The weasel family — the Mustelidae — is a motley crew: they can be slinky and shy like a pine marten or grouchy and taciturn like a badger. Ferrets and otters are playful and curious, and then there are the honey badgers, which are basically just berzerker weasels. But perhaps the most fascinating weasel is the wolverine.
The scientific name for a wolverine is Gulo gulo, which is literally Latin for "Glutton glutton" — not sure if the creators of the X-Men superhero were aware of that when they created their moody, beclawed antihero, Wolverine. But these animals seem legitimately superheroic, not only in what and how much they manage to eat, but how they generally ace life in the northern forests and alpine tundra they call home.
Wolverines Are Omnivorous and Super Active
About the size of a mid-sized dog, but resembling a small bear, a wolverine is a weasel of paradox. Weighing in at between 22 and 40 pounds (10 and 18 kilograms) — the males are larger than the females — they defend territories greater than those presided over grizzly bears (between 40 and 372 miles [65 and 600 kilometers]). And they do it aggressively — they've been known to fight a wolf or even a bear off a kill.
That said, wolverines are omnivores, eating pretty much whatever their sensitive noses lead them to: ground squirrels, moose, mountain goats, carcasses buried meters under the ice and snow, bird's eggs, berries, etc. They'll even dig deep under the snow to kill and eat a hibernating animal. Unlike a lot of other Arctic animals that deal with the long, bitter winters by either hibernating or migrating someplace balmier, a wolverine's dense, frost-resistant coat (which at one time made them a major target for fur trappers), snowshoe-like paws, and the ability to chomp through frozen meat and even bones, make it possible for them to eschew lesser animals' cold weather coping mechanisms and stay outside in the far north year-round.
They're also pretty hyperactive, no matter what time of year it is — one wolverine wearing a tracking device in Grand Teton National Park was found to have walked over 500 miles (805 kilometers) in two months.
"They can go and go and go, no matter what the terrain is like," says Rebeccca Watters, Executive Director of the Wolverine Foundation, based in Bozeman, Montana. "They have crazy metabolisms and they don't hibernate, so they're always out exploring. They've also been known to climb hills and slide down on the snow, repeatedly, just for fun."
They're Nocturnal and Clever
While curious and fearless, wolverines are almost pathologically cagey. They're nocturnal, so they're used to slinking around in the shadows — and they've been known to stalk researchers for miles without being spotted. And just as fur trappers of old had a difficult time catching wolverines (and preventing them from robbing their traps), modern researchers have a hard time finding, following and catching them.
"They're wily, clever and playful — it's very hard to trap a wolverine if you're trying to catch it to kill it, but they know when a research live-trap is out and they'll return again and again for a free meal," says Watters. "Sometimes they'll take apart the camera traps that are set up nearby, or play with loose ropes or wires."
They're Not Called 'Stink Bears' For Nothing
But as difficult as they are to find in the flesh, it's not tough to find where they've been. One of the common names for wolverines is "skunk bear" or "stink bear" because they spray various landmarks (and sometimes their enemies) with a special conconction of methylbutanoic acids (the smell of which has variously been described as "sweaty," "cheesy" and "like a barnyard") that comes from their anal gland. They do this to communicate with each other, since one male might have three or more females living in his territory, raising his kits, or babies, with him (males do help raise the babies). Wolverines also communicate vocally with each other, and especially their kits.
Although wolverines are currently considered a species of least concern, having bounced back after nearly going extinct during the 19th century due to habitat loss and aggressive hunting, poisoning and extermination campaigns, they're currently facing new threats:.
"Habitat loss and fragmentation are issues for the population in the lower 48 states, due to development," says Watters. "Wolverines require cold and snow, which is mostly found at high elevations in the lower 48. Wolverines have very large territories, so a single mountain range can only hold a few adult animals, and young animals have to find uninhabited territories, often in a different range, if they want to reproduce. All of this is, of course, compounded by climate change, which is reducing the amount of cold and snowy habitat in the mountains. As the snowy winter season becomes shorter, wolverine habitat shrinks."