Study Duration: January 2008 – December 2010
“…better than any other animals the bighorns typify the Tetons.”
-F. Fryxell, 1938
-F. Fryxell, 1938
The Teton Range bighorn sheep herd resides year-round at high elevation in Grand Teton National Park and on the Bridger-Teton and Caribou-Targhee National Forests. It is Wyoming’s smallest and most isolated native herd- a remnant population of perhaps 100-125 sheep derived from a much larger bighorn sheep complex that historically lived in northwest Wyoming. The population’s hold on the future is tenuous owing to its small size, likely isolation and the combined effects of loss of historic winter ranges, habitat alteration due to fire suppression and threats posed by increasing recreation in and near important seasonal ranges. Furthermore, there is a need for up-to-date information regarding these threats and the status of the population. Of the native ungulates present in Grand Teton National Park, bighorn sheep face the most precarious future.
The overall goal of this study is to improve our understanding of how and why bighorn sheep use the Teton landscape through identifying locations, characteristics, and use patterns of seasonal habitats and movement corridors by collecting data from GPS radio-collared bighorn ewes. Because the herd has been eliminated from much of their historic habitat, their current distribution is unlikely to be a reliable indicator of habitat patches critical to their long-term persistence. Instead, a habitat selection study is required to connect sheep use to the habitat attributes of the study area. Furthermore, a better understanding of the relationship between human activities and sheep habitat use is needed to evaluate whether sheep avoid high human use areas and to devise appropriate management strategies.
This is a collaborative project, involving the University of Wyoming, the Wyoming Game and Fish Department, Grand Teton National Park, and the Bridger-Teton and Caribou-Targhee National Forests. The study objectives have been identified by these agencies and in the Teton Range Bighorn Sheep Working Group’s Strategic Plan (1996) as areas where data concerning this bighorn sheep population is lacking.
1. Compile and map historic sheep distribution using historical data sources;
2. Document locations, characteristics, and use patterns of seasonal habitats and movement corridors;
3. Quantitatively assess the habitat selection patterns of the herd (in winter and summer);
4. Quantitatively assess avoidance of seasonal habitats by bighorn sheep due to human activities;
5. Evaluate the effects of retiring domestic sheep allotments on the Teton Range bighorn sheep herd;
6. Determine lamb production and lamb survival to mid-summer for the sample of radio-collared adult female sheep;
7. Analyze bighorn sheep nutrition in the Teton Range during summer;
8. Determine causes of mortality for radio-collared bighorn ewes throughout the study period;
9. Provide community education on bighorn sheep and this study in the form of public presentations, written materials, website, local media, etc.
The data from our study will provide the most extensive and complete picture of bighorn sheep habitat use, seasonal distribution, movement, and recruitment (lamb survival) in the Teton Range to date. For many people, this bighorn sheep population serves as an icon of Grand Teton National Park and the wild character of the Rocky Mountain West. This native herd is currently facing an uncertain future due to its small size, likely isolation from neighboring herds, and the combined effects of loss of historic winter ranges, habitat alteration due to fire suppression and threats posed by increasing recreation in and near important seasonal ranges. Our findings will provide area managers with the information they need to develop informed and effective management strategies to protect this unique population.
Wyoming Cooperative Fish and Wildlife Research Unit
Department of Zoology and Physiology
University of Wyoming
Laramie, WY 82071
Phone: (307) 766-6415