Being Caribou: Five Months on Foot with an Arctic Herd

For eons, female members of the Porcupine caribou herd have made the 2,800-mile journey from their winter feeding grounds to their summer calving grounds. They once roamed borderless wilderness; now they trek from Canada, where they're protected, to the United States, where they are not. What's more, beneath the calving grounds lay vast reserves of oil. Determined to convey both the enormity of the caribous’ migration and the delicacy of their habitat, Karsten Heuer and his wife spent their h…