Twenty Rocky Mountain Bighorn Sheep Radio Collared for Study

Interagency News Release
Grand Teton National Park
Wyoming Game and Fish
Bridger-Teton National Forest

February 25, 2008

Twenty female bighorn sheep were successfully netted from a helicopter, captured and fitted with GPS (Global Positioning System) radio collars on Thursday, February 14 and Friday, February 15 at various locations in the Teton Range; the capture operation occurred without any injury to either the bighorn sheep or the wildlife capture professionals. The capture operation launches an interagency study intended to gather valuable information about the health and future of the bighorn herd that occupies high elevation habitat spanning federal lands in the Tetons. Interagency partners for the study include Grand Teton National Park, Bridger-Teton National Forest, Caribou-Targhee National Forest, and the Wyoming Game and Fish Department.

Winter-time offers some distinct advantages for capturing bighorn sheep: animals tend to be concentrated in a relatively small area and are therefore easy to locate; the snow pack helps to slow down the pace of an animal before the net is deployed from the helicopter; and snow can cushion the fall of a netted animal, reducing the chance of injury.

The GPS collars are programmed to periodically record vital location data as bighorn sheep move across their range throughout the year. After two years, the collars will automatically drop off and biologists will then recover the collars via radio-telemetry to download the data onto computers, providing detailed information about habitat selection, travel routes and other factors (i.e. lamb production and survival) that are critical to ensuring the long-term survival of this bighorn population.

The Teton Range bighorn sheep population is Wyoming’s smallest and most isolated native herd, numbering just 100-125 animals. Federal and state biologists have been concerned for many years about the long-term survival of this particular herd. Due to a loss of historic low-elevation winter range, the herd now lives year-round at high elevation in the Teton Range, where because of their small population they are vulnerable to a single event—disease, harsh winter weather or avalanches—that could quickly reduce their numbers and lead to potential extirpation of the herd. Although broad scale information is available about bighorn sheep seasonal distributions, further detailed information on habitat selection, travel routes and movements is urgently needed and critical to the herd’s long-term persistence.

Growing recognition of the questionable future for this bighorn sheep population led to the formation of a Teton Range Bighorn Sheep Working Group in 1990—a group comprised of representatives from Wyoming Game and Fish Department, Bridger-Teton and Caribou-Targhee national forests, and Grand Teton National Park, as well as several individuals with expertise in bighorn ecology who are affiliated with non-governmental organizations.

Previous efforts to improve the Teton Range herd’s survival included seasonal closures of sheep winter ranges to reduce disturbance impacts during an especially stressful time of year, and the retirement of domestic sheep allotments in forest locations on the western slopes of the Teton Range. Although progress has been made in reducing some of the threats to the long-term survival of Teton Range herd, uncertainties still remain regarding their current distribution, and whether bighorn sheep avoid areas of human activity. Consequently, there is a critical need to further assess habitat selection patterns and general population status of this isolated sheep herd.