S1, E1: No place on Earth is like Yellowstone in winter. This world of fire and ice has thousands of boiling hot springs, geysers, and bubbling mud pots. In Yellowstone every animal struggles to find food and stay alive against an onslaught of heavy snows, polar temperatures, and ferocious predators. Beavers and grizzly bears retreat under cover from the endless blizzard, while the wolves, red fox, and river otters face winter head on.