After a decade of debate, the U.S. Fish and Wildlife Service last week announced protections for the distinct population segment of the wolverine in the lower 48 as a threatened species under the Endangered Species Act (ESA). In Wyoming the species is extremely rare, though a small population exists in Yellowstone National Park and the Shoshone National Forest.

Wolverines are now similarly protected to the area’s distinct population of grizzly bears. Grizzly bears in the 48 contiguous states are also currently protected as a threatened species and, like the wolverine, have stable populations in Alaska and Canada.

The Service initially proposed listing the species as threatened in 2013. Unlike an endangered listing, when a species is listed as threatened, prohibitions identified in section 9 of the act do not automatically apply to that species. Under section 9, it is illegal to import, export or take endangered species for any purpose, including commercial activity. The term “take” means to harass, hunt, shoot, capture, trap, kill, collect, wound, harm or pursue an ESA-listed species, or attempt any of these activities.

There are numerous examples of protections affecting development, including a recent fight in Nevada. In July the Department of Interior (DOI) banned further construction of a geothermal energy plant near Fallon, Nevada after the Fish and Wildlife Service listed the Dixie Valley Toad for protections as an endangered species.

In the toad’s case, the area is the only place that the tiny toad exists and the Service said the plant would likely result in the species becoming extinct. However, the wolverine has stable populations elsewhere and the Service also issued an interim ruling to exempt the take of wolverines related to research activities, incidental trapping mortality and forest management activities reducing the risk or severity of wildfire. 

A distinct population segment is a “population or group of populations that are distinct from other populations of the species and significant to the entire species,” the Service said in its announcement. Under the ESA, species, subspecies or distinct population segments of vertebrate species are eligible for listing.

Local population

Wyoming wildlife biologists studying the species detected wolverines at 15 monitoring sites across the state in 2021-22, their most recent monitoring program. The results were encouraging after the department only found wolverines at six sites in 2016-17. However, no wolverines were detected in the Snowy Mountain Range or the Bighorns.

“We are not sure of the population within the state, our monitoring does not give us a population estimate,” reported department spokesperson Breanna Ball.

After the 2016-17 monitoring program, an official with the department said they only knew of about 10 wolverines in the state.

“I would be fairly comfortable saying that we know we have at least eight,” said then department Non-game Wildlife Biologist Nichole Bjornlie.

As rare as they are, wolverines have been seen in the southeast part of Yellowstone and in the Shoshone National Forest in Park County. Wolverine populations historically extended as far south as California and New Mexico, but by the 1920s the animals were almost extirpated in the contiguous states because of unregulated trapping, habitat loss and the common practice of predator poisoning.

Preliminary results from a range-wide, multi-state survey are expected this winter/spring. Officials are unsure of the exact results but preliminary results of occupancy appears to be about the same as the previous monitoring effort, which in part led to the protections.

Wyoming is planning to conduct another round of monitoring in 2026-2027, Ball said.

Challenges

A new comprehensive genetic evaluation spanning the U.S.-Canada border was completed in 2023 and evaluated 887 unique individuals. The research identified issues with low genetic diversity and increasing population fragmentation at the southern extent of the wolverine’s range in western North America. It also found that large highways in southern British Columbia appeared to be restricting the effective dispersal of females from Canada to the U.S.   

According to the DOI, connectivity with Canada is essential to the long-term viability of wolverines in the lower 48 states.  

Climate change is also impacting the species, as wolverines are a snow-adapted species that depend upon areas with persistent spring snow for survival, in addition to denning and reproduction in the alpine habitats of the contiguous U.S.  

Also, new research points to human development in valley bottoms between core habitats as limiting wolverine dispersal and population connectivity to some extent, especially for females.

“Human disturbance and food availability were major drivers of wolverine distribution in winter and may change competition dynamics with other carnivores that are advantaged in areas affected by some human disturbance,” the department said in the announcement.   

Research also shows that backcountry winter recreation is “negatively associated with wolverine habitat use,” according to the Service, and recreation is likely to increase and become more concentrated in the future as snow-covered areas decline due to climate change. 

The analysis included various studies concerning the effects of backcountry recreation in wolverine habitat. The studies looked at various types of backcountry recreation including skiing, snowboarding, snowshoeing, and snowmobile use. The studies found that wolverines avoided high-quality habitats within their home ranges where these activities were occurring.

“The Service is not concerned about the effects of winter recreation in established and developed areas such as ski resorts at this time,” the announcement said. 

At this time, critical habitat is not determinable. The Service has an additional year from the publication of the final listing to determine critical habitat designation.

“The science is clear: Snowpack-dependent species like the wolverine are facing an increasingly uncertain future under a warming climate,” said Michael Saul, Defenders of Wildlife Rockies and plains program director. “The protections that come with Endangered Species Act listing increase the chance that our children will continue to share the mountains with these elusive and fascinating carnivores.”

A popular species

Evidence shows strong appreciation for wolverines in the U.S. A recent three-second video shared on Yellowstone’s Facebook page amped interest in the mammal and created an explosion of media attention. The clip generated dozens of media outlets requesting interviews for local, state and national stories.

“It really says a couple of things to me: Like the power of Yellowstone, a symbolic place of wilderness and wildlife. And also the power of video or photos of an animal to tell a story,” said Yellowstone wildlife biologist Dan Stahler, who captured the video with a motion-triggered scout camera.

“That one image generated a lot of interest to this rare, elusive mid-sized carnivore,” he said.

Wyoming’s monitoring effort saw Game and Fish researchers traveling out in wilderness areas during winter on skis, snow shoes, snowmobiles, tracked side-by-sides and trucks when possible.

“Anything we can use to move over the snow,”  Bjornlie said in a 2021 interview.

Bjornlie now is the conservation assistance planning coordinator and military lands conservation coordinator for the Fish and Wildlife Service.

In the most isolated areas, cameras were set up in fall and then checked the following spring. Studies are extremely difficult due to the range of the species. Females have home ranges of approximately 100 square miles and males will have home ranges as large as 500 square miles.