- Associated Press - Sunday, April 20, 2014

CASPER, Wyo. (AP) - Each spring, a herd of mule deer leaves the Red Desert and follows a trail of greening grass and retreating snow along the western slope of the Wind River Range. Months later, the animals arrive in the Hoback Basin south of Jackson, more than 150 miles away.

It is the farthest recorded mule deer migration in the world, and an ancient rite vital to the long-term survival of Wyoming’s iconic mule deer populations.

And its future is uncertain.

The journey from desert to mountains takes the herd over fences and across roads, near subdivisions and through narrow passageways flanked by towns and lakes. There are no National Parks or wilderness areas to offer refuge. The deer contend with the elements and whatever obstacles people put in their way.

Scientist believe the migration has lasted this long because large swaths of land between the deer’s summer and winter ranges have remained undeveloped.

In many ways the migration, like bison roaming the plains, is a symbol of the old West. It is a possibility only states like Wyoming can still offer, and one that may not always remain.

“We’ve been blind to a large chunk of this migration to date, and been fortunate that that landscape has remained intact,” said Hall Sawyer, a researcher at Western Ecosystems Technology Inc. who discovered the migration. “But it’s important for us to understand where this route is so we can take a proactive approach in helping shape future land use practices.”

Researchers didn’t even know the migration existed until two years ago.

The Bureau of Land Management had contacted Sawyer to find out where a group of deer living in the Red Desert call their winter and summer ranges.

Sawyer, 43, has studied elk, pronghorn and deer migrations for two decades. He also uncovered the famous pronghorn herd that travels more than 100 miles from the Upper Green River Basin near Pinedale to Grand Teton National Park, which, until now, held the title of longest migrating mammal in the Lower 48.

In 2011, Sawyer caught and collared 40 deer east of Rock Springs for the BLM study and commissioned a pilot to track the herd. Yet following the deer proved more difficult than expected. On the first flight, the pilot found only a few.

Sawyer asked him to fly even farther north, near Pinedale, to see if they’d joined deer on the south end of the Wind Rivers. The pilot called an hour later and said he picked them up, 100 miles away from where they’d started.

“That was the beginning of it,” Sawyer said. “It took us a couple of flights to make sure this was really happening. Then I thought, ‘How will we have the flight budget to fly half of the state of Wyoming looking for deer?’”

He discovered that a group of about 500 mule deer starts north of Rock Springs, winding 50 miles through canyons and past sand dunes to join almost 5,000 more. The mass then snakes like a living train for another 100 miles. The original group ultimately climbs 3,000 to 4,000 feet in elevation.

Sawyer finished his project for BLM, at the same time working with Matt Kauffman, leader of the Wyoming Cooperative Fish and Wildlife Research Unit at University of Wyoming and director of a new effort called the Wyoming Migration Initiative.

Story Continues →