Credit: Susanne Nilsson / Creative Commons

The U.S. Fish and Wildlife Service rejected Endangered Species Act protections for wolverines on Thursday, saying the snow-dependent species does not face an imminent threat from a warming climate.

The determination walks back a 2013 finding by agency scientists that wolverines are likely to be harmed by a lack of snowpack in many areas that pregnant females use for dens. 

Conservation groups have already promised to challenge the decision, saying an intent to sue could be filed as soon as next week.

Once extirpated from the Lower 48, an estimated 300 wolverines now live in the contiguous United States, including much of western Montana. Individuals of the species, which have ranges of hundreds of miles, rely on large territories in remote landscapes at high elevations for survival. 

“In the time since our original proposal, the science on wolverine has been greatly advanced thanks to the work of state wildlife agencies and researchers in the U.S. and around the world,” said Noreen Walsh, regional director for the Fish and Wildlife Service, in a press release. 

Walsh had previously reversed course on the 2013 listing decision, determining in 2014 that the species was not threatened. After that new decision was challenged by conservation groups, U.S. District Court Judge Dana Christensen chastised Walsh for the “arbitrary and capricious” decision in a 2016 ruling that required the agency to go back to the drawing board and reassess the science underpinning it. Christensen said Walsh had solicited scientific opinions “in the eleventh hour to back fill her foregone conclusion to withdraw” the 2013 proposed rule. 

Christensen said Walsh’s decision was likely influenced by “immense political pressure” from states, most notably Montana. “The listing decision in this case involves climate science, and climate science evokes strong reactions,” the judge wrote.

Andrea Zaccardi, a senior attorney at the nonprofit Center for Biological Diversity, said Thursday’s decision ignores “years and years of science showing that climate change will negatively impact snow levels that wolverines need to den and survive.”

The Trump administration has taken steps to weaken the role that climate science can play in Endangered Species Act rulings. In 2018, the Fish and Wildlife Service finalized a rule change that effectively limited how far scientists can project into the future to determine changing climate impacts to species, said Taylor Jones, endangered species advocate at the nonprofit WildEarth Guardians.  

“It’s part of a larger pattern of climate denial,” Jones said.

Despite Christensen’s 2016 decision having directed the service to act quickly, the agency did not make another determination until forced by a court decision to do so by Aug. 31. That Aug. 31 decision is the one announced Thursday. 

Matt Bishop, an attorney with the nonprofit Western Environmental Law Center, which was one of the litigants in the successful 2016 challenge, said wolverine science hasn’t significantly advanced in the past few years.

“Our position is nothing has really changed since then,” Bishop said.

The 2018 species status assessment conducted by FWS provides some evidence for removing protections, the service said. In a Q & A published along with the press release, the agency says wolverine populations have been observed outside modeled habitat projections, indicating that snow for denning is less important than previous research had indicated. The agency also said climate models through 2055 show enough snow for wolverines. 

But Tim Preso, an attorney with nonprofit Earthjustice who helped litigate the 2016 case, said that document “seems to be significantly flawed.”

Preso said the agency “cherry-picked” data from the snowiest places in wolverines’ ranges and relied on one-year snapshots of wolverine detection that don’t offer a picture of long-term population stability. 

In Thursday’s decision, which is set to be released in the Federal Register next week, the U.S. Fish and Wildlife Service determined that the wolverine population is stable.

But researchers don’t know much about wolverine populations, said Jeff Copeland, a board member of the Wolverine Foundation, a nonprofit organization of wildlife scientists that raises awareness about the animals. Male wolverines have ranges of up to 500 miles, while females have ranges of about 200 miles, making them hard to locate. And in recent years the species has become less populous in many mountain ranges in Montana, Idaho and Wyoming, including the Tetons, the Absarokas, the Centennials, the Henrys Lake Mountains, the Sawtooths and the Smokies, according to Copeland, a retired wolverine researcher who spent decades working for the Idaho Fish and Game Department and the U.S. Forest Service.

“We don’t know why it’s happening. Any suggestion that the population is stable is a little absurd,” Copeland said. 

FWS also said in a press release that it determined that the U.S. population is linked to Canadian and Alaskan wolverine populations, and therefore isn’t a distinct population segment requiring ESA protections. 

Copeland, who advised both the federal and state governments as well as the conservation groups in the 2016 lawsuit, said there is little evidence to back up that claim, and that research shows little gene flow between the Lower 48 and Canadian populations.

“It’s a little disappointing to see. I don’t know what they’re basing their science on to come to this conclusion, but it’s certainly not from any data I’m aware of,” Copeland said

While wolverines can occupy pretty much any terrain north of the 56th parallel, more than 90% of suitable wolverine habitat in the Lower 48 states is on mountain peaks on public land, according to the agency. There remains suitable habitat for them in the Southern Rockies, including Colorado, where they generally do not live now, Preso said.

Preso said arguing that the wolverine is fine because it lives in Canada and Alaska is like saying the Lower 48 doesn’t need species like the bald eagle, grizzly bear, gray wolf and Canada lynx because they live in Canada and Alaska as well.

“I don’t think the Endangered Species Act was designed to turn a blind eye to the wildlife in the Lower 48 just because the species live outside of the Lower 48,” Preso said. 

Copeland said a species with such low population density as the wolverine is always in danger of going extinct. 

“This is an animal that needs attention,” Copeland said. “I’m concerned about collecting data, whether we decide that the Endangered Species Act is the best tool to ensure the wolverine’s persistence. Whatever the case, the animal needs something. We need to be able to pay attention and monitor this animal to understand what it needs to survive.”

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Johnathan Hettinger is a journalist based in Livingston. Originally from Central Illinois and a graduate of the University of Illinois, he has worked at the Midwest Center for Investigative Reporting, the Livingston Enterprise and the (Champaign-Urbana) News-Gazette. Contact Johnathan at and follow him on Twitter.