The wolverine (or carcajou in French) is the largest terrestrial member of the Mustelidae, the weasel family. They are adapted to survival in extreme northern habitats, and are powerful predators. The wolverine can be found throughout northern Canada and Scandinavia.

General biology and behaviour

The wolverine has a passing resemblance to some bears, but upon seeing the animal move there is no mistaking its relation to other members of the weasel family. They are powerfully built animals, with heavy skulls and very developed teeth. Males generally weigh about 15 kg, while females are somewhat smaller at 8-10 kg. Their brown fur is thick and longer on the tail than the rest of the body. Frequently, the fur near the toes and face is a lighter colour, often becoming completely white.

Wolverines are remarkable predators, preying principally upon ungulates like deer, moose or caribou. While they are capable of killing live deer, the majority of their ungulate consumption occurs as a result of scavenging. In the winter months when ungulate prey are not available, like wolves the wolverines rely upon local rodent populations to supplement their diet. Their scavenging lifestyle puts them at times into direct conflict with mountain lions and wolves. These two species are known to prey upon adult wolverines, and likely the young. Given the extent to which female wolverines go to secure nests for their kits, biologists believe that the risk of predation on young wolverines must be quite high.

Wolverines are highly territorial animals, patrolling home ranges on the order of 400 to 1500 square kilometers. As a result of their huge home ranges, wolverine densities, even in optimal habitats, are quite low, making them susceptible to extirpation (see Conservation status). The size of the home range is supposedly negatively correlated to prey abundance, and some scattered evidence supports this contention. Also, the home range size and position for males is directly related to the home ranges of females of reproductive age.

Wolverines communicate with one another by using vocalizations and marking their territories. They can scent their territories using both their urine and abdominal rubbing. While they, like most mustelids, have anal glands, their musk is used mostly for defense rather than communication.

Wolverines are distributed circumpolarly. They can be found in the northern parts of Canada in the taiga or tundra, but can also be found at high elevations further south. There are extant southern populations in British Columbia, Montana and Idaho. In Eurasia, they are found throughout Scandinavia and east to Siberia and Asia. Unlike most other northern species, however, they do not hibernate.

Both male and female wolverines attain sexual maturity relatively quickly (15 months for the females, 24 months for the males). Wolverines do not form breeding pairs like wolves, but some evidence suggests that males may remain in a female's territory to help with the early care of the young. Females go into heat once per year (they are monestrous) and breeding takes place from May to August. Males begin to have elevated testosterone levels and sperm production by early April, but they revert to a non-breeding state by August. Unlike many animal species, the female initiates copulation. After fertilization, the eggs remain at the blastocyst stage for several months. Further embryonic development does not begin until November or December and females give birth the following March or April. 2-3 kits are produced per average litter, and feed from their mother for roughly 10 weeks. After weaning, they remain with their mothers for a number of months before leaving to begin their solitary existence.

Conservation status

Given the very low densities and large home ranges of wolverines (see General biology and behaviour), the species is one at considerable risk of extinction by humans. Not only habitat destruction but also habitat fragmentation have resulted in extirpation of local populations. Not only do wolverines need considerable areas to survive, but these areas must also be uninterrupted by human influences. Forestry and mining in northern reaches negatively influence wolverines in three ways. First, they perturb the habitat, removing forest stands and low-lying vegetation preferred by wolverines. Second, their presence reduces the density of ungulates, meaning there are fewer prey for the wolverines. Third, the construction of access roads significantly modifies the movement patterns of wolverines, thus reducing their ability to find one another, mate and forage for food.

Humans also trap wolverines for their pelts. Trapping is legal in British Columbia, Alberta, Alaska and Montana, despite the low densities reported for the species. They are considered endangered in eastern Canada, threatened in Western Canada and the United States, and have been listed by CITES in some Scandinavian countries. It is also listed as vulnerable by the IUCN.

Importance to humans

Wolverines have been trapped by humans for hundreds of years for their lush, warm pelts. They have also been targeted by trappers due to the fact that they often raid previously laid traps and steal the carcasses for food.

They are animals of some importance to the spiritual lives of the Innu. The wolverine (Kuekuatsheu) is seen to be a highly intelligent but foolish trickster, and plays a role in many Innu myths and stories.


Order: Carnivora
Family: Mustelidae, the weasels
Subfamily: Mustelinae
Genus, species: Gulo gulo1
1Some scientists believe that there are sufficient morphological differences between wolverine populations to justify the creation of three subspecies: the Old World wolverine, Gulo gulo gulo, the New World wolverine, G. g. luscus, and the Vancouver Island wolverine, G. G. vancouverensis.
Just a quick note about two of the w/u's above. Sudderth is incorrect in claiming that the wolverine was desended from wolves; they have completely separate evolutionary histories, and are related only inasmuch as they are both members of the order Carnivora. And Cobra Rax states that the French call the animal Glouton and while that is a synonym, it is more often known as the carcajou, which Stavr0 tells me is derived from the Innu name Kuekuatsheu.
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