Wolverine

(Gulo gulo)

Photo by William F. Wood
Alternate coat with silvery mask and patches: Link

The wolverine, also referred to as the glutton, carcajou, quickhatch, and many other nicknames, is the largest land-dwelling mustelid found throughout the far Northern Hemisphere. There is a common impression that the wolverine’s sinewy physique makes them the largest mustelid overall. However, this title (depending on which metric one prefers) can belong to either the giant otter (the longest) or the sea otter (the heaviest).

Appearance

A mustelid with a robust yet athletic build, with relatively short neck, powerful shoulders and stocky body to help them preserve heat in cold climates. Legs are among the longest in relation to the overall proportions, equipped with paws that are the broadest of all mustelids to function as snowshoes. The tail is relatively short and bushy.

They have highly hydrophobic fur that is a thick, glossy, brown to brownish-black, with a yellow or gold stripe extending from the crown of the head laterally across each shoulder and to the rump, where the stripes join at the tail. A light silvery facial mask and white hair patch on the throat and or chest is distinct in some individuals.(1)

Habitat

The wolverine is primarily found in the remote forest habitats and open plains of the Northern Hemisphere.

Behaviour

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Reproduction

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Diet

Wolverines are versatile, opportunistic predators, and will prey upon almost any small to mid-sized mammal.(2) They often pursue live prey caught in traps, newborn mammals, and animals weakened by winter or immobilised by heavy snow. However, wolverines are thought to be primarily opportunistic scavengers(3)—feeding on dead animals (carrion) that have died of starvation or disease, or were killed by another animal. They will also occasionally enter occupied camps overnight to steal freshly hunted meat, or break into unoccupied cabins to steal anything edible. Despite these raids, there are no official records of a wolverine attacking a human.(4) In some areas wolverines will consume ground nesting birds, insect larvae, berries, and even fish.(5) Wolverines are known to cache food during lean times. This allows lactating females to have easy access to stored food during late winter and early spring—a time when food is scarce.(6)

They are not actually gluttons

The wolverine’s reputation as a supposed habitual overeater is reflected in their most common nickname “glutton”. However, despite popular belief, this name is an overanthropomorphised misnomer, given that a wolverine eats what it needs to survive in its harsh environment, and for this reason does not fit the definition of a glutton. How often they hunt or cache their food has no relevance to overeating.

Some believe the wolverine is labelled a glutton because they are known to consume every part of their prey, including the bones.(7) But when you live in an environment where food is often scarce, that is not gluttony that is efficiency.

Predators and threats

Wolverines are robust and aggressive animals, but they are certainly not as invincible as the pubic frequently portrays them. Young or inexperienced wolverines can fall prey to wolves, mountain lions, black bears, brown bears, and golden eagles, with the grey wolf in particular being considered the greatest threat to adults.(2)(8)(9)(10) The latter is made even more evident in the documentary film Wolverine – One Tough Mother. There are also exaggerated and unsupported claims of wolverines occasionally killing adult bears, when in reality it is the other way around.(11)(12)

Due to the increase of property development and recreational lands, wolverines are coming into conflict with humans more frequently. Hunting and trapping of wolverines have reduced their numbers, causing them to disappear from large parts of their former range.(13) Given the wolverine’s dependence on long-term snow cover, conservationists are also concerned that climate change will threaten their way of life.(4)(6)

Sensationalism and overanthropomorphising in media

Despite being primarily an opportunistic scavenger, the wolverine has been branded a “vicious killing machine”, “vengeful”, and even superstitiously, “devilish”. They are one of the world’s most elusive mammals and have maintained a strongly negative reputation amongst the public. The common notion that wolverines are simply bad-tempered and bloodthirsty gluttons with a grudge against every living creature is an overanthropomorphised and sensationalistic myth. Their ferocity is an instinctual drive for survival, not an inherent nastiness. Unfortunately, even though there is still much for us to learn about the wolverine’s nature, many people continue perpetuate this stereotype, which inadvertently further detracts attention away from their vulnerabilities and true behavioural traits.

Wolverines are indeed aggressive and robust animals, but such characteristics are not unique among many animals in the Carnivora order. Few also take into consideration that most encounters with wolverines have occurred while they are stuck in man-made traps or other stress-inducing situations, and that it is natural to observe them behaving extremely aggressively in such predicaments. Like most wild animals with good survival instincts, wolverines primarily try to avoid trouble.(14)

Wolverines ultimately have their strengths and weaknesses and do not possess the magical powers people often attribute to them. Nevertheless, they are very resourceful and elusive vagabonds of the north—acknowledging the reality of their imitations should not make them any less impressive.

Geographic range

Body length: 65–107 cm / 26–42 in (males), 63–89 cm / 25–35 in (females)
Tail length: 17–26 cm / 6.7–10.2 in
Weight: 9–32 kg / 22–71 lb (males), 8–12 kg / 18–26 lb (females)
Lifespan: Up to 13 years (wild), up to 17 years (captivity)
Range: The Northern boreal forests, subarctic, and alpine tundra of the Northern Hemisphere.
Conservation status: Least concern
Subfamily: Guloninae
Recognised subspecies(15)

  1. North American wolverine – (G. g. luscus)
  2. Eurasian wolverine – (G. g. gulo)

References

  1. Landa, Arild; Lindén, Mats & Kojola, Ilpo (2000). “Action Plan for the conservation of Wolverines (Gulo gulo) in Europe” (PDF)Nature and environment, No. 115. Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention). Archived (PDF) from the original on 29 April 2015. Accessed 22 February 2021.
  2. Patsy, V. and M. Sygo 2009. Gulo gulo (On-line), Animal Diversity Web. Accessed November 22, 2020.
  3. Van Dijk, Jiska, et al. “Diet shift of a facultative scavenger, the wolverine, following recolonization of wolves.” Journal of Animal Ecology 77.6 (2008): 1183-1190.
  4. Bonamy, Morgane, Thora Martina Herrmann, and Andrew Blair Harbicht. “‘I think it is the toughest animal in the North’: human-wolverine interactions among hunters and trappers in the Canadian Northwest Territories. Polar Geography 43.1 (2020). p. 3.
  5. Beauvais, Gary P., and Lain Johnson. Species assessment for wolverine (Gulo gulo) in Wyoming. US Department of Interior, Bureau of Land Management, Cheyenne, Wyoming (2004). p. 20. Accessed 03 December 2020.
  6. Parry, Wynne. Live Science. (2012). “Climate change could melt wolverines’ snowy refrigerators“. Accessed 01 December, 2020.
  7. Magoun, Audrey J. Summer and winter diets of wolverines, Gulo gulo, in arctic Alaska. Canadian field-naturalist. Ottawa ON 101.3 (1987): 392-397.
  8. Burkholder, Bob L. “Observations concerning wolverine.” Journal of Mammalogy 43.2 (1962): 263-264.
  9. White, K. S., Golden, H. N., Hundertmark, K. J., & Lee, G. R. (2002). Predation by Wolves, Canis lupus, on Wolverines, Gulo gulo, and an American Marten, Martes americana, in Alaska. Canadian Field-Naturalist, 116(1), 132–134.
  10.  “White River National Forest (N.F.), Land and Resource Management Plan: Environmental Impact Statement”. 2002.
  11. Science Daily. 6 May, 2003. When Predators Attack (Each Other): Researchers Document First-known Killing of a Wolverine by a Black Bear in Yellowstone. Accessed 15 February, 2022.
  12. Krebs, John, et al. Synthesis of survival rates and causes of mortality in North American wolverines“. The Journal of Wildlife Management 68.3 (2004): 493-502.
  13. Glenn Hurowitz (2008-03-05). First wolverine in 30 years spotted in California
  14. Woodford, Riley. Alaska Department of Fish and Game. Wolverines: Behind the Myth. Accessed 15 February, 2022.
  15. Copeland, J.P. and J.S. Whitman. 2003. Wolverine (Gulo gulo). Pages 672-682 in Wild Mammals of North America: Biology, Management, and Economics. G.A. Feldhamer, B.C. Thompson, and J.A. Chapman, editors. The Johns Hopkins University Press. Baltimore, Maryland USA.

What Are Mustelids?

Badgers | Ferret-Badgers | Fisher | Grisons | Martens | Otters | Tayra | Weasels | Wolverine