As we follow the grip of winter over the course of six freezing months, we chart the fortunes of Yellowstone's wildlife in a finely balanced fight to survive.
S1, E2
Summer
As the spring melts the winter snow, the herds of elk, pronghorn and bison return from their winter feeding grounds to take advantage of America's richest natural grasslands.
S1, E3
Autumn
Winter is around the corner and there are just two months for all Yellowstone's animals to get ready or get out.