Remembering Deer 255: Wyoming muley renowned for longest migration dies

The most famous mule deer in Wyoming died April 11 on a brushy pocket in the middle of the Red Desert. A mountain lion likely killed the 10-year-old doe known for migrating more than 200 miles each spring and fall in search of nourishing meals. 

Her fame came from her epic journey, traipsing from winter range in southwest Wyoming through subdivisions and mountains and across highways and fences into Idaho. That trek was so notable, in fact, that researchers never gave her a formal name, simply calling her Deer 255. And while followers of the intrepid deer will mourn her the same way they mourned her predecessors including Jet and Mo, researchers note she was one deer in a population of many. What she symbolizes, they say, is much more than the novelty of cervid endurance.

She and the tens of thousands of other animals that migrate across Wyoming and the West are physical manifestations of what an open landscape can sustain. Biologists say they’re proof of the nature we can still witness in an increasingly developed world. 

“It’s not a mistake that a movement like that happens in the greater Yellowstone ecosystem and doesn’t happen in the Front Range of Colorado or the Greater Salt Lake Area,” said Matthew Kauffman, leader of the Wyoming Migration Initiative. “It happens here because it still can.”

But while Kauffman and other migration experts tout the progress made in protecting migrations, they also note these advances with a bit of a caveat. We have the information we need to maintain these animals’ connected worlds, they say, and now we have to find the social and political will to get it done. 

‘It’s humbling’

At this point, Deer 255’s story in the migration world is as familiar as other celebrity creatures like Grizzly 399 known for parading her young around walls of photographers in and near Grand Teton National Park. 

Researchers with the Wyoming Migration Initiative collared Deer 255 for the first time in March 2016 as part of a broader project looking at how deer benefit from long distance migration. They watched as her collar showed her migrating to the Hoback Basin with the rest of her herd and then beyond that for another 90 miles.

It was a fluke, they figured. And then her collar stopped working. 

Two years later, a pilot looking for deer for another round of captures saw a doe with a collar emitting no radio signal. He caught her and brought her to researchers who realized she was 255. 

Adorned with a new collar, she made that general migration again every year. 

She’s part of the Red Desert segment of the Sublette Mule Deer herd, which is generally broken in three segments, the ones that stick around their winter range each year, the ones that go about 60 miles, and the ones that migrate 150 miles from the desert to the Hoback Basin. The discovery of deer walking 150 miles was surprising enough. When researchers realized 255 moved almost 100 miles farther, they were floored. 

“We try to make sense of these movements and seasonal ranges because when you’re doing science you have to compartmentalize and categorize these things,” Kauffman said. “And then an animal like 255 comes along and breaks all the classifications we have. It’s humbling.”

Researchers tried to capture her fawns to see if they made the same journey as their mother, but despite her tendency to produce twins almost every year, scientists only successfully captured one, which died not far into its spring migration. 

So Kauffman hedges when people ask him if other deer make that same journey or if she’s the only one — a tenacious ultrarunner among mere marathoners. He doesn’t think she’s alone, but on the other hand, the Migration Initiative has collared hundreds of deer in the past decade and has never caught another one that makes the same journey. 

To him, she epitomizes how these deer make similar migrations over and over but very much remain individual animals with individual needs. 

“We do a good job of identifying the common patterns, but the rarer ones are harder to sample,” he said. “Even today, there are surprises out there waiting to be discovered of some quirky or odd or remarkable movement that an individual or few have figured out.”

Those diverse strategies are why protecting migrations, and as a result the abundant wildlife Wyoming and the West still hold, requires more than one overpass or a couple fence removal projects, researchers say. It requires landscape-level understanding and protections. 

And that is where the discussion often moves from exciting deer facts into controversial public policy. 

Progress with caveats

When 255 was born, likely some early summer day in 2013, little migration policy existed for big game. 

People knew wildlife migrated. The tribes living across the state have known for millennia that animals move from one place to another, following green up and escaping snow. But it wasn’t until big game migration researcher Hall Sawyer used radio-collar technology to document the Red Desert Hoback migration in 2011, a couple years before 255 was born, that conversations really began. 

And since then, even the most ardent environmentalists agree they’ve seen progress. Wildlife crossings now yawn over and snake under highways; landowners have put almost 20,000 acres into permanent easements protecting the land from development in that migration corridor alone; and Game and Fish has spearheaded removing or replacing about 700 miles of fencing just in Sublette County — largely to benefit migrating deer. The U.S. Geological Survey, along with state and tribal partners, have mapped more than 180 migrations around the West and 42 in Wyoming. And in 2023, the U.S. Department of Agriculture created the Migratory Big Game Initiative bringing tens of millions of dollars to Wyoming and other western states to conserve migration corridors.

“Clearly, the speed with which we have learned more about where the migrations are, how the animals use the habitat and the importance to the population abundance has been tremendous,” said Julia Stuble, Wyoming state director of The Wilderness Society. “Now I wouldn’t be able to say with a straight face the policy has kept up with the pace at a state or federal level.”

While noting the positives — Gov. Mark Gordon’s big-game migration executive order placed an emphasis on conserving pronghorn and mule deer migrations, and a Department of Interior executive order directed the USGS to map migrations and has brought almost $100 million to enhance corridors — Stuble says much more work needs to be done. The state also remains deeply divided over the Bureau of Land Management’s land use plan for millions of acres in the Rock Springs area that includes portions of the Red Desert to Hoback migration. 

The slicing and dicing of Wyoming’s open spaces by subdivisions is what keeps Jill Randall, Wyoming Game and Fish’s migrations coordinator, up at night. “We’re losing ground at a faster rate than we were 10 years ago.” 

She also worries about invasive species like cheatgrass that outcompete good food for mule deer and countless other species. 

The creatures’ journeys are long and arduous without human caused hurdles, she said. Even before our fences, roads, dogs, oil and gas development and modified landscapes that foster invasive species, deer like 255 still had to navigate predators, snow, wind, drought and the caloric toll of the epic march, which is proof of how valuable those journeys are to deer. The most recent research from the Migration Initiative project shows the deer that move the farthest are the ones that stay the fattest. 

It’s up to us, researchers, conservationists, hunters and land managers say, to conserve the remaining migrations so we can appreciate the abundance they create as we follow along with the next celebrity deer.