Evaluating factors influencing elk recruitment in Colorado

Evaluating factors influencing elk recruitment in Colorado

Evaluating Factors Influencing Elk Recruitment n Colorado

Led By
Nathaniel Rayl, Mat Alldredge, and Chuck Anderson

Other Personnel:
Aberle, J. Alley, T. Bonacquista, K. Bond, M. Brown, M. Caddy, M. Calahan, Z. Chrisman, A. Cole, D. Corcoran, K. Crane, S. Crew, A. Davis, B. de Vergie, K. Duckett, L. Emerick, D. Finley, P. Firmin, K. Fischer, M. Fisher, K. Fox, A. Friedel, M. Gallagher, M. George, L. Gephert, J. Goncalves, K. Hayes, A. Kircher, J. Lambert, D. Leer, E. Los, K. Middledorf, L. Miller, M. Miller, S. Mollett, H. Mondin, E. Monfort, E. Newkirk, P. Nol, K. Oldham, S. Olson, M. Ortega, J. Ortiz Calo, J. Pollock, J. Potter, N. Renneker, B. Rubalcaba, E. Sawa, S. Sinclair, G. Smith, B. Smith, R. Sralla, M. Trujillo, E. VanNatta, A. Vitt, S. Waters, H. Westacott, M. Wood, CPW; J. Clark, H. Cushman, B. Dooling, A. Orlando, R. Swisher, S. Swisher, Quicksilver Air, Inc. Project support received from Federal Aid in Wildlife Restoration, Rocky Mountain Elk Foundation, and CPW Big Game Auction and Raffle

Study Areas
Uncompahgre Plateau elk hurd (DAU E-20), Trinchera elk herd (DAU E-33), Bear’s Ears elk herd (DAU E-2)

Project Status
Ongoing

Study Objectives

• Estimate calf and adult female survival and cause-specific mortality rates
• Quantify pregnancy rates and nutritional condition
• Evaluate factors influencing survival, pregnancy rates, and nutritional condition

Project Description
In Colorado, elk (Cervus canadensis) 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 3^rd study area 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.

Study Objectives

• Estimate calf and adult female survival and cause-specific mortality rates
• Quantify pregnancy rates and nutritional condition
• Evaluate factors influencing survival, pregnancy rates, and nutritional condition

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.