The Wolverine: A 40-Pound Scavenger Built for Snow and Running Out of It

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The real wolverine, Gulo gulo, is about the size of a medium dog, 24 to 40 pounds, and nothing like the bear sized monster of legend. What it has is equipment. It walks flat on oversized paws that work like snowshoes, climbs ice with claws like crampons, and wears oily fur that sheds frost. An upper molar rotated 90 degrees shears meat frozen as hard as wood, and its jaw bone measured 940.8 newtons of compressive strength, the highest of any carnivore tested. Its reputation as a glutton may come from a mistranslation, when a Norwegian name meaning mountain cat was confused with a German word meaning devours much.

This episode takes the animal apart piece by piece: how it shadows wolf packs to scavenge their kills, how it brings down a moose trapped in deep snow, and how a female pauses her pregnancy for months until her fat reserves justify it. It also explains why such a tough animal is in trouble. Wolverines need enormous territories and deep spring snow for their dens, and the snow is melting earlier. In November 2023 the species was listed as threatened in the lower 48 states.

• After summer mating, the embryo sits unimplanted in the uterus for months. If the mother has not stored enough calories by midwinter, her body reabsorbs it.
• Females dig multi-chambered dens under the snowpack and bury frozen meat nearby, using the snow as both insulation and freezer.
• Males are not absent loners. Fathers visit their kits until weaning at around 10 weeks, and juveniles have been documented traveling with them later.
• A male tagged in Wyoming in 2009 as M56 walked more than 500 miles to become the first confirmed wolverine in Colorado since 1919. He was shot in North Dakota in 2016.
• Michigan calls itself the Wolverine State, yet a single sighting there in 2004 was major news. In Innu tradition the wolverine is both the creator of the world and a trickster.