Species Fact Profile: Wolverine (Gulo gulo)

Wolverine

Gulo gulo (Linnaeus, 1758)

Range: Canada, Northern United States, Scandinavia, Russia
Habitat: Boreal Forest, Tundra
Diet: Small Mammals, Ungulates, Birds, Eggs, Carrion, Roots, Berries, Seeds
Social Grouping: Solitary, Territorial (male territories encompass several females)
Reproduction: Mating takes place in late spring and summer.  Implantation of embryo is delayed for up to 6 months after breeding, after which pregnancy is 30-50 days.  Average of 3 kits born in den dug in the snow.  Weaned at 3 months, independent at 5-7 months, and sexually mature at 2-3 years old
Lifespan: 10-15 Years
Conservation Status: IUCN Least Concern

• Largest member of the Mustelidae (weasel family).  Body length 65-105 centimeters, tail length 13-26 centimeters, shoulder height 36-45 centimeters.  Weigh 9-30 kilograms.  Females are usually about two-thirds the size of the males
• Body is short and stocky with short legs, a large head with small ears, and semi-retractable claws.  The paws are broad and hairy to assist in traveling across thick snow
• Fur is brown or black with a yellowish stripe extending from the crown across each shoulder and meeting up again on the tail
• Excellent sense of smell and good sense of hearing, but relatively poor vision
• Have a reputation for ferocity, famous for challenging larger carnivores, such as pumas and wolves, for access to a carcass.  Adults have few natural predators, except for occasionally wolves.  Youngsters may be preyed upon by pumas, bears, or eagles
• Range is believed to be limited by snow, requiring enough snow late into the spring that prey can be cached and kept fresh until the kits are old enough to forage on their own
• Does not hibernate.  Primarily active by night, but will also forage by day
• Capable of killing large ungulates such as caribou that are stranded in deep snow.  Large kills will be befouled with musk and urine to dissuade other animals from eating them
• Sometimes hunted for the fur, which is frost resistant, but little trade in their pelts.  It is possible that Michigan's nickname as "the Wolverine State" is due to Detroit's historical importance in the fur trade; it is unknown as to whether the species was found historically in Michigan
• Persecuted historically for predation of trapped fur-bearing animals and domestic reindeer, as well as the animals' tendency to break into trappers cabins and befoul them with musk.  Very difficult to trap, reported to spring and destroy or bury traps set for them
• Prominently featured in folklore and myth, often as a trickster or devil spirit, sometimes as a creator
• Two subspecies - the North American (G. g. luscus) and the Eurasian (G. g. gulo).  Both look very similar, differences are mostly genetic.  Vancouver Island population shows some differences in skull morphology, may represent a third subspecies, G. g. vancouverensis
• Populations in decline, in part due to loss of large carnivores that they can scavenge off of.  Very sensitive to human disturbance, breed slowly

Zookeeper's Journal: Most people only know the wolverine as an X-Men character, and its no surprise.  The world's largest weasel is seldom seen in zoos, where it has proven challenging to breed.  I've only seen wolverines at three facilities, and only one of those was outside of the species natural range.  For such notoriously tough animals, wolverines are rather delicate and sensitive in their climatic preferences, and easily become too hot or uncomfortable.  Unfortunately, the future in the wild may be too hot for them to handle; while polar bears are the poster species for global climate change, wolverines may prove to be even more vulnerable as they lose the snow dens where they raise their young become a thing of the past.