Migration's "larger purpose" draws admiration from humans

Animal Migrations article by David Quammen, photographs Joel Sartore, citing research by Dr. Hugh Dingle.

Pronghorn funnel through a 150-ft space between a new housing development and a steel knoll on their way between winter grounds in Green River Basin, WY and summer grounds in Grand Teton NP. Rattlesnakes dodge farm and road vehicles migrating between high winter dens and low prey-filled plains of Alberta. Sandhill cranes miraculously travel from winter grounds in West Texas, around the east and northern sides of the Rockies, through Alaska, over the Bering Strait, into their summer grounds in East Russia!