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NATURAL HISTORY

AMERICAN WOLVERINE } Gulo gulo luscus
FAMILY: Mustelidae

Gulo means “glutton” in Latin.

DESCRIPTION: The largest terrestrial member of the weasel, or mustelid, family, the wolverine has an average length of 36 inches and a height of 12 inches. Males weigh more than females, up to 45 pounds. Wolverines have a compact, powerful build, a thick, bushy coat, a broad head, short, furry ears, and curved, semi-retractile claws. The coloring is blackish brown with a band of pale chestnut beginning on each shoulder and meeting near the tail; the throat and chest often display large white patches.

HABITAT: Wolverines in the lower 48 states inhabit remote mountains and boreal forests usually at or above the timberline.

RANGE: In North America, wolverines historically occurred throughout Alaska, Canada, and the United States, with their U.S. population extending from California through the Midwest and to the Northeast. Currently, populations remain in high-elevation habitat in Montana, Idaho, and Wyoming, and possibly Colorado, Minnesota, Washington, Oregon, and California. Sightings have also occurred in Michigan, Wisconsin, Utah, New Mexico, North Dakota, and South Dakota.

MIGRATION: Wolverines have a very large home range, up to almost 400 square kilometers for females and more than 900 for males. Food availability is the most influential factor governing wolverine movement.

BREEDING: Wolverines are probably polygamous, and mate in winter. In the spring, females give birth to one to four kits in secluded tunnels and chambers in high-elevation basins. Kits are nursed in dens and are weaned after about 10 weeks, staying with their mother for at least six months after that.

LIFE CYCLE: Wolverines are thought to live about 10 years in the wild.

FEEDING: Wolverines are scavenger-predators that eat carrion — mostly sheep, caribou, and moose — and small mammals, including porcupines, squirrels, beavers, and rabbits. Wolverines have been observed killing large animals like caribou and deer.

THREATS: Wolverines have been in decline for more than 100 years due primarily to trapping and habitat loss. Now, in addition to these dangers, the animals face disturbance by winter motorized recreation and the overarching threat of global warming, which melts the deep snow wolverines depend on for everything from travel corridors to snow dens where they raise their young.

POPULATION TREND: The number of wolverines in the United States has dropped significantly in the past 100 years. Fewer than 500 wolverines left in the lower 48 states represent a distinct population that is only tenuously linked to the Canadian population.

Photo by Gerald and Buff Corsi © California Academy of Sciences