Description The Emperor Penguin (Aptenodytes forsteri) is the tallest and heaviest of all living penguin species and is endemic to Antarctica. The male and female are similar in plumage and size, reaching 122 cm (48 in) in height and weighing anywhere from 22 to 45 kg (49 to 99 lb). The dorsal side and head are black and sharply delineated from the white belly, pale-yellow breast and bright-yellow ear patches. Like all penguins it is flightless, with a streamlined body, and wings stiffened and flattened into flippers for a marine habitat. It has several adaptations to facilitate diving at depth, including an unusually structured hemoglobin to allow it to function at low oxygen levels, solid bones to reduce barotrauma, and the ability to reduce its metabolism and shut down non-essential organ functions. Habitat The Emperor Penguin has a circumpolar distribution in the Antarctic almost exclusively between the 66° and 77° south latitudes. It almost always breeds on stable pack ice near the coast and up to 18 km (11 mi) offshore. Breeding colonies are usually located in areas where ice cliffs and icebergs shelter them from the wind. The total population is estimated at around 400,000–450,000 individuals, which are distributed among as many as 40 independent colonies. Around 80,000 pairs breed in the Ross Sea sector. Major breeding colonies are located at Cape Washington (20,000–25,000 pairs), Coulman Island in Victoria Land (around 22,000 pairs), Halley Bay, Coats Land (14,300–31,400 pairs), and Atka Bay in Queen Maud Land (16,000 pairs). Two land colonies have been reported: one on a shingle spit at Dion Island on the Antarctic Peninsula, and one on a headland at Taylor Glacier in the Australian Antarctic Territory. Vagrants have been recorded on Heard Island, South Georgia, and in New Zealand. Breeding The Emperor Penguin is perhaps best known for the sequence of journeys adults make each year in order to mate and to feed their offspring. The only penguin species that breeds during the Antarctic winter, it treks 50–120 km (31–75 mi) over the ice to breeding colonies which may include thousands of individuals. The female lays a single egg, which is incubated by the male while the female returns to the sea to feed; parents subsequently take turns foraging at sea and caring for their chick in the colony. The lifespan is typically 20 years in the wild, although observations suggest that some individuals may live to 50 years of age. Diet Its diet consists primarily of fish, but can also include crustaceans, such as krill, and cephalopods, such as squid. In hunting, the species can remain submerged up to 18 minutes, diving to a depth of 535 m (1,755 ft). Threats The Emperor Penguin's predators include birds and aquatic mammals. The Southern Giant Petrel (Macronectes giganteus) is 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. The known aquatic predators are both mammals: the Leopard Seal (Hydrurga leptonyx), which takes some adult birds, as well as fledglings soon after they enter the water, and the Orca (Orcinus orca), which takes adult birds. 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.