In the winter of 2011, a team led by biologist Hall Sawyer put tracking collars on 40 mule deer near the Leucite Hills in Wyoming’s Red Desert. Given Sawyer’s previous knowledge, he didn’t expect these deer to migrate far from the Red Desert in the course of the year. But instead of tracking a sedentary herd, Sawyer uncovered an extraordinary animal journey that has ranged across wide open spaces of Wyoming since time immemorial.