Not long ago, a group of friends in a national park in the Canadian Rocky Mountains took a hike on a popular trail known for high grizzly bear (Ursus arctos) activity. A couple of miles along the trail, they had an encounter with what appeared to be a grizzly. The animal came at them growling and hissing, making horrific sounds. All in the group climbed trees to get away from it, except for one person, who was able to flee to the warden office for help. Upon arriving at the incident site, a park warden discovered that the animal involved was actually a wolverine (Gulo gulo luscus). The astonished hikers reported that it had behaved so ferociously that they’d been certain it was a grizzly. While wolverines don’t normally threaten humans, this story illustrates the species’ formidable nature.