Pronghorn

Projects

What are the migration patterns of buck mule deer in Wyoming? There has been such an emphasis on mule deer migration research lately that folks probably think researchers and managers know the answer to this question. They don’t. That is because all of our mule deer research efforts over the last decade and a half have been focused on does. We have learned a lot about the timing, distance, stopover use, and migration routes of mule deer does. This study seeks to understand whether timing, distance-traveled, fidelity to routes, and ability to track high quality forage differ between bucks and does.

The Wind River Reservation provides vast and intact winter range for at least 10,000 elk and approximately 5,000 deer on the Owl Creek and Wind River Mountain winter ranges in northwest WY. Large groups of elk (1,000+) have been routinely observed moving onto tribal lands in early winter and moving onto lands managed by the Wyoming Game and Fish Department in the summer and fall. Thus, the Wind River Reservation provides crucial winter range for elk that are hunted on public land during the fall. Elk also provide recreational, cultural and subsistence values to thousands of enrolled Eastern Shoshone and Northern Arapaho members of Wind River Reservation. Despite these benefits, we do not know the location of migration corridors, stopover areas used by elk or mule deer. Understanding the location and use of these areas is critical to conserving and managing these herds for future generations. Further, we have a limited understanding of the demography of this herd (adult survival, pregnancy rates), and how diseases such as Brucellosis could be influencing population growth. Our proposed work seeks to fill these knowledge gaps to better manage these important herd into the future.

There has never been a detailed study of moose in the Bighorns. Consequently, seasonal ranges and migration corridors have not been mapped using current methods. Additionally, moose are not native to the Bighorns. Managers from the Bighorn National Forest have expressed concerns to the Wyoming Game & Fish Department regarding the amount of wild ungulate (especially moose) use of willow and aspen in many areas. Thus, there is a need to understand the intensity of moose browsing and how it influence moose habitat use and demography. This proposed project seeks to evaluate the population performance and seasonal range use of moose in the Bighorns.

Although Wyoming has approximately half of the world’s total population of pronghorn, factors influencing local herds have been little studied. We propose to study the effects of wind energy development on the movement of pronghorn that winter in Shirley Basin south to the town of Medicine Bow. The broad objective of this 6-year study is to evaluate whether pronghorn change their seasonal movements or winter habitat use in response to wind energy development. Study results will aid wildlife managers to evaluate likely impacts and explore potential solutions to minimize habitat loss for wintering pronghorn.

Interstate-80 is a barrier to ungulate movement across Southern Wyoming. Pronghorn (antilocapra Americana) are particularly affected by the Interstate, as it impedes their ability to roam in winter range. Meanwhile, our understanding of the environmental influences of migrations is continuing to develop into a more complete picture which can help inform restoration and mitigation efforts for wildlife. As wildlife overpasses are becoming an increasingly popular tool to improve habitat connectivity, our research is interested in trying to inform where would be the optimal locations to restore movement across the Interstate. This project will assess where pronghorn are most frequently moving along the Interstate to identify locations where pronghorn appear most affected by the barrier effect.

Although migration may be the most optimal strategy in numerous ungulate systems, many migratory herds contain individuals that do not migrate or migrate relatively short distances – a phenomena known as partial migration. If long-distance migration, however, is commonly viewed as the most profitable strategy promoting herd fitness and population performance, what allows residents – or other strategies – to persist over the long-term?

Mule deer in the Sweetwater mule deer herd move seasonally from high elevations in Green and Crooks Mountains to wintering habitats at low elevations along the Sweetwater River, but relatively little is understood about the timing of migration and the critical migration routes used by these mule deer. It is important to identify migration routes to ensure mule deer are protected and routes remain permeable to mule deer movement. The broad objective of this study is to understand movements, migrations, and seasonal ranges of the Sweetwater mule deer herd.

Completed Projects

Our study population, the Clarks Fork elk herd, is a partially-migratory population of about 4,500 individuals near Cody, Wyoming. Collars were distributed evenly throughout its migratory and nonmigratory subpopulations.

We are working to understand the changing demography and distribution of the Clarks Fork elk herd, which ranges widely in the Absaroka Mountains between Cody, WY and the headwaters of the Lamar River inside Yellowstone National Park (YNP).

This project has been conducted in collaboration with the U.S. Fish and Wildlife Service, the Wyoming Game and Fish Department, and many private ranches. An important part of our field work was to capture wolves so that we could monitor their movements in relation to native and domestic ungulates.

The Absaroka Wolf-Cattle project was created to evaluate wolf habitat selection and predation in a multiple-use landscape in the Absaroka Mountains of Wyoming, an area characterized by high levels of wolf-cattle conflict and a changing distribution of migratory and nonmigratory elk.

Energy development is economically important for Wyoming and the nation. Unfortunately, much development occurs in previously intact habitats that are important for wildlife, including many species listed as Species of Greatest Conservation Need by the Wyoming Game and Fish Department. (Photo: Stewart Point Rig, 2003, L. Baker. Courtesy of Wyoming Outdoor Council.)

With over 200 Species of Greatest Conservation Need (SGCN) identified by Wyoming’s State Wildlife Action Plan, and energy infrastructure likely to double in the next twenty years, there are insufficient time and resources to conduct species-specific, detailed studies.

Devils Canyon

Over the past 120 years, many bighorn sheep (Ovis canadensis) herds throughout Wyoming and the Rocky Mountain west have declined or been extirpated due to disease, habitat loss and fragmentation, and competition with domestic sheep. Since 1934, Wyoming has conducted a number of bighorn sheep reintroduction efforts into historically occupied ranges, which are commonly xeric, canyon habitats. Most Wyoming transplants utilize bighorn sheep from a source herd on Whiskey Mountain, near Dubois, Wyoming. Bighorn sheep from this herd are migratory and adapted to summering in high-elevation alpine habitat.

Elk Nutritional Condition

For many animal taxa, nutritional condition (i.e., fat levels) is a balance of food intake that increases condition versus energy outputs (i.e., cost of reproduction) that diminish condition. While nutritional condition gradients are common in nature, relatively little is known about how nutritional condition influences behavior. Current management practices in Wyoming offer a rare opportunity to evaluate the influence of nutritional condition on the behavioral strategies of a large, free-ranging population of elk (Cervus elaphus). The Wyoming Game and Fish Department (WGFD) operates 22 winter feedgrounds for population and disease management.

Rural development in Western Wyoming provides an example of habitat fragmentation that alters mule deer use of migration route habitat.

We are evaluating the influence of development type and intensity on migratory behavior of several western Wyoming mule deer (Odocoileus hemionus) populations using GPS collar data. These migration routes span a gradient of development, from intact habitat to housing infrastructure to landscapes developed for petroleum extraction.

We are evaluating how the bark beetle epidemic occurring in Wyoming’s forests may influence elk and hunter movements and interactions. Landscape-level changes to the forest as a result of the bark beetle may result in changes in where elk forage, in turn, potentially changing the ability of hunter to access and harvest elk. Understanding how the bark beetle epidemic is affecting elk and hunters will help wildlife and land managers manage Wyoming’s changing forests.

During winter, available browse includes the stems of willows, aspen, bog birch, and subalpine fir, among others. Moose spend a lot of their time along the edges of willow and conifer patches for food and cover.

We are working to understand the influnece of seasonal limitations and limiting factors on ungulate populations. Landscapes are being altered at increasing rates from both anthropogenic and natural causes.

female elk and female cow at watering hole in Arizona

Brucellosis is a bacterial disease resulting in abortions for some ungulates. It remains endemic to elk and bison in the Greater Yellowstone Ecosystem and can be transmitted to cattle via comingling between March and May when most abortions occur. We are using GPS collar data from adult female elk captured on winter feedgrounds in Wyoming to a) develop a movement model for elk, b) simulate elk distribution under varying annual weather patterns, and c) map areas of high risk for interspecific brucellosis transmission.

Mule deer in western Wyoming migrate 18-140 km to high-elevation summer ranges where they access high quality forage and accumulate fat reserves that help them survive the harsh winters. The ability to identify and prioritize these migration routes may improve management and land-use planning.

Increased levels of energy development across the Intermountain West have created a variety of wildlife management and conservation concerns. Because many of the energy resources in the region occur in shrub-dominated basins, management concerns have focused on native shrub communities and associated species, including mule deer. Two of the more pressing concerns are how mule deer respond when critical habitats (e.g., winter range) are impacted by development and how their migration routes can be identified and prioritized for conservation.

Burbot are a species of conservation concern in Wyoming. We are using otolith microchemistry to differentiate populations, reconstruct movement patterns, and determine natal origins

Reconstructing the life histories of fish has been a challenging problem for fisheries biologists. Unlike terrestrial organisms, the aquatic environments fish inhabit make direct observations difficult. Traditionally, fisheries biologists have tracked fish using unique fin clips, tagging, telemetry, and use of food dyes that mark bony parts of fish that can be viewed using UV lighting.

Populations of Shiras moose (Alces alces shirasi) in Wyoming and most western states have experienced declines in population size, and recruitment of young in recent decades. Wildlife managers have expressed increasing concern for moose populations and harvest quotas have been reduced accordingly throughout much of their range.

The objectives of the Sublette Moose Project are 3-fold: First, we are providing a baseline synthesis of Sublette moose seasonal-habitat use, nutrition and demography for that herd, which is the largest in Wyoming. Second, we are assessing the relative influence of predator density (wolves and grizzly bears), habitat condition and weather on the demography of the Jackson and Sublette moose herds. Third, we are testing the influence of wolf presence on movement rates and habitat use of moose in the Jackson region.

Field crews tracked GPS-collared bighorn sheep using radio-telemetry during summers 2008, 2009, and 2010.

Loss of migration and access to traditional seasonal ranges are threats facing many ungulate populations in Wyoming and worldwide. This study evaluates the seasonal habitat selection strategies of a formerly migratory bighorn sheep population and the impact of winter backcountry recreation on habitat use.

Wildlife managers have struggled for decades to maintain populations at or near local carrying capacities because they often lack the tools necessary for identifying when and where resources, such as food, are limiting. Accordingly, the goal of this study is to identify the habitat, climatic, behavioral and nutritional characteristics that reflect a population experiencing resource limitation. By using a variety of field and lab methods to identify resource limitations, we will develop a tool-set that managers can use to measure resource limitation and make science-based management decisions.

(photo credit: Arthur Middleton)

The Wyoming Game and Fish Department’s survey, data collection, and modeling protocols have evolved over the years but may not be optimized to allow efficient management of mule deer and other ungulates under current fiscal, logistical, or environmental constraints. There is a need to ensure monitoring and modeling practices generate the most accurate and cost-effective population estimates possible.

Bar-tailed Trogon.

Island biogeography theory resulted in now-classic predictions about how habitat fragmentation influences species richness. In particular, small and isolated remnants should have fewer species than larger and less isolated remnants as a result of higher extinction rates and lower colonization rates.

Traditional herd composition surveys are completed using helicopters or fixed wing aircraft, proving to be both costly and dangerous. Remote photography could provide an alternative method for collecting composition data that is more cost efficient and safer. Trail cameras are providing data pertaining to both herd composition and herd migration timing; information useful to regional biologists who manage these populations through sustainable harvest practices. We are investigating the efficacy of this new methodology and it’s potential for long term monitoring of migratory elk herds in the Greater Yellowstone Ecosystem.