Despite the odds, there are countless stories of the most unlikely cross-species relationships imaginable.
Sea otters cannot even swim on their own when they are born. In the wild, a mother otter takes her pup everywhere to protect and educate her baby.
There are some 120 species of duck, representing a wide variety of shapes, sizes and behaviors.
An orphan otter pup learns a few lessons at The Monterey Bay Aquarium from a surrogate mother otter.
A baby sea otter abandoned on the beach was brought in to the Monterey Bay Aquarium. This is the aquarium's 501st attempt to save an orphan otter. Against all odds, will she be able to return to her home in the wild?
Even if 501 aces all of her otter lessons, there are a plenty of challenges she may face in the wild including shark attacks.
Cranes and geese rise over Venice, Dover, Edinburgh and the monkey-guarded Rock of Gibraltar. In Rome, the Loire Valley, Holland and Hungary, birds gather by the millions to breed and two by two to raise their families.
Wildlife cinematographer Neil Rettig and Laura Johnson trained the snow geese who star in the North American hour of Earthflight. In this video, Rettig and Johnson search for their geese which they lost track of somewhere in Brooklyn, New York.