Wolverine

September Furbearer Playmate of the Month

Wolverine

The Wolverine, a relative of the mink and weasel, is the largest terrestrial member of the family Mustelidae. Also known as devil bear, carcajou, or woods devil, its scientific name is Gulo gulo, meaning "glutton." Wolverines occur in small numbers throughout their range and require large expanses of wilderness. Formerly distributed across most arctic and subarctic regions in North America, the Wolverine has disappeared from most of the eastern United States and Canada. In Alaska, there have always been significant Wolverine populations throughout mainland Alaska and some of the islands of southeast Alaska.

The Wolverine is valued by Alaskans as a fur resource and as a symbol of wilderness. Its fur is commonly used for parka trim and hoods because of its beauty and durability and because the guard hairs of Wolverine fur resist frost accumulation.

General Description

The long dense fur of the Wolverine is generally dark brown to black with a creamy white to gold stripe running from each shoulder along the flanks to the base of the tail. It has a thick body, short legs, short ears, and a broad flat head. The Wolverine is primarily a scavenger and has large teeth and powerful jaws to crush bones and eat frozen meat. Adult males generally weigh 20 to 45 pounds (9 to 20 kg) while adult females weigh 15 to 30 pounds (7 to 14 kg). Its non-retractile claws are long and curved.

Wolverines are primarily found in the wilder and more remote areas of Alaska. They are solitary creatures throughout most of the year. Wolverines are active at any time of day, year round. They have tremendous physical endurance and can travel up to 40 miles a day in search of food. Because of their great endurance and strength, Wolverines have become a center of folklore. However, their fierce reputation has often been exaggerated. They have been known to steal furbearers from traps and to damage cabins, but these tales can normally be traced to individuals in some situations and not to the species as a whole. Wolverines will rarely attack any predator larger than itself, like a wolf or a bear. Instead, they will try to avoid these animals. Wolverines will fiercely defend a food source or its territory against other Wolverines or smaller predators.

Life history

Wolverines become sexually mature in their second year. The breeding season extends from May through August. After mating, the embryo floats in the uterus until late fall or early winter. This type of reproduction is known as delayed implantation and allows a female Wolverine to become pregnant when food supplies are best and when she is in good physical condition. Adults may fail to produce young in some years even when they successfully breed. The abundance of food determines whether a pregnancy will be maintained and the number of young that will be born.

Wolverine litters are born between January and April. In Interior and northern Alaska most young are born in snow caves. These caves usually consist of one or two tunnels that can be up to 60 yards long. No litters larger than four have been reported in the wild and most are in the range of one to three. Baby Wolverines, called kits, are born blind and weigh less than 1 pound (0.4 kg). They develop rapidly and are weaned at about 8 weeks of age. They leave their mothers at approximately 5 or 6 months to forage for themselves. Wolverines attain most of their adult size and weight within their first year.

Wolverines travel extensively in search of food. Home range sizes are vast, with adult males using areas up to 240 square miles. Adult females use smaller home ranges encompassing between 50 and 100 square miles. Adults maintain their home ranges more or less separate from those belonging to adjacent Wolverines of the same sex. The home range of the resident male may encompass the ranges of up to four to six females. The breeding season is the only time during the year that males and females interact.

It appears that few Wolverines live longer than 5 to 7 years in the wild. Some, however, do survive to 12 or 13 years of age. The primary natural mortality factors are starvation and being killed by other predators, primarily wolves. However, most Wolverine mortality is due to trapping by humans.

Food habits

Wolverines are opportunistic, eating about anything they can find or kill. They are poor hunters but are well adapted for scavenging. The Wolverine has a powerful jaw and large neck muscles allowing it to crush and use bones and frozen flesh. Also, Wolverines can survive for long periods on little food. Their diet reflects annual and seasonal changes in food availability. In the winter, Wolverines primarily rely on remains of moose and caribou killed by wolves and hunters or animals that have died of natural causes. Throughout the year, Wolverines feed on small and medium-sized animals such as voles, squirrels, snowshoe hares, and birds. In the right situations, Wolverines can kill moose or caribou, but these occurrences are rare.

Population management

The continued health of Wolverine populations in Alaska is best assured by both protecting large expanses of wilderness and preventing overharvest. Wolverines prefer vast areas of wilderness, and preservation of their habitat is of key importance to their successful management. Much Wolverine habitat is now protected in the state through various federal and state land dedication programs. Harvests are controlled by seasons and bag limits. Annual catches and the effects on the population are closely monitored by the Alaska Department of Fish and Game to ensure that harvest by humans will not be a negative factor on Alaska's Wolverine populations.

Text: Ken Taylor and Craig Gordon
Used by permission of the Alaska Department of Fish and Game

Illustration copyright The Wolverine Foundation, Inc., used by permission



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Mail: P. O. Box 82177
Fairbanks, Alaska 99708
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