Land predators of the various penguin species include lizards, skuas, snakes, other birds and ferrets. Water predators consist largely of killer whales, leopard seals and sharks. While penguins are now protected, humans have been known to hunt them illegally for their oil and eggs.
The flightless birds are safer on land, with young penguins, penguin eggs and the parents protecting them the most likely to be attacked by terrestrial predators. Though they present little defense, they act aggressively towards land enemies. Since penguins swimming alone in open water are the ones most often attacked in the sea, they tend to hunt in groups.