Emperor Penguins Huddle for Warmth | Nature on PBS

To breed in the coldest place on Earth, Emperor penguins must also become part of a crowd. Their chicks are born in the depths of the Antarctic winter. Their only protection from the cold is their parents' brood pouch, but as winter storms set in, this isn't enough. As temperatures reach 40 below, even the adults' only chance of survival is to huddle together. They start to waddle with a single purpose. All converge on the same central point until a huddle begins to form. Each penguin must find a place to tuck in. But by speeding up the action, it's clear that something more organized is going on. Soon, the huddle numbers thousands, and still more keep coming. While those on the outside take the brunt of the storm, those on the inside take tiny steps that move the huddle in waves. The densely packed penguins continue to shift and rotate from the center. By keeping constantly on the move, no penguin is left permanently out in the cold.