The Gulo Gulo, also known as Glutton and Wolverine.

• Class: Mammalia
• Order: Carnivora
• Family: Mustelidae
• Subfamily: Mustelinae
• Genus Gulo
• Species: Gulo gulo

Geographic Range

Palearctic, Nearctic: The Wolverine ranges from northern Europe and Siberia through northern North America. Their distribution once extended as far south as Colorado, Indiana, Pennsylvannia, and perhaps Michigan.

Physical Characteristics

Mass: 7 to 32 kg.

One of the largest extant mustelids, Gulo gulo 's head and body length is 65-105 cm and tail length is 17-26 cm. Females are at least ten percent smaller than males in linear measurements and 30 percent less in weight. Gulo gulo is reminiscent of a large marten with a heavy build, large head, relatively small and rounded ears, a short tail, and massive limbs. Wolverines have long, dense fur which is generally blackish brown with a light brown band extending along each side of the body from shoulder to rump and joining over the base of the tail. Gulo gulo has keen senses of smell and hearing but fairly poor eyesight. Wolverines are extremely strong and aggressive for their size, and they have been reported to drive bears, cougars, and even packs of wolves from their kills.

Natural History

Food Habits

The Wolverine has a diet that can include anything from small eggs to full-sized deer. The wolverine is capable of bringing down prey that is five times bigger than itself. It is equipped with large claws and with pads on its feet that allow it to chase down prey in deep snow. Some prey species include reindeer, roe deer, wild sheep, and elk. The wolverine can be very swift when it is on the attack, reaching speeds of over thirty miles an hour.

Reproduction

Wolverines are monestrous and give birth only once every two years. Between May and August, animals come together in pairs to breed. Pairs last only for a few days and both males and females may remate several times with other individuals. Ovulation is believed to be induced by copulation. The embryo is not implanted immediately, but rather waits in diapause for six months. After implantation, gestation takes only another 30-50 days. Dams build snow-dens in which they give birth and nurse. Births occur from January through April. Litters are from one to six and individuals in a litter may have different fathers. These young typically nurse for 8-10 weeks, are separated from the mother in the autumn, and attain adult size after 1 year. Wolverines are sexually mature at 2-3 years of life. Females up to 10 years old have bred in captivity. Wolverines may live up to 17 years in captivity, but they generally succumb after 8-10 years in the wild.

Behavior

Wolverines are mainly terrestrial and move with a loping gallop. They can climb trees with great speed and are excellent swimmers. Wolverines gallop with great endurance, sometimes moving 10-15 km without rest, although their speed probably does not exceed 15 km per hour. They may cover up to 45 km in one day in their activities. Home ranges can cover as much as 2,000 sq km in winter. Wolverines are largely nocturnal, but they are often active in daylight. In areas where there are extended times of light or darkness, wolverines may alternate three- to four-hour periods of activity and sleep. Wolverines do not appear to be bothered by snow and are active year-round, even in the most severe weather.

After the females give birth they hide with their young. The mother defends her territory and intruders are not tolerated. This territorial behavior continues until the young are ready to hunt on their own. In general, wolverines are solitary (except during the breeding season) and territorial and do not tolerate individuals of the same sex in their territories. Territories are marked with secretions from anal scent glands and urine. Wolverines also spray their food caches with scent gland secretions to discourage other animals from raiding them. Wolverines are rarely vocal, except for occasional grunts and growls when irritated.

Wolverines have large home ranges and may defend smaller territories. Play has been observed between mates and between siblings as well as between kits and their mothers. Wolverines are also known to play with objects.

Habitat

Wolverines inhabit boreal forests, mountains or open plains and brushlands. They construct rough beds of grass or leaves in caves or rock crevices, in burrows made by other animals, or under a fallen tree. They occasionally construct their nests under the snow.

Biomes: tundra, taiga, temperate forest & rainforest, temperate grassland, mountains, ice cap

Economic Importance for Humans

Positive

The Wolverine has been an important source of pelts for the fur industry, but their skins are no longer used widely in commerce. The fur is especially valued as lining for the hoods of parkas by persons living in the Arctic, because of its frost resistant properties.

Negative

Wolverines are often suspected of killing livestock. Many Wolverines are shot due to their habit of preying upon animals that are trapped for fur. Gulo gulo has been extensively hunted in Scandinavia because of its alleged predation on domestic reindeer. It has been considered a nuisance throughout its range because it will eat animals already caught in fur traps and will break into cabins and food caches, eating and spraying the contents with its strong scent. Wolverines can even break into canned goods with their sharp canines. Wolverines are supposedly very difficult to trap; when a wolverine finds a trap, it may spring it by turning it upside down or by dropping a stick into it. Wolverines have also been known to carry traps away and bury them deep in the snow.

Conservation

Status: threatened

Wolverines generally occur at relatively low population densities and have vanished from most of their former range in the United States. In Scandinavia, the estimates vary from one individual per 200-500 sq km. Numbers have declined due to both fur trapping and hunting by those believing the wolverine to be a nuisance (see negative importance below). Wolverines have been nearly eliminated in the United States and have disappeared over most of southeastern and south-central Canada. In Europe, they can only be found now in parts of Scandinavia and the northern Soviet Union.

Other Comments

This is truly a beautiful animal, quick, silent, deadly, and determined to win. Although Gulo luscus is a name often used for North American wolverines, there is considerable evidence that they are simply a subspecies of Gulo gulo .

References

Jackson, H.H.T. 1961. Mammals of Wisconsin. The University of Wisconsin Press, Madison, Wisconsin.

Kurta, A. 1995. Mammals of the Great Lakes Region. The University of Michigan Press, Ann Arbor, Michigan.

Nowak, R.M. and J.L Paradiso. 1983. Walker's Mammals of the World. 4th edition. John Hopkins University Press, Baltimore, MD.

Rue, L.L. 1967. Pictorial guide to the mammals of North America. Thomas Y. Crowell Company, New York.

Drake, The Encyclopedia of Mammals Vol. II.

Science Digest, The Quick and the Dead, Nov. 85, pg.7-