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Type:Article
Subject:Male/female ratio
Mule deer
<em>Odocoileus hemionus</em>
Rates of pregnancy
Sex ratio
Synchrony
Timing of parturition
Ungulate management
Description:Evaluating how management practices influence the population dynamics of ungulates may enhance future management of these species. For example, in mule deer (Odocoileus hemionus), changes in male/female ratio due to male-biased harvest may alter rates of pregnancy, timing of parturition, and synchrony of parturition if inadequate numbers of males are present to fertilize females during their first estrous cycle. If rates of pregnancy or parturition are influenced by decreased male/female ratios, recruitment may be reduced (e.g., fewer births, later parturition resulting in lower survival of fawns, and a less synchronous parturition that potentially increases susceptibility of neonates to predation). Our objectives were to compare rates of pregnancy, synchrony of parturition, and timing of parturition between exploited mule deer populations with a relatively high (Piceance, CO, USA; 26 males/100 females) and a relatively low (Monroe, UT, USA; 14 males/100 females) male/female ratio. We determined rates of pregnancy via ultrasonography and timing of parturition via vaginal implant transmitters. We found no differences in rates of pregnancy (98.6% and 96.6%; z = −0.821; P = 0.794), timing of parturition (estimate = 1.258; SE = 1.672; t = 0.752; P = 0.454), or synchrony of parturition (F = 1.073 P = 0.859) between Monroe Mountain and Piceance Basin, respectively. The relatively low male/female ratio on Monroe Mountain was not associated with a protracted period of parturition. This finding suggests that relatively low male/female ratios typical of heavily harvested populations do not influence population dynamics because recruitment remains unaffected. [show more]
Description:

Funding: This research was funded by Colorado Parks and Wildlife (16-IAA-82320) and the Colorado State University Energy Institute. Colorado State University’s Intuitional Animal Care and Use Committee approved this research under protocols 15-6086A and 16-6367.Abstract: Oil development has expanded dramatically in Colorado over the last decade. Associated with this rapid expansion has been a significant increase in the number of accidental releases into the environment. On January 2013, West Creek which flows along a scenic byway in Unaweep Canyon, Colorado, was impacted by a petroleum spill from an overturned tanker truck. 22,700 liters of gasoline and 7,300 liters of diesel discharged into the stream killing an estimated 1,206 Brown Trout, Salmo trutta, and 8,172 Mottled Sculpin, Cottus bairdii. Subsequent electrofishing surveys indicated that the fishery was not quickly recovering particularly with regard to Mottled Sculpin populations, but also Brown Trout. In June and October 2015, as part of ongoing efforts to determine long term effects of this spill, we explored health indicators across multiple levels of biological organization. Histopathological abnormalities (e.g., ectopic neural tissue, cystic kidney, increased melanomacrophage aggregates) were observed in Mottled Sculpin collected from the spill site and nearby downstream sites. Altered benthic macroinvertebrate community structure was observed at the spill site compared with a reference site one kilometer upstream. Interestingly, a GC-MS finger-printing analysis of polycyclic aromatic hydrocarbons (PAHs) in stream sediment revealed that PAH concentrations were typical of minimally impacted streams flowing adjacent to roads. These results suggest that effects of the spill were persisting after contaminant concentrations had returned to ‘normal’ by Fall 2015. Subsequently, we conducted two mesocosm experiments, using naturally colonized benthic macroinvertebrate communities. Exposure to simulated spill conditions caused concentration-dependent macroinvertebrate drift and substantial mortality that occurred rapidly after the spills were initiated and at lower concentrations than expected. In addition, concentration-dependent lethal and sub-lethal effects were observed in Rainbow Trout, Oncorhynchus mykiss, during simulated spill bioassays. Periphyton biofilms were also adversely affected. We conclude that petroleum spills in coldwater streams risk adverse acute, chronic, lethal and sub-lethal effects to aquatic communities across numerous levels of biological organization. And these effects were evident after the 2013 West Creek petroleum spill. Moreover, by utilizing field observations, mesocosms and bioassays we gained insights into consequences of petroleum spills using an ecotoxicological weight-of evidence approach. Importantly, the methods used in this project can be employed at future spill events as field useful bioassessment techniques to aid in the process of holding responsible parties appropriately accountable for damages to stream communities.

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Type: Article
Subjects: Alces alces
Calving success
Colorado
Moose, nutrition
Reproduction
Salix
Willow
Type:Article
Subject:Alces alces
Calving success
Colorado
Moose, nutrition
Reproduction
Salix
Willow
Description:Across much of North America, populations of moose (Alces alces) are declining because of disease, predation, climate change, and anthropogenic-driven habitat loss. Contrary to this trend, populations of moose in Colorado, USA, have continued to grow. Studying successful (i.e., persistent or growing) populations of moose can facilitate continued conservation by identifying habitat features critical to persistence of moose. We hypothesized that moose using habitat with higher quality willow (Salix spp.) would have a higher probability of having a calf-at-heel (i.e., calving success). We evaluated moose calving success using repeated ground observations of collared individuals with calves in an occupancy model framework to account for detection probability. We then evaluated the impact of willow habitat quality and nutrition on moose calving success by studying 2 spatially segregated populations of moose in Colorado. Last, we evaluated correlations between willow characteristics (browse intensity, height, cover, leaf length, and species) and willow nutrition (dry matter digestibility [DMD]) to assess the utility of using those characteristics to assess willow nutrition. We found willow height and cover had a high probability of being positively associated with higher individual-level calving success. Willow DMD, browse intensity, and leaf length were not predictive of individual moose calving success; however, the site with higher mean DMD consistently had higher mean estimates of calving success for the same year. Our results suggest surveying DMD is likely not a useful metric for assessing differences in calving success of individual moose but may be of use at population levels. Further, the assessment of willow morphology and density may be used to identify areas that support higher levels of moose calving success. [show more]
ID: Elk
Type:
Subjects:
Elk
Description:

CPW website species profile: ElkElk serve as one of Colorado’s most ecologically and economically important mammals. Therefore, it is critical that wildlife managers have the information and tools they need to properly manage elk populations. This involves understanding changes in habitat, climate, predator communities, and human development and how these changes impact elk population demography and behavior.

Current Elk Research Projects:

Completed Elk Research Projects
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Type: Article
Subjects: Brucellosis Brucella abortus
Cross-species pathogen spillover
Elk Cervus canadensis
Human–wildlife conflict
Partial migration
Resource selection function
Wildlife disease
Type:Article
Subject:Brucellosis Brucella abortus
Cross-species pathogen spillover
Elk Cervus canadensis
Human–wildlife conflict
Partial migration
Resource selection function
Wildlife disease
Description:
  1. Wildlife migrations provide important ecosystem services, but they are declining. Within the Greater Yellowstone Ecosystem (GYE), some elk Cervus canadensis herds are losing migratory tendencies, which may increase spatiotemporal overlap between elk and livestock (domestic bison Bison bison and cattle Bos taurus), potentially exacerbating pathogen transmission risk.
  2. We combined disease, movement, demographic and environmental data from eight elk herds in the GYE to examine the differential risk of brucellosis transmission (through aborted foetuses) from migrant and resident elk to livestock.
  3. For both migrants and residents, we found that transmission risk from elk to livestock occurred almost exclusively on private ranchlands as opposed to state or federal grazing allotments. Weather variability affected the estimated distribution of spillover risk from migrant elk to livestock, with a 7%–12% increase in migrant abortions on private ranchlands during years with heavier snowfall. In contrast, weather variability did not affect spillover risk from resident elk.
  4. Migrant elk were responsible for the majority (68%) of disease spillover risk to livestock because they occurred in greater numbers than resident elk. On a per-capita basis, however, our analyses suggested that resident elk disproportionately contributed to spillover risk. In five of seven herds, we estimated that the per-capita spillover risk was greater from residents than from migrants. Averaged across herds, an individual resident elk was 23% more likely than an individual migrant elk to abort on private ranchlands.
  5. Our results demonstrate links between migration behaviour, spillover risk and environmental variability, and highlight the utility of integrating models of pathogen transmission and host movement to generate new insights about the role of migration in disease spillover risk. Furthermore, they add to the accumulating body of evidence across taxa that suggests that migrants and residents should be considered separately during investigations of wildlife disease ecology. Finally, our findings have applied implications for elk and brucellosis in the GYE. They suggest that managers should prioritize actions that maintain spatial separation of elk and livestock on private ranchlands during years when snowpack persists into the risk period.
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Description:

Current or Recent Research Projects

  • Wolf ecology
    • Wolf habitat selection and movement during re establishment in Colorado
  • Wildlife management
    • Statistical estimation of wolf abundance
    • Quantifying the effects of management practices and disease on wildlife harvest
  • Wolf-livestock dynamics
    • Identifying and examining potential nonconsumptive effects of wolves on cattle
  • Predator-prey dynamics
    • Examining wolf and hunter effects on elk movement, space use, and aggregation patterns
    • Quantifying conditions under which predators influence prey diseases​

Areas of Interest and Expertise

My background is in terrestrial wildlife ecology with a focus on carnivores (primarily gray wolves) and infectious diseases. I am interested in many facets of wildlife ecology, especially social behaviors, predator-prey interactions, population dynamics, and disease dynamics. My work intersects wildlife ecology, wildlife management, statistics, and disease ecology.​

Select Publications

Education

  • Ph.D., Ecology – Pennsylvania State University, 2021
  • B.S., Wildlife Biology –​ University of Montana, 2015 

Current or Recent Positions

  • Wildlife Research Scientist – Colorado Parks and Wildlife, 2022-Present
  • Postdoctoral Associate –​ Wisconsin Cooperative Wildlife Research Unit, Dept. of Forest and Wildlife Ecology, University of Wisconsin-Madison, 2020-2022

Contact Information

317 W. Prospect Rd.​Fort Collins, CO 80526

Email: ellen.brandell@stat​e.co.us​

Phone: ​970-698-0252

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Description:Our researchers have set out to evaluate how human recreation may be influencing Colorado's elk populations and created a film titled "Emblems of the West" to help tell that story.
Type: Article
Subjects: Biotic interactions
Canada lynx
<em>Lepus americanus</em>
Canada lynx
Niche theory
Predator–prey system
Snowshoe hare
Species distribution modeling
Tropic interaction distribution model
Type:Article
Subject:Biotic interactions
Canada lynx
<em>Lepus americanus</em>
Canada lynx
Niche theory
Predator–prey system
Snowshoe hare
Species distribution modeling
Tropic interaction distribution model
Description:Niche theory is a well-established concept integrating a diverse array of environmental variables and multispecies interactions used to describe species geographic distribution. It is now customary to employ species distribution models (SDMs) that use environmental variables in conjunction with species location information to characterize species' niches and map their geographic ranges. The challenge remains, however, to account for the biotic interactions of species with other community members on which they depend. We show here how to connect species spatial distribution and their dependence with other species by modeling spatially explicit predator–prey interactions, which we call a trophic interaction distribution model (TIDM). To develop the principles, we capitalized on data from Canada lynx (Lynx canadensis) reintroduced into Colorado. Spatial location information for lynx obtained from telemetry was used in conjunction with environmental data to construct an SDM. The spatial locations of lynx–snowshoe hare encounters obtained from snow-tracking in conjunction with environmental data were used to construct a TIDM. The environmental conditions associated with lynx locations and lynx–hare encounters identified through both SDM and TIDM revealed an initial transient phase in habitat use that settled into a steady state. Nevertheless, despite the potential for the SDM to broadly encompass all lynx hunting and nonhunting spatial locations, the spatial extents of the SDM and TIDM differed; about 40% of important lynx–snowshoe hare locations identified in the TIDM were not identified in the lynx-only SDM. Our results encourage greater effort to quantify spatial locations of trophic interactions among species in a community and the associated environmental conditions when attempting to construct models aimed at projecting current and future species geographic distributions. [show more]
Type:Article
Subject:Animal movement
Energy development
Home range
<em>Odocoileus hemionus</em>
Utilization distribution
Description:

Aim

The space an animal uses over a given time period must provide the resources required for meeting energetic needs, reproducing and avoiding predation. Anthropogenic landscape change in concert with environmental dynamics can strongly structure space-use. Investigating these dynamics can provide critical insight into animal ecology, conservation and management.

Location

The Piceance Basin, Colorado, USA.

Methods

We applied a novel utilization distribution estimation technique based on a continuous-time correlated random walk model to characterize range dynamics of mule deer during winter and summer seasons across multiple years. This approach leverages second-order properties of movement to provide a probabilistic estimate of space-use. We assessed the influence of environmental (cover and forage), individual and anthropogenic factors on interannual variation in range use of individual deer using a hierarchical Bayesian regression framework.

Results

Mule deer demonstrated remarkable spatial philopatry, with a median of 50% overlap (range: 8–78%) in year-to-year utilization distributions. Environmental conditions were the primary driver of both philopatry and range size, with anthropogenic disturbance playing a secondary role.

Main conclusions

Philopatry in mule deer is suspected to reflect the importance of spatial familiarity (memory) to this species and, therefore, factors driving spatial displacement are of conservation concern. The interaction between range behaviour and dynamics in development disturbance and environmental conditions highlights mechanisms by which anthropogenic environmental change may displace deer from familiar areas and alter their foraging and survival strategies.

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