Uncovering the 'Secrets of the Penguins' in new National Geographic series)

On this Earth Day, what the Emperor Penguins now face. In the new National Geographic docu-series, Secrets of the Penguins, from ABC's parent company, Disney, Nat Geo explorer and cinematographer, Bertie Gregory, following colonies of penguins for months at a time. This wind's starting to crank up. In Antarctica, Emperor Penguins only lay one egg a year, and they keep it warm by passing it from mother to father. The egg's so fragile and the conditions so brutal, eggs cannot touch the ice for much more than a minute. The docu-series capturing behaviors for the first time ever on camera. Mother and father practicing passing the egg with small pieces of ice. And in this first-of-its-kind footage, the chicks making their way to a 50-foot cliff before diving in for food. I can't believe it. She's made it. One after another. Scientists say it's a sign of the penguins' resilience. Tonight, the penguins and those defining milestones now captured on camera on this Earth Day. The penguins and their determination.