Penguins

Penguins are flightless marine birds that dwell only in the southern hemisphere. They do not inhabit the Arctic, where polar bears live. There are seventeen generally recognized species of penguins. Six species, the Adelie, gentoo, chinstrap, rockhopper, king, and emperor penguins, live in the cold environments of the Antarctic region. The rest live in subantarctic and temperate regions. The macaroni, fiordland, Snares, erectcrested, yellow-eyed, fairy, and royal penguins live off the coasts of New Zealand and Australia and nearby islands. The Magellanic and Humboldt penguins live off the coast of South America. The African penguin lives off the southern coast of Africa, and the GalГЎpagos penguin is native to the GalГЎpagos Islands. Penguins spend much of their lives in the ocean, coming to shore mainly to breed.

Physical Characteristics
All penguins are black with white undersides, and are commonly described as wearing tuxedos. This color pattern acts as camouflage when the penguin is swimming, protecting it from predators. From underneath, the white belly blends with the bright water surface, and fromabove, the black back is indistinguishable from the dark water. Penguin species can be grouped according to common characteristics. Banded penguins have black and white stripe patterns on their chests and heads. The crested penguins all have bright yellow or orange plumes on their heads. Brushtail penguins have long stiff tail feathers. The king and emperor penguins have bright yellow and orange chest and head patches, and the yellow-eyed penguin has a yellow crown. The fairy penguin's feathers are bluish. The emperor penguin is the largest, at nearly four feet tall and seventy-five pounds. The small fairy penguin is sixteen inches tall and about three pounds. All have solid, heavy bones that help them dive deeply into the water. They have streamlined bodies that move smoothly through the water as they pump their strong, flipperlike wings and steer using their webbed feet and tails as rudders. Penguins can hold their breath for many minutes at a time, and they frequently leap out of the water, porpoiselike, to take inmore air. On land, penguins walk with an awkward sideways waddle. Because their short legs are set back on their bodies, they stand erect and must hold out their flippers for balance. Penguins often toboggan themselves by flopping on their bellies and pushing with their flippers and feet. Penguin feathers are tiny and stiff, overlapping to form a waterproof coat. An underneath layer of down helps to trap warm air and protect the penguin from the cold water and wind. Penguins of the Antarctic region have an insulating layer of blubber. Those in temperate climates often have to cool themselves down by ruffling their feathers and holding out their flippers. They can control the flow of blood to their unfeathered areas, such as the feet and under their flippers, which helps regulate their body temperature. Penguins preen their feathers regularly, to spread waterproofing oil from a gland near the tail.

Feeding Behavior and Enemies
Penguins are carnivores. They eat many types of small sea creatures, such as fish, squid, and krill. After locating a school they snatch quickly with their sharp beaks. The tongue and upper palate are covered with stiff spines that grip the slippery food and assist in moving it toward the throat. Penguins make several catches per dive, swallowing the prey whole along with some seawater. Their specialized salt glands above each eye help them drain the extra salt they ingest. Penguins usually enter and exit the water in large groups, to protect themselves from predators who often lurk near the shore. Their main enemies are sea lions, leopard seals, and killer whales. On land, adult penguins are safe. Petrels, skuas, gulls, and sheathbills hunt babies and eggs.

Reproduction
Most penguins follow an annual breeding cycle that begins in the spring, but timing varies according to species and climatic conditions. The GalГЎpagos penguin will breed any month that the water temperature is right, and sometimes twice a year. Emperors begin their cycle in autumn, so there is a good food supply when their chicks hatch in spring. King penguins only reproduce twice every three years, because they follow a fifteen-month cycle. Some penguins nest on the shore and others travel many miles inland to reach their rookeries, and they return to the same ones each year. Penguins are social, and one rookery may have thousands of penguins in closely spaced nests. They often squabble over nesting materials, mates, and territory. Nests are built of grass or stones on the ground, in rock crevices, or in burrows. The male engages in an ecstatic display to attract a female, pointing his beak, flapping his flippers, and squawking. Penguins usually mate for life, and in subsequent years the pair will greet each other affectionately. Two eggs are laid, and the parents take turns incubating for a few weeks at a time while the other leaves to feed. The incubating parent does not eat, and often loses a great deal of weight. Each penguin has a brood patch, an area of bare skin on its lower belly, that allows for better heat transfer to the eggs. Incubation varies fromfive weeks for the small fairy penguin to nine weeks for the emperor. The king and emperor penguins are exceptions to the nesting rule. They lay only one egg, which they cradle on their feet instead of building a nest. They cover it with a flap of skin to keep it warm. Kings take turns incubating, while with emperors, only the male incubates. Chicks are born down-covered, except for emperor chicks, which are naked. The parents brood them while they are young and feed them regurgitated food. When the chicks get too large for brooding, they huddle in crГЁches while the parents leave to hunt for food. When the chicks are grown and go off on their own, the parents molt. They cannot go into the water without their full coats of feathers, so they fast during this two- to four-week period.