Whooping Crane and Sandhill Cranes, Platte River Valley, Nebraska. A rare site, a lone whooping crane stands tall in a sea of sandhill cranes taking flight from the river roost at first light on a misty gray morning along the Platte. The sandhill crane with a population of roughly 600,000, is the most populous of the world's 15 crane species, the whooping crane is the rarest and at 200 or so individuals, is critically endangered.