Watch Natural World Season 23 Episode 13 Online

Across the top of North America, millions of caribou are led on their never-ending journey by the mothers of the herd. Driven by the demands of motherhood, they travel 3000 miles on a trek from their winter range at the edge of the northern forests to calving grounds and back again. The senior female members are the leaders of the matriarchic society that are the caribou. As winter sets in in the Northern tundra, the female caribou with their antlers, eight weeks pregnant, guide the herd to begin the annual pilgrimage. The males, without antlers at this time of year, follow the lead of the females. Throughout this journey, their constant companions the wolf packs trail them ceaselessly. The caribou keep themselves to open ground for visibility of their predators. The wolves are not far behind. The largest females sometimes surround the wolves by running around them in circles. They prance and trot around the wolves, their gait like an ancient dance, as if to show off their strength and speed.