Wolverine (Gulo gulo): Facts, Strength, Habitat and Diet

Appearance

A wolverine looks more like a small bear than a weasel. It has a broad, rounded head, small eyes, short rounded ears, a heavy body and short, thick legs. The back is slightly arched and the bushy tail is fairly short. Its large, five-toed feet carry long, curved claws that work like crampons on ice, rock and tree trunks.

The coat is long, dense and dark brown to almost black. A pale buff or golden stripe runs from each shoulder along the flanks and meets above the tail, and many wolverines have a lighter, silvery mask across the forehead. Some individuals have white or cream patches on the throat and chest, which researchers use to recognize individuals on camera traps.

The fur is oily and sheds water and frost very well, which is why Arctic peoples traditionally used it to trim the hoods of parkas. Like other mustelids, the wolverine has strong anal scent glands, and the musky smell has earned it nicknames such as “skunk bear”.

How big is a wolverine?

Wolverines are the heaviest of the land-living weasels. Only a few water-living relatives, the sea otter, the giant otter and the African clawless otter, are larger. The European badger can reach a similar weight in autumn.

Males are about 10–15% larger than females in body length and can be 30–40% heavier. Weights above 20 kg (44 lb) appear in some older reports from Siberia, but they are exceptional and some are doubted. Scandinavian and North American wolverines are similar in size.

Habitat and range

The wolverine has a circumpolar range across the boreal forest (taiga), Arctic tundra and high mountains of the Northern Hemisphere. The largest populations live in Alaska, northern and western Canada, and across Russia from the Kola Peninsula to the Pacific. In Europe it survives in the mountains and forests of Norway, Sweden and Finland, and in Asia it also reaches Mongolia and northeast China.

In the contiguous United States, wolverines live in small numbers in the North Cascades of Washington and the northern Rocky Mountains of Idaho, Montana and Wyoming, with occasional animals in Oregon, California, Colorado and Utah. They once lived much farther south, including the Great Lakes region, New England and the southern Rockies, but trapping, poisoning and habitat loss wiped them out there.

Wolverines need large areas of wild country and cold winters. Most live where snow lies deep and lasts well into spring, because females dig their breeding dens in that snow. For a closer look at where they live today, see where do wolverines live?.

What do wolverines eat?

Wolverines are carnivores and, above all, scavengers. In winter and early spring, much of their food is carrion: reindeer, caribou, moose and deer that died of hunger, cold, avalanches or were killed by wolves, lynx or bears. A wolverine can find a carcass buried under snow by smell and will follow wolf packs to feed on what they leave.

They are also capable hunters. In summer they catch voles, lemmings, ground squirrels, marmots, hares, porcupines, beavers and ground-nesting birds, and they raid nests for eggs. In deep, soft snow, a wolverine’s wide feet let it run on top of the surface while hoofed animals sink, and it can kill reindeer, caribou and deer that are weakened or stuck in the snow. Berries, roots and insect larvae make up a small part of the diet.

Wolverines cache surplus food in snow, rock crevices and bogs, where the cold keeps it fresh for weeks or months. A special upper molar, turned sideways in the mouth, and very strong jaws let them tear meat and crunch bones that are frozen solid. The full menu is covered in what do wolverines eat?.

Behavior and home range

Wolverines are mostly solitary and active by night and day, often alternating a few hours of activity with a few hours of rest. They do not hibernate and keep moving through the harshest winter weather. They travel in a loping gallop and can keep going for long distances; individuals have been tracked covering 30–45 km (19–28 mi) in a day and crossing high mountain passes in deep snow.

Their home ranges are enormous for an animal of their size. Adult males commonly use 500–1,500 km² (190–580 sq mi) or more, overlapping the smaller ranges of two or three females. Adults keep out of the ranges of others of the same sex and mark their areas with urine, feces and musk from their scent glands. They also spray their food caches to claim them.

Wolverines are good climbers and strong swimmers. In Glacier National Park, Montana, researchers tracked a male that climbed about 1,500 m (4,900 ft) up a steep mountain face in roughly 90 minutes. This combination of toughness and stamina is the basis of the wolverine’s fierce reputation, explored in how strong is a wolverine?.

Reproduction and snow dens

Wolverines mate in late spring and summer, mostly from May to August. Like many mustelids, they have delayed implantation: the fertilized egg floats in the womb for several months and only attaches in early winter. After that, the pregnancy lasts another 30–50 days, so kits are born between January and April, when food is scarce and the snow is deep.

The female digs a den deep in the snowpack, often among boulders, fallen trees or in avalanche debris. These dens can include long snow tunnels and several chambers, and they keep the kits safe from cold and from predators. Litters usually contain two or three kits, with a range of one to five. Newborn kits weigh about 85 g (3 oz) and have a thick white or cream coat.

Kits are weaned at about 10 weeks and grow very fast, reaching nearly adult size by their first autumn or winter. They usually leave their mother’s range at 5–7 months and later travel far to find a territory of their own. Females typically breed for the first time at two or three years old and often produce a litter only every other year, so wolverines reproduce slowly.

Lifespan, predators and threats

Wild wolverines usually live 5–7 years, and a few reach about 13. In zoos they can live 15–17 years or more. Starvation, especially in young animals, is a major cause of death.

Gray wolves are the wolverine’s most important natural enemy, and packs sometimes kill wolverines at carcasses or near their dens. Brown bears, black bears and cougars can also kill adults, and golden eagles take young kits. Human causes include trapping, which is still legal and regulated in parts of Alaska, Canada and Russia, road traffic and habitat fragmentation.

Climate change is a growing worry. Because breeding females rely on snow that lasts into late spring, warmer winters and earlier snowmelt could shrink suitable den areas, especially at the southern edge of the range. Winter recreation such as snowmobiling and backcountry skiing may also disturb denning females.

Conservation status

The IUCN Red List classifies the wolverine as Least Concern worldwide, because it still has a very wide range and large populations in Canada, Alaska and Russia, although its overall numbers are decreasing. Regional pictures are less rosy. On the European regional Red List the species is classed as Vulnerable, and it is protected in Norway, Sweden and Finland, where populations have recovered in recent decades.

In November 2023 the U.S. Fish and Wildlife Service listed wolverines in the contiguous United States as Threatened under the Endangered Species Act, citing the small, scattered population and the effects of climate change on snowpack. In 2024 Colorado passed a law allowing wolverines to be reintroduced to the state’s mountains, where they have been absent as a breeding animal for about a century.

Myths and facts

Myth: wolverines are mindless gluttons. The scientific name Gulo means “glutton”, and many European names carry the same idea. The wolverine does eat quickly and caches large amounts of food, but this is a survival strategy for an animal that may go days without a meal in winter, not greed.

Myth: wolverines attack people. Wolverines are famously fierce with other animals, but they are shy of humans and very rarely seen. There are no well-documented records of healthy wild wolverines killing people.

Fact: they can stand up to much larger predators. Wolverines have been seen driving wolves and bears away from carcasses, although they also lose such fights and are sometimes killed. Their courage is real, but so are the risks.

Relationship with people

For many Indigenous peoples of northern North America, the wolverine is an important figure in stories. The Innu of Quebec and Labrador tell of Kuekuatsheu, a trickster wolverine who helped create the world, and other Algonquian and Dene traditions also feature the wolverine as a clever, mischievous character.

Wolverine fur has long been valued for parka trims because frost from the breath can be brushed off it easily. Today the animal is better known as a symbol of toughness. Michigan is nicknamed the Wolverine State, the University of Michigan’s teams are the Wolverines, and the Marvel Comics hero took his name from the animal.

Wolverines are among the hardest North American and European mammals to see in the wild. Most of what we know comes from radio collars, camera traps and DNA from hair snagged on wire brushes. Other cold-country animals that share its world are featured in our list of Arctic animals.