Wolverine

The wolverine is the largest land-dwelling member of the weasel family and, pound for pound, one of the toughest predators on Earth. It lives alone across enormous ranges of the coldest forests and mountains, and it has built a mythology around its willingness to fight anything.

Overview

Wolverines occupy the boreal and subarctic zone right around the Northern Hemisphere — the taiga and tundra of Canada, Alaska, Scandinavia, and Russia — plus a fragile toehold in the high Rocky Mountains of the United States. They need cold, snow, remoteness, and space. A single male may patrol more than 1,000 km², and populations are naturally sparse everywhere they exist.

Built for the far north

• Fur that is dense, oily, and frost-resistant, historically prized for parka ruffs because ice does not stick to it.
• Wide, heavily furred feet that spread the wolverine’s weight so it can travel on soft snow where hoofed prey sinks.
• Jaws and teeth built to process frozen carcasses — including a specialised upper molar turned sideways in the jaw, giving extra shearing power against bone and ice-hard meat.
• A powerful, low-slung body with a loose hide that lets it twist and bite while grappled.

Diet and hunting

The wolverine is primarily a scavenger, and it is superbly equipped for it. An acute sense of smell lets it locate a carcass buried under several metres of snow, and it will follow wolf packs and bears to feed on what they leave — or muscle in and take the carcass outright. What it cannot eat it caches, wedging chunks into rock crevices and snowbanks where they freeze, creating a larder that carries it and its young through winter.

It also hunts: ground squirrels, hares, birds, and porcupines year-round, and, in deep late-winter snow, it can bring down deer, caribou, and even moose that are trapped by the drifts.

Reproduction and life cycle

Wolverines mate in summer, but the embryo does not implant until the following winter — delayed implantation times birth to late winter and lets the female abandon a pregnancy if she is in poor condition. She digs a den in deep, persistent snow, often several metres down, and gives birth to two or three white kits in February or March. The kits stay with her for up to a year, and one or two years later disperse across huge distances to find unclaimed range.

Because females can only raise a litter every two to three years and each needs a reliable spring snow den, wolverine populations grow very slowly.

Threats and conservation

The wolverine is listed as Least Concern worldwide but is declining in many regions:

• Habitat fragmentation. Roads, logging, and development break up the large connected wilderness wolverines need to disperse and stay genetically healthy.
• Trapping, historically for fur and now often incidental.
• Climate change. The deep spring snowpack that females depend on for denning is melting earlier and thinning, and models project a significant contraction of suitable habitat, especially at the southern edge of the range.