“When wildlife biologist Hall Sawyer strapped radio collars to dozens of mule deer wandering southwestern Wyoming’s Red Desert in January 2011, he thought the humble animals were as rooted as the landscape’s windblown sage, low hills and staked fence posts.
Then the deer vanished out of radio range.
He chartered a plane to search all of western Wyoming. When the pilot found them, Sawyer was amazed. In just a few months, hundreds of Red Desert deer had walked more than 150 miles north into the craggy mountains south of Yellowstone National Park. Their trek, a 300-mile round trip, marks the longest known migration of any mammal in the contiguous United States.” – From Revealed: Biologists discover longest mammal migration in Lower 48 by Nate Schweber