Population, Conservation Status, Threats:
Wolverines are considered least concern by the IUCN, although their populations have been declining across their range since the 1800s. They are frequently killed, legally and illegally, as a threat to livestock. Decreasing and fragmented populations threaten their genetic diversity.
Physical Description:
Wolverines are stocky, bear-like mustelids, as large as a mid-sized dog. They have long claws and a broad snout and head with small, rounded ears. They are dark brown to black overall, with a distinct light stripe running down their sides and across their forehead. They possess unique white mottling on the chest and throat, which can be utilized as an identifier of individuals.
North American wolverine range from Montana Field Guide. Wolverines are rarely seen in the lower 48 states. Wolverines are also found across northern Eurasia.
Habitat:
Wolverines require habitats with ample snowpack. They occupy both tundra and forests, frequently in high-altitude and mountainous terrain.
Behavior:
Wolverines are solitary and elusive, primarily active at night, with vast home ranges of up to 380 square miles. Wolverines are well-adapted to travelling over snow and ice, being able to travel up to 15 miles a day, and are good climbers and swimmers. Like other mustelids, they produce a pungent odor that is used for scent marking.
Diet:
Wolverines are heavily opportunistic carnivores that rely on both fresh-killed prey and carrion to survive. In the winter, they tend to scavenge more, able to dig carcasses out from feet of heavy snow; their strong jaws are well adapted to crushing through both bone and frozen flesh, allowing them to feed on carcasses left behind by wolves and other predators unable to utilize bones as a food source. In the warmer months, they tend to hunt more often, going after small-to-medium mammals and birds and the young of larger species like sheep, caribou, and moose.
Reproduction:
Wolverines may breed in the spring through fall, but implantation is delayed until the winter. After implantation, gestation takes 30-50 days. Young are born in early spring in dens built into deep snow. 2-3 kits are born on average per litter, and only the mother is responsible for their care. Young are weaned and independent after about 5 months, but may remain with their mother or within her territory for 1-2 years. Both males and females reach sexual maturity at 2 years of age.
Associated Species:
Wolverines and wolves have a complex relationship, as wolves are a natural predator of wolverines at the same time as their abandoned kills can provide food for scavenging individuals. Large alpine ungulates like elk and moose are often eaten by wolverines, mostly in the form of carrion, though wolverines are capable of taking down young or weak individuals. Snowshoe hares are frequently predated upon by wolverines.
Illustration by Willow Sedam