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When deer number 255 walked almost 250 miles from southern Wyoming to Idaho, researchers wondered if it was a fluke. But then she came back.

It was impressive, they said, but what it meant was unclear.

Maybe she’d gotten confused, they thought.

Maybe she just changed her route once. Surely she didn’t go on that epic journey each year, they cautioned.

Then she did it again.

The story of mule deer 255 is almost unbelievable in today’s world of sprawling development, and it’s made possible by large, relatively intact landscapes like wilderness areas and national parks. It also begs the question that if deer have been making this migration undetected – in an area where they’ve been studied for years – how many other journeys are yet to be documented?

“It’s amazing that these mule deer migrations are still out there for us to discover in 2018,” said Matt Kauffman, leader of the Wyoming Migration Initiative and the USGS Cooperative Fish and Wildlife Unit at the University of Wyoming. “That part is exciting that there are still these discoveries to be made, and that mule deer have ways to exploit these habitats that we are struggling to document and understand.”


Deer number 255 – so named because of her GPS collar – was one of over a hundred captured and collared in the Red Desert as part of migration work by the Cooperative Fish and Wildlife Unit.

Wildlife biologist Hall Sawyer discovered the now-famous Red Desert to Hoback migration route almost a decade ago, and countless research projects followed. The route was the longest in the country for mule deer. Researchers wanted to know more.

That’s why 255 ended up with her collar. But instead of stopping to feast on the lush, green grasses of the Hoback for the summer like everyone else in her herd, she continued on. She went north over the Gros Ventre Range, around Jackson Lake, over the foothills of the Tetons and eventually into Island Park, Idaho.

Then her collar stopped working. Kauffman figured it had all been a mistake. She likely joined another herd and became an Idaho deer. It wasn’t until March, when a deer researcher caught her again in the Red Desert, that they realized what may have been happening.

This year she went back again, following the same path. And she was pregnant with twins.

“It brings to light the bigger picture of looking at all of the aspects of what that movement encompasses and how we can specifically target conservation efforts, whether habitat treatment or conservation efforts,” said Joshua Coursey, president and CEO of the Muley Fanatic Foundation.

“(Migration) is a sexy conversation right now … This only reinforces those are the right processes we should be trying to pursue.”


Part of the Migration Initiative’s work with the Red Desert-to-Hoback route was to identify perils to deer travel.

While some mule deer don’t travel far at all each year – perhaps only 10 to 20 miles – many go farther. They’re following what is called the “green wave,” a seasonal change in grass and other vegetation that deer chase each spring. The migrations, and the creatures’ ability to use a variety of places and food sources, is what allows Wyoming to still host some of the largest mule deer herds in the West.

But their routes are not without potential barriers. The Migration Initiative initially identified issues such as highway crossings, bottlenecks and fencing, then offered that information to state and federal agencies, landowners and nonprofits, which have worked to fix some of them.

What additional barriers deer 255 and others on her route may face, Kauffman doesn’t yet know. Much of the rest of her journey wanders through wilderness areas and Grand Teton and Yellowstone national parks – places that are already protected. The biggest issue is likely two road crossings at the John D. Rockefeller Memorial Parkway and at Moran Junction.

But maybe she has figured those out for now.

This summer, deer 255 hopped across the highway between 7 p.m. and 2 a.m.

“Hundreds of thousands of people from across the U.S. drive through the road every day to see the natural wonders of Yellowstone and Grand Teton, and none of them know there’s this migration corridor and there’s this animal and maybe more that cross this road and use this 240-mile corridor to get from summer to winter range,” Kauffman said.


While Kauffman might not know exactly how many deer make doe 255’s journey, he has no doubt there are others.

“One way to think about it, for this corridor to have persisted and be passed on from generation to generation, it very likely couldn’t have persisted by just one animal,” he said. “... I suspect there might be hundreds.”

He also wonders if other deer join her for portions of her journey. If, for example, only a few begin in the Red Desert, but meet up with a larger group near Farson or Pinedale and finish the migration.

He and other researchers want to understand how those herds piece together. They have cameras at a pinch point on one of the large ranches along the foothills of the Wind River Range that might help show them how many deer move with her.

“They are doing this elaborate highly choreographed dance on the landscape, and we can only see a tiny little part of it when they move through someplace where we happen to be observing them but we can’t imagine the entire migration until we get a collar on one of them,” Kauffman said. “To me it’s more the secret lives of the migratory animals in the West that we are still trying to understand.”

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