JACKSON, Wyo. — She did it again. That spectacular, astonishing, hard-charging mule deer just marched and munched her way more than 200 miles on a fall migration that has scientists once again amazed.

Probably wildlife biologists poo-poo the anthropomorphizing of a study subject of the genus Odocoileus hemionus known to researchers commonly as “Deer 255.” But forgive us. This doe is dope.

Decked out in an ear tag and a radio collar, Deer 255 stands out amongst mule deer of her ilk. The data the collar collects makes the 7-year-old something of a rock star as well.

Remember back when you first heard about this deer? It was spring 2018. Scientists began trumpeting the news about a deer that made a world record migration of some 242 miles. Previously, the longest anyone had documented a deer traveling between seasons was 150 miles.

Only in the Rocky Mountain West can these epic treks take place. Development everywhere in the U.S. has cutoff ancient migration routes and made long, uninterrupted journeys like that of Deer 255’s almost impossible. Almost.

Then along comes a fleek of nature like #255.Combined with a growing appreciation and understanding of these seasonal migrations that has recently resulted in NGO and political action alike, well, it’s just heartening to see a deer eat its way from Rock Springs to Island Park and back. Twice now.

That’s our girl, captured by chance on trail cam making her way back to the Red Desert last fall. Photo: Courtesy Wyoming Migration Initiative

Mommy Deerest

Deer 255 winters in Wyoming’s Red Desert near Superior. She’s in good company. At least a thousand other of her kind find the milder winters just north of Rock Springs better than the deep snows of Pinedale or Jackson. But unlike her hooved brethren, 255 follows spring green up further than any other muley.

While her herdmates have been evidenced to scatter to all points north for the summer—maybe the Upper Green River region or Lander—Deer 255 goes to the extreme. In 2018, the long-distance traveler was recorded making a 242-mile trip from near Superior, Wyoming to outside of Island Park, Idaho.

And, apparently, that was no fluke. Researchers just confirmed Deer 255 spent last summer near Moran, Wyoming just between Grand Teton National Park and Yellowstone National Park. Not as far as Island Park again, but still, that meant she had roughly a 200-mile journey to get home to her winter range in the Red Desert last fall. Which she did.

As to the question of why: Why does this particular deer travel so far when others don’t? Well, you’d have to ask her momma. Scientists at the University of Wyoming published landmark findings last fall that paint a clearer picture of why, when and where ungulates go during seasonal migrations.

They don’t go by instinct. It’s not hardwired into their DNA. That holds true for some species like birds and insects. Mule deer, on the other hand, have to be shown the way. They learn the ancient route of migration by watching another animal do it, usually a ‘bell cow’ of sorts, or one’s mother.

Deer 255 was herself a mother of twins on her journey last spring. Limited accessibility prevented biologists tracking her movements this past summer to see if she successfully reared the fawns. Undergraduate researcher Tanner Warder’s camera trap south of Pinedale appeared to show #255 without fawns as she returned to the Red Desert during the fall 2019 migration.

However, during December captures, researchers noticed she was lactating, which suggests that she might have had one or two fawns with her. So, it remains a mystery if Deer 255 has been able to successfully pass on her knowledge of this migration to her offspring.

Healthy, happy, and pregnant

By all accounts, Deer 255 wintered well. As we write, she is likely noticing the days getting longer and warmer, and feeling that age-old rhythm tugging her northward. When she notices new plants sprouting up, she’ll get a move on.

Doctoral student Anna Ortega reports it was a favorable winter for Deer 255. Mild enough to keep her in good health. She began winter at 11% body fat. In March, readings indicate she was down to just under 6%.

Not bad, say researchers. That should give her plenty of energy reserves to make another trek up north. And she’ll need her strength. She’s pregnant again. Twins again.

Deer 255’s fall 2019 migration stats
Started fall migration: October 4, 2019
Arrived on winter range: December 11, 2019
Migration duration: 68 days (2 months, 7 days)
Age: As of December 2019, she was 6.5 years old

The information in this article is possible only because of the hard work and open collaboration between the Wyoming Migration Initiative and University of Wyoming. Thanks also to Dr. Kevin Monteith from the Haub School of Environment and Natural Resources and biologists with Wyoming Game and Fish Department and Bureau of Land Management – Wyoming.

The cartographic team at the University of Oregon InfoGraphics Lab Department of Geography, University of Oregon made possible the visualization in 3D of Deer 255’s migration. It was produced by Gregory Nickerson, Joanna Merson, and Matt Kauffman.
Migration video by Joe Riis. Camera stills by Tanner Warder.