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Monday Mustelid - Gulo gulo Edition

You’d better pay attention to today’s mustelid, bub.

Before I dig in to the awesomeness that is the Wolverine, I just want to mention that today’s post might have been about the Vietnam Ferret-badger if there were more available information. Currently there are very few pictures of these animals, let alone of live specimens, and the species has only recently been categorized as separate from the other Asian Ferret-badger species. So I do want to give it a shout-out, but unfortunately it’s a shout-out with very little detail.


The Wolverine (Gulo gulo) is the largest species of mustelid that dwells exclusively on land. The only other mustelids that come close to it in terms of mass are the Sea Otter and Giant Otter. They are found exclusively in the Northern Hemisphere, specifically Canada, Alaska, Siberia, Russia and northern Europe. Historically it was found south of the Nordic countries as well, but it has been extirpated from that part of its range. The Wolverine’s preferred habitats are tundra and boreal forest. It is a solitary animal that is known for its super-sized fighting spirit, and is able to take down prey much larger than itself.

The Wolverine is the only member of the genus Gulo, and it has a unique physique among mustelids. Its build has been compared to that of a bear, because it is stocky and muscular in the shoulders. Adult males can grow up to 42 inches (1.07 meters) in body length, and some exceptionally large specimens have weighed 71 pounds (32 kg). A more common upper weight limit is closer to 55 pounds (25 kg). Wolverines have short, round ears and large paws, which help it move efficiently through deep snow. Their dark brown coats repel water, which is the primary characteristic that appeals to hunters and trappers. There is some variation with pale or buff-colored bands on some individuals.


The Wolverine is both a scavenger and a predator. Much of its prey consists of smallish mammals, but there have been quite a few documented instances of Wolverines taking down caribou, deer, sheep, moose, and even lynx and coyotes. When going after big prey, Wolverines typically target individuals that have been weakened in some way, perhaps hindered by deep snow or caught in traps. Wolverines also consume a great deal of carrion, which is their primary food source in the harsh winter and spring months. Wolverines are also known as “gluttons”, because their eating style is relentless.


Wolverines establish fairly permanent territories, and a male’s territory often overlaps that of two or three females. The male will likely mate with each of those females every summer, and males whose territory contains no females will likely not mate that year. Females delay implantation of the fertilized embryos until the beginning of the winter season, and in years when food is scarce they may not produce any kits at all. After 50 days of active gestation, females give birth to litters of two to three kits. The kits will reach adult size within a year, after which they will strike out to find their own territories.


Because Wolverines have such a low population density and require such large territories, it’s difficult to get an accurate picture of the health of the overall population. It is known that they have declined from their historic range due to hunting, trapping and habitat destruction. When their territories do border the edges of human populations, it can engender conflict if the wolverine targets livestock. All that said, they are currently considered to be a species of least concern by the IUCN.


Source for all images used in this post.

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