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Scientific Name: Gulo gulo

Status: State Endangered


Wolverine have a reputation larger than life, but they are impressive weasels by any standard. Wolverine are three feet long, with a rather short tail, just one-quarter the total length. Otters are longer, but wolverines are the heaviest of weasels, tipping the scale at 20 to 30 pounds or more. They are stocky mammals, built like a small bear. Their fur is dark brown to black, and the sides have a characteristic yellowish brown to whitish stripe. Like other weasels, wolverine have anal musk-producing glands.


Wolverine are animals of high alpine environments in both North America and Eurasia. In North America, they occupy western mountains in Alaska and Canada; the southern portion of their current range extends into the contiguous United States, including Washington, Idaho, Montana and Wyoming.


Wolverine have a circumpolar distribution in the Northern Hemisphere and are found in tundra, taiga, boreal and alpine biomes. These relatively unproductive habitats are areas where daily low temperatures can fall below freezing most of the year, growing seasons are short and snow persists into the summer months. The wolverine occupies a unique niche by accessing scarce food resources available in these environments, despite the presence of deep snow-cover, and caching these resources in cold, rocky areas that inhibit competition from insects, bacteria and other scavengers.

In Colorado, nearly all historical and recent reports of wolverines are from higher elevation, alpine areas that occur in an island-like fashion. Until recently, the last confirmed wolverine sighting in Colorado was in 1919. Occasional reports of wolverine sightings were investigated, but wolverine were never officially documented. In spring 2009, researchers with the Greater Yellowstone Wolverine Program tracked a wolverine from Grand Teton National Park south into north central Colorado. This was the first wolverine confirmed in the state in 90 years.


Wolverine eat small rodents, rabbits, porcupines, marmots and other small mammals. They may attack large game (for example, weakened deer or other large prey, especially when bogged in deep snow), but most ungulate remains in their diet are probably from carrion.

Wolverine and cubs. Credit: Mark Packila, ©Wildlife Conservation Society Wolverine are legendary marauders of the North, renowned for their strength, cunning and viciousness. Pound for pound, they are probably no stronger than the next weasel. "Cunning" and "vicious" are terms best reserved for people. People can be cunning and vicious. Wolverine probably are just hungry and quite capable of satisfying it. Reproduction:

Wolverine breed during the warmer months. Embryos implant in January. Two to four young are born in late March or early April. Growth of the blind, toothless newborns is rapid, and they will be half-grown when they disperse in autumn.

Additional Information:

Have you seen a Wolverine?

Think you've seen a wolverine in Colorado? View our Wolverine Identification Guide for more information to ensure you have positively identified a wolverine. If you have seen a wolverine, please help biologists by filling out the Wolverine Sighting Form.​​​

Wolverine Confirmed in Colorado

Researchers from the Greater Yellowstone Wolverine ​program say they have confirmed the first wolverine in Colorado in 90 years. A male wolverine, tracked via GPS-satellite collar, was confirmed in the north-central part of Colorado in early June 2009.​​​

While many wolverine sightings have been investigated by wildlife officers in the past decade, the last confirmed wolverine in Colorado was in 1919. Biologists believe it is possible that other wolverine are in the state but they have been unable to find definitive proof of other wolverine in Colorado.

The newcomer wolverine, labeled M56, was captured near Grand Teton National Park in northwestern Wyoming in May 2009 as part of a study to understand these wide-ranging little-known animals. The wolverine traveled approximately 500 miles to reach Colorado.

Colorado Parks and Wildlife is working with recovery program researchers to track the wolverine in order to monitor its movements and activities.

On July 8, 2010, at its meeting in Gunnison, the Parks and Wildlife Commission granted CPW’s request to begin having conversations about restoring wolverines with CPW’s partners and stakeholders. CPW is having these discussions with a broad spectrum of user groups, government agencies and other interested people and organizations.

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