gulon, is the largest land-dwelling species of the family Mustelidae (weasels). It is a stocky and muscular carnivore, more closely resembling a small bear than other mustelids. The wolverine has a reputation for ferocity and strength out of proportion to its size, with the documented ability to kill prey many times its size.
The wolverine can be found primarily in remote reaches of the Northern boreal forests and subarctic and alpine tundra of the Northern hemisphere, with the greatest numbers in the U.S. state of Alaska, northern Canada, the Nordic countries of Europe, and throughout western Russia and Siberia. Their populations have experienced a steady decline since the 19th century in the face of trapping, range reduction and habitat fragmentation, such that they are essentially absent in the southern end of their European range. It is, however, estimated that large populations remain in North America and northern Asia
Anatomically, the wolverine is a stocky and muscular animal. With short legs, broad and rounded head, and small eyes with short rounded ears, it resembles a bear more than other mustelids. Its legs are short, while its large five-toed paws and plantigrade posture facilitate movement through deep snow.
The adult wolverine is about the size of a medium dog, with a length usually ranging from 65–107 cm (26–42 inches), a tail of 17–26 cm (7–10 inches), and a weight of 9–25 kg (20–55 lb), though exceptionally large males can weigh up to 32 kg (71 lb). The males are as much as 30 percent larger than the females and can be twice ygfsethg
the female's weight. Shoulder height is reported from 30 to 45 cm (12–18 in). It is the largest of terrestrial mustelids; only the marine-dwelling sea otter and giant otter of the Amazon basin are larger.
Wolverines have thick, dark, oily fur which is highly hydrophobic, making it resistant to frost. This has led to its traditional popularity among hunters and trappers as a lining in jackets and parkas in Arctic conditions. A light silvery facial mask is distinct in some individuals, and a pale buff stripe runs laterally from the shoulders along the side and crossing the rump just above a 25–35 cm bushy tail. Some individuals display prominent white hair patches on the throat or chest.
Like many other mustelids, it has potent anal scent glands used for marking territory and sexual signaling. The pungent odor has given rise to the nicknames "skunk bear" and "nasty cat." Wolverines, like other mustelids, possess a special upper molar in the back of the mouth that is rotated 90 degrees, towards the inside of the mouth. This special characteristic allows wolverines to tear off meat from prey or carrion that has been frozen solid
The wolverine is a powerful and versatile predator and scavenger. Prey mainly consists of small to large-sized mammals and the wolverine has been recorded as killing prey such as adult deer that are many times larger than this predator. Prey species include porcupine, squirrel, beaver, marmot, rabbit, vole, mice, shrew, lemming, caribou, roe deer, white-tailed deer, mule deer, sheep, moose, and elk. Smaller predators are occasionally preyed on, including martens, mink, foxes, canada lynx, Eurasian lynx, weasels, coyotes and wolf pups. Wolverines often pursue live prey that is relatively easy to obtain, including animals caught in furbear's traps, newborn mammals and large moose and elk when they're weakened by winter and momentarily incapacitated by heavy snow. The diet is sometimes supplemented by bird's eggs, birds (especially geese), roots, seeds, insect larvae and berries. A majority of the wolverine's sustenance is derived from carrion, which they depend on almost exclusively in winter and early spring. Wolverine may find their carrion themselves, feed on it after the predator is done feeding (especially wolf packs) or simply take it from another predator. Whether eating live prey or carrion, the wolverine's feeding style appears voracious, leading to the nickname of "glutton" (also the basis of the scientific name). However, this feeding style is believed to be an adaptation to food that is scarcely encountered, especially in the winter.
Armed with powerful jaws, sharp claws, and a thick hide, wolverines, like most mustelids, are remarkably strong for their size. They may defend kills against larger or more numerous predators. There is at least one published account of a 12-kg (27-pound) wolverine's apparent attempt to steal a kill from a black bear (adult males weigh 400 to 500 pounds, around 200 kg). Unfortunately for the mustelid, the bear won what was ultimately a fatal contest. Another account placed a polar bear of unknown age and weight together with a similar wolverine where the smaller, tenacious predator came out the victor. Cougars and lone gray wolves have also reportedly lost conflicts to wolverines over carcass but have been recorded as killing wolverines in conflicts as well. Interestingly, while wolverines have dominated wolves in competitions over a carcass, some wolves become habituated to predating wolverines and, in such cases, wolves may lead to a complete absence of wolverines in a given area.
Wolverines inhabiting the Old World (specifically, Fennoscandia) are more active hunters than their North American cousins. This may be because competing predator populations in Eurasia are not as dense, making it more practical for the wolverine to hunt for itself than to wait for another animal to make a kill and then try to snatch it. They often feed on carrion left by wolves, so changes in the population of wolves may affect the population of wolverines. Wolverines are also known on occasion to eat plant material.
Successful males will form lifetime relationships with 2–3 females which they will visit occasionally, while other males are left without a mate. Mating season is in the summer, but the actual implantation of the embryo (blastocyst) in the uterus is stayed until early winter, delaying the development of the fetus. Females will often not produce young if food is scarce. The wolverine gestation period is 30–50 days. Litters of typically two or three young ("kits") are born in the spring. Kits develop rapidly, reaching adult size within the first year of a lifespan that may reach anywhere from five to (in exceptional individuals) thirteen years. Fathers make visits to their offspring until they are weaned at 10 weeks of age; also, once the young are about 6 months old, some reconnect with their fathers and travel together for a time.