The emperor penguin's predators include birds and aquatic mammals. Southern giant petrels (Macronectes giganteus) are the predominant land predator of chicks, responsible for up to 34% of chick deaths in some colonies though they often scavenge dead penguins as well. The south polar skua (Stercorarius maccormicki) mainly scavenges for dead chicks, as the live chicks are too large to be attacked by the time of its annual arrival in the colony.[60] Occasionally, a parent may defend their chick from attack, although it may be more passive if the chick is sickly.[61]
The only known predators thought to attack healthy adults, and who attack emperor penguins in the water, are both mammals. The first is the leopard seal (Hydrurga leptonyx), which takes some adult birds, as well as fledglings soon after they enter the water.[28] Orcas (Orcinus orca), mostly take adult birds, although they will attack penguins of any age in or near water.[61] If one of a breeding pair dies or is killed during the breeding season, the surviving parent must abandon its egg or young and go back to the sea to feed.