The Glutton or Skunk Bear

(Otherwise known as the Wolverine)
By Denny L. Vasquez

Order; Carnivora
Family; Mustelidae
Subfamily; Mustelinae

Growing up in the southwestern portion of the US, I often heard tales about the fierce and wild creatures that inhabited the snow and ice covered reaches of the far north. I remember reading the hunting magazines of the ‘60’s and early ‘70’s as they talked about such ferocious denizens of the north as the man-eating timber wolf, which chased it’s prey in vicious packs, before tearing them apart. Or the hump backed, silver haired monster grizzlies that seemed to kill for the pure pleasure of it. And what about the “White Death” of the northlands, the polar bears. These pure white bears had even been known to go right into a house and drag it’s victim screaming from their bed. But the worst adversary that man might encounter among the snow covered pines of the North Country, at least according to the legends, was the WOLVERINE!

The largest member of the mink and weasel family has a reputation that stretches far beyond what its physical size would seem to warrant. It was “documented” by the “experts” which co-existed with these nightmares of the north, that they were vicious, man killers who would destroy things for the sheer pleasure of it.

One story that circulated around the campfires of the early ‘70’s involved a group of hunters who had inadvertently sat up camp right on a wolverine’s favorite trail to the local watering source. During the middle of the night, when the wolverine got thirsty, it proceeded to head for its favorite drinking hole. Low and behold what should it find in its way but a strange looking tent. Rather than retreat, like most inhabitants of the wild would do when confronted by man, the wolverine charged into the camp and proceeded to tear it apart. In the end, the tent was in shreds, the hunters’ equipment was scattered across the countryside, one hunter had a broken leg and another had lacerations on his left calf that he claimed were bite marks. Truly a tale indicating that, the wolverine was not a creature that you would want to meet by yourself in a dark alley. But the truth does not always bear out the claims of fiction.

The wolverine is the largest land dwelling member of the scientific family known as Mustelidae. This makes him a cousin to minks, skunks and weasels. Some of the other names that wolverines have acquired over the centuries are devil bear, carcajou, skunk bear, devil beast or woods devil. A wolverine’s scientific name is Gulo gulo, which means “glutton.”

Wolverines are not as common as we are led to believe because they occur in only small numbers throughout their range and require large expanses of wilderness terrain in order to survive. In North America, before the appearance of Europeans, they were distributed across most of the arctic and subarctic regions. Today, the wolverine has all but disappeared from most of the eastern United States and Canada. However, they thrive across the western portions of Canada and the northwestern US.

The relationship of Old and New World wolverines has been debated for years. Currently, based upon a 1959 study, most wildlife biologists consider Gulo gulo the only extant representative of the genus separating the wolverine into two subspecies, the Old World Gulo gulo gulo and New World Gulo gulo luscus. Sub-specific designation may be also be warranted for the Vancouver Island wolverine (Gulo gulo vancouverensis) based on variation in skull size and shape from those on the British Columbia mainland. Although ecotypic variation appears present, no further specific or sub-specific separation has been proposed.

One of the reasons for the demise of this fierce creature is that it has been valued as a resource for exceptionally fine fur. Wolverine fur is commonly used for parka trim and hoods because of its beauty and durability. The ability of the guard hairs to resist frost accumulation is a trait that has made it a sought after commodity in the early fur trade of this continent.

Wolverines have long dense fur, which is generally dark golden brown to black. They have a creamy white to gold stripe running from each shoulder along the flanks to the base of the tail. A light, silvery facial mask is distinct in some individuals. A white hair patch, or “diamond”, on the neck and chest is often prominent in some individuals while virtually nonexistent in others. White hair on the digits, feet and forelegs is not uncommon.

They have a powerfully built body, which is 36-44 inches long, including a 15-18 inch bushy tail. Even though it slightly larger than a Springer Spaniel, their body is thicker in overall proportion than other minks or weasels. Their physique, with the short legs, short ears, and a broad flat, badger like head, is indicative of a structural morphology that is particularly well adapted for winter survival. Its appearance is somewhat bear-like although movement and behavior are more characteristic of the weasel. They will stand about 16″ at the shoulder. They have a loping or galloping stride and can travel at speeds reaching 10 mph. for sustained periods. They are also good swimmers and tree climbers, but bad eyesight and hearing offset these characteristics.

Wolverines are primarily scavengers, whose large teeth, powerful jaws and associated musculature are designed to crush bones and eat frozen meat. The dental formula of the wolverine is incisor 3/3, canine 1/1, premolar 4/4, molar 1/2 for a total of 38 teeth. Generally, an adult male will weigh 20-45 pounds, with a few specimens reaching 50 pounds, while adult females will weigh 15-30 pounds. Unlike the feline family, wolverines have non-retractile claws, which are over one and a half inches long, curved, light in color and very sharp.

The wolverine’s head is broad and rounded, with small dark eyes, short rounded ears and a black, pointed nose. Its legs are short, with five toes on each foot; and its posture is considered plantigrade or flat-footed, although the metatarsal pads of the hind feet rarely contact the ground. The feet are extremely large for the size of the animal with the hind foot of a large male being up to 4″ in length. It is these large feet and the flat-footed posture that aid the wolverine in walking or traveling through deep snow. Because of this arrangement, the wolverine paw prints that you see in the wild are about one half of actual size.

Wolverines communicate with each other through vocalizations and scent marking. A variety of vocalizations are used in the presence of close relatives and kits. Chemical communication is accomplished via scent marking with urine and abdominal rubbing. Although wolverines have well-developed anal musk glands, musking appears to be used primarily as a fear-defense mechanism and is associated with cautionary raised tail posture. Contact with humans will usually elicit a vocal as well as chemical response.

Today, wolverines are primarily found in the wilder and more remote forests and alpine habitats, from the mountains to the lowlands, regions of northern North America, Europe and Asia. They have a circumpolar distribution that corresponds with the boreal zone of the Northern Hemisphere. The area covered is throughout the holarctic taiga and forest tundra of the higher latitudes, south to 37 degrees north in North America and 50 degrees north in Eurasia. These arctic and sub-arctic regions contain the lakes, rivers, ponds, creeks, marshes, mountains, plains, tundra, tiaga, and alpine regions that the wolverines prefer as they travel through the muskeg, over the hummocks, and through the forest.

The historical North American distribution of the wolverine included the northern part of the continent southward to the northernmost tier of the United States, from Maine to Washington. It extended south, along the Sierra-Cascade axis through Oregon, into the southern Sierra Nevada in California and along the Rocky Mountains into Arizona and New Mexico. On the East Coast, it may have extended as far south as Maryland. Archeological records of the wolverine, within the upper mid-west, pre-date those of human settlement. However, by the early 1900’s they had all but disappeared from the lower 48 states.

Today, the only populations of wolverines known to exist in the western United States appear to be extensions of Canadian populations. And while there have been persistent reports of wolverine sightings in the Rocky Mountain States, only Idaho and Montana report populations of any measurable size.

The Canadian population of wolverines is sparsely distributed through out the boreal forests, from east to west, and they inhabit the Arctic Archipelago, as far north as Ellesmere Island. Historically, wolverines inhabited much of eastern Canada except for Prince Edward Island, Nova Scotia, Newfoundland, eastern New Brunswick, Gaspe Peninsula, and Anticosti Island. Today, a wolverine sighting in Quebec and Ontario is extremely rare, and there are no recent records available from Labrador.

In the western provinces of Manitoba and Saskatchewan, wolverine numbers appear to be on the decline as the southern limits of their range has receded to the north so that today, wolverines are now confined to the northern portions of these provinces. In Alberta, the historical range of this species once included all the coniferous forests of the province, but now they are found only in remote areas in the north and in the Rocky Mountains. In the western portions of Canada, wolverines occur throughout mainland British Columbia, except for the southern agricultural areas, and throughout the Yukon Territory and mainland Northwest Territories, with an estimated 4,200 south of 66 degrees. They occur continuously in mainland Alaska and on some of the southeastern islands.

In Eurasia, wolverines are found from Scandinavia eastward through Europe, Siberia, and Asia. Records from Scandinavia show that in modern times wolverines have only occurred in low population densities. Most of these animals are concentrated in the mountain chains of northern Norway and Sweden, and along the south central Norwegian Mountains. In Sweden, wolverines are restricted to remote areas in the northwest. The numbers appear to be increasing; however, the distribution is very irregular. In 1986, a maximum of 40 wolverines was recorded in Finland, and the species is now considered endangered. Wolverines are also found in the tundra and forest zones of Eastern Europe, Russia, and northern Asia. In western Siberia, wolverines are widely distributed in the tundra and taiga, and are relatively common in extreme eastern Russia.

Throughout most of the year, they are solitary creatures that can be active at any time of day, year round. Despite their small bodily stature, they have tremendous physical endurance and have been known to travel up to 40 miles a day when searching for food. It is because of their great endurance and strength that wolverines have become a center of folklore, such as in the tale mentioned above.

For the most part, it is the “experts” in the field that have exaggerated this fierce reputation. It is true that individual animals have been known to steal furbearers from trapper’s traps. And several have been known to damage remote and isolated cabins. But for the most part these tales can be traced back to specific individuals and not to the species as a whole. Rarely, will a wolverine attack a predator larger than itself, like a wolf or a bear. Rather, they will try to avoid these animals at all costs. However, they will fiercely defend a food source or their territory against other wolverines or smaller predators.

Sexual maturity comes in their second year when they are able to breed for the first time. The breeding season is from May through August. After successful mating has taken place, the fertilized embryo floats in the female’s uterus until late fall or early winter. This is a type of reproduction, which is known as delayed implantation. It is nature’s way of allowing a female wolverine to become pregnant when food supplies are abundant and when she is in good physical condition. Then later, when the conditions are right, she can complete the pregnancy. It is not uncommon for females to fail to produce young in some years, even when they breed successfully, because it is the abundance of food which determines whether a pregnancy will be maintained and the number of young that will be born.

The litters of young wolverines are born between January and April, depending upon the female’s home range. In the far northern reaches of the wolverine’s range, most young are born in snow caves or natal dens. These caves usually consist of one or two tunnels that can be up to 30 yards long and are dug into soft snow. Most are located next to cliffs, snow filled ravines or among rock talus.

A litter of four youngsters is the largest reported in the wild, while most are in the range of one to three. Baby wolverines, which are called kits, are born blind and are 5 inches long, have fuzzy tails about 1 inch long, are covered by fine white fur, weigh less than 1 pound and have no teeth at birth. Their physical development proceeds rapidly, until they are weaned at about 8 weeks of age. At approximately 5 or 6 months of age, they will leave their mothers care and begin to forage for themselves. Most of their adult size and weight is attained within their first year of life.

As with most inhabitants of the wild, locating adequate food resources occupies most of a wolverine’s time. Consequently, the home range of a mature wolverine is vast, with some adult males known to use areas up to 240 square miles in size. Adult females usually have smaller home ranges that will cover between 50 to 100 square miles. Adults will maintain their home ranges separately from those belonging to adjacent wolverines of the same sex. Even though the home range of the resident male may encompass the ranges of up to four to six females, the breeding season is the only time during the year in which males and females interact with each other. All wolverines mark their territory using specialized scent glands and urine. This tells other wolverines that the area has been taken.

Based upon various studies conducted during the 1980’s and 1990’s, it appears that wolverines prefer the timber and forests during the winter while utilizing the higher elevation habitats during summer. This utilization of the higher elevation habitats during summer may be related to the availability of prey there during that time of year or as a means of achieving human avoidance. It may also be because the lower elevation forest types commonly associated with wild ungulates likely provide the highest carrion availability during the winter months.

In the wild, few wolverines will live longer than 5 to 7 years. In rare cases, there have been a few who survived up to 12 or 13 years of age. The two main adversaries that wolverines have in the natural world are starvation and being killed by other predators, primarily wolves, golden eagles, mountain lions and grizzly bears. Nonetheless, this mammal is rarely preyed upon due to its long claws, sharp teeth, strong jaws, and fierce attitude. And of course, some wolverine mortality is due to trapping by humans.

A mature wolverine can defend themselves against one, two or even three wolves successfully, but when a wolf pack closes in on a wolverine the scales tip in favor of the wolves, because a wolverine can’t defend himself against that many adversaries at once. The sad news is that, although wolves may attack and kill a wolverine they will rarely eat the carcass. Bears are also a threat to wolverines, especially brown and polar bears, which have been reported to kill wolverines. Usually, however, a bear will not attack a wolverine unless there’s a fight over food.

Wolverines are omnivorous and opportunistic scavengers. They will eat just about anything they can find or kill, even food they cached during the summer. They are poor hunters but are well adapted by nature for their role of scavenging. Their powerful jaws and large neck muscles allow them to crush and utilize bones and frozen flesh. And because of the harsh conditions encountered over much of their range, nature has given them the ability to survive for long periods of time on little food.

It is this continuous searching for food that is responsible for the fluctuation in habitats that takes place in a wolverines world as it moves from higher to lower elevations. In lower elevations, wolverines seek areas of shrubbery, tundra, ice, and rock. In the winter, they prefer opposite conditions; wolverines search out areas in basins, southeastern facing slopes, or rocky locations. Wide-open spaces, such as cleared forests, are avoided in order to elude easy detection by predators.

The diet of a wolverine reflects the annual and seasonal changes in food availability with in its home range. In the winter, wolverines primarily rely on remains of moose and caribou killed by wolves and hunters or animals that have died of natural causes. Throughout the year, wolverines will feed on small and medium-sized animals such as grouse, ptarmigan, snowshoe hares, voles, lemmings, marmot, mink, weasels, ermines, pika and arctic ground squirrels and birds. They have been known to kill moose or caribou, but only when the right circumstances are encountered. So, these occurrences are quite rare.

Wolverines will cache any extra meat to be eaten later when food is scarce. Foxes and other animals also cache their food and it is not uncommon for wolverines and foxes to steal from each other’s caches.

They prefer to hunt in the late evening and early morning hours. They snare their prey by gently pouncing on small animals to pin them and before grabbing them with their teeth. For larger animals, they will jump onto their back and before tearing into the animal with their claws and teeth. The world of the wolverine is a harsh one as they must compete for their food with the fox, wolf, bear, coyotes, goshawks, eagles, and owls. Even the ravens and grey jays scavenge the leftovers.

The continued health and stability of wolverine populations in the wild is best assured by both protecting large expanses of wilderness and preventing over harvesting of their fur. A major threat to the wolverine is the loss of habitat due to human invasion and activities. Road systems, snow machine activity, and other intrusions into the wolverine’s territory force them into other areas. Since they prefer vast areas of wilderness, preservation of their habitat is the key to any successful management program. This is evident when one considers that the wolverine mostly populates the virgin areas of Canada, Alaska, and parts of the United States.

Intensive hunting of ungulates by humans is another major cause of the decrease of wolverine populations throughout North America, especially since ungulates are the principal wintertime food source of wolverines. In western Canada, the practice of poisoning wolves has also been detrimental to wolverines, since many have died from the poison

A good example of steps that have been taken to preserve the remaining wolverine populations can be seen in Alaska’s approach where suitable wolverine habitat is now protected in the state through various federal and state land dedication programs. Fur harvests are controlled by seasons and bag limits as the Alaska Department of Fish and Game works to ensure that harvest by humans will not be a negative factor on Alaska’s wolverine populations and closely monitors annual catches, and the overall effects on the population.

In Canada, hunting and trapping of wolverines is now prohibited in Quebec and Newfoundland, while in other provinces, there are regulations to control hunting and trapping. There, hunting permits are being utilized to establish hunting or trapping seasons, and quotas on the number of wolverines that can be captured. And records are now being kept on the sale of wolverine furs that records the origin of the furs so as to permit the fixing of an annual national export volume.

The only areas of the United States where wolverines may be legally harvested is Alaska and Montana. Outside of these two states there is a lack of basic information on wolverine distribution and habitat requirements. This has resulted in little actual management beyond administrative protection. Appropriately responsive management programs will require a better knowledge of the nature, extent, and correlation of wolverine occurrences. Thus the conservation status of these carnivores is itself uncertain.

The wolverine was listed as threatened in California by the California Fish and Game Commission in 1971, and was listed as endangered in Colorado in 1973. It was made a federal Category 2 Candidate species in 1985. This category means that the listing of wolverines as threatened or endangered under the federal Endangered Species Act (ESA) may be appropriate but there is insufficient evidence to support a proposal to list. Oregon classified the wolverine as threatened in 1989. In most of its range in the lower 48, the wolverine is classified as a “Sensitive” species by the USFS.

Well, hopefully this article has provided you with some new information about this often-misunderstood mammal, the wolverine. Until next time, keep the sun at your back, the wind in your face and your powder dry.