Wolverine Facts: The Toughest Animal Pound for Pound

The wolverine (Gulo gulo) is the largest land-dwelling member of the weasel family, and it is not large: adult males weigh 24 to 40 pounds and females 13 to 26. It lives across the far north of the Northern Hemisphere, in country where food is scarce and spread thin, and nearly everything about it follows from that. It travels far, eats almost anything, stores what it cannot finish, and holds on to a carcass it has claimed.

Tough, within limits

Wolverines have powerful jaws built for biting and crushing bone and frozen meat, and they defend food aggressively. The popular extension of that, that a wolverine will drive a bear, a cougar or a wolf pack off a kill, does not hold up. A wolverine will not attack a larger predator and instead avoids wolves and bears, and a state biologist who has worked with them says he has never seen one chase a bear off or known anyone who has.

The traffic runs the other way. Wolves and bears kill wolverines. Between January 2022 and April 2023, biologists near Anchorage had five wolves from one pack and four wolverines with overlapping territories wearing GPS collars. Members of that wolf pack killed three of the four wolverines, and did not eat any of them.

A huge range for a small animal

Resident males in Alaska use home ranges of 200 to 260 square miles, and females up to 115. In south-central Alaska, males traveled 8 to 21 kilometers a day and females about 12. Wolverines hold those ranges by marking them actively: urine, a scent gland on the belly rubbed along the ground, glands on the foot pads, and anal glands.

A nose for buried food

Wolverines can smell food over long distances and buried well under snow. No reliable measurement puts a depth on that. It lets them find and dig out carcasses left by avalanches, winter kill, wolves and hunters, which carry them through the lean months.

Gulo gulo: the glutton

Life history

• Claws: the toes can make the claws look semi-retractable, and some agencies describe them that way, but anatomically they are fixed.
• Breeding: females generally do not have a first litter until about three years old, and then breed about every other year. Wolverines use delayed implantation, which lets a female adjust litter size to the food available. Litters average two to three kits, never more than four recorded in the wild, born between February and April in dens dug into snow.
• Kits: young reach adult size by early winter and probably stay associated with their mother and siblings until they mature at two or three years old.
• Lifespan: few wolverines live longer than 5 to 7 years in the wild, though some reach 12 or 13.
• Status: wolverines in the contiguous United States were listed as threatened under the Endangered Species Act in November 2023, a listing tied to the loss of the deep, lasting snowpack they need for denning.

The wolverine's reputation for toughness is earned in endurance rather than combat: a 30-pound animal that covers a 250-square-mile range through an Arctic winter, digs its food out of the snow, and raises its young in a snow cave. A single wolverine can range over hundreds of square kilometers, which the wolverine Beastfile puts in context.

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