Wolverine in Montana. Photo courtesy of Wild Things Unlimited.

Gulo gulo: Super-weasel of the Wilderness By Phil Knight

The Wolverine (Gulo gulo) is a medium-sized carnivore and the largest terrestrial member of the family Mustelidae, which includes badger, otter, mink, marten, fisher and weasel. Weighing a maximum of about 35 pounds, the species occupies tundra and boreal forest in North America, Scandinavia and Asia. Wide-ranging and solitary, wolverines were never abundant, but once existed across vast areas of the boreal and temperate zones in the northern hemisphere.

Wolverines may be the ultimate Lowbaggers, living nearly anywhere wild and existing on whatever is available. They were once reviled due to their propensity to monkeywrench traplines and trappers’ caches, eating animals caught in traps and destroying furs and other supplies. For its efforts, the wolverine earned the latin name Gulo gulo – glutton glutton. Now regarded more with fascination than hate, they are fierce, secretive wild animals that seek out the most remote, rugged areas of the planet as their home.

Wolverines are considered to be scavenging predators because they feed largely on carrion, but they will also eat berries, insects, birds, rodents and sometimes full-sized prey such as reindeer and moose. The reliance on carrion limits the number of individuals that an area can support.

The home range of a male wolverine can be larger than 1500 km2  and may contain a number of female home ranges. Solitary except during mating season, which runs from May into July and August, a male wolverine will mate with as many females as he can find in his home range. Young are born in late February to early March. Female wolverines with kits are known to be especially sensitive to human disturbance and may move their young following human activity near the den site, possibly to a less suitable site. Average litter size is generally less than three. Reproduction is limited by relatively late sexual maturity and poor survival success of young.

Wolverine tracks in Montana's Absaroka Range. Photo by Phil Knight.

Among the limiting factors for wolverine survival are loss of isolated habitat, a reduction in the availability of large ungulate carrion, and trapping pressure.  Human settlement and habitat fragmentation has greatly reduced available habitat. Big game hunting may reduce the availability of carrion.

The global status of the wolverine, according to the World Conservation Monitoring Center (1996), is “vulnerable.” In Norway, Sweden and Finland, it is considered “endangered.” Data on the distribution of Wolverines in Eurasia are sketchy. The species’ range in Scandinavia appears to be concentrated in the mountainous central and northern portions of Norway and Sweden, as well as in Finland. Wolverines also occupy the taiga and northern coniferous forest of the former Soviet Union.

Wolverines have been extirpated from large portions of their range in southern and eastern Canada and are now considered ‘endangered’ in eastern regions of this country.  Small populations have recently been re-discovered in Quebec and Labrador. They are also found in Northern British Columbia and Alberta, Manitoba, Saskatchewan, and northwestern Ontario. The entire Northwest Territories, Alaska and the Yukon support wolverines, though the status of the populations there is generally unknown. The wolverine is considered to be ‘vulnerable’ in western Canada, and at risk of further population decline.

The U.S. government considers the wolverine a “Sensitive” animal, although attempts to list it under the federal Endangered Species Act have thus far failed. Small, scattered populations remain in the Northern Rocky Mountains and Cascade and Sierra Nevada ranges of the U.S. with a total estimated population of 750 animals.

Sighting a wild wolverine is one of those lifetime events for travelers of remote areas. I have seen one, at a distance, running away at full speed. But I have also been lucky enough to find their tracks in many areas of the mountains near where I live in Greater Yellowstone. It sickens me to think that they are still legally trapped here.

In the lower 48 states and in southern and eastern Canada, trapping could eliminate remnant wolverine populations and eliminate any chance of recovering the species. At a minimum, trapping of wolverine should be suspended wherever there is concern over their population status.

Conserving this amazing animal will ultimately require maintaining large areas of wild, remote country with minimal human disturbance. They also need relatively safe corridors between remote areas. Conservation initiatives such as Yellowstone to Yukon show promise of preserving enough country in its primitive state that the wolverine (among other wilderness-dependent animals) can survive, but these initiatives must be embraced and supported by federal and state governments.