Wolverines

Montana is one of the few places wolverines are still sought by trappers. Fortunately, Montana Fish, Wildlife, and Parks carefully monitors the trapping of this incredible and unique animal. Known by names as unusual as the animal, wolverines have been called 'skunk bears', 'Indian Devils', and 'Devil Bears'. Wolverines are rarely seen, however, studies suggest several claim sections of the Centennial Mountains as part of their 'range'.

Although an extremely private animal more adept at alluding observers than most, the wolverine looks to find itself in the middle of a controversial debate. Brewing for the last twenty years, this controversy appears about to erupt here in the great northwest.

Battle lines are being drawn between outdoor enthusiasts, and those who see their presence in the back country as an unacceptable intrusion. However, the issues won't center around the wolverine's physical characteristics, nor its diet, nor its personality, nor its reproductive practices (although they are somewhat unique). No, the controversy looks to focus on their denning habitat and range. Sadly, since little is know about these reclusive animals, only time will tell whether the battle will prove to their benefit.

Solitary creatures, wolverines have never reached high population densities, even in the most desirable conditions. Reasonable density estimates suggest 1 wolverine to every 124 - 155 square miles. In addition to their reclusive nature, wolverines possess an insatiable need to be on the move. Jeff Copeland, a scientist who has studied wolverines for several years in Idaho describes them as, ". . .a different sort of a beast than anything else traveling out there."

Known as the ‘devil bear,' ‘woods devil,' and ‘skunk bear,' the scientific name for the wolverine is Gulo gulo, which means ‘glutton'. Probably one of the most misunderstood mid-sized mammals, scientists have only scratched the surface in studying this illusive animal.

The largest member of the weasel family, the wolverine is short and thick like a small bear. Fully developed males weigh 24 - 45 pounds and females 15 - 30. The wolverine's strong jaw is probably its most important and striking feature. Their vice-like jaw and large neck muscles allow them to crush bone and tear frozen flesh from their prey. With their ‘grizzly-bear like' vocal cords, they can sound as big and bad as the much larger mammals whose prey they scavenge.

The wolverine's feet boast large pads which allow them to chase potential prey through deep snow. When on the chase, they have the ability to reach speeds up to 31 miles an hour. Additionally, their long claws enable them to dig through 6 feet of snow searching for the small mammals which winter underneath.

A creamy white stripe runs from their shoulder to tail, cutting a swathe through their long dense dark brown to black fur. Not many years ago this fur was in great demand as trim for parka hoods. Its beauty and durability; and the frost resistance of the guard hairs, made it quite valuable in snow country. This demand led to the wolverine's near extinction in several areas in the northwest, Canada, and Alaska. Even today, with trapping at a near standstill, a prime pelt can bring $400.

Poor hunters, wolverines rely primarily on the success of other hunters to fill their bellies. Although they can survive long periods on little food, their poor hunting skills can result in starvation. They exist primarily on scavenged carrion, but they have also been known to hunt small mammals such as: voles, squirrels, marmots, porcupines, lemmings, birds, and mice. In addition, this scavenger has been documented bringing down live prey up to five times larger than itself. Although rare, these kills have included: reindeer, roe deer, wild sheep, elk, and caribou. However, their ability to eat the hide, hair, bones, and hooves, (the less ‘desirable' parts) makes them the ideal scavenger.

Nowhere abundant, little is known about the wolverine's specific habitat preference. We do know they have not re-colonized former ranges in Labrador and Quebec, even though these areas offer abundant food and undisturbed habitat. Obviously our lack of knowledge makes it more difficult to manage and protect them.

The male wolverine's home range may encompass that of four to six females. Nevertheless, breeding season is the only time they interact. Young wolverines become sexually active as they reach two years old and breed from May to August. Once successfully bred, the fertilized egg floats in the female's uterus until late fall or early winter. This process, called delayed implantation, allows the female to become pregnant when the food supplies are at their peak, and when her physical condition is at its best. Due to our limited knowledge, we still do not know why some females, even when successfully bred, fail to produce young. However, some speculate the abundance of food determines whether a pregnancy is successful, and the number of young produced.

Wolverine kits are born between January and May. Litters range from one to three, although six are possible. Kits are born blind, weighing less than 1 pound. It is not unusual for some to die before reaching weaning age due to starvation and predation. Those which survive develop rapidly. Weaned at 8 - 10 weeks, they reach their full growth by 7 months.

Current concerns surrounding the future of wolverine populations revolve primarily around denning habitat. Studies have suggested mother wolverines are highly selective in choosing their denning site, often using multiple dens prior to weaning their kits. Some think they prefer secluded high elevation deep, steep-walled basins which are shaped like a half bowl. However, studies have found wolverine dens in the most unexpected places. Jeff Copeland's study in Idaho found 34 dens in burned areas, 3 in logged areas, 1 in a clear cut, and 2 near active timber sales. In Sweden wolverines have been known to den near snow machine trails.

This suggests wolverines are highly individual. In addition, wolverines studied in Idaho were not hesitant to cross clear cuts, as compared to those studied in Montana which were. In Alaska, mother wolverines did not appear to be disturbed by human observers during studies conducted by Magoun (1985). But, when studies were conducted in Finland and Scandinavia a year later, female wolverines abandoned their dens when disturbed by humans. The same result occurred during studies done in 1996 in Idaho. Den abandonment, however, does not mean kit abandonment. Since other studies have shown mother wolverines use multiple dens prior to weaning, one must wonder - 'Were some of them packed and ready to move anyway?'

Additional questions are raised by the seemingly disparaging facts found researching these unusual animals. For example, one study has determined wolverine kits are at high risk to predation by large carnivores. However, another study concluded wolverines have few natural predators. Yet another study determined kits leave their mother at approximately 5 to 6 months of age. Still a different researcher found young staying with their mother for their first 2 years. Another area where researches cannot agree is the typical life span of the wolverine. One study says they rarely live longer than 5 to 7 years in the wild, while another says they survive to 12 or 13 years of age.

Obviously more research is needed. Unfortunately, wolverines are difficult and expensive to study due to their large home ranges, their low densities, and their reclusive natures. To date only 5 field studies have been conducted in North America, less in the Continental U.S. Past research, which focused on the wolverine's home range, movements, desirable habitat, food habits, and factors effecting their denning location and reproduction levels, has created more questions than it has answered.

Scientist still want to know: what controls wolverine distribution, what effects their reproduction, what causes them to select one habitat area over another, and what effects, if any, are human activities and developments having on populations? They want to know: how dependent wolverines are on large predators, if the seasonal movement of prey effects them, and the BIG question - Do they really avoid humans as some would have us believe? If so, why are they found in dumps, near a ski lodge in Banff, and near snow machine trails in Sweden? Clearly more answers are needed before we can properly manage and care for the wolverine.

Nonetheless, in 2000, six groups submitted a petition to the government, requesting the wolverine be listed as a threatened or endangered species. The petitioners claimed wolverines had been trapped to near extinction in the western states in the early 20th century. They stated wolverine range and numbers had decreased dramatically since Pre-Columbian times due to human activities and developments. They suggested less than 1,000 animals currently reside in the lower 48 states. However, in their 1981 study, Hornocker and Hash asserted wolverines have obtained stable populations across their study area (in Montana) having rebounded from near extinction in the 1920's to 1940's. Other scientific reports suggested the wolverine was not likely to become threatened in the lower 48 states in the foreseeable future. In fact, due to the wolverine's solitary and illusive nature, Banci, (1994) said a lack of sightings does not necessarily mean the animals are not present.

Thus wildlife officials decided it would be scientifically unsound to make estimations of population size at that time, particularly for the entire contiguous U.S. In fact, they felt it should not be considered unusual for wolverine populations to appear low when they are compared to other species which have different population dynamics.

In face of the prospective controversy, one particular observation made by Hornocker and Hash (1981) ought to be particularly noted. During their study they found no difference in wolverine population densities in wilderness areas as compared to non-wilderness areas. They also found wolverine movement, habitat usage, and behavior did not differ in one area versus another. This observation should be enough to suggest to those charging to the wolverine's ‘defense' that possibly this unique animal, which defines the term ‘wild,' may not be as sensitive as has been assumed.

While some are now promoting the wolverine as a landscape indicator species, studies show we do not know enough about them to make well-educated judgments as to their needs or their sensitivity. Yet, there are those who would have us believe healthy wolverine populations are a reliable gauge of overall ecosystem health. And, they may be right. But, how can the wolverine be used as an accurate indicator of ecosystem health when we don't know enough to determine the health of their species?

On one point the experts agree - we know too little about the wolverine to intelligently determine what, if any, dangers are threatening them. Unfortunately history has shown some possess the need to use our lack of knowledge as an excuse to close suspected sensitive areas to humans; and this based purely on presuppositions of danger. It behooves us to think logically, not with our emotions, as we seek to protect, manage, and care for the creatures around us. When the major species which inhabit the area are experiencing healthy population growth, it seems foolhardy at best and an attempt to manipulate nature at worst, to attempt to use, as our single indicator species, an animal we know next to nothing about.