A doe pronghorn and her two fawns made a potentially fatal mistake by failing to migrate out of Jackson Hole.

The trio, reportedly in good health, has been seen repeatedly in recent days, foraging the National Elk Refuge near the bike path adjacent to U.S. 191. The vast majority of the of valley’s herd, estimated at about 400, migrated out via the “path of the pronghorn” through the Gros Ventre drainage by late December. 

When pronghorn winter in the valley, they frequently die. In past winters, they’ve perished by the dozens.

Pronghorn, or Antilocapra americana, are ill-equipped to deal with extreme cold and deep or hard snow that buries forage, said refuge biologist Eric Cole.

“They’re definitely not migrating out of Jackson Hole at this point,” Cole said. “They don’t fair well in severe winter conditions. Survival has been reasonably high when they’ve stayed and the conditions have been mild.”

Cole said he had not witnessed the family in person, but had received reports of observations from residents.

The refuge’s feeding program won’t help. Pronghorn do not take to supplemental feed, which was first distributed Thursday, the biologist said.

“They don’t seem to be participating in feeding,” Cole said. “There’s a dominance hierarchy on the refuge. It starts with bison, and ends with elk calves. The pronghorn would probably be below the elk calves in their ability to compete for pellets.”

Tim Mayo, a wildlife photographer from Jackson, said he spotted the pronghorn family on two occasions over the past week. On Friday, the family was bedded down and foraging on the stalks of cattails along Flat Creek, Mayo said.

“They looked incredibly healthy — their ribs weren’t showing or anything like that,” he said.

In mid-December, well after the pronghorn migration usually ends, as many as 34 pronghorn were observed on the refuge, Cole said. The group’s fate is a mystery, he said.

“Because there were no collared animals, we just don’t know what happened to them,” Cole said.