Marine flightless bird, family Spheniscidae, order Sphenisciformes, mostly black and white, found in the southern hemisphere. They comprise 18 species in six genera. Males are usually larger than the females. Penguins range in size from 40 cm/1.6 ft to 1.2 m/4 ft tall, and have thick feathers to protect them from the intense cold. They are awkward on land (except on snow slopes down which they propel themselves at a rapid pace), but their wings have evolved into flippers, making them excellent swimmers. Penguins congregate to breed in ‘rookeries’, and often spend many months incubating their eggs while their mates are out at sea feeding. They feed on a mixture of fish, squid, and krill.
The wing is long and has no covert or quill feathers, and always remains open. The feathers are tiny, with very broad shafts and little vane or web. The legs of the birds are placed far back, and in the water the feet are stretched out straight behind and held motionless, the wings working rapidly as if being used in flight. Moult in penguins is general and areas of feathers are lost at once. It is usually a rapid process unlike the ordered progressive moult of flying birds. Penguins generally moult once a year, and have to stay out of the water during this time, without feeding.
The nest is often no more than a slight hollow in the ground, but some penguins, especially the Adelie penguins Pygoscelis adeliae, collect stones, with which they bank the nest round. One or two eggs are laid, and both birds, but chiefly the male, attend to their incubation. Both parents are very devoted to the young, one always staying to guard them, the other bringing them sea crustaceans and other small animals, which the young take by pushing their beaks far down the parent's throat.
They are very social birds, living together, and usually breed in vast colonies, always returning to the same rookery (breeding group). The young gather in groups while the parents are foraging for food. When the parents return, the chicks often have to chase for food, with the stronger chick being fed first. They spend much time preening themselves and each other (allopreening).
It was estimated in 1997 that the penguin population fell 20% in 10 years. Zoologists blame over-fishing, particularly by large trawling fleets.
Species Most species are confined to the colder regions, and large rookeries have been found at very low latitudes. Largest is the emperor penguinAptenodytes forsteri 1.2 m/4 ft tall. Its plumage is dark slate on the back and white on the underparts, with yellow spots on the head. Its single annual egg is brooded by the male in the warmth of a flap of his body skin, so that it rests on his feet. Eggs are laid and hatched during the Antarctic winter on the mainland ice; an astonishing feat. Males and females walk over the ice to the breeding ground, often many miles from the sea. When the egg is laid, the female passes the egg to the male, and returns to the sea to feed. The males huddle together in the total winter darkness at −60°C/−76°F, taking turns to be on the outside of the huddle. During this time the male eats nothing. When the chick is born the male even gives it its first feeds (by regurgitating fat), despite having lost almost half his body weight, until the female returns. The male then has to walk back to the sea, up to 100 km/620 mi, before feeding. Less than 20% of chicks survive to one year.
The macaroni penguinEudyptes chrysolophus, will travel over 100 km/620 mi to feed. As with all six species of crested penguins of the eudyptid (crested) genus, the macaroni penguin lays two eggs but generally abandons the first, smaller one; it is often eaten by predatory birds such as sheathbills. It has a yellow/orange plume. The royal penguinEudyptes schlegeli, found only on Maquarie Island, is similar. Gentoo penguinsPygoscelis papua, are about 75 cm/29 in long. They have a characteristic white patch over the eye, and nest on grass on islands of the southern hemisphere. They lay two eggs, which hatch in five weeks. Gentoo penguins are inshore feeders; they breed as far south as the Antarctic peninsula.
King penguinsAptenodytes patagonicus are the most agile of penguins. They breed on sub-Antarctic islands; the breeding cycle is 14–16 months, and the king penguin needs access to the sea to feed the chick during this period, so it is restricted to islands where the sea never freezes. Their largest breeding ground is the Crozet Islands, with over 300,000 pairs. King penguins usually breed successfully twice in three years, so at any time of the year a colony has pairs at all stages of breeding.
Among the small species is the jackass penguinSpheniscus demersus, which lays two eggs in a scraped hollow in the ground. Jackass penguins have declined in numbers, at first because of egg-collecting by humans, but more recently owing to overfishing, which deprives them of food, and to oil spills near their breeding colonies. It is the only penguin found in Africa, and lives on the west coast of South Africa.
The little penguin or blue penguinEudyptula minor is the smallest of all penguins, at 45 cm/18 in long and a weight of 1 kg/2.2 lb. Unlike all other penguins, it has no colours or plume on its head. It is found on offshore islands of Australia (notably on Phillip Island in Victoria, where its nocturnal habits are a popular tourist attraction), and on the mainland of New Zealand.
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