The biologists who are losing sleep over sheep

by Jerry Painter
| March 17, 2020 1:00 AM

They’re working to solve the thorny problem of mixing bighorn sheep, backcountry skiers

It turns out the Teton Range bighorn sheep don’t like people much.

That dislike was confirmed by a master’s thesis study done by wildlife biologist Aly Courtemanch a few years ago.

Courtemanch and fellow researchers put 28 GPS tracking collars on Teton bighorn sheep and followed their movement every day for two years. At the same time, they gave handheld GPS trackers to skiers heading into the Teton backcountry to play.

“We found that the bighorn sheep were showing very strong avoidance of areas where skiers were going, even if those areas were otherwise good sheep habitat,” Courtemanch said. “We found this very strong response, where it appears that sheep are very sensitive to that type of human activity in the wintertime.”

Another key finding of the study was that sheep living in areas with a lot of skiing activity moved around much more than sheep that didn’t.

“Those sheep that lived in areas with a lot of skiing exerted a lot more energy on a daily basis,” she said “In the wintertime, an animal that’s kind of on the edge and trying to survive is burning a lot more calories and energy. It’s not a very good thing.”

The details of Courtemanch’s study will be used to look for solutions to the challenge of balancing the Teton’s bighorn sheep winter habitat with backcountry recreation in Jackson, Wyo.

The Teton Range Bighorn Sheep Working Group seeks to develop community-based recommendations for this issue, according to a Teton Backcountry Alliance director Gary Kofinas and is collecting input from representatives from Grand Teton National Park, Wyoming Game and Fish — who Courtemanch works for — and biologists from the Bridger-Teton and Caribou-Targhee national forests.

No formal proposals or decisions have been made on the issue.

“The main product that we want to get out of this process is a list of concrete suggestions and ideas from the community of how we want to address this issue,” Courtemanch said.

Organizers plan to submit suggestions to government agencies to start a formal decision-making process.

Workshops were organized to discuss the history and importance of winter backcountry recreation in the Tetons and the status of bighorn sheep. Not only is the isolated herd of bighorn sheep under pressure from increased backcountry winter recreation use, but also from encroaching non-native mountain goats.

“We are a voice for backcountry skiers,” Kofinas said. “We’re trying to bring backcountry recreationists together with the biologists and start thinking about what are the solutions to conserve this resource.”

Backcountry skiing and snowboarding are also under increased scrutiny for other impacts. Winter users on Teton Pass have caused avalanches blocking the highway and hitting vehicles. Parking is also beyond capacity.

“We’ve seen in the past couple of decades the increasing numbers of people skiing in the Tetons and increasing expanse of areas that people are going,” Courtemanch said. “At the same time the technology has improved, equipment is getting a lot lighter than it used to be and people are able to go much farther and deeper into the backcountry in recent years. Maybe 20 years ago there were places bighorn sheep lived in the Tetons with very little to no exposure from humans in wintertime. That’s becoming really less and less. People are going to almost all areas now where sheep live in the Tetons.”

Courtemanch said the Teton herd of bighorn sheep essentially became isolated from other Rocky Mountain herds around 1950.

“Historically, we know that they used to migrate,” she said. “They would spend the summer in the Tetons and then in the winter, the majority of the herd would migrate down into the valleys to the lower elevations like a lot of our big game species do. Around the early 1900s with the settlement of Jackson Hole and Teton Valley, Idaho, those migration routes were beginning to be cut off. By about 1950, that was the last time that we have evidence of those sheep migrating.”

With migration routes cut off, the Teton bighorns stayed high all winter. A herd of bighorns does spend its winters on the east side of the National Elk Refuge.

“Those sheep (living) down here in the wintertime are part of a different herd called the Jackson herd from the Gros Ventre Mountains,” Courtemanch said. “Right now, they are doing pretty well. They’ve had some devastating die-offs over the past 20 years or so.”

The Jackson herd die-offs were caused by bouts of pneumonia, a deadly disease to bighorns. “If it gets into a herd it’s not uncommon to have over 50 percent of that herd die in a series of months,” she said.

Because of the possible exposure to outside disease, biologists have ruled out, for the time being, augmenting the Teton bighorn herd with animals from other areas — a favorite method of bolstering a dwindling population.

Jerry Painter can be reached at