The mass arrival is believed to be caused by a drastic change in Antarctic food supply. | Guide to Iceland

Watch as these Galápagos penguins herd fish into a baitball, a hunting technique usually only seen in mammals like dolphins. Galápagos penguins are considered the rarest penguin species in the world, with just 2,000 individuals in the wild. Penguins may seem far from home in the tropics, however National Geographic Explorer Bertie Gregory spent time with these rare penguins to discover how they live and thrive in their warm, watery home. Watch Secrets of the Penguins this Earth Day. Tuesday Apri