Each fall a quarter-million caribou come together to form the Western Arctic Caribou Herd, a group that makes an epic migration through northwest Alaska. The caribou move south from their calving grounds in the Utukok River Uplands to their winter range on the Seward Peninsula. Fall is also the time when scientists attach radio collars to members of the herd, to track their location and health, and to gain information that will help conserve the species. When spring arrives, the caribou will complete the trip again in reverse, covering a total of 2,000 miles each year, give or take.