Wildlife officials in Yellowstone National Park captured an “unusual” sight of a stocky grizzly bear with a pack of hunting wolves, then escape by killing them.
The sensational video, posted on the National Parks Service’s Facebook page, shows an October incident in which wolves from the Junction Butte herd in north Yellowstone joined lumbering wolves as they hunted down a herd of elk.
After the wolves kill the elk, the bear moves in and steals the carcass: a phenomenon known as robbery parasitism, or robbery parasitism, in which one species steals the resources, often food, of another.
The NPS said the Yellowstone incident was unusual, because wolves and bears usually compete for food and hunt separately. While bears stealing food stolen by wolves is not uncommon, in this case the bear decided that its best interests were being served by actively joining in the hunt.
“From a bear’s perspective, it takes a lot of energy to pursue a wolf pack, but the reward is high if you succeed in controlling a carcass,” said NPS.
“A fresh elk carcass is a wonderful source of fat and protein for a grizzly bear preparing for hibernation. It seems that this bear discovered that following the wolves in the morning would increase its chances of encountering a high-calorie meal.”
The wolves were forced to wait for the bear to finish his meal before taking advantage of killing them.
“Usually wolves succumb to incoming bears,” NPS said. “Because hunting is dangerous and often unsuccessful, it is better for wolves to wait their turn at a carcass that has been raped by a bear than to keep hunting.”
Previous videos from Yellowstone show wolves and bears facing each other. In one episode, filmed in 2019, a tour guide took close-up photos of a grizzly defending itself from a pack of wolves trying to retrieve an elk carcass.
Yellowstone is home to about 123 gray wolves, NPS says, and 90% of their winter diet consists of elk. The park, which spans parts of Idaho, Montana, and Wyoming, is home to about 150 grizzly bears, which were listed as endangered in 1975.
A federal judge reinstated protection for grizzlies in the Greater Yellowstone ecosystem in September 2018, after the US Fish and Wildlife Service claimed a “remarkable recovery,” delisting the species a year earlier.