Study eyes wolverines and skiers in Tetons

Aim is to determine how recreation influences rare mustelid, researcher says.

By Mike Koshmrl | Jackson Hole News&Guide

Biologists have selected the Tetons as the site of a multiyear study of wolverine habitat, in part because of the amount of human-powered winter recreation in the range. Now in its fifth field year, a research project headed by Salt Lake City-based Round River Conservation Studies is attempting to determine how wolverines respond to winter recreation, including snowmobiling and fast-growing backcountry skiing.

Researchers with the project moved into the Tetons this winter. The Tetons are one of two sites — the other being the McCall, Idaho, area — where the research is continuing. Field efforts in five other parts of Idaho have ceased.

Round River plans to continue studying wolverines on the west flank of Jackson Hole through next winter, conservation science director Kim Heinemeyer said.

“It’s only winter recreation that we’re looking at, and to date we haven’t really been able to get [good information on] backcountry skiing,” said Heinemeyer, who leads the project.

“The Tetons will be really important to help us fill that data gap, because there’s such a great backcountry skiing culture in that area.”

Data collected from the Tetons so far is too preliminary to make any judgments about impacts to local animals, Heinemeyer said. However, across the entire study area biologists are starting to better understand how winter recreation influences wolverines.

“We found that movement rates notably increase when animals are found within higher-recreated areas of their home range,” a 2013 “progress report” for the study says. “Additionally, we have found that increased movement rates in these popular recreation zones are highest on the days of the week when recreation levels are high (i.e., weekends).

“Depending upon the amount of time a wolverine spends in these recreated portions of their home range and the relative amount of high-quality habitat that is affected,” the document said, “there may be significant additive energetic effects on wolverines during the critical winter months and denning periods.”

Round River researchers have not yet found any displacement-level effects from winter recreation, Heinemeyer said.

In the McCall area, where there’s lots of snowmobiling, for instance, “the animals don’t appear, in that landscape, to be alienated,” she said.

In order to complete the study, researchers collared 18 wolverines through the winter of 2012-13, according to the progress report. To assist with the study’s recreation portion, snowmobilers, skiers and other over-snow travelers volunteered to temporarily carry GPS tracking devices that were distributed at trailheads.

Round River is working with at least a dozen partners, including the Wyoming Game and Fish Department, the Caribou-Targhee and Bridger-Teton national forests and Grand Teton National Park, The Teton Range supports only about four adult wolverines, biologists estimate.

“That would be pretty typical,” Heinemeyer said. “They have huge home ranges.

“That’s why we keep going to different landscapes: because we can’t get the sample size that we want in any one spot,” she said.

Weighing 20 to 55 pounds, the wolverine is a large cousin of the weasel. Wolverine home ranges can encompass more than 500 square miles.

About a year ago the U.S. Fish and Wildlife Service announced it was recommending that North American wolverines be managed as “threatened” under the Endangered Species Act.

The proposed listing is still being reviewed and is subject to public comment through May 6.