The wolverine ( Gulo gulo ) is a fascinating and powerful member of the weasel family (Mustelidae), inhabiting the cold, remote regions of the northern hemisphere. Often described as resembling a small bear with skunk-like markings, the wolverine is known for its strength, tenacity, and adaptability. This article delves into the wolverine's dietary habits and hunting behaviors, exploring its role as both a predator and a scavenger in its challenging environment.
Physical Characteristics and Distribution
The wolverine is the largest member of the weasel family in North America. Adults typically measure 31-44 inches in length and weigh around 40 pounds, although males are generally larger than females by approximately 10% in linear measurements and 30% in weight. Their stocky body is covered in long, thick, water-resistant, dark, glossy brown fur, often adorned with silver to yellowish bands that run over its shoulders and hips, merging at the rump and extending along the top of the tail. Some individuals exhibit patches of silver to yellowish fur over their eyes and on the crown of their heads.
Wolverines possess a large head with small eyes and small, rounded ears. They have a keen sense of smell and hearing but relatively poor eyesight. Their large, strong teeth and powerful jaws are essential for ripping frozen meat from carrion. The wolverine's legs are powerful, equipped with padded feet and large claws, aiding in their movement across snowy terrain. They have 5 toes on each paw and walk primarily on their metatarsals.
The wolverine's current range spans from northern Europe and Siberia through northern North America into Alaska, Idaho, and Montana. Sightings have also been reported in the Cascade region of Washington and Oregon. Historically, they occurred in Arizona, California, Colorado, Idaho, Indiana, Iowa, Maine, Michigan, Minnesota, Montana, Nebraska, Nevada, New Hampshire, New Mexico, New York, North and South Dakota, Ohio, Pennsylvania, Utah, Vermont, Wisconsin, and Wyoming. However, the wolverine's population and range have shrunk due to hunting, habitat loss, and fragmentation.
General Behavior and Lifestyle
Wolverines are generally solitary animals, except during the mating season, which extends from May to August. Both males and females are very territorial and will aggressively defend and mark their territories using scent markings from their anal scent glands and urine. A male's home range can be more than 1,000 square miles, overlapping the ranges of several females, sometimes those in overlapping ranges. Wolverines are mainly terrestrial and move with a loping gallop, but they can climb trees with great speed and are excellent swimmers. Although not particularly fast, with a top speed that does not exceed 15 km per hour, they can travel tirelessly over long distances. They are active at any time of the day, even in the most severe weather.
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The wolverine is constantly in motion and marks the terrain with its faeces, urine and secretions from its anal glands. The wolverine is always peeking into holes and tussocks and it will readily climb a tree for a better vantage point if it senses that something edible is nearby. It is a skilled climber and it will also climb trees when it’s playing or afraid.
Reproductive Habits
Both sexes reach reproductive maturity during their second summer. Mating takes place from April to October. A delayed implantation occurs, with an active gestation period of 30-50 days. The mating season for wolverines is in June-July. Similarly to the bear, the wolverine has delayed foetal development. The cubs are finally born into a den dug into snow in March-April. The wolverine births two to four cubs and they follow their mother at least until the following autumn, sometimes even until the next litter is born.
Female wolverines mate every other year, with females being in heat from June to August. Interestingly, while the breeding season extends from May through August, females initiate copulation. After mating, the fertilized eggs do not implant immediately but rather waits in diapause for about 6 months. Actual gestation takes only another 30 to 50 days.
Females construct dens in the snow, thickets, or rock crevices to give birth and nurse their young. The cubs are born between January and April, with an average litter size of 3 kits, each weighing around 85 grams. The babies nurse for 8-10 weeks and will stay with their mother for up to two years. The female gives the young extensive care for up to one year, after which she drives them from her territory. Young are born, when they disperse. The wolverine births two to four cubs and they follow their mother at least until the following autumn, sometimes even until the next litter is born.
Diet and Hunting Behavior
The wolverine is a carnivore and an opportunistic scavenger. Its diet can include anything from small eggs to large ungulates. It is also an opportunistic scavenger and frequently eats carrion from other animal's kills. The wolverine is very quick and can run at speeds of up to 30 miles per hour when chasing its prey. The wolverine also pounces on its prey from trees. The wolverine stores its food in caches to eat later. It spray its caches of food with a stinky musk that keeps other animals away.
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The wolverine is a carrion feeder. This is why it chooses to prioritise scavenging over hunting when searching for food: the wolverine may travel up to 20-40 km in a single day. In a sense its life consists of continuous exploration. Wolverine.
Wolverines mainly eat the flesh of mammals or birds. They are generally too large to subsist well on small game, too small to effectively kill large game regularly, and too slow to pursue swift animals. As a result, they often resort to scavenging carrion. Often, they subsist almost entirely on winter killed animals or the kills of other predators. The wolverines will hunt and kill whenever the opportunity presents itself, and they are tireless and persistent in their hunting activities. They will take a wide variety of foods, including hares, mice, lemmings, ground squirrels, chipmunks, marmots, and beaver. Berries are often eaten in late fall. When food is scarce, the wolverine will attempt to kill big game animals, and there are authentic records of attacks upon mountain goats, moose, deer, and elk.
The wolverine's hunting practices seem somewhat amateurish. It is very strong for its size and its prey can include large animals like deer, moose, wild sheep and elk. It also eats smaller mammals like rabbits, beavers and squirrels. The wolverine's diet also include eggs, roots and berries.
The wolverine has been described as a facultative scavenger due to seasonal preferences for carrion versus live prey. Wolverines would probably not persist in the absence of ungulate populations, although evidence suggests at least a seasonal reliance on local rodent abundance. Seasonal and regional variation in diet may also be related to prey availability and may be influenced by the presence of other large carnivores. Wolverines take over carcasses that have been killed by other large predators, cougars, and even packs of wolves from their kills in order to take the carcass. They have also been reported scavenging whale, walrus, and seal carcasses.
A study in Scandinavia tracked the eating habits of 41 wolverines in four locations. The study determined that wolverines utilize the most abundant and available food sources. During warmer months, when young reindeer are abundant, wolverines hunt more. If it can take down a large kill, a wolverine will bury the remaining meat in the snow to keep it fresh.
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The wolverine diet can include anything from small eggs to large ungulates. Wolverines will often urinate on carcasses, fouling them so that no other animal will eat them.
Hunting Techniques and Prey
The wolverine is very strong for its size and its prey can include large animals like deer, moose, wild sheep and elk. It also eats smaller mammals like rabbits, beavers and squirrels. The wolverine's diet also include eggs, roots and berries.
The wolverine is very quick and can run at speeds of up to 30 miles per hour when chasing its prey. The wolverine also pounces on its prey from trees. The wolverine stores its food in caches to eat later. It spray its caches of food with a stinky musk that keeps other animals away. The wolverine has a powerful jaw and large neck muscles allowing it to crush and utilize bones and frozen flesh. Also, wolverines can survive for long periods on little food. Their diet reflects annual and seasonal changes in food availability.
In the winter wolverines primarily rely on carrion, remains of moose and caribou killed by wolves and hunters or animals that have died of natural causes. Throughout the year, wolverines feed on small and medium-sized animals such as voles, squirrels, snowshoe hares, and birds. In the right situations, wolverines can kill moose, Dall sheep or caribou, but these occurrences are rare. Wolverines are mainly terrestrial and move with a loping gallop. Although not particularly fast, they can climb trees with great speed and are excellent swimmers. The diet of the wolverine varies from one region to another.
In Finland, reindeer killed by wolverines are almost exclusively recorded in winter. Wolverines in the boreal zone also prey on mountain hares. As a predator the wolverine is clumsy when compared to the other large carnivores in Finland. If the snow conditions allow it, the wolverine will prey on reindeer but it can't take down an adult moose. The wolverine is considered a cruel beast because it doesn't always kill the reindeer instantly but instead might paralyse it by biting it in the spine. In the winter the wolverine may kill several reindeer in quick succession. This is typical weasel behaviour: they kill animals for storage, so to speak. The wolverine often returns to the carcass, just like the bear. It rips off the prey animal's neck tendons and rarely leaves any claw marks on the animal.
The wolverine is capable of taking large ungulates as live prey, and while ungulate presence in the wolverines diet most likely results from scavenging, ungulates were reported as the predominate prey item across seasons in British Columbia and Idaho. Ground squirrels were most prevalent in late winter and spring diets in Alaska, while snowshoe hare contributed the highest proportion of any single species to the wolverine’s diet in Yukon. Hoary marmot was a prevalent prey item at reproductive dens of Canadian wolverines.
Caching Behavior
The wolverine stores its food in caches to eat later. It spray its caches of food with a stinky musk that keeps other animals away. Wolverines will often urinate on carcasses, fouling them so that no other animal will eat them. The wolverine is known to cache its food, placing a food item in a special place to be eaten later. They use gland secretions to discourage other animals from raiding them.
Conservation Status and Threats
The wolverine's population and range have shrunk due to hunting and habitat loss and fragmentation. The wolverine is valued as a fur resource and as a symbol of wilderness. Hunters and trappers in Alaska harvest about 550 wolverines each year. Because wolverine reproductive potential and survivorship is low it’s important to understand where and when animals are harvested to be sure the population is not overharvested. Harvests are controlled by seasons and bag limits. Annual catches and the effects on the population are closely monitored by the Alaska Department of Fish and Game to ensure that harvest by humans will not be a negative factor on Alaska's wolverine populations.
Wolverines live in remote areas where human populations are sparse. They are shot due to their habit of preying upon animals that are trapped for fur. The most viable and widespread population of wolverines in the contiguous 48 states occurs in the Rocky Mountains of Montana. Wolverines occur in the western third of Montana in the Rocky Mountain range. They are a furbearer and are managed and protected.
The wolverine's current range extends from northern Europe and Siberia through northern North America into Alaska, Idaho, and Montana. Wolverines have been sighted in the Cascade region of Washington and Oregon. Arizona, California, Colorado, Idaho, Indiana, Iowa, Maine, Michigan, Minnesota, Montana, Nebraska, Nevada, New Hampshire, New Mexico, New York, North and South Dakota, Ohio, Pennsylvania, Utah, Vermont, Wisconsin and Wyoming. The wolverine's population and range has shrunk due to hunting and habitat loss and fragmentation.