“Even though it was not expected, it wasn’t particularly surprising given the high nutritional value of whitebark pine nuts,” he said. The nuts are also a favorite food of grizzly bears in the fall.

Fox fecal samples screened by Cross have so far shown the Beartooth animals dining on 16 different foods, including grouse whortleberry and shrews.

“This is really cool stuff,” he said. “It’s exciting because it illuminates part of the natural history of what this animal is doing. It’s also illustrating that whitebark pine nuts might be even more important than we already guessed.”

Log trap

Trapping the Beartooth foxes in winter is important because it allows Cross the opportunity to use the foxes’ food stress to his advantage. Using small, square live traps made out of logs, the foxes are trapped inside when they pull on the bait that is hooked to a trip wire. Remote camera photos have shown skittish foxes running in and out of the boxes at first, wary of being trapped.

“We can load this thing up with elk quarters,” Cross said as he demonstrated how the traps work. “We can overload the fox’s sense of security because there’s more meat in the trap than it will get all winter.”