What are penguins?
Penguins are birds that cannot fly, but they swim very well and spend most of their lives in the sea. Some species, or kinds, of penguin, spend as much as 75% of their lives in the water. Penguins look as though they are flying when they swim underwater or leap across the top of the waves. However, they lay their eggs and raise their chicks on land.
There are different species of penguin, but they all live in the Southern Hemisphere. This is because they cannot reach the cold Arctic waters without crossing huge distances of ocean that is too warm for them. The largest penguins are emperor penguins, the smallest are little penguins (formerly called fairy penguins) found only in Australia and New Zealand.
Not all penguin species live in ice and snow. Penguin habitats range from frozen Antarctica to warmer waters close to the equator as far north as the Galapagos Islands. They are quite defenceless birds, so they usually live in remote places.
There are 17 species, or kinds, of penguin.
Four species, the Adelie, the emperor, the chinstrap and the gentoo, breed in Antarctica. Several other species are found in the Antarctic: about 24 million penguins visit the continent. The penguin colonies on Antarctica are huge; for example, there are millions of pairs of chinstrap penguins, the most numerous creatures in the area.
Body and Behaviours
All penguins have a big head and a short, thick neck. Their bodies are a streamlined shape with a short, wedge-shaped tail. They have heavy bones which allow them to stay underwater. Their wings have developed into flippers. They dive deep into the water and 'fly' underwater at great speed. They have webbed feet which help their swimming.
Penguins have a lighter color on the belly and a darker color on their back, which helps camouflage them when they are in the water. When swimming, the dark colour is on top, making them hard to see from above. When predators underwater look up at the penguins, the white part is hard so see against the light.
Their bodies have a thick layer of fat to help keep them warm, a layer of downy feathers next to their skin traps air and keeps them warm, and waterproof outer feathers to keep their skin dry. Penguins have more feathers than most other birds - about 70 feathers every 5 square cm. They produce oil from a gland near the tail, and they use this to coat their feathers to keep them waterproof. They have a gland above their eyes that filters salt in their bodies from the seawater they swallow with their food. Penguins do drink fresh water in pools and streams, or eat snow.
Like most birds, penguins have very little sense of smell and a limited sense of taste. Scientists think penguins may be shortsighted on land but that their eyesight is better when they are underwater. Penguins are very social birds. Rookeries (nesting areas) may contain thousands of individual birds. Even at sea, they tend to swim, feed and come ashore in groups.
All birds moult through the year as some feathers are shed and new ones grow. Penguins moult only once a year, and lose them all at once. It takes about three weeks for the new feathers to grow, and they can't go into the water without them, so they can't get food for those weeks. They eat a lot of food before they moult to fatten up so they last without eating.
Some penguins are in a group called crested penguins, and have a feathery crest on their heads. Included in that group are the royal, macaroni and the rockhopper penguins.
Penguins feed in the ocean. They eat fish, crustaceans (such as krill and shrimp), and squid.
Being birds, female penguins lay eggs after mating. Most species of penguins build nests, but the nests may consist only of a pile of rocks or scrapings or hollows in the dirt. Emperor penguins do not build nests; males hold the egg on top of their feet under a fold of skin called a brood patch. The newly hatched chicks keep warm there. Penguin chicks have big appetites and grow quickly, many soon becoming almost as big as their parents. The chicks have a short time before they are independent of adults.
The smallest penguin species
Little penguins are also known as little blue penguin, or its old name, fairy penguin. They are about 33cm tall and weigh about one kg. They are found only in southern Australia along the coastline from Perth to Sydney, and around Tasmania, and in New Zealand. They live where water temperatures are 13 - 20ºC.
Little penguins can swim up to about 100 km in one day and hold their breath for two minutes. They spend long periods of time at sea, but during the breeding season they return every evening to feed their young. In the safety of evening, they come ashore and return to their burrows.
Little penguins do not necessarily pair for life. Female little penguins have a thinner beak than the males. The males have a small hook at the end of their beak. After mating with a male, a female lays two eggs in a short burrow that both partners have dug, usually in soft sandy soil, but sometimes a cave is used. Both partners, but mostly the male, make the nest using grasses from nearby. Both male and female take turns to incubate the eggs, which take about 35 days to hatch. Even though there may be up to 60 hours difference in the time they were laid, both eggs hatch at the same time. Chicks are covered with grey down feathers, which are replaced soon after by dark brown down. Feathers start to grow at four weeks. Both parents look after the chicks. For a few days, one goes to sea while one guards the nest, but after two weeks, both parents go to sea, returning in the evenings to their hungry chicks who are noisily demanding food. Chicks leave the nest and go to sea at about 8 weeks of age.
On land a group of penguins is called a waddle of penguins.
At sea, a group of penguins is called a raft of penguins.
When chicks are older and always hungry, both parents have to feed them. Chicks are left huddled together in a group while parents get food for them. A group of penguin chicks is called a creche.
A group of nesting penguins is called a rookery or a colony.
A group of rookeries is also called a colony. The terms 'rookery' and 'colony' are sometimes interchanged.
Conservation status and Threats
The erect-crested, the yellow-eyed, and the Galapagos penguins are classified as Endangered.
The gentoo, Magellan and Emperor penguins are classified as Near Threatened.
Threat: Global warming has led to a decrease in the Antarctic pack ice, which has an impact on their habitat and where penguins have their nesting colonies.
Threat: Less ice also means less habitat for penguins and the loss of critical food, such as shrimp-like krill, which depend on polar ice to reproduce.
Threat: In the oceans, penguins hunted by sharks, orcas, leopard seals, sea lions and fur seals.
Royal, rockhopper, macaroni , African, Humboldt and Fjordland crested penguins are classifed as Vulnerable, with declining populations.
The Snares Island penguins are also classified as Vulnerable, but with stable populations.
The Royal, Little, King, Adelie, and Chinstrap penguins are classified as being of Least Concern.
Threat: On land, threats to little penguins are breeding areas affected by erosion or grazing by farm animals, and by feral animals such as rabbits, who change the habitat so much that it becomes unsuitable for little penguins.
Threat: Dogs and cats kill many penguins.
Threat: Habitat is also damaged by oil spills, the use of pesticides, and by construction in areas where penguins nest.
Threat: Discarded plastic in oceans and on land is a danger to penguins.