Editor’s Note: This story accompanies the May 2016 issue of National Geographic magazine, devoted entirely to America’s first national park. Find more at natgeo ...

This story appears in the November 2010 issue of National Geographic magazine ... Rattlesnake migration on the Great Plains of western Canada is a peculiar but illuminating case.

Credit: Staying Wild Productions Inc. Debuting at 10pm Eastern Time on Saturday, March 29, on Nat Geo WILD, Wildlife Rehab is a six-part nature series centered on the Living Sky Wildlife ...