The wolverine (Gulo gulo) is one of North America's most elusive and vulnerable mammals. Despite the name, they're not closely related to wolves, nor bears as the nicknames "skunk bear" and "devil bear" would imply. Their closest relatives are badgers, ferrets and other members of the Mustelid or weasel family. Wolverines are the largest and rarest land-dwelling member of this family. As of 2014, scientists estimate only 250 to 300 of these small but tenacious carnivores remain in the lower 48 states.
Wolverines live in the alpine habitat of the arctic and subarctic of Alaska and Canada, as well as high elevations in the northern Cascade and Rocky Mountains. They once occupied the northern states and all of the Rockies, but fur trappers and planned predator control nearly killed off the species by 1900. In 2009, the Wildlife Conservation Society tracked one radio-collared wolverine from Grand Teton National Park to Colorado. It marked the first time a wild wolverine was seen in the state in nearly 100 years.
Dark brown to black dense fur protects wolverines from cold and frost. A horseshoe-shaped white or goldish stripe marks their backs. Their short legs hold up thick bodies and broad heads with short, furred ears. Their snowshoe-like feet are well adapted to their often snowy habitat. They have long, curved claws and teeth sharp enough to chew frozen meat. Males can weigh from 20 to 45 pounds, while females fall between 15 and 30 pounds.
Its scientific name, Gulo gulo, means glutton. Wolverines are primarily scavengers, relying upon moose or caribou carcasses abandoned by wolves or humans, or that died of natural causes. They prey upon small mammals, such as voles, squirrels and snowshoe hares, as well as birds. Wolverines have been known to take larger prey, though this is considered rare.
Wolverines are solitary creatures. They maintain home ranges and will defend their territory against smaller animals. A male's range is typically 240 square miles while females occupy a range of 50 to 100 square miles. Males allow some female overlap on their range, but will not share with other males who occupy adjacent territory. Recently, Wildlife Conservation Society scientists discovered that wolverines are expanding territory due to food shortages. One male held a range of 500 square miles.
Population and Status
Wolverine habitat is threatened by development, resource extraction, and warming temperatures. Because their home ranges are so expansive, wolverines need vast tracts of alpine habitat to survive. The Greater Yellowstone ecosystem encompasses millions of acres of largely intact wolverine habitat, including national parks, national forests, wilderness areas and wildlife corridors. Although wolverines may live to 12 years, their average life span in the wild is only 5 to 7 years. Trapping continues, regulated with seasons and limits. Most wolverines die from starvation, predation by wolves or human trapping.