Deer 255, a mule deer famous for her yearly 240-mile migration from southwest Wyoming to central Idaho, has died. According to researchers with the Wyoming Migration Initiative, who announced her death this morning, her GPS collar data indicates that she died in Wyoming’s Red Desert around noon on April 11, just three days into her spring migration. The physical evidence suggests that she was killed by a predator, most likely a mountain lion.
At 10 years and 10 months old, Deer 255 had spent years leaping fences, crossing highways and avoiding predators in search of nourishing food for herself and her fawns. To the many humans who followed her travels, she exemplified the extraordinary endurance — and vulnerability — of the deer, pronghorn and elk that sustain themselves and their herds by migrating hundreds of miles every year. As Christine Peterson wrote in our April issue:
Deer 255 is fat and elusive and, according to researchers, can get huffy with her fawns, nudging them to keep moving with body language familiar to the parents of Homo sapiens. During her journeys, she crosses land managed by the National Park Service, the U.S. Forest Service, the Bureau of Land Management and the state of Wyoming, not to mention innumerable private parcels and busy roads …
Between 2019 and 2022, four animated videos of her 240-mile annual trek from southwest Wyoming to central Idaho — the longest one-way mule deer migration ever recorded — racked up almost 4 million views online. Her collar number became synonymous with marathon feats.
Deer 255’s herd mates are currently completing their spring migration; many will spend the summer south of Grand Teton National Park in Wyoming. Their migration routes, like those of most other migrating mammals, still await permanent protection.
This story is part of High Country News’ Conservation Beyond Boundaries project, which is supported by the BAND Foundation.
