Nature - Season 44

The walrus is one of the Arctic's most enigmatic animals. With three-foot-long tusks and a droopy mustache, everyone knows what these marine mammals look like, but few ever see them in the wild. For Kirk Johnson, a paleontologist and Sant Director of the Smithsonian National Museum of Natural History, the walrus has been a creature close to his heart for 40 years. Most of the world's walrus, about 250,000 of them, live in the frigid seas between Russia and Alaska. Johnson embarks on an Arctic adventure to uncover the hidden lives of these lumbering giants and the threats they face as climate change shrinks the sea ice. He follows the fate of one young orphan, who is rescued and rehabilitated at the Alaska Sealife Center. What kind of future lies ahead for her and for the walruses in the wild?

A unique, non-invasive, mountain lion study uses a giant network of trail cameras scattered throughout Montana's Sapphire Mountains over a decade to piece together the lives of a female mountain lion called Willow and her kittens. This film weaves clips of mountain lions and their complex interactions with each other and the rest of the forest world into a story about life and death that contains never-before-captured events and behaviors at every turn.

"The Pigeon Hustle" follows in the footsteps of London and New York's pigeon flocks to uncover their secret world. Witness the challenges of city life and how the humble pigeon has overcome them! With a world population hundreds of millions strong, feral pigeons are our most familiar neighbors. They have been an ever-present companion to people for millennia, yet despite such familiarity, there's still so much we don't know about the remarkable, resilient pigeon!

On a remote stretch of Costa Rica's Pacific coast, the lush, volcanic landscape gives way to a startlingly different world: a dry tropical forest – one of the last of its kind on the planet – where a newly resurgent population of jaguars has reclaimed their kingdom. In the waters at its edge, legions of olive ridley sea turtles emerge from the ocean for one of nature's most spectacular events, a mass nesting ritual called the arribada. Here, two unlikely creatures – the sea turtle and the jaguar – meet with spectacular consequences for both their species and the very different environments they inhabit.