North American Wolverine

Reintroduction pending. No wolverines have been released yet. Recovery and Conservation Status explains what has to happen before the first release.

Overview

The wolverine (Gulo gulo) is the largest land-dwelling member of the weasel family — a muscular, bear-faced predator that looks improbable and behaves accordingly. It crosses mountain ranges in days. It drives grizzly bears off kills. It travels routes that would exhaust a backcountry skier. For an animal that weighs less than 40 pounds, it occupies an almost mythological space in the ecology of the high Rockies.

In Colorado, wolverines occupy a peculiar conservation status: protected but, for now, absent. The last one confirmed here was M56, a collared male who walked from Wyoming’s Togwotee Pass area into north-central Colorado in 2009. CPW tracked him until 2012; he was shot in North Dakota in 2016. He was a single documented disperser from Wyoming — a scout, in effect, testing whether Colorado’s alpine landscape can support a breeding population. No breeding has been documented in the state.

That framing is changing. A 2024 state law authorized CPW to bring wolverines back, and in January 2026 CPW released a formal Wolverine Restoration Plan; its numbers, release zones and the steps still ahead are under Recovery and Conservation Status below.

After nearly three decades of legal battles, petitions, and withdrawn listing proposals, the U.S. Fish and Wildlife Service listed the wolverine as Threatened under the Endangered Species Act in November 2023. The listing explicitly identified climate change — specifically the loss of persistent spring snowpack — as the primary driver of decline.

Habitat in Colorado

Wolverines are creatures of the high country in the most literal sense. Suitable habitat in Colorado is subalpine and alpine terrain — spruce-fir forest, krummholz, and alpine tundra — where snow lingers well into spring.

What makes habitat suitable is not just elevation but snowpack. Female wolverines den in deep spring snow. The snow serves as insulation — keeping den temperatures stable while kits develop — and the den must hold through April and May when cubs are most vulnerable. Research has tied wolverine reproduction to snow cover that persists into mid-May, which females need for dens. Colorado’s highest terrain currently provides this, but modeled projections suggest significant portions of that habitat become marginal by mid-century under most climate scenarios.

Males use very large home ranges, which means suitable Colorado habitat must connect to larger populations to the north. Isolated mountain ranges surrounded by lower-elevation terrain act as barriers to dispersal.

Primary Threats

Climate change and snowpack loss is the threat that drove the 2023 federal listing. Wolverines are among the most climatically vulnerable mammals in North America because their reproductive biology is physically tied to deep spring snow. As snowpack arrives later, melts earlier, and decreases in depth across the Rockies, the window of suitable denning conditions contracts. Models project roughly a third of wolverine habitat in the contiguous United States lost by mid-century and about two-thirds by late century (McKelvey et al. 2011). In Colorado, this compression occurs from below — as lower treeline sites warm, the band of suitable habitat retreats upslope toward summits that offer diminishing returns in terms of area.

Isolation and low connectivity compounds the climate threat. M56 was a lone disperser from Wyoming. For a breeding population to establish in Colorado, animals must successfully navigate hundreds of miles of fragmented terrain — crossing highways, developed areas, and lower-elevation habitat that wolverines typically avoid. A female making this journey is extraordinarily rare.

Low reproductive rate means any losses are slow to recover. Females typically breed every two years, producing litters of two to four kits (CPW). A population absorbing consistent adult mortality — from trapping, vehicle strikes, or habitat loss — cannot replace losses quickly.

Historical trapping is why the state starts from zero. Poisoning, trapping, and unregulated killing eliminated wolverines from Colorado; the last confirmed record before M56 was in 1919. No population has returned on its own in the century since.

Recovery and Conservation Status

The November 2023 Threatened listing was the culmination of a process that began with the first formal listing petition in 1994. USFWS proposed listing in February 2013 and withdrew the proposal in August 2014. A federal court vacated that withdrawal in April 2016; USFWS withdrew again in October 2020, and a court vacated that decision in May 2022. The final threatened listing was published November 30, 2023 — the first durable federal protection wolverines have received.

Colorado moved quickly after the listing. In May 2024, Governor Polis signed Senate Bill 24-171, authorizing CPW to reintroduce wolverines to the state. The legislature committed about $1.8 million over four fiscal years, including $750,000 from the Species Conservation Trust Fund. On January 15, 2026, CPW released its formal Wolverine Restoration Plan — a 106-page document detailing the framework for releasing up to 45 wolverines, up to 15 per winter over three or more winters, favoring pregnant females, into Colorado’s high country. CPW ranked Alberta and British Columbia as the best source populations and identified three release zones: north of I-70 including Rocky Mountain National Park, the Elk and West Elk mountains, and the San Juans.

Colorado holds an estimated 20 percent of all modeled wolverine habitat in the contiguous United States, according to CPW’s restoration plan, making it one of the most significant potential recovery sites for the species anywhere in its lower-48 range.

No release date has been set. Before animals can be moved, CPW must finalize a livestock depredation compensation rule and USFWS must issue a federal 10(j) nonessential experimental population rule. Colorado law (SB 24-171) bars releases until that rule takes effect; as of September 2026, none has been proposed, and no wolverines have been released.

Critical habitat has not yet been designated for the wolverine. USFWS issued a recovery outline in December 2023; no recovery plan has been completed.

CPW monitors wolverine presence through remote camera networks and winter track surveys. The state’s wolverine program is now formally structured around restoration rather than passive monitoring.

What You Can Do

• If you observe what you believe is a wolverine in Colorado, report it to Colorado Parks and Wildlife through their wildlife observation system at CPW’s wolverine sighting form. Wolverine detections are rare and scientifically valuable; CPW biologists will follow up. A general area description — mountain range, wilderness unit, or county — is sufficient.
• Support snowpack and climate policy. Wolverine recovery in Colorado is inseparable from the trajectory of the Rocky Mountain snowpack. Organizations working on Western water and climate policy are effectively working on wolverine habitat.
• Follow CPW’s wolverine reintroduction process. Public comment opportunities will arise as CPW finalizes the livestock compensation rule and other steps required before releases occur. Engaged public support for the reintroduction is meaningful.
• Practice low-impact winter recreation in wolverine country. CPW’s three planned release zones (listed in Quick facts) are the most likely areas for future wolverine activity in Colorado. Staying on established routes during late winter and spring minimizes disturbance during the period when wolverines, if present, would be denning.