Effects of human disturbance on the nutritional ecology of mule deer


Winter can be a challenging time for North American ungulates. As availability of forage on summer ranges diminishes with accumulating snow, many ungulates in North America migrate to winter ranges to access available forage. Although forage is generally more available compared to summer ranges during this time, the nutritional quality of forage on winter ranges is often marginal. To combat this seasonal limitation in nutritious forage, many ungulates, including mule deer, rely on fat reserves to promote reproduction and survival. This well-adapted strategy has allowed ungulate populations to persist for thousands of years, but what happens when a novel disturbance is introduced to winter ranges?

In the last couple decades, energy development has increased dramatically in many areas of western Wyoming, and much of which has occurred on sage-steppe winter ranges of GasDevelmany migratory ungulates. We know from previous research that mule deer avoid energy development (by up to 7km), but the effects of this indirect habitat loss on the nutritional carrying capacity (i.e., number of animals a specific range can support based on nutritional demands and the nutritional quality of the habitat) of the landscape are unknown. Furthermore, behavioral responses to human disturbance can vary among individuals, but the relationship between behavioral responses and nutritional condition (i.e., fat reserves) of individuals is unknown. If human disturbance alters behavior of animals in a way that affects use of fat reserves, disturbance could influence population performance via effects on the nutritional dynamics of wintering animals.

Our main objective is to evaluate how human disturbance influence behavior, nutritional condition, and population performance of mule deer. Specifically, our research is aimed at addressing the following questions:

  • How does indirect habitat loss resulting from avoidance of human disturbance affect the nutritional carrying capacity of winter ranges?
  • How do behavioral responses to human disturbance affect nutritional condition of mule deer?

WinterRange_studyAreaSince March 2013, we have fitted 148 mule deer with GPS collars among three winter ranges of varying degrees of energy development. Each fall and spring (as animals arrive to and depart from winter ranges), we have recaptured collared individuals to measure nutritional condition (e.g., fat reserves and body size) and life-history characteristics (e.g., reproductive status and age). With these data, we can link seasonal changes in nutritional condition to the environmental conditions individuals encounter including exposure to human disturbance and evaluate the fitness consequences (i.e., reproduction and survival) of these interactions.

Understanding how human disturbance may affect the well-adapted nutritional relationship between an animal and its environment is pivotal for management of populations exposed to human disturbance. Furthermore, as the global demand for energy resources remains, it is crucial that we understand the potential impacts that behavioral responses to energy development can have on population performance.




Samantha Dwinnell

Masters Student

Wyoming Cooperative Fish and Wildlife Research Unit

University of Wyoming

Dept. 3166, 1000 E. University Ave.

Laramie, WY 82071

Email: [email protected]


Kevin Monteith
Assistant Professor
Haub School of Environment and Natural Resources
Wyoming Cooperative Fish and Wildlife Research Unit
University of Wyoming, Dept 3166
1000 E. University Ave.
Laramie, WY 82071
Email: [email protected]


Hall Sawyer

Research Biologist

WEST, Inc.

200 S. 2nd St.

Laramie, WY 82070

Email: [email protected]


Gary Fralick

Wildlife Biologist

Wyoming Game and Fish Department

P.O. Box 1022

Thayne, WY 83127

Email: [email protected]

Project Lead

Sam is a Masters Student with the Wyoming Cooperative Fish and Wildlife Research Unit. Her research is focused on nutritional ecology of mule deer in western Wyoming.



Funding & Partners

Wyoming Game and Fish Department · Muley Fanatic Foundation of Wyoming · Bureau of Land Management · Wyoming Wildlife and Natural Resource Trust · Western Ecosystems Tech, Inc. · Boone and Crockett Club · Knobloch Family Foundation · Wyoming Governor’s Big Game License Coalition · Wyoming Outfitters and Guides Association · Wyoming Animal Damage Management Board · Bowhunters of Wyoming, Inc. · U.S. Forest Service · U.S. Fish and Wildlife Service – Cokeville Meadows National Wildlife Refuge