Wolverine

For the comic book character of the same name, see Wolverine (comics).
Wolverine[1]
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Mustelidae
Genus: Gulo
Pallas, 1780
Species: G. gulo
Binomial name
Gulo gulo
(Linnaeus, 1758)
Wolverine range

The wolverine, pronounced /ˈwʊlvəriːn/, Gulo gulo (Gulo is Latin for "glutton"), also referred to as glutton, carcajou, skunk bear, or quickhatch, 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.[2]

Contents

Taxonomy

Genetic evidence suggests that the wolverine is most closely related to the tayra and martens (scientific names Eira and Martes respectively), all of which shared a Eurasian ancestor.[3]

Within the Gulo genus, there is a clear separation between two subspecies: the Old World form Gulo gulo gulo and the New World form G. g. luscus. Some authors had described as many as four additional North American subspecies, including ones limited to Vancouver Island (G. g. vancouverensis) and the Kenai Peninsula in Alaska (G. g. katschemakensis). However, the most currently accepted taxonomy recognizes either the two continental subspecies or recognize G. gulo as a single Holarctic taxon.[4]

Recently compiled genetic evidence suggests that most of North America's wolverines are descended from a single source, likely originating from Beringia during the last glaciation and rapidly expanding thereafter, though there is considerable uncertainty to this conclusion due to the difficulty of collecting samples in the extremely depleted southern extent of the range.[4]

Physical characteristics

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.[5]

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).[6][7][8] The males are as much as 30% larger than the females and can be twice the female's weight. Shoulder height is reported from 30 to 45 cm (12–18 in).[9] 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.[5]

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.[10][11]

Behavior

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.[12] Smaller predators are occasionally preyed on, including martens, mink, foxes, canada lynx, weasels, young Eurasian lynx,[13] and coyote and wolf pups. Wolverines often pursue live prey that is relatively easy to obtain, including animals caught in traps, newborn mammals and deer (including adult moose and elk) when they're weakened by winter or immobilized 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. Wolverines 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.[14]

Armed with powerful jaws, sharp claws, and a thick hide,[15] 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.[16] 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.[17][18] 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.[19] 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.[8]

Wolverines inhabiting the Old World (specifically, Fennoscandia) are more active hunters than their North American cousins.[20] 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.[21] Wolverines are also known on occasion to eat plant material.[22]

Successful males will form lifetime relationships with 2–3 females which they will visit occasionally, while other males are left without a mate.[23] 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.[23]

Range

Wolverines live primarily in isolated northern areas, for example the arctic and alpine regions of Alaska, northern Canada, Siberia, and Scandinavia; they are also native to Russia, the Baltic countries, and Northern China and Mongolia. In 2008 and 2009, wolverines were sighted as far south as the Sierra Nevada, near Lake Tahoe, for the first time since 1922.[24][25][26] They are also found in low numbers in the Rocky Mountains and northern Cascades of the United States, and have been sighted as far south and east as Michigan.[27] However, most New World wolverines live in Canada.[22]

The world's total wolverine population is unknown. The animal exhibits a low population density and requires a very large home range.[21] The range of a male wolverine can be more than 620 km2 (240 sq mi), encompassing the ranges of several females which have smaller home ranges of roughly 130–260 km2 (50–100 sq mi). Adult wolverines try for the most part to keep non-overlapping ranges with adults of the same sex.[11] Radio tracking suggests an animal can range hundreds of miles in a few months.

Female wolverines burrow into snow in February to create a den, which is used until weaning in mid-May. Areas inhabited nonseasonally by wolverines are thus restricted to zones with late-spring snowmelts. This fact has led to concern that global warming will shrink the ranges of wolverine populations.[23]

The Wildlife Conservation Society reported in June 2009 that a wolverine researchers had been tracking for almost three months had crossed into northern Colorado. Society officials had tagged the young male wolverine in Wyoming near Grand Teton National Park and it had traveled southward for approximately 500 miles. It was the first wolverine seen in Colorado since 1919, and its appearance was also confirmed by the Colorado Division of Wildlife.[22]

Country Population Area Year State of population
Sweden 265+[5] Norrbotten[5] 1995–97[5] Stable[5]
Norway 150+[5] Snøhetta plateau and North[5] 1995–97[5] Decline[5]
Finland 155–170[5] Karelia and North[5] 2008[5] Stable[5]
Russia 1500[5] Taiga[5] 1970, 1990,[5] Decline[5]
Russia – Komi 885[5] – 1990[5] –
Russia – Archangelsk Oblast 410[5] Nenetsky Autonomous Area[5] 1990[5] Limited[5]
Russia – Kola Peninsula 160[5] Hunting Districts[5] 1990[5] Decline[5]
United States – Alaska[28] Unknown[28] Kobuk Valley National Park,[28] Selawik National Wildlife Refuge[28] 1998[28] Decline[28]
United States – Alaska[29] 3.0 (± 0.4 SE) wolverines/1,000 km2[29] Turnagain Arm and the Kenai Mountains[29] 2004[29] -[29]
United States – Rocky Mountains[30] 28–52[30] Montana, Idaho, Wyoming[30] 1989–2007[30] Unknown[30]
United States – California[21] 1[21] Tahoe National Forest[21] 2008[21] Unknown[21]
Canada – Yukon 9.7 (± 0.6 SE) wolverines/1,000 km2[29] Old Crow Flats[29] 2004[29] -[29]
Canada – Ontario[31] Unclear[31] Red Lake – Sioux Lookout to Fort Severn – Peawanuck[31] 2004[31] Stable to expanding[31]
Canada – Overall[32] 15000–19000[32] Overall[32] -[32] Stable[32]

This requirement for large territories brings wolverines into conflict with human development, and hunting and trapping further reduce their numbers, causing them to disappear from large parts of their former range; attempts to have them declared an endangered species have met with little success.[21]

In captivity

Around a hundred wolverines are held in zoos across North America and Europe, and they have been successfully bred in captivity, but only with difficulty and high infant mortality.[33]

Name

The wolverine's questionable reputation as an insatiable glutton (reflected in the Latin genus name Gulo) may be in part due to a false etymology. The animal's name in Old Swedish, fjellfräs, meaning "mountain cat", worked its way into German as Vielfraß, which means roughly "devours much". Its name in other West Germanic languages is similar (e.g. Dutch: veelvraat).

The Finnish name is ahma, derived from ahmatti, which is translated as "glutton". Similarly, the Estonian name is ahm, with the equivalent meaning to the Finnish name. In Lithuanian is ernis, in Latvian—tinis.

The Eastern Slavic росомаха (rosomakha) and the Polish and Czech name rosomak seem to be borrowed from the Finnish rasva-maha (fat belly). Similarly, the Hungarian name is rozsomák or torkosborz which means "gluttonous badger".

In French-speaking parts of Canada, the wolverine is referred to as carcajou, borrowed from the Innu-aimun or Montagnais kuàkuàtsheu.[34] However in France, the wolverine's name is Glouton (glutton).

Purported gluttony is reflected neither in English nor in North Germanic languages. The English word wolverine (alteration of the earlier form wolvering of uncertain origin) probably implies "a little wolf". The name in Proto-Norse, erafaz and Old Norse, jarfr, lives on in the regular Icelandic name jarfi, regular Norwegian name jerv, regular Swedish name järv and regular Danish name jærv.

In culture

Many cities, teams, and organizations use the wolverine as a mascot. For example, the U.S. state of Michigan is, by tradition, known as "The Wolverine State", and the University of Michigan takes the wolverine as its mascot. The association is well and long established: for example, many Detroiters volunteered to fight during the American Civil War and George Armstrong Custer, who led the Michigan Brigade, called them the "Wolverines". The origins of this association are obscure; it may derive from a busy trade in wolverine furs in Sault Ste. Marie in the 18th century or may recall a disparagement intended to compare early settlers in Michigan with the vicious mammal. Wolverines are, however, extremely rare in Michigan. A sighting in February 2004 near Ubly was the first confirmed sighting in Michigan in 200 years.[35] The animal was found dead in 2010.[36]

The wolverine figures prominently in the mythology of the Innu people of eastern Québec and Labrador. In at least one Innu myth, it is the creator of the world.[37]

Wolverine is the name of a popular fictional character by Marvel Comics—named for his highly individualistic and aggressive behavior, as well his great ferocity despite his small stature.

Film

The 91-minute 1994 motion picture Running Free (also known as One Paw) is about a young boy and his friendship with an Alaskan wolverine. The wolverines seen in the film were born in captivity and directed by U.S.D.A.-licensed filmmaker, Steve Kroschel. Many of the wolverine scenes are documentary footage of trained wolverines that are being filmed in their natural habitat. The movie was screened on October 5, 1994. The American Humane Society was involved before the start of filming and during some of the filming.[38]

The PBS series "Nature" released a documentary, "Wolverine: Chasing the Phantom" as episode #166 on 14 November 2010.[39] This 53 minute documentary [40] focuses on the efforts of a number of naturalists in the United States to track wolverines, collect genetic data, and learn more about wolverine populations, individual behavior and social behavior. It also tracks the raising of two male wolverines in captivity at an Alaska nature reserve from birth to maturity, and profiles the naturalists making these efforts.

The guerrilla force in the 1984 film Red Dawn was named the Wolverines, after a high school athletic team.

Gallery

References

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External links