (Miller and
McNeil, 1997). Rabbits were exsanguinated after receiving three 0.5 ml doses

�248
of vaccine at 2-wk intervals. All rabbits responded to vaccination by
producing anti-leukotoxin antibodies. Protein profiles from Western blots
(blotted with vaccinated rabbit serum) transferred from 12% precast PAGE gels
containing the vaccine components of both PhSV lot #970520 and multivalent
vaccine lot# 940902 (Miller et al., 1997) also showed strong vaccine-induced
antibody reactivity.
Based on these findings, a small pilot study in bighorn sheep was conducted.
Six captive Rocky Mountain bighorn sheep were used. Sheep were paired on the
basis of age and vaccination history. One bighorn from each pair received 2
ml PhSV lot #970520 intramuscularly; the other animals received 1 ml PhSV lot
#970520 and 1 ml Presponsee mixed in the same syringe, delivered
intramuscularly. (Presponsee is a commercially available supernatant vaccine
of Pasteurella haemolytica Al.) We used this approach to establish whether the
presence of P. haemolytica serotype Al was necessary to drive the marked
increase in leukotoxin neutralizing titer seen in previous studies (Miller et
al., 1997; Kraabel et al., 1998). Animals were bled prior to vaccination and
again at day 7 and day 14. Serum leukotoxin neutralizing antibody titers
stimulated by the two treatments were measured and compared using methods
described by Miller et al. (1997).

Delivery of Pasteurella haemolytica supernatant vaccine to bighorn sheep
(McNeil and Miller): Thirty captive bighorn sheep were used in this study.
Animals were divided into three groups of ten based on their vaccine history
and baseline neutralizing titers. The three treatment groups included hand
injection, biobullet implantation and oral gavage of vaccine. Four additional
animals were intramuscularly injected with saline to monitor for changes in
antibody titers unrelated to vaccination during the study period.
PhSV lot #970520 was used for all treatments. Vaccine was lyophilized for use
in biobullets and microspheres. The standard dose for intramuscular injection,
2 ml (Miller et al., 1997; Kraabel et al., 1998), yielded about 0.025 g
lyophilized vaccine. Biobullets were packed with about 0.030 g lyophilized
vaccine, then filled with methylcellulose filler for remote delivery.
Lyophilized vaccine was also sent to Dr. Harm HogenEsch of Purdue University
for encapsulation in alginate microspheres; 5 ml of alginate microsphere
suspension was recommended as equivalent to a 2 ml dose of vaccine.
The hand injection group received 2 ml PhSV injected intramuscularly into the
left haunch. The biobullet group were vaccinated with the use of a
specialized biobullet rifle from a distance of approximately 4 meters.
Animals in this group had a small area on their left hindquarters shaved to
facilitate confirming implantation. Animals receiving vaccine orally were
dosed with the aid of a small stainless steel gavage tube. The tube was
inserted into the animal's mouth and laid along the teeth; 5 ml of vaccine was
then squirted into the sheep's mouth and subsequently swallowed.
Animals were bled prior to vaccination and again at 1, 2, 4, 8 and 12 weeks
postvaccination. Sera were collected and used to assess serological responses.
Titers were measured using a leukotoxin neutralization assay, along with three
separate direct agglutination assays that incorporated formanilized
Pasteurella haemolytica serotypes Al, A2 or Tl0 as antigen (Miller et al.,
1997; Kraabel et al., 1998).

use of Pasteurella haemolytica supernatant vaccine in free-ranging bighorn
.ab.e,ep (Miller, George, and Vayhinger): A total of 110 free-ranging bighorn
sheep from 4 different herd units in central Colorado were vaccinated with

�249

PhSV during January-March 1998 (Table 1). Bighorns from Georgetown herd unit
were vaccinated just prior to translocation to the Arkansas River canyon for
release; nearby resident bighorn populations appear to have recurrent problems
with respiratory disease in this area, and translocated bighorns were
considered potentially at risk. Bighorns in the Black Canyon and Twin Eagles
herd units of the Tarryall-Kenosha complex were vaccinated in an attempt to
prevent spread and/or minimize impacts of a pasteurellosis epidemic that
started in the Sugarloaf herd unit in December 1997 (see WP7610-T4 for
details); a few sheep in the Sugarloaf herd also were vaccinated in an attempt
to enhance postepidemic survival in that subpopulation. Survival of vaccinated
and unvaccinated individuals was compared opportunistically in conjunction
with ongoing field studies.
RESULTS AHD DISCUSSION

Refinement of experimental Pasteurella haemolytica supernatant vaccine
(McNeil, Miller, and Shewen): We observed no adverse effects in bighorns
receiving PhSV lot #970520. All vaccinated bighorns responded with an increase
in leukotoxin neutralizing titer. Based on these results, PhSV lot #970520
was judged an appropriate vaccine for use in the delivery experiment and in
field applications.

Delivery of Pasteurella haemolytica supernatant vaccine to bighorn sheep
(McNeil and Miller): other than a mild transient lameness in animals
vaccinated intramuscularly or remotely, no adverse reactions were observed
following vaccination.
Serum neutralizing antibody titers to P. haemolycica leukotoxin differed among
delivery treatments (P=0.009) as well as among baseline titer/vaccination
history groups (P=0.013). Neutralizing titers were highest among hand-injected
bighorns; no serum antibody response was detected among bighorns vaccinated
orally. Although neutralizing titers were lower among implanted bighorns than
in the hand injected controls for ~2 weeks post vaccination (P &lt; 0.021),
seroconversion rates (defined as a ~2 log 2 increase in titers) in response to
implantation (6/10) and hand injection (9/10) did not differ (P=0.303).
Agglutinating antibody titers to Tl0 were high and did not differ over time or
between delivery treatments. In addition, agglutinating antibody titers to Al
did not vary over time or between groups. Agglutinating antibody titers to A2
were higher in the hand injected group than the orally vaccinated sheep
during the time period between 2 and 4 weeks post vaccination (P &lt; 0.026); A2
agglutinating titers in hand-injected and implanted sheep did not differ
during the same time period (P = 0.07). Vaccination history/baseline titer
categorization affected responses to serotype A2 surface antigens (P =
0.0001).
our data support previous observations (Miller et al., 1997; Kraabel et al.,
1998) that hand-injected P. haemolycica supernatant vaccines stimulate marked
antibody responses in bighorn sheep; it follows that delivery via projectile
syringe should stimulate similar antibody responses. Although our data
demonstrate that hand-injection elicits higher absolute titers than either
biobullet implantation or oral vaccination, biobullet implantation may also
stimulate effective antibody responses to P. haemolycica supernatant vaccines.
Whether lack of serum antibody response to oral vaccination truly reflects
failure to stimulate immunity remains undetermined. Further evaluation of
biobullet vaccination against pneumonic pasteurellosis in free-ranging
populations of wild bighorn sheep appears warranted.

�250

use of Pasteurella haemolytica supernatant vaccine in free-ranging bighorn
Jlhe8l2 (Miller, George, and Vayhinger): As with previous captive animal studies
(Miller et al., 1997; Kraabel et al., 1998; McNeil and Miller, above), no
adverse effects were observed in free-ranging bighorns that received PhSV via
hand-injection, projectile syringe, or biobullet implant.
No mortality was been detected among vaccinated bighorns in the 4-6 mo after
vaccination; however, little or no mortality occurred among unvaccinated
bighorns in these populations during that time. We will continue to monitor
survival rates among vaccinated and unvaccinated bighorns in the Tarryall and
Kenosha subpopulations in conjunction with other ongoing studies. These data
should be useful in evaluating efficacy of vaccination in protecting freeranging bighorns from pasteurellosis under field conditions.

Kraabel, B. J., and M. W. Miller, J. A. Conlon, and H.J. McNeil. 1998.
Evaluation of a multivalent Pasceurella haemolytica vaccine in bighorn
sheep: Protection from experimental challenge. Journal of Wildlife
Diseases 34: 325-333.
Miller, M. W., J. A. COnlon, H.J. McNeil, J.M. Bulgin, and A. C. S. Ward.
1997. Evaluation of a multivalent Pasceurella haemolycica vaccine in
bighorn sheep: Safety and serologic responses. Journal of Wildlife
Diseases 33: 738-748 .

....._.L.-..lH.cer
Wildlife Research Veterinarian

Table 1. Free-ranging bighorn sheep treated with multivalent Pasceurella

haemolycica supernatant vaccine during Jan-Mar 1998.

Population
(Herd Unit)

Delivery

Status
Band

Dart

Biobullet

healthy -translocated
to Arkansas R.

25

0

0

healthy, future
exposure likely

35

4

5

(Twin Eagles)

healthy, future
exposure likely

21

6

3

(Sugarloaf)

pasteurellosis
epidemic (12/97)

11

0

0

Georgetown
(Georgetown)

Tarryall-Kenosha
(Black Canyon)

�287

Colorado Division of Wildlife
Wildlife Research Report
July 1999

JOB PROGRESS REPORT

-------~-~----

State of
Colorado
Project No. --------'W-'--.....1=5"-3--=-R"---=12=-----.........,.
___________
Work Plan No.
3004
Task No.
3

____

-------------

Cost Center 3430
Mammals Program
Management of Other Ungulates
Strategies for Managing Pasteurellosis in
Mountain Sheep Populations

Period Covered: July I, 1998 -June 30, 1999
Authors: M. W. Miller, H.J. McNeil, and J. L. George
Personnel: K. Larsen, S. Berry, J. Vayhinger

ABSTRACT
A pasteurellosis epidemic that began in the Sugarloaf Mountain subpopulation of the Tarryall-Kenosha
bighorn herd complex extended to two adjacent subpopulations (Black Canyon, Twin Eagles) during winter
1998-1999. Sick and dead bighorns were found in the Twin Eagles subpopulation by December 1998, and
in the Black Canyon subpopulation by January 1999. Based on preliminary data, vaccination with PhSV 911 mo earlier did noi appear to improve bighorn survival during subsequent epidemics.
A group of bighorns translocated from Dome Rock to the Holy Cross Wilderness received PhSV during
winter 1998-1999. No adverse effects have been observed in free-ranging bighorns that received PhSV last
winter, or during 1997-1998.
We began developing and evaluating a modified-live P. haemolytica vaccine. Using polymerase chain
reaction (PCR) techniques, we screened candidate carrier strains and further characterized bacterial
genomes linked to leukotoxin production. Leukotoxin A (//eta) gene of P. haemolytica TIO Eco. 100 was
successfully amplified, and subsequent sequencing revealed that the I/eta gene ofthis bighorn-derived strain
was approximately homologous to the published //eta gene of P. haemo/ytica TIO. We successfully ligated
123 and 1767 bp gene fragments. Initiaj. attempts to use PCR to increase yields for cloning failed, but such
efforts continue. Plasmid transfers of I/eta are planned for next segment.

�288

�289

EXPERIMENTS TO IDENTIFY AND MANAGE STRESS
IN MOUNTAIN SHEEP POPULATIONS
M. W. Miller, H.J. McNeil, and J. L. George

P. N. OBJECTIVES
1.

Design, conduct, and report on experiments evaluating Pasteurella haemolytica vaccines and vaccine
delivery systems and identify those with potential application in managing free-ranging bighorn
populations.

2.

Design, conduct, and report on field experiments evaluating management strategies for preventing
pasteurellosis epizootics in bighorn populations

SEGMENT OBJECTIVES
1.

Report results of an experiment evaluating options for delivering a multivalent Pasteurella
haemolytica supernatant vaccine to bighorn sheep.

2.

Provide multivalent Pasteurella haemolytica supernatant vaccine for use in select bighorn sheep
management activities statewide.

3.

Begin development and evaluation of a modified-live Pasteurella haemolytica vaccine for use in
bighorn sheep.

STRATEGIES FOR MANAGING PASTEURELLOSIS
IN MOUNTAIN SHEEP POPULATIONS
Inability to control infectious disease outbreaks and subsequent mortality in mountain sheep populations
represents a significant obstacle to long-term success in their management. Although the "bighorn
pneumonia complex" has been studied intensively for over 3 decades, little is known about many aspects of
its etiology and epizootiology. Moreover, management interventions recommended for preventing or
controlling this problem remain untested.
Although viral, bacterial, and parasitic agents have all been incriminated in these outbreaks, Pasteurella
spp. are perhaps the most common pathogens associated with bronchopneumonia in bighorns (Miller,
1999). Two species, P. haemolytica and P. multocida, and several biotypes and/or serotypes within those
species, have been isolated from bighorns during epizootics. Unfortunately, despite extensive diagnostic
and experimental investigation, the epizootiology of pasteurellosis in wild bighorn populations is poorly
understood. In the absence of knowledge about the epizootiology ofpasteurellosis, effective strategies for
managing pneumonia iif bighorn populations have not emerged. Here, we report on a series of ongoing
research studies designed to improve knowledge about various aspects of pasteurellosis epizootiology and
management in bighorn sheep.

�290

METHODS AND MATERIALS

Delivery of Pasteurella haemolytica supernatant vaccine to bighorn sheep (McNeil and Miller): Last
segment we conducted an experiment evaluating options for delivering a multivalent Pasteurella
haemolytica supernatant vaccine (PhSV) to bighorn sheep. A draft manuscript describing that research was
accepted for publication in the Journal of Wildlife Diseases (see abstract, Appendix A).
Use of Pasteurella haemolytica supernatant vaccine in free-ranging bighorn sheep (Miller, George, and
Vayhinger): We continued evaluating survival of free-ranging bighorn sheep vaccinated with PhSV in the
face of a pneumonia epidemic during winter 1997-1998 by comparing survival rates of vaccinated
bighorns to those of unvaccinated individuals. Our evaluation was conducted in conjunction with other
ongoing studies of the Tarryall-Kenosha bighorn herd complex.
In addition, PhSV was used in select field operations during the winter of 1998-1999 (Table 2). We also
continued exploring ways of adding Pasteurella multocida antigens to our vaccine formulation.
Development of a modified-live Pasteurella haemolytica vaccine for bighorn sheep (McNeil, Lo, and
Miller): We prepared a study plan and began developing and evaluating a modified-live Pasteurella
haemolytica vaccine. Highlights of preliminary laboratory technique development and evaluations are
reported.
Bacteria: Pasteurella haemolytica TIO &lt;Ea,_100) was obtained from a bighorn sheep that died during a
pasteurellosis epidemic in southcentral Colorado in 1990 (Kraabel et al., 1997). Bacterial stocks were kept
frozen at -70° C in Brain Heart Infusion Broth (BHIB) with 15 % glycerol. Thawed stock was used to
inoculate blood agar plates incubated at 37° C overnight (0/N). A small volume (50 ml in a 175 ml
Erlenmeyer flask) ofBHIB was inoculated with a single colony from the 0/N agar plate and incubated at
37° C, 120 rpm 0/N. The resulting culture was used to extract DNA for use in polymerase chain reactions
(PCR).
Preparation ofgenomic DNA: Two commercial kits were used to extract maximum amounts of genomic
DNA fromP. haemolytica TIO &lt;Eco.100). A QIAGEN Genomic-tip® (QIAGEN Inc., Mississauga, ON,
Canada) was used and DNA was extracted according to the Bacterial DNA Isolation Protocol in the
QIAGEN Genomic DNA Handbook. A PUREGENE® genomic DNA isolation kit (Gentra Systems, MN,
USA) was also used to improve yields. Genomic DNA was used as template for subsequent PCR.
PCR: PCR was utilized to amplify the leukotoxin A gene (lkta) of P. haemolytica TIO &lt;Ea,_100). Many
different primers and conditions were assessed. The gene was successfully amplified using primers based
on the published P. haemolytica TIO Ieukotoxin A gene sequence (Genbank Accession Z26247).
5'-ATGGGAACTAAACTAACCCT-3'
5'-TAAGCTGCTCTAGCAAATTG-3'
Conditions were optimized at 3.5 mM [Mg++] using the genomic DNA prepared by the PUREGENE®
method as template. The thermal cycler (Perkin Elmer-,Cetus, NoFWalk, Connecticut, USA) was
programmed for 94 C for 30 seconds, 51 C for 30 seconds, 72 C for 3 minutes and 30 seconds. This was
repeated for 30 cycles.
Two sections of the lkta gene also were amplified via PCR for use in subsequent ligation. Similarities
between the sequence of the lkta gene for Eco. 100 and P. haemolytica Al (Genbank Accession M20730)
were considered. Previous work in our laboratory (R. Lo, unpubl. data) used two existing Nael sites on the

�291

lkta gene to delete a section of the gene and ligate the smaller fragments together to form a truncated gene.
Although the Nae! sites on the lkta Eco.ioo were not a perfect match, using primer design, two sections were
amplified. These sections incorporated exact Nae! restriction sites.

The 123 base pair segment from the 5' end of the gene was amplified using the following primers:
5'-GGATCCCTIATGGGAACTAAAC-3'
5'-0TCTGGCCGGCTIGGGTIAA-3'
The 1767 base pair segment from the 3' end of the gene was amplified using the following primers:
5'-TGCCGCCGGCTCTGTGGTI-3'
5'-CGAAACAATCTAGAGTIGCCAATC-3'
Conditions were optimized at 3.5 mM [Mg++] using the genomic DNA prepared by the PUREGENE~
method as template. The thermal cycler was programmed for 94 C for 30 seconds, 59 C for 30 seconds, 72
C for 3 minutes and 30 seconds. This was repeated for 30 cycles.
PCR was also used to try to increase the amount of ligated product. The following primers were used:
5'-GGATCCCTTATGGGAACTAAAC-3'
5'-CGAAACAATCTAGAGTTGCCAATC-3'
Conditions were optimized at 3.5 mM [Mg++] using gel purified ligated product as the template. The
thermal cycler was programmed for 94 C for 30 seconds, 64 C for 30 seconds, 72 C for 3 minutes and 30
seconds. This was repeated for 30 cycles.
All PCR products were run on 0.75 % agarose gels (85 V for 23-45 minutes) and stained with ethidiurn
bromide. Bands were visualized using ultra-violet (UV) light and the image captured by a GelDoc 1000
machine (Bio-Rad Laboratories, Mississauga, ON, Canada).
PCR Product Purification: PCR products to be sequenced or used for further manipulation were purified
using a QIAGEN QIAquick PCR purification kit~. Purified product was run on gels as before purification
to ensure that the band in question was still visible.

In instances where extraneous bands were visible, gel extraction was used to isolate the desired product. A
low melting point 1.0% agarose gel was loaded with product and run at low voltage overnight (8-9 V, 1216 hours). The gel was then stained with ethidiurn bromide and visualized using UV light on a
transillurninator. The desired band was cut out using a sterile scalpel blade and put into a tube. The tube
was heated to melt the agar. This material was then purified in the same manner as the non-gel purified
PCR products.
Restriction Enzyme Digestion: Purified 123 bp and 1767 bp fragments were digested using Nae!
(Promega 'Corporation, Madison, WI, USA ) with the recommended buffer for 1 hour at 37 C. The enzyme
was then inactivated at 60 C for 15 minutes. A 1 µI aliquot was run on a 0.75% agarose gel to ensure
product integrity. These products were to be ligated together.

Restriction enzyme digestion was also used for mapping the ligated product_ Digestions were performed
using Nae!, Apa! (Promega Corporation, Madison, WI, USA) and Sacl (New England Biolabs Ltd.,

�294

APPENDIX A
EFFECTS OF DELIVERY METHOD ON SEROLOGICAL RESPONSES OF BIGHORN SHEEP
TO A MULTIVALENT PASTEURELLA HAEMOLYTICA SUPERNATANT VACCINE
Heather J. McNeil,1 Michael W. Miller,2 Jennifer A. Conlon,3 Ian K. Barker,1 and Patrica E. Shewen1
1

Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, NlG
2Wl, Canada
2
Colorado Division of Wildlife, Wildlife Research Center, 317 West Prospect Road, Fort Collins,
Colorado 80526-2097, USA
3
Merial Incorporated, 115 Transtech Drive, Athens, Georgia, 30601-1649, USA
ABSTRACT: The efficacy and safety of a multivalent Pasteurella haemolytica supernatant vaccine
(serotypes A2 and TIO) using different delivery systems were examined in captive Rocky Mountain
bighorn sheep (Ovis canadensis canadensis). Twenty bighorn sheep were grouped according to baseline
leukotoxin neutralizing antibody titers (~2 or &gt;2 log/) and vaccination history (previously vaccinated or
unvaccinated). Within these groups, animals were randomly assigned to one of two delivery treatments:
hand injection (control) or biobullet implantation. All bighorns received a single dose from the same lot of
vaccine (n = IO/treatment); four additional animals were injected intramuscularly with 0.9% saline as
unvaccinated sentinels. Mild, transient lameness one day after hand injection or biobullet implantation was
the only adverse effect. Serum neutralizing antibody titers to P. haemolytica leukotoxin differed among
delivery treatments (P = 0.009) and among baseline titer/vaccination history groups (P = 0.013).
Neutralizing titers were highest among hand-injected bighorns. Although neutralizing titers were lower
among implanted bighorns than hand-injected controls at 1 wk (P = 0.002) and 2 wk (P = 0.021) after
vaccination, seroconversion rates in response to implantation (6/10) and hand injection (9/10) did not differ
(P = 0.303). Agglutinating antibody titers to TIO were high and did not vary over time or between
delivery treatments. Agglutinating antibody titers to A2 in the hand-injected controls were not different (P
£ 0.07) than those in bighorns vaccinated with biobullet implantation. These data demonstrate that
although hand injection elicits higher absolute titers, biobullet implantation may also stimulate effective
antibody responses to P. haemolytica supernatant vaccine. Further evaluation of biobullet vaccination
against pneumonic pasteurellosis in free-ranging populations of wild bighorn sheep is warranted.
Key words: Bighorn sheep, Ovis canadensis, Pasteurella haemolytica, pasteurellosis, vaccine delivery,
vaccination.

�277
\

Colorado Division of Wildlife
Wildlife Research· Report
July 2000

JOB PROGRESS REPORT
State of _ _ _ _ _....
C=o=lo=rad=o'-------

Cost Center 3430

Project No. -----'W;.;.....:-1=5=3--=R....--=-1=-3_ _ _ __

Mammals Program

Work Plan No.

___.................
3004 ______

Task No. _ _ _ _ __.:.,1_ _ _ _ __

Management of Other Ungulates
Strategies for Managing Pasteurellosis in Mountain
Sheep Populations

Period Covered: July 1, 1999 - June 30, 2000
Authors: M. W. Miller, R E. Briggs, and H. J. McNeil
Personnel: K. Larsen, S. Berry, J. George, J. Vayhinger
\
/

I

ABSTRACT

We continued developing and evaluating modified-live Pasteurella spp. va~ines for use in bighorn sheep
mangement. Based on preliminary successes in protecting both cattle and domestic sheep from
experimental pasteurellosis, we began a pilot study to evaluate a genetically-modified live P. haemolytica
vaccine (GMLPhV)in captive bighorns. Vaccine was supplied by USDA/ARS/NADC in Ames, IA. Of3
bighorns receiving about 7 x 108 colony forming units (CFUs) ofGMLPhV, 1 died about 3 days after
vaccination and another showed signs of moderately severe respiratory disease from days 2-10
postinoculation (Pl); the GMLPhV strain was most likely responsible for morbidity and mortality in
. vaccinated bighorns. Two previously unvaccinated bighorns housed with the 2 surviving vaccinates
·beginning 2 weeks PI seroconverted to P. haemolytica serotype 2 2-3 weeks later, suggesting colonization
of these in-contact animals by GMLPhV strain despite failure to actually isolate GMLPhV strain from
either in-contact bighorn. Both in-contact bighorns remanied healthy through 7 weeks postexposure.
Ability of GMLPhV to protect bighorns from pasteurellosis will be evaluated via experimental challenge in
early July. Further evaluation of this or a similar GMLPhV strain hinges on the vaccine's ability to prc!ect
bighorns from expennental challenge.

)

We also continued attempts to engineer an antigenic but nonpathogenic P. trehalosi strain for use as a
modified-live vaccine in bighorns. Recent ligation attempts yielded a product of appropriate size, and
restriction enzyme mapping indicated ligation was successful. As before, attempts to use polymerase chain
reaction (PCR) to increase yields for cloning were disappointing, insofar as there were extraneous bands.
However, we used gel purification to prepare concentrated ligated product to use in the subsequent insertplasmid ligation in E. coli. Several recipient colonies were recovered. A small number were screened and
carried a plasmid of appropriate size (~ 7Kb). Restriction mapping results were encouraging. One cloned

�278
construct (D22) showed favorable and consistent results. When used as a PCR template, plasmid from this
clone produced a single, clear, 1889 bp band. Attempts to amplify the gfp gene using PCR were
successful. A single band of appropriate size was visualized. Unfortunately, attempts to insert the gfp into
the p2 l 76 containing the modified leukotoxin gene (referred to as D22) have been, as yet, unsuccessful.
Short-term plans for continuing this work include PCR to amplify the green fluorescent pigment (gfp) gene
with constructed blunt end restriction enzyme sites on each end. We hope to successfully clone this gene
into the Nael site on the plasmid carried in D22. We then will electroporate the plasmid into P. trehalosi
serotype 10 &lt;Eco. 100) and replace the existing lktA with our LJ/ktA-gfp. We anticipate having a P. treha/osi
vaccine strain available for testing in captive bighorn sheep sometime in the 00/01 segment.

�279

EXPERIMENTS TO IDENTIFY AND MANAGE STRESS IN
MOUNTAIN SHEEP POPULATIONS
M. W. Miller, R. E. Briggs, and H. J. McNeil

P. N. OBJECTIVES

I. Design, conduct, and report on experiments evaluating Pasteurella haemolytica vaccines and vaccine
delivery systems and identify those with potential application in managing free-ranging bighorn
populations.
2. Design, conduct, and report on field experiments evaluating management strategies for preventing
pasteurellosis epizootics in bighorn populations

SEGMENT OBJECTIVES
I. Continue development and evaluation of a modified-live Pasteurella haemolytica vaccine for use in
bighorn sheep.

STRATEGIES FOR MANAGING PASTEURELLOSIS
IN MOUNTAIN SHEEP POPULATIONS
Inability to control infectious disease outbreaks and subsequent mortality in mountain sheep populations
represents a significant obstacle to Iong-tenn success in their management. Although the "bighorn
pneumonia complex" has been studied intensively for over 3 decades, little is known about many aspects of
its etiology and epizootiology. Moreover, management interventions recommended for preventing or
controlling this problem remain untested.
Although viral, bacterial, and parasitic agents have all been incriminated in these outbreaks, Pasteurella
spp. are perhaps the most common pathogens associated with bronchopneumonia in bighorns (Miller
2000). Three species, P. haemolytica, P. trehalosi, and P. multocida, and several biotypes and/or
serotypes within those species, have been isolated from bighorns during epidemics. Unfortunately, despite
extensive diagnostic and experimental investigation, the epidemiology of pasteurellosis in wild bighorn
populations is poorly understood. In the absence of knowledge about the epidemiology of pasteurellosis,
effective strategies for managing pneumonia in bighorn populations have not emerged. Here, we report on
a series of ongoing research studies designed to improve knowledge about various aspects of pasteurellosis
epidemiology and management in bighorn sheep.

METHODS AND MATERIALS
Evaluation of a genetically-modified live Pasteurella haemolytica vaccine in bighorn sheep (Miller and
Briggs): Based on preliminary successes in protecting both cattle and domestic sheep from experimental
pasteurellosis (Briggs and Tatum, 1999), we began a pilot study to evaluate a genetically-modified live P.
haemolytica vaccine (GMLPhV)in captive bighorns.
The experimental GMLPhV strain ("Pasteurella haemolytica St2, Foreyt delta 3) was derived from a
hemolytic, serotype 2 P. haemolytica strain (WSU-1) originally recovered from bighorn sheep cohoused

�280
with domestic sheep (Foreyt 1989). The original strain was highly pathogenic in bighorns (Foreyt 1989,
Foreyt et al. 1994, Foreyt and Silflow 1996), produced leukotoxin (Foreyt et al. 1994, Kraabel and Miller
1997) and carried a naturally-occurring leukotoxin gene (Green et al. 1999). Methods for genetic
modifications used to produce vaccine strain are proprietary (R. Briggs, USDNARS). The candidate
vaccine strain had not been tested previously in bighorn sheep. However, parallel pilot studies on safety and
efficacy this vaccine strain via pareneteral delivery are underway in Pullman, WA, and other geneticallymodified P. haemolytica strains (Al from cattle and A5/6 from domestic sheep) already have been
demonstrated as both safe and effective in respective domestic host species (Briggs and Tatum 1999, R.
Briggs unpubl. data). Vaccinated bighorns received about 7 x 108 colony forming units (CFUs) of
GMLPhV, sprayed intranasally, on 25 April 2000.
Our pilot study focussed on safety, immunogenicity, transmissibility, and efficacy ofGMLPhV.
To evaluate safety and immunogenicity, we used three pairs of previously unvaccinated captive bighorn
sheep (4 males, 2 females). One bighorn from each pair was randomly assigned to one of two groups:
intranasal vaccination with GMLPhV (n=3) or intranasal phosphate-buffered saline solution (PBS) in
volumes equivalent to vaccine doses (control; n=3). Vaccinated and control groups were housed in
separate I 00 m2 isolation pens. After a 2-wk acclimation period, respective vaccine and control treatments
were administered as described(= wk 0). Blood for serology and pharyngeal swabs for bacteriology will
be collected at wk-2, 0, 1, and 2. Safety and immunogenicity were evaluated by comparing morbidity,
mortality, strain-specific P. haemolytica colonization rates, and humoral immune responses between
groups over a 2-wk period.
We used 4 captive bighorns from the safety study to evaluate vaccine transmissibility. Bighorns from the
intranasal vaccination(= surviving prirrtiuy vaccinates; n=2) and control(= secondary vaccinates; n=2)
groups were housed together in a single 200 m2 isolation pen immediately after sampling at wk 2 of the
safety pilot. Additional blood for serology and nasal and pharyngeal swabs for bacteriology were collected
at wk 3, 4, 5, 7, and I 0. Safety, immunogenicity, and transmissibility were evaluated by further
monitoring of morbidity, mortality, strain-specific P. haemolytica colonization rates, and humoral immune
responses between groups over an 8-wk period.
We plan to use the four vaccinated bighorns (2 primary vaccinates, 2 secondary vaccinates) from the
foregoing pilot studies and a fifth unvaccinated male bighorn to evaluate vaccine efficacy. After challenge,
all five bighorns wiU be housed together in a single 200 m2 isolation pen. Subject bighorns will be
challenged at 10 wk after vaccination of primary vaccinates. For challenge, we will use about 1 x 107 CFU
of serotype 2 P. haemolytica strain (WSU-1) sprayed intranasally.Vaccine efficacy will be evaluated by
comparing morbidity, mortality, strain-specific P. haemolytica colonization rates, and humoral immune
responses of vaccinated bigho_rns to the control and to results from a previous study (Kraabel et al. 1998) .
Development of a modified-live Pasteurella trehalosi vaccine for bighorn sheep (McNeil, Lo, and Miller):
We continued developing and evaluating a modified-live Pasteurella trehalosi serotype 10 vaccine strain
for use in bighorn sheep. Highlights of ongoing laboratory technique development and evaluations are
reported.
Polymerase chain reaction: We used polymerase chain reaction (PCR) techniques to amplify a 122 base
pair segment from the 5' end of the leukotoxin gene, as previously described; using the following primers:

5'-GAAITCCCITATGGGAACTAAAC-3'
5'-GTCTGGCCGGCITGGGITAA-3'

�281
Conditions were optimized at 3.5 rnM [Mg++] using genomic DNA prepared by the PUREGENE® method
as template. The thermal cycler was programmed for 94 C for 30 seconds, 59 C for 30 seconds, 72 C for 3
minutes and 30 seconds. lbis was repeated for 30 cycles.
PCR was also utilized to try to increase the amount of ligated product. The following primers were used:
5'-GAATICCCTIATGGGAACTAAAC-3'
5'-CGAAACAATCTAGAGTIGCCAATC-3'
Conditions were optimized at 3.5 rnM [Mg++] using gel purified ligated product as the template. The
thermal cycler was programmed for 94 C for 30 seconds, 64 C for 30 seconds, 72 C for 3 minutes and 30
seconds. This was repeated for 30 cycles.
The above primers (used to amplify the ligated product) were also used to amplify the ligated product once
it had been inserted into the plasmid p2176, as a means of mapping and confirmation.
All PCR products were run on 0. 75 % agarose gels (85 V for 23-45 minutes) and stained with ethidiwn
bromide. Bands were visualized using ultra-violet (UV) light and the image captured by a GelDoc I 000
machine (Bio-Rad Laboratories, Mississauga, ON, Canada).

PCR Product Purification: We purified PCR products to be sequenced or used for further manipulation
using a QIAGEN QIAquick PCR purification kit®. Purified product was run on gels as before purification
to ensure that the band in question was still visible.
I

In instances where extraneous bands were visible, gel extraction was used to isolate the desired product. A
low melting point 1.0 % agarose gel was loaded with product and run at low voltage overnight (8-9 V, 1216 hours). The gel was then stained with ethidiwn bromide and visualized using UV light on a
transillwninator. The desired band was cut out using a sterile scalpel blade and put into a tube. The tube
was heated to melt the agar. lbis material was then purified in the same manner as the non-gel purified
PCR products.

Restriction Enzyme Digestion: Purified 122 hp fragment was digested using Nae! (Promega Corporation,
Madison, WI, USA) with the recommended buffer for I hour at 37 C. The enzyme was then inactivated at
60 C for 15 minutes. This product was ligated to the 1767 hp fragment described previously.
Restriction enzyme digestion was also used for mapping the ligated product. Digestions were performed
using Nae!, Apa! (Promega Corporation, Madison, WI, USA) and Sad (New England Biolabs Ltd.,
Mississauga, ON, Canada). Appropriate buffers were used for each reaction which was carried out at 37
C for I hour. Reactions were terminated by heat inactivation at 60 C for 15 minutes. A sample of product
was run on a 0.75% agarose gel, stained with ethidiwn bromide and photographed.
Restriction enzyme digestion was also used for mapping the plasmid construct (containing the 1889 hp
insert). Digestions were performed using Nae!, Apa!, Sac!, EcoRI, Xbal, San and C/al. Enzymes are
from Amersham Pharmacia Biotech, Baie d'Urfe, Quebec, Canada, unless otherwise indicated previously.
The commercially available plasmid pBluescriptll (Stratagene, Aurora, ON, Canada) was used to
troubleshoot digestion problems.

Blunt End Ligation: Equal volwnes of the fragments to be ligated were mixed with T4 DNA ligase buffer
(Gibco, Burlington, ON, Canada) according to manufacturer's instructions. Ligase (10% final volwne)

�282
was then added and mixed thoroughly. The reaction was left at 16 C O/N. The ligated product was then
run on a gel for visualization as well as used as template in further PCR. The product was then gel
purified as previously described and used as template in further PCR.
Blunt end ligation was also used in the preparation of the construct. Different ratios ofvector:insert were
used to maximize the opportunities for ligation. Conditions were the same as above.
Construct: Plasmid p2176 was digested with EcoRl andXbal in a double digest for I hour at 37 C. The
ligated 1889 hp product was also double digested with the same two enzymes to prepare for ligation with
the plasmid. After the digestion, enzymes were heat-inactivated for 15 minutes at 65 C. The plasmid
digest mixture was then treated with calf intestinal alkaline phosphatase to minimiz.e the chances of
recirculariz.ation. The reactions were then purified and concentrated using GENECLEAN® (BiolOI-Inc,
from BioCan Scientific). These concentrated products were used in a blunt end ligation as reported above.
Following ligation, the plasmid was transformed into competent E. coli cells (HB IO I) as described below.
Preparing Competent E.coli Cells by CaC/2: A single colony of E.coli HBIOI was used to inoculate 3 ml
of LT broth and incubated at 37 C O/N with shaking. This culture was then subcultured 1/40 in LT broth
and incubated with the same conditions for I hour and 15 minutes. This culture was then put on ice for 40
minutes. After centrifugation (5000 rpm) for 5 minutes, the pellet was resuspended in ½ volume of cold,
sterile 50mM CaC12 . This mixture was left on ice for I hour. After centrifugation, the pellet was
resuspended in 1/10 volume of cold, sterile 50mM CaC12• These cells were used after 24 hours at 4 C, at
which time maximum competency for foreign DNA uptake is expected.
Transformation: In small glass tubes, 0.2 ml of competent cell suspension was mixed with IO µl of
potentially ligated insert-plasmid and put on ice for I hour. This was followed by a 2 minute heat-shock at
42 C. Each tube was then supplemented with 0.3 ml of LT broth and left to "recover" at 37 C for 15
minutes. These cells were then plated onto LT agar plates containing ampicillin. The plasmid p2 l 76
carries an ampicillin resistance gene.
Negative controls containing no insert DNA (digested plasmid only) as well as control cells containing no
foreign DNA were used.
Plates were incubated O/N at 37 C. Visible colonies were re-plated and screened by plasmid preparation
and restriction enzyme mapping.
Plasmid Preparations: Plasmid preparations were made by growing the colony to be screened O/N in 20
mis of LT broth containing ampicillin in a 125 ml erlenmyer flask. To incr~e plasmid yield (p2176 is a
low copy plasmid), spectinomycin was added (50 µg/ml final concentration). Plasmid was then purified
using Qiagen's QuickSpin® columns. Plasmid was then run on agarose gels to look for a product of
expected size. Those which were of the expected size were further examined using restriction enzyme
mapping.

RESULTS AND DISCUSSION

Evaluation of a genetically-modified live Pasteurella haemolytica vaccine in bighorn sheep (Miller and
Briggs): Of3 bighorns receiving about 7 x 108 colony forming units (CFUs) ofGMLPhV, I died about 3
days after vaccination and another showed signs of moderately severe respiratory disease from days 2-10
postinoculation (PQ. Although bacteriology results were somewhat confounded by the reported isolation
of a hemolytic P. haemolytica strain from lung tissue, the GMLPhV strain was most likely responsible for

�283
morbidity and mortality in vaccinated bighorns. The sick bighorn recovered without medical intervention,
and both surviving primary vaccinates showed strong elevations in both agglutinating and leukotoxin
neutralizing antibody titers in response to vaccination (Fig. I).
Two previously unvaccinated bighorns housed with the 2 surviving vaccinates beginning at wk 2 (2 weeks
Pl) seroconverted to P. haemolytica serotype 2 2-3 weeks later (Fig. I), suggesting colonization of these incontact animals by GMLPhV strain despite failure to actually isolate GMLPhV strain from either incontact bighorn. Agglutinating antibody responses appeared to be less that those stimulated by primary
vaccination (Fig. IA), and leukotoxin neutralizing antibody responses in secondary vaccinates were
negligible (Fig. 1B). Both in-contact bighorns remanied healthy through 7 weeks postexposure (= wk 9).
Ability of GMLPhV to protect bighorns
from pasteurellosis will be evaluated via
experimental challenge beginning in early
July. Further evaluation of this or a
similar GMLPhV strain hinges on the
vaccine's ability to protect bighorns from
expermental challenge, as well as the
need for further modifications to improve
vaccine strain safety in bighorn sheep.
Development of a modified-live
Pasteurella haemo/ytica vaccine for
bighorn sheep (McNeil, Lo, and Miller):'
Failed attempts to insert the ligated 123
bp-1767 bp fragment into p2176 led to
the discovery of an error that was easily
rectified. A different short fragment ( 122
bp) was prepared in the same way and
ligated to the 1767 bp incorporating a
different restriction enzyme on the 5'-end.
Ligation of the 122 bp fragment to the
1767 bp fragment appears to have been
successful. The product is the
appropriate size, and restriction enzyme
mapping supported our conclusion of
successful ligation. As before, attempts
to use PCR to increase yields for cloning
were disappointing, insofar as there were
extraneous bands. However, gel
purification was used to prepare a high
concentration of ligated product to use in
the subsequent insert-plasmid ligation.

Weeks postinoa.llation

Figure 1. Serological responses of captive bighorn sheep to
GMLPhV. A Agglutination titers rose in both primary (solid lines)
and secondary (dashed lines) vaccinates after direct or indirect
vaccination. B. Leukotoxin neutralizing (LN) titers showed marked
elevation in primaryvaccinates; in contrast, LN titer responses were
relatively weak in secondary vaccinates. An unvaccinated control
showed no change in titers. Different symbols represent different
individual bighorn sheep.

Several recipient E. coli colonies were
recovered. A small nwnber were
screened and carried a plasmid of the appropriate size (~7Kb). Restriction mapping has been encouraging.
One cloned construct (022) shows the most favourable and consistent results. When plasmid from this

�284
clone is used as template in a PCR (using the 5'-primer used to make 122 bp fragment and the 3'-primer
made to use the 1767 bp fragment) a single, very clear band of appropriate size ( 1889 bp) is visualized.
We were concerned about the failure of Nae I digestion to create a single linearized band of 7 Kb, as
expected. However, NaeI also failed to properly digest pBluescriptll, a commercially available plasmid
vector with a single NaeI site. We concluded that the problem lies with either the enzyme or the digestion
technique rather than with the insert in p2 l 76. It is important to sort out the problem with the Nae I
because that is the proposed site for cloning the green fluorescent protein (gfp) gene. Other workers at the
University of Guelph have shown that gfp can be expressed in P. haemolyti(!a.
Short-term plans for continuing this work include PCR to amplify the gfp gene with constructed blunt end
restriction enzyme sites on each end. We hope to successfully clone this gene into the NaeI site on the
plasmid carried in D22. We then will electroporate the plasmid into P. haemolytica TIO CEco. 100) and
replace the existing lktA with our .dlktA-gfp. We anticipate having a vaccine strain available for testing in
captive bighorn sheep sometime in the 00/01 segment.
LITERATURE CITED

Briggs, R. E., and F. M. Tatum. 1999. New mucosal vaccine in beef cattle imparts rapid resistance to
pneumonic pasteurellosis after mass-medicating on feed. USDA, REE, ARS, NADC, Ames IA.
Unpublished report presented at USAHA, San Diego, CA, October 1999, 4 pp.
Foreyt, W.J. 1989. Fatal Pasteurella haemolytica pneumonia in bighorn sheep after direct contact with
clinically normal domestic sheep. Am. J. Vet. Res. 50:341-343.
Foreyt, W.J. and R. M. Silflow. 1996. 1Attempted protection of bighorn sheep (Ovis canadensis) from
pneumonia using a nonlethal cytotoxic strain of Pasteurella haemolytica, biotype A, serotype 11. J.
Wildl. Dis. 32:315-321.
Foreyt, W.J., K.P. Snipes, and R. W. Kasten. 1994. Fatal pneumonia following inoculation of healthy
bighorn sheep withPasteurella haemolytica from healthy domestic sheep. J. Wildl. Dis. 30:137-145.
Green, A. L., N. M. DuTeau, M. W. Miller, J. Triantis, and M. D. Salman. 1999. Polymerase chain
reaction techniques for differentiating cytotoxic and noncytotoxic Pasteurella trehalosi from Rocky
Mountain bighorn sheep. American Journal of Veterinary Research 60:583-588.
Kraabel, B.J., and M.W. Miller. 1997. Effect of simulated stress on susceptibility of bighorn sheep
neutrophils to Pasteurella haemolytica leukotoxin. J. Wildl. Dis. 33:558-566.
Kraabel, B.J., M.W. Miller, J.A. Conlon, and H. McNeil. 1998. Evaluation ofa multivalent
Pasteurella haemolytica vaccine in bighorn sheep: Protection from experimental challenge. J. Wildl.
Dis. 34:325-333.
Miller, M. W. 2000. Pasteurellosis. In Infectious Diseases of Wild Mammals, 3rd edition, E. S. Williams
and I. K. Barker, eds. Iowa State University Press, Ames, Iowa, in press.
Miller, M. W., J. A. Conlon, H.J. McNeil, J.M. Bulgin, and A. C. S. Ward. 1997. Evaluation of a
multivalent Pasteurella haemolytica vaccine in bighorn sheep: safety and serologic responses. J.
Wildl. Dis. 33: 738-748.
Silflow, RM., Foreyt, W.J., and R.W. Leid. 1993. Pasteurella haemolytica cytotoxin dependant killing
of neutrophils from bighorn and domestic sheep. J. Wildl. Dis. 29:30-35.

Prepared by _ _ _ _ _ _ _ _ _ _ __
Michael W. Miller
Wildlife Research Veterinarian

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                  <text>241
Colorado Division of Wildlife
Wildlife Research Report
July 1998

JOB PROGRESS REPORT

state of

Colorado

cost center 3430

Project No.

W-153-R-11

Mammals Program

3004

Work Package No.
Task No.

1

Period covered:
Author:

&amp;2

:

Management of other ungulates
Pronghorn Data Analysis_and Reporting

July 1, 1997 - June 30, 1998

T.M. Pojar

Abstract
A herd structure estimate was made on the Middle Park pronghorn population
during August, 1997 amd the total winter population estimate was made during
January 1998. This information, along with like information since 1986 was
incorporated into a spreadsheet population model. This model was provided to
management personnel for.projecting effects of various management options.
It
was also used in public meetings for exploring public opinion of the proposed
options.
A manuscript was prepared summarizing the results of experiments in pronghorn
inventory methods. It was submitted to the Journal of Wildlife Management and
rejected on the basis that the topic addressed a relatively narrow issue. The
manuscript will be modified and submitted either to the Wildlife Society
Bulletin or the African Journal of Wildlife Management. The abstract is
included in the results section.

�243
PRONGHORN DATA ANALYSIS AND REPORTING
Thomas M. Pojar

P,H,QBJECTIYES
Task 1 Test for density dependence in Middle Park population parameters and
summarize the findings in manuscript format suitable for submission to a
professional wildlife management or ecological journal.
Task 2 Analyze and summarize the results of experiments in pronghorn inventory
methods and report the findings in manuscript format suitable for submission
to a professional wildlife management journal.

SEGMENT OBJECTIVES
Task 1 Test for density dependence in Middle Park population parameters and
summarize the findings in manuscript format suitable for submission to a
professional wildlife management or ecological journal.
Task 2 Analyze and summarize the results of experiments in pronghorn inventory
methods and report the findings in manuscript format suitable for submission

RESULTS

Task 1 Key population information in the form of herd structure estimates and
a count of the wintering population was collected. This was included in the
population data set that began in 1986 and used to build a spreadsheet
population model. This model was used to project population responses to
proposed management options and was provided to managment personnel. The
overall objective of Task 1 was not fulfilled during this segment.
Task 2 A manuscript was prepared that analyzed and summarized the results of
experiment in pronghorn invenorty methods. It was rejected by the Journal of
Wildlife Management as having too narrow a focus. The manuscript will be
modified and sumbitted either to the Wildlife Society Bulletin or the African
Journal of Wildlife. The following is the abstract for this article.
PRONGBORH DENSITY ESTIMATES:
HELICOPTER QUADRAT SURVEYS

COMPARISON OF FIXED-WING LIRE TRANSECT ARD

THOMAS M. POJAR1 , Colorado Division of Wildlife, 317 w. Prospect Road, Fort
Collins, CO 80526, USA
DAVID c. BOWDEN, Department of Statistics, Colorado State University, Fort
Collins, CO 80523, USA
JEFF D. MADISON, Colorado Division of Wildlife, P.O. Box 1181, Meeker, CO
81641, USA
Estimates of pronghorn (Antilocapra americana) density in northwest
Colorado sagebrush (Artemisia spp.) steppe habitat were compared using fixedwing line transect and helicopter quadrat surveys. Fixed-wing line transects
offer wildlife managers a survey method that is both economical and
statistically valid but this technique has not been evaluated with a standard
or known density for pronghorn. We used the helicopter quadrat survey method
as the standard and compare density estimates to fixed-wing line transect
Abstract:

�244
surveys. Fixed-wing line transect estimates were always less than quadrat
estimates (t=0.682, P = 0.050) and were 83%, 69%, and 83% of the quadrat
estimates respectively, for 3 years data.
In addition, we analyzed the first
and second line transect intervals as narrow strips of 50 m and 100 m,
respectively. The narrow strips were not different from either the quadrats
or lines (P &gt; 0.070) and may offer managers a method that combines the economy
of line transects with the analysis simplicity of quadrat data. We conclude
that line transect density estimates should be adjusted upward by considering
them approximately 0.78 (SE= 6.32) of quadrat estimates. At the density of
pronghorn encountered in this study (approximately 5/km'), the cost of fixedwing line transect sampling for large scale management application is about 510% of the cost of helicopter quadrats for similar precision.

Prepared
Wildlife Researcher

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                  <text>295

Colorado Division of Wildlife
Wildlife Research Report
July 1999

JOB FINAL REPORT

State of _ _ _ _ _ _C=o=l=o=rad=o_ _ _ __
Project No. ----~W'-'---......1....5___
3-___R___--=12"---_ __
Work Plan No.
3004
Job No. - - - - - - - - ' 4 ' - - - - - - -

----~~-----

Mammals Research
Mountain Goat Investigations
Mountain goat numbers, distribution, and
dispersal in the northern Collegiate range.

Period Covered: July 1, 1998 - June 30, 1999
Author: D. F. Reed

ABSTRACT
A manuscript titled "Mark-resight population estimates of mountain goats in Colorado" (Reed and Vayhinger
[in preparation]) was prepared. Additionally, a manuscript titled "A conceptual interference competition model
for introduced mountain goats" was prepared and submitted to the Journal of Wildlife Management (Reed [in
review]) and collaboration with Natural Resources Ecology Laboratory (NREL) occurred to extent and refine
some of the Mt Evans data.

�296

�297

MOUNTAIN GOAT NUMBERS, DISTRJBUTION, AND DISPERSAL IN THE NORTHERN
COLLEGIATE RANGE
Dale F. Reed

P.N. OBJECTIVE
To improve estimates of mountain goat populations by mark-resight methodology, to determine distribution,
and to estimate dispersal rates in an increasing mountain goat population.

SEGMENT OBJECTIVE
I. Analyze data and prepare manuscripts.

STUDY AREA
The study area is described in the Program Narrative (Reed 1995).

ME1HODS AND MATERIALS
The methods are outlined in the Program Narrative and 1995 and 1996 progress reports (Appendix A in Reed
1995, Reed 1996).

RESULTS
Results have been reported in Reed ( 1996), Reed ( 1997), and in a manuscript titled "Mark-resight population
estimates of mountain goats in Colorado" (Reed and Vayhinger [in preparation]. Additionally, a manuscript
titled "A conceptual interference competition model for introduced mountain goats" was prepared and
submitted to the Journal of Wildlife Management (Reed [in review]) and collaboration with NREL (ref Rocky
Mountain National. Park contract) occurred to extent and refine some of the Mt Evans data by evaluating
spatial distribution, habitat segregation, and implications of competitive displacement.

LITERATURE CITED
Reed, D. F. 1995. Mountain goat numbers, distribution, and dispersal in the northern Collegiate range. Colo.
Div. Wildl. Res. Rep. July, 223-234pp.
Reed, D. F. 1996. Mountain goat numbers, distribution, and dispersal in the northern Collegiate range. Colo.
Div. Wildl. Res. Rep. July, 255-263pp.
; .·
Reed, D. F. 1997. Mountain goat numbers, distribution, and dispersal in the northern Collegiate range. Colo.
Div. Wildl. Res. Rep. July, 165-167pp.

Prepared by _ _ _ _ _ __
DaleF. Reed

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