Wolverine

Wolverine

THE SPECIES: Gulo gulo 

"... a ravenous monster of insatiate voracity, matchless strength, and supernatural cunning, a terror to all other beasts, the blood thirsty monster of the forest." Elliott Coues, the renowned 19th century naturalist who wrote these words, was describing the general opinion of the wolverine.

Tales tell of grizzlies and wolves backing down from the wolverine in confrontations over food. It has been blamed for breaking into cabins and caches, rendering the contents useless with its urine and musk. But this stocky member of the weasel family has a reputation that is largely undeserved. Although common in the Yukon, the wolverine is one of the rarest of mammals, and perhaps one of the best representative of all that is considered wilderness.

DISTRIBUTION

In the Yukon, wolverines occur in all habitats, from forested valleys to alpine and arctic tundra. However they are most abundant in mountainous regions that support a variety of habitats and a diversity of prey. Our best wolverine range, the southwest Yukon, supports approximately one wolverine per 180 square kilometres.

CHARACTERISTICS

The wolverine has been called "skunk-bear", because of the light coloured stripe that originates on the shoulders, traverses both sides of the body, and merges into one stripe at the base of the tail. The stripe is usually blonde, and contrasts with the dark brown to near black background fur, but it may be darker or absent in some individuals.

If not for its bushy tail, the wolverine might be mistaken for a small bear. Males are the larger sex, weighing 11 to 16 kilograms: female weights range from 8 to 11 kilograms.

THE LIFE OF A SCAVENGER

Despite popular opinion, the wolverine is not a hunter of large mammals. Its relatively small size and solitary habit are not favourable attributes for bringing down an adult moose or caribou. Instead, it obtains much of its food by scavenging, particularly by cleaning up kills of moose, caribou, or sheep after the original hunters (usually wolves) have finished their meal. The wolverine is well adapted for such a lifestyle. Its teeth are robust and the muscles of the neck are large, allowing it to crush bone and tear frozen flesh.

But the wolverine diet is not limited to carrion. It does hunt small mammals, including voles, mice, lemmings, red squirrels, ground squirrels, marmots, pikas, porcupine, snowshoe hare, fish, and birds. It will also kill Dall lambs and caribou calves on occasion. In summer, when alternate foods are more abundant, diets are more diverse and include roots, berries, insects, and bird eggs.

Wolverines breed during May through August, and females have a form of reproduction known as delayed implantation. Development stops shortly after the eggs are fertilized. The embryos float in the uterus until November-January, when implantation into the uterine wall occurs. Litters are normally small, with two to four kits being born during January to March, although most births occur in early spring.

As scavengers, wolverines may be faced with scarce food supplies, and delayed implantation allows a female to continue her pregnancy only if she is in good condition. Some females resorb the embryos, especially if they have had young the previous spring and are in poor condition.

Home ranges of adult males vary from 300 to 500 square kilometers in size, while those of adult females vary from 100 to 350 square kilometers. The size depends partly on the quality and quantity of food in the area. If food is not abundant, the range will be larger because the wolverine will have to cover a larger area to meet its nutritional requirements.

The home range of a male overlaps the ranges of three to six adult females during the breeding period. Home ranges do not overlap among adult females or among adult males. The kits are adult size by fall and, by late winter, they usually disperse. Young males may travel hundreds of kilometres before they find an empty range they can claim as their own. Young females are tolerated by adults of both sexes and they establish home ranges next to their mothers, or assume part of her range.

WOLVERINE AND PEOPLE

Traditionally, Yukon First Nations respected the strength and determination of the wolverine. Baby boys were sometimes rubbed with wolverine fur in the hope that they would develop these same qualities. Since the wolverine spirit was so powerful, it was acquired as a spirit helper by some shamans.

Wolverine pelts are highly valued because of their frost resistant properties and over 90% of the fur is sold in Canada. But the relationship between wolverine and trapper is a mixed one. A wolverine can be a source of irritation to a trapper when it breaks into a cabin or cache, or removes the catch from a trapline.

While most people are not bothered by the presence of this rare mammal, the wolverine can be seriously affected by human activity. Large wilderness areas are essential to the its survival. If these areas are diminished by transportation networks, agricultural clearings, or human habitation, wolverine populations may decline. Excessive trapping can cause local shortages of wolverine, but most Yukon trappers avoid this problem by protecting a breeding population.

VIEWING OPPORTUNITIES

In winter, you may be lucky enough to see a wolverine on an open ridge, alpine slope, frozen river, or even on a glacier. On your return trip, you may find that a curious wolverine has been following your tracks. Although sightings of a wolverine are rare, Yukoners have a good chance of seeing its tracks. Following them over mountain and valley bottom is an adventure in itself. You may have to be a good mountain climber!

The wolverine track is large and somewhat rounded. It may be confused with that of a wolf but the five toes of a wolverine's foot, and the length and pattern of its gait, provide positive identification. Along the trail, you may find where a wolverine picked up a scent and uncovered a raven's wing; where it followed the trail of a fox; or where it killed a snowshoe hare or ptarmigan. The only evidence of the event may be the tracks and a drop or two of blood.

In summer, carry binoculars and/or a spotting scope, particularly in subalpine and alpine areas where visibility is good. Look in places where wolverine food sources are found, such as ground squirrel colonies or the summer ranges of caribou. Keep in mind that bears frequent the same areas and be alert for their presence.