THE FIRST MULE DEER to become famous was named Jet, after the University of Wyoming graduate student who MacGyvered her tracking collar. The name fit an animal that walked, bounded and sometimes ran 150 miles north every spring, chasing greener pastures, and then trekked 150 miles south each fall to escape deep snow.
Thousands of people followed Jet’s seasonal journeys on Facebook and Twitter, and mourned when she died of exposure in December 2016.
The following year, a deer that researchers named Mo for her momentum caught the public’s attention. Julie Legg, a 49-year-old woman living in the almost-ghost town of Superior, Wyoming, was so inspired by Mo’s long migration that she’s spent the last seven years driving two-track roads and hiking hillsides and creek bottoms, photographing and videoing deer for a growing online audience.
Deer 255 didn’t need a name. 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.
“Oh! A celebrity!” chirped a University of Wyoming student as scientists weighed a 2.5-year-old female deer on a frigid day last December near Superior. Like 255, Deer 665 had acquired a reputation for epic walkabouts, migrating more than 220 miles in the spring of 2022. Researchers captured her, using a net shot from a helicopter, then blindfolded her to keep her as calm as possible while they drew blood and measured her body fat, all part of an ongoing effort to understand why some mule deer travel so far.
It’s no wonder that deer like 255 and 665 fascinate us: Despite migrating almost 500 miles over multiple mountain passes in just six months, they finish the year fatter than deer that stay home. But this story is about more than just a few celebrity cervids. Countless mule deer, pronghorn and elk have made such long-distance journeys, year after year, for thousands of years, from sagebrush steppe to alpine meadows and back again. Paradoxically, these grueling trips help sustain herd numbers when conditions are harsh and food is scarce. More and more, however, the West’s migrating ungulates must navigate a treacherous human landscape.
Deer, pronghorn and elk leap over or crawl under fences and dodge highway traffic. They skirt rural subdivisions and race across oil fields, often with offspring in tow. They time their movements to avoid deadly trudges through crusty snow. But the fact that many ungulates still survive their long and increasingly dangerous journeys doesn’t mean they always will. Many of their routes have already been blocked by roads, subdivisions and industrial development. All this stymied movement — combined with chronic wasting disease, drought-diminished food supplies and loss of habitat — is taking a toll: Colorado’s mule deer population plunged from 600,000 in 2006 to about 433,000 in 2018, while Wyoming’s dropped from about 578,000 in 1991 to about 330,000 in 2021.
“I am significantly concerned about mule deer,” Brian Nesvik, Wyoming Game and Fish Department director, said in November.
Yet efforts to conserve migratory routes are also struggling to move forward, facing pushback from critical lawmakers, wary landowners and skeptical industry leaders. Meanwhile, deer like 255 and 665 still follow the ancient pathways they likely learned from their mothers, headed for the best food they can reach.
documented the longest migration of land mammals in the Lower 48 somewhat by accident. Sawyer, a wildlife biologist, lives in southeast Wyoming, where he studies deer, pronghorn and elk for government agencies
