Young animals face new challenges as winter envelopes the Rocky Mountains, and spring means the end of childhood. A grizzly mom prepares her cubs for hibernation, a mountain lion raises her kittens and a bison calf must learn to survive the snow.

On NATURE, Born in the Rockies, journey deep into the wild heart of the Rocky Mountains and experience this rugged land through the eyes of its iconic wildlife. Watch as newborns make their way in one of the world’s most challenging and spectacular habitats.

Meet Rodrigo Medellin, an ecologist who braves hurricanes, snakes, tombs and seas of cockroaches to track the lesser long-nosed bat’s epic migration across Mexico in order to save the species.

Alaska’s Arctic National Wildlife Refuge has long protected survivors of the Ice Age, but this once remote and frozen fortress is on the brink of change. For the musk oxen, caribou, polar bears and Arctic foxes, their ice age is slipping away.

NATURE visits Big Bend: The Wild Frontier of Texas. Meet the wildlife that exists in the arid and rugged environment along the Rio Grande’s Big Bend in the southwest of the state – including the Texas horned lizard, rattlesnakes, scorpions, black bears and bighorn sheep.

Travel to the mountains of Chile to discover the secrets of the puma, the area’s biggest and most elusive predator. Discover how this mountain lion survives and follow the dramatic fate of a puma mother and her cubs.

Despite the odds, there are countless stories of the most unlikely cross-species relationships imaginable: a goat guiding a blind horse; a doe who regularly visits her Great Dane surrogate mother; a juvenile gibbon choosing to live with a family of capuchins, and so on. Instincts gone awry? The subject has mystified scientists for years. Now, NATURE investigates why animals form these special bonds. Informed by the observations of caregivers and noted scientists Temple Grandin and Marc Bekoff, the film explores what these relationships suggest about the nature of animal emotions.