The Adelie penguin (scientific name: Pygoscelis adeliae) is one of the species of penguins that are native to Antarctica. It is the bird that breeds the farthest south and therefore in the coldest temperatures. Ross Islands has the main colony of this species of penguins with about 500,000 birds. In all there are about 38 colonies totalling about 5 million of them in the Ross Sea. Because of the cold temperatures of this region, the Adelie penguins have several unique adaptive features that enable them to conserve the body heat enabling them to survive in this environment.
Adelie penguins are mid-sized and are easily identified by the white ring around the eye. The back is covered with feathers that are slightly elongated so that they form a type of crest down its length. The bill is red, but most of it is hidden by the feathers. Their tail is slightly longer than the tail of other species. They usually measure from 18 to 30 inches in length and can weigh between 8 and 12 pounds. The young of this species can be distinguished from the adults by the color of their chin, which is white rather than black, and they do not yet have the white ring around the eyes.
Colonies of Adelie penguins can number from about twenty to several thousand. However, within the larger colonies, sub-colonies do exist. The nests are mainly depressions in the ground and the penguins line them with small stones. This practice is designed to protect the eggs from the melting snow. In this region of the world that is covered with ice and snow, stones for nests are precious and few, which often leads to fights breaking out among the penguins when they are building their nests.
The Adelie penguin feeds mainly on Antarctic krill, which are invertebrates very similar to shrimp. They also eat Antarctic silverfish and Glacial Squid, which can grow as long as a foot in length. There is a surplus of krill in the waters because there is a lack of predators that can compete with the penguin for this source of food.
October to February is the breeding period of the Adelie penguin. This is when they start building their nests and both parents take turns incubating the eggs, especially during December, which is the warmest month of the year in this part of the world. The parent who is doing the incubating does not eat during this time. In March, the parents and the young return to the sea. These penguins are only on land while they are breeding.