Being Caribou (2005)

Wildlife biologist Karsten Heuer and his wife, environmentalist Leanne Allison follow a herd of 120,000 caribou on foot across 1500 km of Arctic tundra, hoping to raise awareness of the threats to the caribou's survival. Along this journey, they brave torrid conditions, dangerous wildlife and treacherous terrain all in the hopes of learning the truth about this epic migration.