Autumn

Elk move down from the mountains to find food, and beavers repair dams before ice freezes their ponds. Yellowstone's forests - the aspens, cottonwoods and maples - start to shut down, their colours painting the park a blaze of red and gold. Meanwhile another tree is coming into its own, the whitebark pine. It offers up a bumper crop of pine nuts which fatten grizzly bears and squirrels alike. But its nuts are meant for another animal - the Clark's nutcracker - a small bird with a colossal memory, and one that will reward the tree's efforts well by carrying its seeds far and wide. As the snow and ice return, many animals move out from the heart of Yellowstone, away from the protection of the national park. Here, their fight is not only to survive the cold, but also to find what little wild space remains in the modern world.