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Colorado West Slope Mule Deer Strategy
Colorado West Slope Mule Deer Strategy
Mule Deer


Studying & Managing Mule Deer

Colorado Parks and Wildlife has a long history of studying and managing mule deer, dating back to the agency’s origins. In recent decades, CPW has invested millions of dollars annually to manage, monitor and study mule deer, with many of these efforts focused in western Colorado. To capture this history and set the stage for moving forward, CPW produced a three-page publication titled Colorado's Mule Deer Story

Together with the public and stakeholders, CPW will work to stabilize, sustain and increase mule deer populations in Colorado and, in turn, increase hunting and wildlife-related recreational opportunities.

CPW’s Predator Management Strategy

CPW’s population objective for mule deer is approximately 560,000 statewide; the latest estimate puts the statewide population at under 450,000. CPW is not suggesting that the removal of predators is the solution to increasing statewide deer numbers to 560,000. These two research projects are designed to evaluate the extent to which predation is limiting deer population size in the two specific study areas. For more information, please listen to the presentation of Piceance Basin and Arkansas River Basin Predator Control Plans and review the following resource. 

Predator Control Plans

TOPIC: Presentation of Piceance Basin and Arkansas River Basin Predator Control Plans. Presented by Jeff Ver Steeg at the December 14, 2016 Commission Meeting in Fort Collins, Colorado.


Presentation of Piceance Basin and Arkansas River Basin Predator Control Plans

Predator Management Q & A

  1. Why is CPW focused on deer populations in the Piceance Basin and Upper Arkansas River study areas?

    1. Recent research and monitoring efforts suggest predation may play more of a role than previously thought in limiting mule deer populations. CPW proposes to test this idea in two areas of the state where habitat conditions do not appear to be limiting those populations. Maintaining healthy wildlife populations for future generations is one of the primary goals for CPW.

    2. This represents a potential paradigm shift where previous research addressing primarily habitat limited systems showed that predation was largely compensatory (summarized by Ballard et al. 2001 and Forrester and Wittmer 2013). 

    3. Mule deer population declines have occurred throughout the western US since the 1980s. While predation may have exhibited relatively minor influence in initial population declines, increasing predator populations with milder winter conditions may have pronounced influence on the ability for some populations to recover.

      1. Decline in frequency of severe winters recently, resulting in milder winter conditions overall, has resulted in higher winter survival rates, but deer populations have generally remained at lower levels than were evident prior to the 1990s. 

      2. New information suggests that some deer populations in Colorado are no longer nutritionally limited by poor habitat and therefore predation may be a more important mortality factor affecting population performance.

      3. Predation was likely not the primary reason for declines that occurred since the 1980s, but may be at least partially related to the lack of recovery observed with lower frequency of periodic severe weather events.

    4. CPW is addressing potential factors limiting mule deer populations outlined in our West Slope Mule Deer Strategy that was adopted by the CPW Commission in December 2014.

      1. Landscape-scale habitat management to improve habitat

      2. Predator management where predation may be limiting deer survival

      3. Protect habitat and mitigate development impacts

      4. Reduce the impacts if highways on mule deer survival, movements and migration

      5. Reduce the impacts of human recreation on mule deer

      6. Regulate doe harvest and provide youth opportunity

      7. Maintain a strong ungulate population and disease monitoring program and conduct applied research to improve management of deer populations.

  2. Why does CPW need this research now?

    1. Colorado is evolving- the population is growing and the landscape is changing. CPW needs to plan ahead for emerging wildlife issues for future generations.

    2. With these studies, CPW intends to make a meaningful contribution to the body of scientific wildlife knowledge.

    3. What CPW is proposing in the Upper Arkansas River study is unique in size and scope. Piceance research is addressing predator control/management in a more focused and fine scale manner - as suggested by Ballard et al. 2001 and the Mule Deer Working Group - this idea has not been tested previously.

      1. CPW's Upper Arkansas River study will be conducted over a 9-year period and the Piceance Basin study will span 6 years including 3 years of pretreatment data collected 2012-2014.

    4. These two research projects are designed to evaluate the extent to which predation is limiting mule deer populations in the specific study areas. 

  3. How is CPW conducting these studies?

    1. The Piceance Basin Predator research study will monitor fawn survival in two areas over the next three years. One area will receive predator reduction, the other will not. CPW anticipates removing between five and ten mountain lions and ten to twenty-five black bears annually in the one area of the study.

    2. The Upper Arkansas River Predator research study will monitor adult female and fawn survival in two areas over the next 9 years relative to contrastingly different lion densities.

      1. In years one through three, mountain lion densities will be reduced, while mountain lions in the other area will experience minimal hunter harvest

      2. In years four through six the suppressed population will be allowed to increase towards natural habitat potential, similar to the area receiving low hunter harvest.

      3. In years seven through nine, removal efforts will flip from the first stage—with the first area that saw predator removal now seeing low harvest (~10%) and the second area now having a higher percentage of mountain lions removed (~50%).

    3. In the Piceance Basin study, we propose to reduce the fawn predation rates in the treatment study area by 20% to determine whether predation control will increase fawn survival.

  4. Is CPW only pursuing these research studies to increase hunting licenses and/or revenue?

    1. No. Revenues were not a factor in determining where and how to proceed and revenues have never been a driver in setting hunting license numbers. In fact, the CPW Commission reduced the total number of deer licenses in the Piceance Basin by 85% since 2007.  The number of licenses adjusted by possible outcomes of these studies is minimal in light of CPW's overall budget challenges and no future management actions are being contemplated prior to the completion of the research.

    2. Ongoing research in the Piceance Basin suggests predation rather than other factors (habitat, energy development) is most likely limiting this population.

      1. CPW is pursuing the seven actions (outlined in #1) identified in the West Slope Mule Deer Strategy. Habitat is a primary focus in other areas where habitat may be more limiting than the two areas where the influence of predation is being examined. 

West Slope Mule Deer Strategy

In recent years, mule deer populations in Colorado have decreased in several areas on the West Slope. The agency hosted a series of public meetings in 2014, designed to gather input from sportspeople and others interested in conserving the species. 

The outreach culminated in the development of the West Slope Mule Deer Strategy, a plan consisting of seven components specifically aimed at addressing the decreasing numbers. 

$500,000 has been allocated initially to implement the strategy and CPW may spend approximately $5 million over the next ten years. These funds will be used for continuing efforts to stop the slide, including monitoring, extensive research and habitat improvement projects.

Colorado Parks & Wildlife Commission Meeting Update

TOPIC: Mule Deer Strategy: Summary of Public Input: Julie Shapiro, Brooke Trainum: The Keystone Center. Update provided at the July 2014 Commission Meeting

Colorado Parks & Wildlife's  Mission

The mission of Colorado Parks and Wildlife(CPW) is to perpetuate the wildlife resources of the state, to provide a quality state parks system, and to provide enjoyable and sustainable outdoor recreation opportunities that educate and inspire current and future generations to serve as active stewards of Colorado's natural resources.

CPW is a nationally recognized leader in conservation, outdoor recreation and wildlife management. As a science-based wildlife management agency CPW has a duty to understand the predator/prey relationship to support the healthy balance of wildlife populations.

Colorado boasts one of the most diverse and abundant wildlife populations in North America due to the diligence and dedication of our researchers, field staff and especially funding from hunters and anglers.