Yellowstone naturalist guide Doug MacCartney recently encountered an incredible sight: 13 wolverines that appeared to be chasing a group of grizzly bears. The wild incident took place on August 8, 2022, and was shared on Facebook in an October 2 post by Yellowstone Insight, a local ecotourism agency. MacCartney says he spotted the unusual wildlife interaction while attempting to summit a mountain with his friends Bill and Steve.

“There was a band of snow we would have to ascend. We chose our spot and headed for it. As we approached, I noticed a grizzly sow with two cubs of the year leaving a spit of snow a few hundred yards east of our spot. We started climbing the snowfield while keeping an eye on the bears,” wrote MacCartney. “Suddenly Bill noticed that the bears were running. I looked to see why and noticed a wolverine leaving the top of a big rock and going in the bear’s direction. I then spotted another wolverine running toward the bears, and then another. Bill and Steve thought I was crazy till they saw them, too.”

It didn’t end there. MacCartney says that he and his buddies soon spotted another group of wolverines join the chase. Eventually, the bears moved out of the bowl and escaped along a rocky ledge. Meanwhile, the wolverines moved up into a higher snowfield and then ascended a near-vertical rock wall next to it.

“It was very hard for us to keep track of all of the wolverines and the bears as they fled the area. I counted, for sure, a total of 12 wolverines at one time. Steve said he counted 13, which I don’t doubt,” wrote MacCartney. “The route the bears took looked crazy but the routes the wolverines took looked insane. Some had gained 1,000 feet and were nearing the summit in five or ten minutes before we could no longer follow their movements against the rock face.”

Read Next: Utah Collars First Wolverine in State History—After the Predator Killed or Injured 18 Sheep

Yellowstone Insight reached out to retired wolverine researcher Jeff Copeland, who currently serves on the board of The Wolverine Foundation, to analyze the sighting. Copeland theorized that the large numbers of wolverines might have been congregating at higher elevations to feed on army cutworm moths, which grizzlies are known to do. Another local expert, James Halfpenny, said that there might have been a carcass nearby that was attracting the predators. Either way, a sighting of 12 to 13 wolverines in one place is exceptional, especially in the Lower 48.

According to National Geographic, wolverines are typically solitary creatures. They travel up to 15 miles per day and are known to be fierce predators. They typically weigh 24 to 40 pounds but can take down prey much larger than themselves. According to Colorado Parks and Wildlife, there are fewer than 400 wolverines left in the contiguous U.S. The U.S. Fish and Wildlife Service is currently considering protecting the species under the Endangered Species Act.