Only two species, the Adelie and the Emperor, breed in Antarctica. Most of the others live on rocky islands in the Antarctic Ocean. They have no predators on land and are, therefore, friendly towards humans. In the Antarctic waters however, the Leopard Seal and the Killer Whale prey on the small breeds of penguins and the young, naive penguins out for their first swims. Penguins communicate by complex ritual behaviors such as head and flipper waving, calling, bowing, gesturing and preening.
Territorial disputes lead to aggressive postures such as stares, pointing and even charging.
This can result in a mass trumpeting by other males, which is believed to help synchronize the breeding cycle. They travel large distances in winter, but always remain within the pack ice region. Breeding adults travel between 5 and 120 km offshore to catch food for their chicks. Feeding trips range from 5 to 72 hours in duration. Adelie penguins are capable of diving to depths of up to 175 m but usually feed within the upper 70 m of the water column.