Nearly pushed to extinction and now holding on only in remote parts of the Rocky Mountains and the Arctic, a pair of wolverines gave birth in Minnesota for the first time in decades.
Two young, playful female wolverines — called kits — were born in January and are now on display at the Minnesota Zoo, the only zoo in the United States with a mating pair of wolverines. The predators are so rare that fewer than a dozen zoos in the country still have them. And their future in the U.S. is a little uncertain because they are almost as difficult to breed in captivity as pandas.
"It's extremely tricky," said Laurie Trechsel, assistant curator at the Minnesota Zoo. "They're very secretive animals and they just don't like to be watched when they're trying to breed."
Wolverines are technically a type of weasel but look more like a cross between a large badger and a small bear. Extremely powerful for their size, they can take down an adult moose in the wild despite weighing less than 40 pounds. However, they don't have the size or the legs to be big-game hunters, Trechsel said. They prefer to scavenge, following wolves to their kills and eating the leftovers.
They once lived in Minnesota, Wisconsin and Michigan but were wiped out by trappers by the early 1900s. While they were being exterminated from the Great Lakes region, they received what Trechsel believes is a somewhat unfair reputation for aggressiveness.
"They have such a bum rap," she said. "If you put a wolverine up against a bear or a wolf, they'd hold their ground. But unless they have to, they try to stay away and are actually very mellow. The kits are always playing and rolling around like puppy dogs."
Adept and opportunistic, wolverines would often make it to a trapper's kill before the trapper, running off with a quick and easy meal.
"Trappers didn't like that, so they trapped the wolverines," Trechsel said.
After being eliminated from much of the U.S., wild wolverine populations have begun to stabilize. There is an estimated 300 to 1,000 left in the Lower 48, primarily surviving in the deep snows of the Rocky Mountains.
There are only a little more than a dozen of the animals in captivity in the U.S. with about 100 wolverines in European zoos. Trechsel hopes the Minnesota Zoo has found something of a blueprint for mating the animals. It received one wolverine from Finland and another from Sweden and immediately put the two adults in a half-acre enclosure out of the public eye. The space temporarily housed the zoo's black bears, before they were moved to a larger pen.
The wolverines have been kept from most human contact since their arrival, with zookeepers monitoring their progress by camera.
While wolverines don't necessarily mate for life in the wild, they do pair off and stay together for some time, often having more than one litter together. So after the two kits were weened, the two adults were left in their private enclosure.
"The public has never seen Mom and Dad and they won't, because wolverines need that extra little secretiveness to be comfortable enough to breed and take care of their offspring," Trechsel said.
Six other American zoos, including one in Detroit, also received pairs of wolverines from Europe in the last few years. While none have successfully mated yet, the hope is they will and that the next generation will be able to pair up with the two Minnesota kits to keep a genetically diverse population alive in a part of the world where the animals once lived.
In the meantime, the kits are rapidly reaching adult size. The best time to view them is in the morning, before the heat of the day wears them out, Trechsel said.
"You just can't see wolverines in the wild," she said. "But they're such a neat animal to watch, especially in this cute baby phase. When people start watching them, they fall in love with wolverines."
Greg Stanley • 612-673-4882