Wolverine  (Gulo gulo)

Classified as Near Threatened (NT) on the IUCN Red List (1).

The elusive wolverine has a fearsome reputation - it is the largest member of the weasel family. The remoteness and voracious appetite of these creatures have led to an aggressive reputation. Males are much heavier than females and both have a stocky body and short legs (3). They are well adapted to the cold habitat of their northern range with a thick, bushy coat and broad, hairy paws (3). The glossy coat is dark brown with a paler stripe across the rump and along the sides of the body; some individuals have white throat patches (4). The powerful jaws and large teeth are able to demolish frozen carrion and bone (3). Wolverines carry their head and tail lower than the arched back and their gait appears somewhat humpy and lumbering although they can move very quickly when necessary (3).

Wolverines have a circumpolar distribution in the northern hemisphere, and are found from the western United States, Canada, and Alaska to Siberia, Russia, Eastern Europe and Scandinavia (3). Previously their distribution extended further south reaching the Baltic States and southern California respectively, but with human encroachment the range has retreated northwards, leaving remnant populations in pockets of remaining wilderness in sub-arctic regions (3). Populations in North America and Europe are sometimes divided into separate subspecies, known as Gulo gulo luscus and G. g. gulo, respectively (5).

Found in alpine, tundra and northern taiga habitats (4).

The wolverine is possibly the least known of the northern hemisphere’s large carnivores (2). Individuals are solitary, except for mothers with their young, and can occupy enormous home ranges depending on habitat and prey availability. Male’s home ranges may encompass those of several females, and the largest have been estimated at around 920 km2 (3). Wolverines tend to alternate periods of activity and sleep throughout the day and night, when awake they are capable of crossing vast distances, climbing trees and swimming rivers (3). Mating occurs from April to August and births take place the following spring, usually within a den or sheltered area appropriated by the mother (4). Litters typically contain two to three cubs, which are born blind and with white fur. Weaned after nine to ten weeks, cubs often stay with their mother for over a year and females are therefore likely to reproduce only every couple of years (4).

Wolverines are reputed to have a voracious appetite and are even known as the ‘glutton’ in some areas (3). They do not hibernate over the cold winter months as some other carnivores do and are opportunistic scavengers, often feeding on carrion (3). The diet varies across their range with wolverines in Scandinavia feeding on wild and domestic reindeer (4), and those in Alaska consuming whale and seal carcases (3). Food may be stored for later consumption but wolverines also actively attack some prey, especially smaller mammals such as domestic sheep (4).

Wolverines have declined through much of their historic range; they are very sensitive to human disturbance and have retreated to remaining areas of wilderness (4). They continue to be threatened by habitat loss and also by a loss of prey species or even other carnivores (such as wolves) that provide carrion (4). Where they do exist near humans they can come into conflict with farmers from attacking livestock; persecution and poaching are therefore pertinent threats (4). In addition, populations that are protected are slow to recover due to slow reproduction rates caused by the small litter size and the fact that females only reproduce every few years (4).

WWF International launched a Large Carnivore Initiative for Europe (LCIE) in 1995 and under this initiative an Action Plan has been drawn up for the conservation of this species in Europe (6). The wolverine is protected in much of its range but more research into the population dynamics and behaviour of this elusive creature are desperately needed. In Europe especially, where there are fewer areas of true wilderness left, any conservation initiative will have to work closely with local people to combat prejudice (4). In the United States, the wolverine is yet to be listed on the Endangered Species Act due to the paucity of data surrounding this species, highlighting once again the need for further research (3).

For more on the wolverine and its conservation see:

• Wolverine Foundation:
  www.wolverinefoundation.org
• Landa, A., Lindén, M. and Kojola, I. (2000) Action Plan for the conservation of Wolverines (Gulo gulo) in Europe. Council of Europe Publishing, EU. Available at:
  http://www.lcie.org/Docs/COE/COE%20NE%20115%20Action%20plan%20for%20wolverines%202000.pdf
• San Francisco State University:
  http://bss.sfsu.edu/geog/bholzman/courses/Fall00Projects/wolverine.html

Authenticated (16/02/05) by Dr Arild Landa of the Norwegian Institute for Nature Research.

• Carnivore: flesh-eating.
• Carrion: the flesh of a dead animal.
• Hibernation: a winter survival strategy characteristic of some mammals in which an animal’s metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer. In insects, the correct term for hibernation is ‘diapause’, a temporary pause in development and growth. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.
• Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
• Taiga: the sub-arctic forest of the high northern latitudes that surrounds the pole and is mainly composed of coniferous trees.
• Tundra: treeless grassland between the icecap and the tree line of Arctic regions, with vegetation consisting of lichens, grasses, sedges and dwarf woody plants.

1. IUCN Red List (May, 2009)
   http://www.iucnredlist.org
2. Macdonald, D. (2001) The New Encyclopedia of Mammals.Oxford University Press, Oxford.
3. San Francisco State University (March, 2003)
   http://bss.sfsu.edu/geog/bholzman/courses/Fall00Projects/wolverine.html
4. Landa, A., Lindén, M. and Kojola, I. (2000) Action Plan for the conservation of Wolverines (Gulo gulo) in Europe.Council of Europe Publishing, EU. Available at: http://www.lcie.org/Docs/COE/COE%20NE%20115%20Action%20plan%20for%20wolverines%202000.pdf
5. Wolverine Foundation (March, 2003)
   http://www.wolverinefoundation.org
6. Large Carnivore Initiative for Europe (April, 2008)
   http://www.lcie.org/