Evaluating Factors Influencing Elk Recruitment in Colorado
description: Led By: Nathaniel Rayl, Mat Alldredge, and Chuck Anderson Study Areas Bear’s Ears elk herd (DAU E-2) Trinchera elk herd (DAU E-33) Uncompahgre Plateau elk herd (DAU E-20) Project Status Ongoing Research Objectives To estimate calf and adult female survival and cause-specific mortality rates To quantify pregnancy rates and nutritional condition To evaluate factors influencing survival, pregnancy rates, and nutritional condition Project Description In Colorado, elk are an important natural resource valued for ecological, consumptive, aesthetic, and economic reasons. In 1910, Colorado had less than 1,000 elk; today, the state population is estimated to be the largest in the country, with more than 290,000 elk. Over the last two decades, however, Colorado Parks and Wildlife has become increasingly concerned about declining calf recruitment (the number of calves making it to adulthood). In 2017, researchers began a 2-year pilot study to investigate factors influencing elk recruitment in two study areas in the state. The initial pilot project was expanded into a 3rd study area in 2019 and the research continues to better understand elk population dynamics in Colorado and determine how predators, habitat, and weather conditions are impacting elk recruitment in Colorado. Reports: Pilot Study: Elk Recruitment and Habitat Use in Colorado (2017-2018) Evaluating Factors Influencing Elk Recruitment in Colorado (2019-current) Publications: Crews, S., N.D. Rayl, M.W. Alldredge, E.J. Bergman, C.R. Anderson Jr., E.H. VanNatta, J.D. Holbrook, and G. Bastille-Rousseau. 2025. Hierarchy in structuring of resource selection: understanding elk selection across space, time, and movement strategies. Ecology and Evolution 15:e71097. Crews, S., N.D. Rayl, M.W. Alldredge, E.J. Bergman, C.R. Anderson Jr., and G. Bastille-Rousseau. 2025. Drivers of spring migration phenology in Rocky Mountain elk. Scientific Reports 15:7807.
creator: Rayl, Nathaniel
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Response of Elk to Human Recreation at Multiple Scales
description: Led By Eric Bergman, Nathaniel Rayl Study Areas Avalanche Creek elk herd (DAU E-15) Bear’s Ears elk herd (DAU E-2) Project Status: Ongoing Research Objectives To assess how elk respond to human recreation To evaluate the influence of human recreation on elk distribution To estimate calf and adult female survival and cause-specific mortality rates To quantify pregnancy rates and nutritional condition To evaluate factors influencing survival, pregnancy rates, and nutritional condition Project Description In Colorado, outdoor recreation contributes 511,000 jobs, $62.5 billion in economic output, and $9.4 billion in local, state, and federal tax revenue. Thus, the economies of Colorado, its counties, and its communities, rely on managing the landscape for a multitude of outdoor recreational opportunities. The sensitivity of elk to human presence and human activity has been a topic of interest for many decades. In Colorado, increasing public concerns over human recreational use have coincided with declines in elk productivity, but a direct relationship to this activity in Colorado remains unaddressed. This research aims to better understand the influence of human recreation on elk behavior and distribution. Reports Response of Elk To Human Recreation at Multiple Scales: Demographic Shifts and Behaviorally Mediated Fluctuations in Local Abundance (2019-Current) Publications Crews, S., N.D. Rayl, M.W. Alldredge, E.J. Bergman, C.R. Anderson Jr., E.H. VanNatta, J.D. Holbrook, and G. Bastille-Rousseau. 2025. Hierarchy in structuring of resource selection: understanding elk selection across space, time, and movement strategies. Ecology and Evolution 15:e71097. Crews, S., N. D. Rayl, M. W. Alldredge, E. J. Bergman, C. R. Anderson Jr., and G. Bastille-Rousseau. 2025. Drivers of spring migration phenology in Rocky Mountain elk. Scientific Reports 15:7807 Bastille-Rousseau, G., S. A. Crews, E. B. Donovan, M. E. Egan, N. T. Gorman, J. B. Pitman, A. M. Weber, E. M. Audia, M. R. Larr…
creator: Rayl, Nathaniel
rights: IN COPYRIGHT - NON-COMMERCIAL USE PERMITTED

Spatiotemporal Effects of Human Recreation on Elk Behavior
description: Led by Eric VanNatta, Nathaniel Rayl, Eric Bergman, Joe Holbrook Study Areas Bear’s Ears elk herd (DAU E-2) Project Status Ongoing Research Objectives To estimate the distribution of human recreation during four time periods relevant to adult female elk: calving, calf-rearing, hunting, and post-hunting To evaluate whether adult female elk alter their movements and habitat selection when exposed to different intensities of human recreation. Project Description The influence of recreational disturbance on ungulate populations is of particular interest to wildlife managers in Colorado, as there is growing concern about its potential impacts within the state. Currently, the western United States is experiencing some of the highest rates of human population growth in the country, with growth in rural and exurban areas frequently outpacing growth in urban areas. Understanding potential impacts of recreational activity on elk spatial ecology in Colorado is critical for guiding management actions, as altered movements may result in reduced foraging time and higher energetic costs, which may decrease fitness. This research will evaluate potential impacts of recreational activities on elk from the resident portion of the Bear’s Ears elk herd in Colorado. Results from this research will be used to develop management recommendations to mitigate any negative effects of recreational activity on elk. Reports Spatiotemporal Effects of Human Recreation on Elk Behavior: an Assessment Within Critical Time Stages (2019-current) Publications Crews, S., N.D. Rayl, M.W. Alldredge, E.J. Bergman, C.R. Anderson Jr., E.H. VanNatta, J.D. Holbrook, and G. Bastille-Rousseau. 2025. Hierarchy in structuring of resource selection: understanding elk selection across space, time, and movement strategies. Ecology and Evolution 15:e71097.
creator: Rayl, Nathaniel
rights: IN COPYRIGHT - NON-COMMERCIAL USE PERMITTED

Effects of Habitat Treatments on Mule Deer Survival and Health During the Winter
description: Led By: Eric Bergman Study Area: Uncompahgre Plateau and adjacent valleys in southwest Colorado Project Status: Completed Research Objectives: To evaluate the impacts of large-scale vegetation habitat treatment on mule deer survival and health during the winter. To develop habitat management strategies for the benefit of deer To put research results into context with historical records and recent declines in mule deer herd populations. Project Description: Mule deer populations in Colorado have shown dramatic fluctuations since the 1960s. Beginning in the 1990s, some western Colorado mule deer herds demonstrated the most recent decline. For many decades, wildlife managers have used habitat management as a way to increase the health and survival of mule deer, but the effect of these efforts had not yet been evaluated. Evaluating these efforts was the focus of this 4-year study to measure the health and survival of mule deer herds during the winter months in areas treated with different levels of habitat management. In the course of this study, researchers monitored fawn survival, mule deer body conditions, and population densities in areas with different levels of habitat management. Habitat treatment varied from mechanical disturbance in the form of hydro-axe clearing and roller-chopping of late seral stage pinyon-juniper forests, chemical control of weeds, and reseeding with desirable mule deer browse species. The results of this study will help managers select the most effective habitat treatments to apply to mule deer winter ranges. Associated Publications Bergman, E.J., C.J. Bishop, D.J. Freddy, G.C. White and P.F. Doherty. 2014. Habitat management influence overwinter survival of mule deer fawns in Colorado. Journal of Wildlife Management 78(3):448–455. Bergman, E.J. 2013. Evaluation of winter range habitat treatments on overwinter survival, density, and body condition of mule deer. Dissertation, Colorado State University, Fort Collins, Colorado, USA, 137pp. Wa…
creator: Bergman, Eric J.
rights: In Copyright - Non-Commercial Use Permitted

Ellen Brandell, Wildlife Research Scientist
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 Draper, J. P., E. E. Brandell, J. Isabelle, C. Jacques, C. McCoy, E. Michel, D. J. Storm, C. Ott-Conn, B. Wojcik, W. C. Turner, and D. P. Walsh. 2025. Doe diligence: a regional analysis of antlerless deer harvest regulations in the Midwestern United States of America. PLoS One, 20(6): p.e0324708. https://doi.org/10.1371/journal.pone.0324708 Inzalaco, H. N. t., E. E. Brandell, S. P. Wilson, M. Hunsaker, D. R. Stahler, K. Woelfel, D. P. Walsh, T. Nordeen, D. J. Storm, and S. S. Lichtenberg. 2024. Detection of prions from spiked and free-ranging carnivore feces. Scientific Reports 14:3804. doi.org/10.1038/s41598-023-44167-7 Cubaynes, S., E. E. Brandell, D. R. Stahler, D. W. Smith, E. S. Almberg, S. Schindler, R. K. Wayne, A. P. Dobson, B. M. vonHoldt, D. R. MacNulty, P. D. Cross, P. J. Hudson, and T. Coulson. 2022. Disease outbreaks select for mate choice and coat color in wolves. Science 378:300–303; DOI: 10.1126/science.abi8745 Meyer, C. J., K. A. Cassidy, E. E. Stahler, E. E. Brandell, C. B. Anton, D. R. Stahler, and …
creator: Brandell, Ellen
rights: In Copyright - Non-Commercial Use Permitted

Shane Frank, Wildlife Research Scientist
description: Current or Recent Research Projects Bobcat Ecology and Management Bobcat ecology Where do bobcats occur? Determining where bobcats select habitats and resources What do bobcats eat? Spatial and temporal variation in prey availability Determining dietary composition and prey use/selection Bobcat monitoring and management How many bobcats are out there? Evaluating statistical methods for estimating bobcat abundance/density What are causes of bobcat mortality? Estimating the relative magnitude of mortality sources Bobcat reproduction Spatial and temporal variation in bobcat family group occurrence Understanding changes in bobcat population size Determining potential important factors affecting bobcat population density and dynamics (e.g. habitat, prey availability, and harvest rate) Improving bobcat data collection methods and population inference Enhancing age classification through dentition and teeth measurements Exploring cutting-edge methods in population size/density estimation Areas of Interest and Expertise​ My background is in terrestrial wildlife ecology with a focus on carnivores (primarily bears and bobcats) and harvest, though my interests vary widely. I have interest in exploring both the lives and deaths of wildlife and how individual contexts scale up to have population level effects. This encapsulates both the contextual decisions of individual animals and how we manage and conserve their populations. I have researched several themes, including animal movement, connectivity, sociality, carcass ecology, and the effects of harvest. Moreover, I have utilized a multitude of data collection methods (e.g. location data, genetics, isotopes) and statistical approaches to answer research questions under these themes. My overarching aim is help provide pragmatic answers to (1) applied questions and (2) contribute to the ever-advancing suite of data collection and analytical tools available to practitioners. Moreover, I hope to (3) help bridge the knowledge gap b…
creator: Frank, Shane
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Chuck Anderson, Head of Mammals Research
description: Chuck Anderson Mammals Research Section Leader Current or Recent Research Projects Mitigating Impacts of Energy Development on Piceance Basin Mule Deer Populations Areas of Interest and Expertise My research focuses on large mammal ecology and management, with an emphasis on population dynamics, population monitoring, and population genetics. Streaming Videos Wild Science: Mule Deer in the Piceance Basin Select Publications Crews, S., N. D. Rayl, M. W. Alldredge, E. J. Bergman, C. R. Anderson Jr., E. H. VanNatta, J. D. Holbrook, and G. Bastille-Rousseau. 2025. Hierarchy in structuring of resource selection: understanding elk selection across space, time, and movement strategies. Ecology and Evolution 15:e71097. https://doi.org/10.1002/ece3.71097 Crews, S., N. D. Rayl, M. W. Alldredge, E. J. Bergman, C. R. Anderson Jr., and G. Bastille-Rousseau. 2025. Drivers of spring migration phenology in Rocky Mountain elk. Scientific Reports 15:7807. https://doi.org/10.1038/s41598-025-91947-4 Hurley, M. A., C. R. Anderson Jr., T. D. Forrester, and J. A. Gude. 2023. Carnivore-prey relationships. Pages 125-139 in J. R. Heffelfinger and P. R. Krausman, editors. Ecology and management of black-tailed and mule deer of North America. CRC Press, Boca Raton, Florida, USA.​ ​Johnston, D. H., and C. R. Anderson Jr. 2023. Plant and mule deer responses to pinyon-juiper removal by three mechanical methods. Wildlife Society Bulletin 47:e1421​. https://doi.org/10.1002/jwmg.22110​ Bonar, M., S. J. Anderson, C. R. Anderson Jr, G. Wittemyer, J. M. Northrup, and A. B. Shafer. 2022. Genomic correlates for migratory direction in a free-ranging cervid. Proceedings of the Royal Society B 289:20221969. https://doi.org/10.1098/rspb.2022.1969​ Johnston, D. H., C. R. Anderson Jr., R. D. Applegate, L. Bailey, E. Cooch, J. Feiberg, A. B. Franklin, R. J. Gutiérrez, K. V. Miller, J. D. Nichols, N. D. Niemuth, D. Otis, C. A. Ribic, M. M. Rowland, and T. L. Shaffer. 2021. Editor's Message: A perspective on the …
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Jake Ivan, Senior Wildlife Research Scientist
description: Jake Ivan Senior Wildlife Research Scientist, Species of Conservation Concern Current or Recent Research Projects Snowshoe Hare Response to Silvicultural Treatments Monitoring Canada Lynx in Colorado Mammal and Breeding Bird Response to Bark Beetle Outbreaks Areas of Interest and Expertise My research focuses on estimating wildlife population parameters and forest carnivore ecology, conservation and monitoring. Streaming Videos Catching pine Lynx: shadows of the forest Snowshoe hare Snowshoe hare releases Snowshoe hare trapping, collaring and release Select Publications Bosco-Lauth, A. M., S. M. Porter, R. M. Maison, K. A. Fox, J. M. Marano, J. S. Ivan, K. Griffin, M. Quilici, and J. J. Root. 2025. Rabbit Hemorrhagic Disease Virus 2 experimental infection in snowshoe hares (Lepus americanus). Journal of Wildlife Diseases 61:674-684. doi: 10.7589/JWD-D-24-00141 Devarajan, K. [numerous authors], J. S. Ivan, [numerous authors]. 2025. When the wild things are: defining mammalian diel activity and plasticity. Science Advances 11:eado3843. DOI: 10.1126/sciadv.ado3843 Ivan, J. S. 2024. Canada Lynx (lynx Canadensis). Pages 129-152 in J. E. Cartron and J. K. Frey, Eds. Wild Carnivores of New Mexico. University of New Mexico Press. Hooten, M. B., M. R. Schwob, D. S. Johnson and J. S. Ivan. 2024. Geostatistical capture-recapture models​​. Spatial Statistics 59:100817. doi.org/10.1016/j.spasta.2024.100817​ Squires, J. R., Olson, L. E., Ivan, J. S., McDonald, P. M., and Holbrook, J. D. 2024. Anthropogenically protected but naturally disturbed: a specialist carnivore at its southern range periphery. Biodiversity and Conservation. https://doi.org/10.1007/s10531-024-02978-8 Hooten, M. B., M. R. Schwob, D. S. Johnson, and J. S. Ivan. 2023. Multistage hierarchical capture-recapture models. Environmetrics 34:e2799. doi.org/10.1002/env.2799 Ivan, J. S., E. S. Newkirk, and B. D. Gerber. 2023. Differential impacts of spruce beetle outbreaks on snowshoe hares and red squirrels in the sout…
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Eric Bergman, Mammals Research Scientist
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Mat Alldredge, Senior Wildlife Research Scientist
description: Senior Wildlife Research Scientist, Carnivores ​ Current or Recent Research Projects Using Non-Invasive Genetic Sampling to Estimate Mountain Lion and Bobcat Abundance, Age Structure and Diet Mountain Lion Demographics and Human Interactions Along the Urban-Exurban Front Range Areas of Interest and Expertise My research interest focuses on large carnivore and ungulate ecology, population parameter estimation, habitat use, avian ecology and population sampling. Streaming Videos Mountain lions in Colorado – a 4 part series Series Trailer Part 1: Mountain Lion Biology & Historical Perspective Part 2: Mountain Lion Habitat & Human Expansion Part 3: Hunting Part 4: What to do if you encounter a mountain lion Colorado Mountain Lions (all 4 videos combined) Select Publications Crews, S., N. D. Rayl, M. W. Alldredge, E. J. Bergman, C. R. Anderson Jr., E. H. VanNatta, J. D. Holbrook, and G. Bastille-Rousseau. 2025. Hierarchy in structuring of resource selection: understanding elk selection across space, time, and movement strategies. Ecology and Evolution 15:e71097. https://doi.org/10.1002/ece3.71097 Crews, S., N. D. Rayl, M. W. Alldredge, E. J. Bergman, C. R. Anderson Jr., and G. Bastille-Rousseau. 2025. Drivers of spring migration phenology in Rocky Mountain elk. Scientific Reports 15:7807. https://doi.org/10.1038/s41598-025-91947-4 Venumière-Lefebvre, C. C., H. E. Johnson, S. W. Breck, M. W. Alldredge, and K. R. Crooks. 2025. Bears avoid residential neighborhoods in response to the experimental reduction of anthropogenic attractants. Frontiers in Ecology and Evolution 13:1657106. doi: 10.3389/fevo.2025.1657106 Fountain-Jones, N. M., S. Kraberger, R. B. Gagne, D. R. Trumbo, P. E. Salerno, W. C. Funk, K. Crooks, R. Biek, M. W. Alldredge, K. Logan, G. Baele, S. Dellicour, H. B. Ernest, S. VandeWoude, S. Carver, and M. E. Craft. 2021. Host relatedness and landscape connectivity shape pathogen spread in the puma, a large secretive carnivore​. Communications Biology 4:12. doi: …
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