561 items found
Type: Text
Subjects: Birds of prey
Wildlife management
Wildlife management
Type:Text
Subject:Birds of prey
Wildlife management
Wildlife management
Description:Where they exist, raptor monitoring databases have generated important insights into various aspects of raptor ecology, and can provide a sound foundation for specific management priorities for individual species or within the larger context of managing targeted habitats and ecosystems (Greenwood 2007). CPW has a statewide raptor nest database, developed by Bob Sacco (GIS Unit), which currently contains records for ~9,000 nest records going back to the 1970s. Currently, the nest database is primarily being used by CPW at a site-specific scale in the oil and gas comment process (CO House Bill 1298) and other local-scale land use input. The potential of this database to assess raptor populations at regional or statewide scales, and the field protocols used to provide records for this database, have not been thoroughly assessed. Other data sources have potential to contribute to our understanding of Colorado raptors, including eBird, Breeding Bird Survey, and Colorado Breeding Bird Atlas. By exploring the possibility of integrating these various datasets, we hope to generate a more comprehensive picture of raptor abundance and occupancy across the state, with the eventual goal being to provide a more concrete understanding of raptor population trends for management purposes. [show more]
Type: Article
Subjects: Razorback Suckers
<em>Xyrauchen texanus</em>
Colorado River basin
Reproduction
PIT-tagged
<em>Xyrauchen texanus</em>
Colorado River basin
Reproduction
PIT-tagged
Type:Article
Subject:Razorback Suckers
<em>Xyrauchen texanus</em>
Colorado River basin
Reproduction
PIT-tagged
<em>Xyrauchen texanus</em>
Colorado River basin
Reproduction
PIT-tagged
Description:Endangered and endemic Razorback Suckers Xyrauchen texanus of the Colorado River basin largely spawn in main-stem rivers and reservoirs. While documenting other native fish use of two intermittent tributaries of the Gunnison River, Colorado, USA, we detected PIT-tagged Razorback Suckers during the 2015–2019 spawning seasons (April–June) and captured reproductively ready individuals. Because the species is rarely documented in small tributaries, we highlight this occurrence. Prior to 2019, up to 30 individual Razorback Suckers were detected annually in Roubideau Creek, a tributary to the Gunnison River near Delta, Colorado. In 2019, use increased as we detected 110 individual Razorback Suckers in Roubideau Creek, and, for the first time, we handled or detected seven in Cottonwood Creek. These fish represented multiple age-classes of hatchery-reared fish repatriated to the Gunnison River to aid recovery. We collected and identified 1,171 larval catostomids from Cottonwood Creek, but none were Razorback Suckers, and even though ripe adults were collected, it remains unclear if reproduction occurred. We suspect that high runoff in 2019 drove increased use of the system. Presence of Razorback Suckers in five consecutive years indicated that intermittent tributaries might be of greater importance than previously thought for this species, and these streams warrant further investigation and protection. [show more]
Type:
Subjects:
Type: Article
Subjects: Kernel density estimation
Space use
Spatial statistics
Utilization distribution
Space use
Spatial statistics
Utilization distribution
Type:Article
Subject:Kernel density estimation
Space use
Spatial statistics
Utilization distribution
Space use
Spatial statistics
Utilization distribution
Description:
[show more]
Summary
- Analyses based on utilization distributions (UDs) have been ubiquitous in animal space use studies, largely because they are computationally straightforward and relatively easy to employ. Conventional applications of resource utilization functions (RUFs) suggest that estimates of UDs can be used as response variables in a regression involving spatial covariates of interest.
- It has been claimed that contemporary implementations of RUFs can yield inference about resource selection, although to our knowledge, an explicit connection has not been described.
- We explore the relationships between RUFs and resource selection functions from a hueristic and simulation perspective. We investigate several sources of potential bias in the estimation of resource selection coefficients using RUFs (e.g. the spatial covariance modelling that is often used in RUF analyses).
- Our findings illustrate that RUFs can, in fact, serve as approximations to RSFs and are capable of providing inference about resource selection, but only with some modification and under specific circumstances.
- Using real telemetry data as an example, we provide guidance on which methods for estimating resource selection may be more appropriate and in which situations. In general, if telemetry data are assumed to arise as a point process, then RSF methods may be preferable to RUFs; however, modified RUFs may provide less biased parameter estimates when the data are subject to location error.
Type: Text
Subjects: Cutthroat trout
Type:Text
Subject:Cutthroat trout
Description:Abstract: The discovery of a distinct lineage of Cutthroat Trout in museum specimens collected from the San Juan basin precipitated an intensive search for any remaining extant populations across the putative native range of this fish. Tissue samples from every known Cutthroat Trout population in the basin were assembled and analyzed with molecular methods. Of these, eight waters harbored Cutthroat Trout with mitochondrial DNA markers that placed them in the San Juan clade (a monophyletic lineage closely aligned with another Colorado River Cutthroat Trout lineage native to the headwaters of the Colorado, Dolores, and Gunnison rivers). Analysis of nuclear DNA amplified fragment length polymorphism markers also suggested they were distinct, with no evidence of introgressive hybridization with Rainbow Trout or Yellowstone Cutthroat Trout. We recommend that morphological studies be conducted on these same fish to evaluate if they can be distinguished with morpho-meristic traits as well. In this report we discuss support for considering these fish as a distinct unit of biodiversity worthy of conservation, as well as the current status of these eight populations. [show more]
ID: Relating the movement of a rapidly migrating ungulate to spatiotemporal patterns of forage quality
Type: Article
Subjects: Fecal nitrogen
Forage quality
Migration
Mule deer
Normalized difference vegetation index
Forage quality
Migration
Mule deer
Normalized difference vegetation index
Type:Article
Subject:Fecal nitrogen
Forage quality
Migration
Mule deer
Normalized difference vegetation index
Forage quality
Migration
Mule deer
Normalized difference vegetation index
Description:Migratory ungulates exhibit recurring movements, often along traditional routes between seasonal ranges each spring and autumn, which allow them to track resources as they become available on the landscape. We examined the relationship between spring migration of mule deer (Odocoileus hemionus) and forage quality, as indexed by spatiotemporal patterns of fecal nitrogen and remotely sensed greenness of vegetation (Normalized Difference Vegetation Index; NDVI) in spring 2010 in the Piceance Basin of northwestern Colorado, USA. NDVI increased throughout spring, and was affected primarily by snow depth when snow was present, and temperature when snow was absent. Fecal nitrogen was lowest when deer were on winter range before migration, increased rapidly to an asymptote during migration, and remained relatively high when deer reached summer range. Values of fecal nitrogen corresponded with increasing NDVI during migration. Spring migration for mule deer provided a way for these large mammals to increase access to a high-quality diet, which was evident in patterns of NDVI and fecal nitrogen. Moreover, these deer “jumped” rather than “surfed” the green wave by arriving on summer range well before peak productivity of forage occurred. This rapid migration may aid in securing resources and seclusion from others on summer range in preparation for parturition, and to minimize detrimental factors such as predation, and malnutrition during migration. [show more]
Type:
Subjects:
ID: Reproductive ecology and population viability of alpine-endemic ptarmigan populations in Colorado
Type: Text
Subjects: Wildlife Conservation
Ecology
Ecology
Type:Text
Subject:Wildlife Conservation
Ecology
Ecology
Description:Understanding factors regulating populations is a fundamental goal of population ecology. Life-history traits such as survival and fecundity are key vital rates responsible for population change and may vary across elevational gradients. At the upper end of this gradient, the alpine zone, populations are faced with extremely short growing seasons, unpredictable winter conditions dictated by snowpack, and the continued threat of habitat loss due to temperatures increasing beyond the range that defines these cold systems. To date, few studies have addressed population regulation of alpine-endemic species in the context of the aforementioned factors. I used long-term demographic data collected over a 51-year period at two study sites (Mt. Evans and Trail Ridge) together with a contemporary field study (2013- 2015) at three sites (Mt. Evans, Trail Ridge, and Mesa Seco) to examine factors regulating alpine-endemic white-tailed ptarmigan (Lagopus leucura) in Colorado. [show more]
Type: Article
Subjects: Natural gas development
<em>Odocoileus hemionus</em>
Survival
<em>Odocoileus hemionus</em>
Survival
Type:Article
Subject:Natural gas development
<em>Odocoileus hemionus</em>
Survival
<em>Odocoileus hemionus</em>
Survival
Description:Natural gas development is increasing across North America and causing concern over the potential impacts on wildlife populations and their habitat, particularly for ungulate species. Understanding how this development impacts reproductive success metrics that are influential for ungulate population dynamics is important to guide management of ungulates. However, the influences of natural gas development on reproductive success metrics of mule deer Odocoileus hemionus have not been studied. We used statistical models to examine the influence of natural gas development and temporal factors on reproductive success metrics of mule deer in the Piceance Basin, northwest Colorado during 2012–2014. We focused on study areas with relatively high or low levels of natural gas development. Pregnancy and in utero fetal rates were high and statistically indistinguishable between study areas. Fetal survival rates increased over time and survival was lower in the high versus low development study areas in 2012 possibly influenced by drought coupled with habitat loss and fragmentation associated with development. Our novel results suggest managers should be concerned with the influences of development on fetal survival, particularly during extreme environmental conditions (e.g. drought) and our results can be used to guide development planning and/or mitigation. Developers and wildlife managers should continue to collaborate on development planning, such as implementing habitat treatments to improve forage availability and quality, minimizing disturbance to hiding and foraging habitat particularly during parturition, directional drilling to minimize pad disturbance density to increase fetal survival in developed areas. [show more]
Type:
Subjects: Whirling disease
Rainbow Trout
Rainbow Trout
Subject:Whirling disease
Rainbow Trout
Rainbow Trout
Description:Whirling disease-resistant rainbow trout development and post-stocking survival and recruitment evaluations in the Upper Colorado River