An analysis of wolverines in Wyoming and the rest of their Lower 48 range paints a grim picture of a low-density species that’s losing its habitat and facing an uncertain future.

The U.S. Fish and Wildlife Service published a 100-page “species status assessment” for North American wolverines in late September. That document presages a final determination that federal wildlife managers must make by late November to satisfy a May 2022 federal court order

The assessment’s closing paragraph hints at what’s likely to happen: Wolverines will no longer be a state-managed species, and instead will be entrusted to federal managers and the protective guidelines of the Endangered Species Act.

“Overall, future wolverine populations in the contiguous U.S. may be less secure than we described in our 2018 [assessment],” the document reads. “Uncertainty over the wolverine’s future condition in the contiguous U.S. is relatively high.” 

Wolverine ecology is plagued by unanswered “key questions” about the population size, gene flow and dispersal corridors across the Canadian border, the assessment states.

“Nevertheless, the best available information suggests that habitat loss as a result of climate change and other stressors are likely to impact the viability of wolverines in the contiguous U.S. through the remainder of this century,” the document says in its closing sentence. 

This map depicts potential wolverine habitat, observations and den sites. (U.S. Fish and Wildlife Service)

In an email, Fish and Wildlife Service officials acknowledged that a jurisdiction change for wolverines is likely weeks away. 

“The Service’s 2013 proposed rule to list wolverines as threatened in the lower 48 states is the current proposal,” Amanda Smith, a Fish and Wildlife public affairs officer, wrote. “Our final determination will be submitted to the Federal Register by November 27, 2023 as required.” 

The wolverine is a 17- to 40-pound member of the mustelid family that is notoriously reclusive. That’s because the alpine critters often dwell amid rock, ice and snow at very low densities. The Teton Range, at one point, had a documented population of one, an animal nicknamed Jed.

Conservation advocacy groups have pushed for a federal wolverine listing for decades, and the species’ classification has been the subject of repeated litigation. States, including Wyoming, have opposed classifying Gulo gulo under the Endangered Species Act in the past, though the scarce mustelid’s whereabouts in designated wilderness and other highly protected lands suggests a listing would have a limited effect on federal land management.

Fish and Wildlife’s decade-old proposed listing rule, reignited by U.S. District Court Judge Donald Molloy’s order, estimated a population of 250 to 300 animals in the Lower 48. The latest assessment, however, doesn’t make an estimate. 

“Systematic surveys to obtain population estimates have not been attempted in the contiguous U.S. given the difficulty of surveying a species that is highly mobile and occurs across large areas that are difficult to access,” the document states. “Therefore, the true population size in the contiguous U.S. is unknown.”

Research found the wolverine population in a 5,400-square-mile swath of the southern Canadian Rockies declined roughly 40% from 2011 to 2020, according to the assessment.

“It is unknown whether the apparent population decline observed in the study area of the southern Canadian Rockies extended beyond the study area boundaries,” Smith wrote in the email, “or whether the decline caused changes in the number of wolverines dispersing south.” 

Despite major knowledge gaps, western state wildlife management agencies have improved understandings of Gulo gulo in the Lower 48 over the last decade by undertaking standardized surveys

Researchers focus on where female wolverines are located to get the best indication of their range in Wyoming. This wolverine was photographed in the Wind River Range. (Meghan Riley)

There were two primary survey periods, one from 2016-’17 and another from 2020-’22. During the earlier surveys, surveyors found lower densities of the animals in suspected wolverine habitat in Wyoming and the Greater Yellowstone Ecosystem than in more northerly Montana, Idaho and Washington wolverine habitat. 

“The species was extirpated from the Lower 48, then because of protections and lack of trapping the species began to recolonize,” said Heather O’Brien, a nongame mammal biologist for the Wyoming Game and Fish Department. 

It makes sense, O’Brien said, that densities would be lower in Wyoming because it’s the southern extent of modern-day wolverine range. There’s also low genetic diversity here, she said.

But the best-available science also suggests Wyoming populations have been on the upswing.  

“During the second survey — that ‘20, ‘21, ‘22 time period — our occupancy in Wyoming actually increased,” O’Brien said. “We had six camera detections during that first survey period. And then 13 [in the second], so we’ve more than doubled our detections in Wyoming.” 

Wolverines in Wyoming are classified as a “species of greatest conservation need” and no hunting or trapping is allowed. A 2020 state management plan supports the expansion of wolverine into suitable habitat and promotes “long-term wolverine viability.” 

O’Brien interpreted Fish and Wildlife Service’s assessment as the precursor to listing wolverines under the Endangered Species Act. Wolverines were proposed as “threatened,” which means they’re “likely to become an endangered species within the foreseeable future throughout all or a significant portion of [their] range.”

“It sounds like the Fish and Wildlife Services is leaning towards listing the species,” she said. “We’ll wait and see what the feds decide to do with their new pile of information, and we’ll go from there.” 

Center for Biological Diversity attorney and Victor, Idaho, resident Andrea Zaccardi, who’s litigated wolverine ESA issues in the past, guessed similarly.

“I hope we’re looking at a positive listing rule by the end of November,” Zaccardi said.

This U.S. Fish and Wildlife Service photo shows a wolverine in 2010. (Roy Anderson)

Mike Koshmrl reports on Wyoming's wildlife and natural resources. Prior to joining WyoFile, he spent nearly a decade covering the Greater Yellowstone Ecosystem’s wild places and creatures for the Jackson...

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  1. You lost me as soon as you inserted the buzzword “climate change” which is ridiculous.
    Just like they said “global warming” would kill off the polar bears and the exact opposite happened, but now we can’t call it “global warming” since the globe is not heating up like the ridiculous predictions they made.
    I’m from the government and I’m here to help. This will not end well for we the people of Wyoming. It will result in more regulations and restrictions hurting the ranchers, hunters, and trappers.

    1. Rick, you’ve lost me. Climates are continually changing and Global warming is a fact. Your “knee jerk” reaction to the proposed regs are premature. Trapping will most likely be affected but the elusiveness of the wolverine is of no real interest to hunters or ranchers.

  2. What will this do to hunting and trapping? Will this be used as a weapon against hunters and trappers? This is what I would expect with this administration and the people that promote Wolves!

  3. Hmm two contradictory statements
    “Systematic surveys to obtain population estimates have not been attempted in the contiguous U.S. given the difficulty of surveying a species that is highly mobile and occurs across large areas that are difficult to access,” the document states. “Therefore, the true population size in the contiguous U.S. is unknown.”

    Research found the wolverine population in a 5,400-square-mile swath of the southern Canadian Rockies declined roughly 40% from 2011 to 2020, according to the assessment.
    —— Too hard to estimate population—but oh yeah research showsCanadian polulation declined ( i guess in Canada they can indeed estmate populations).
    Also Canada probably has less habitat loss and less climate impacts and pop still in decline so feds want to list. What if population is about realtionsip to prey bases availability ? Similar to Lynx and Snowshoe population oscialation cycles??
    Sounds like the feds want to use this to lock uip more land with little science behind it. Typical of US Fish and Wildlife folks who live in a bubble.

  4. This is good news. These animals need more protection. But why print a map of their locations? This tells people where they can find them, for trapping or whatever. As a retired wildlife biologist, I’ve actually seen this happen in MT.

  5. I’m lucky enough to have seen many animals in the wild, on their land. I never have seen a wolverine and sure don’t expect to. But it’s good and important to know they are out there, doing their thing, adding their lives and expertise to the whole picture. I know we can’t “take care of them”; I hope we can make room for them and reap the benefits of one more long-time member of our community.

  6. Will the purchasers of Wyoming hunting and fishing licenses get stuck with the bill for managing wolverines once they are listed??? Grizzly bears are still isted and even though they primarily occupy habitat on federal lands such as the greater Yellowstone ecosystem which encompasses wilderness areas and USFS administered lands – the State of Wyoming – Game and Fish that is – seems to pay much off the cost of managing grizzlies – something like $65 to 72 million to date. The cost of managing these listed species on federal surface should be paid by the American public not hunters and anglers in Wyoming. The ESA needs to be revised to correct this funding problem.

    It seems to me that all trapping should be eliminated in the wolverine designated habitat. Many trapping sets do not discriminate as to which species is caught, and a trap which is intended to catch bobcats, coyotes, and fox may very well catch a wolverine. The wolverine designated habitat will undoubtedly be on federal surface meaning the USFS and National Park Service will control the habitat but how about trapping on Federal surface? To what extent will Game and Fish wardens enforce a trapping ban on Federal surface such as wilderness areas??? Will the Federal agencies – including USFWS – expect Game and Fish to protect wolverines.

    And then, there will be the necessary recovery plans which someone needs to write – and they can cost millions to generate. Will Wyoming Game and Fish be obligated to write a recovery plan for wolverines just like Game and fish did for wolves and grizzlies. Why should a state agency write the recovery plan when the habitat of the wolverines is almost entirely on federal surface? If this goes the way of grizzly bear recovery plans, Game and Fish will get stuck with writing the plan and our hunters and anglers will foot the bill.

  7. I hear the Wolverine saying it’s ok to be middle class, and I’m going to attempt to move back home.