The wolverine (Gulo gulo) is a member of the carnivoran group Mustelidae. Mustelidae also includes weasels, badgers, skunks, and otters, among others. Wolverines live in the taiga and tundra biomes of North America, Europe, and Russia. They inhabit forest, mountain, and plains habitats (Nowak, 1991). Typically, wolverines are categorized as nocturnal. However, individuals have been observed to be active throughout the entire day by alternating between activity and sleep in three to four hour intervals (Pasitscniak-Arts and Larivière, 1995; Nowak, 1991). Wolverines have large and heavily furred paws. During period of heavy snow, their paws function similar to snowshoes, which allows individuals in move and hunt in the winter without high energy costs (Pasitscniak-Arts and Larivière, 1995).
The diet of Gulo consists of bird eggs, lemmings, berries, and carrion (Nowak, 1991). Additionally, wolverines will scavenge off kills made by other carnivores. Individuals have been observed following the trails of wolf and lynx, presumably to their kill sites (Pasitscniak-Arts and Larivière, 1995). Wolverines have been known to occasionally kill large ungulates such as caribou and moose. Unlike ungulates, which have difficulty moving through deep snow, wolverines are quite efficient due to their large paws and can attack under such snowy conditions (Pasitscniak-Arts and Larivière, 1995; Nowak, 1991). Wolverines will cache excess food for later use or for their young (Pasitscniak-Arts and Larivière, 1995).
Wolverines have several predators including wolves, black bears, cougars, and golden eagles. Wolverines often escape from their terrestrial predators by climbing into trees. Predators are most successful in capturing Gulo when cornering an individual in a treeless area (Pasitscniak-Arts and Larivière, 1995).
Individuals are solitary except during the mating season. Mating occurs between April and July, but implantation of the fetus is delayed and occurs between November and March. Females give birth between January and April and due to the delayed implantation, females mate every two years. The size of litters ranged from one to five young (Nowak, 1991). Although the young are born altricial, growth and development occurs quickly with kits attaining adult body size in about seven months (Pasitscniak-Arts and Larivière, 1995).
The geographic distribution of Gulo has been severely reduced over the past few decades. Originally, wolverines were located throughout Scandinavia, Eastern Europe, Siberia, Canada, Alaska, and the northern United States. Currently, wolverines are found in Scandinavia, northern Russia, and Alaska. Wolverine populations in Canada have diminished and most US populations no longer exist (Pasitscniak-Arts and Larivière, 1995; Nowak, 1991).
Additional Information on the Skull
Click on the thumbnails below for labeled images of the skull in standard anatomical views.
Pasitscniak-Arts, M., and S. Larivière. 1995. Gulo gulo. Mammalian Species 499:1-10.
Nowak, R. M. 1991. Walker's Mammals of the World, Volume 2. The Johns Hopkins University Press, Baltimore, MD. 1629 pp.
Gulo gulo page on the Animal Diversity Web (University of Michigan Museum of Zoology)
G. gulo page from San Francicso State University
G. gulo page on Wikipedia.org