Penguins breed in colonies and can be fiercely territorial. They breed closely together mostly because there is very little ice-free space. But they are also highly social animals that recognize individuals and return as adults to the rookery where they were born. The colony helps these birds guard, protect, and defend their young. Within these colonies, penguins build rookeries with pebbles and guano.
Penguins fall prey to leopard seals, sea lions, and killer whales.
Skua gulls are the greatest natural threat to chicks and eggs. Krill is a very large part of the diet. Most penguins submerge for about 1 minute, but Emperors can dive as deep as 180 feet for up to 18 minutes. The Macaroni and Rockhopper penguins are in the same genus, Eudyptes. Both have yellow crests decorating and distinguishing their heads.