Project Summary

Resource selection, seasonal distribution, movement, and recruitment of bighorn sheep (Ovis canadensis) in the Teton Range in northwest Wyoming

Study Duration: January 2008 – December 2010

Project Background
“…better than any other animals the bighorns typify the Tetons.”
-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.

Study Objectives
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.

Project Contact
Aly Courtemanch
Wyoming Cooperative Fish and Wildlife Research Unit
Department of Zoology and Physiology
University of Wyoming
Laramie, WY 82071

Phone: (307) 766-6415
Pregnancy and Disease Analysis of Captured and Radio-Collared Teton Ewes

Completed by: Wyoming State Veterinary Laboratory, Laramie, Wyoming
Date: 3/28/2008

17/20 ewes tested positive for pregnancy.
2 of the non-pregnant ewes had not yet reached reproductive maturity (< 3 years old).

· All bighorn sheep blood samples tested negative for:

Brucella ovis, wildlife brucellosis serology, epizootic hemorrhagic disease
virus (EHD), paratuberculosis (Johne’s disease), bluetongue virus, parainfluenza virus
(PI3), respiratory synctial virus (RSV), bovine viral diarrhea type 1a & type 2 (BVD),
infectious bovine rhinotracheitis (IBR), ovine progressive pleuropneumonia (OPP), caprine
arthritis encephalitis (CAE).

· All bighorn sheep ear swabs tested negative for mites.


These disease test results are unusual for a bighorn sheep population. Most bighorn sheep populations in Wyoming have been previously exposed to or are currently infected with some of these diseases. Many of these diseases are tested for using serological assays, which identify the presence/absence of antibodies to the particular disease, not the disease itself. Serological assays indicate whether an animal has ever been exposed to a disease, and thus, developed antibodies to it. In the case of these Teton bighorn sheep, the serological assays produced results showing no or very low previous exposure levels.

From a disease point of view, these results suggest that this population is likely to have been isolated from mixing with other populations for a long time.

Radio Collaring Successful

From February 14th-15th 2008, we successfully captured and radio-collared 20 female bighorn sheep in the Teton Range, in northwest Wyoming for the Teton Range Bighorn Sheep Study. For each captured bighorn sheep, we fitted her with a GPS radio-collar, recorded her weight and age, and collected a blood sample for pregnancy testing.

The GPS radio-collars are programmed to automatically connect with orbiting satellites and record the bighorn sheep’s GPS location every 5 hours and store the information inside the collar. After 2 years, the radio-collars automatically release from the bighorn sheep. We then collect the collars from the field, and download the location information, producing a map of the animal’s travels for the entire 2 years.

By looking at these spatial data for all 20 radio-collared bighorn sheep we can get an idea of which areas in the Teton Range are most important for the population during summer and winter,important travel corridors,and identify crucial bighorn sheep habitat areas to protect in the future.

Above photos courtesy: Mark Gocke, Wyoming Game and Fish

Brunton Supports the Sheep Project

We are very proud to announce that Brunton, a fellow Wyoming operation, has very generously donated optics, compasses and solar panels/chargers to the Bighorn Sheep Project. Brunton also manufactures stoves, headlamps and cookware. We'd like to offer a very big thank you to everyone at Brunton who helped make this donation a reality.

Jet Boil Supports Sheep Project

The good folks at Jet Boil have generously donated stoves, cook sets and fuel to the Sheep Project. Jet Boil is well known in mountaineering circles for manufacturing the best stoves around. A big thank you for supporting our project!