The Adelie Penguin is an average-sized penguin, about 28 in in total length, with white plumage on throat and abdomen and black on the head and the back down to the tail, without any special distinguishing marks. The only feature differentiating it from other members of the genus Pygoscelis is a ring of white feathers around the eye which stand out in contrast to the black of the cheeks. They live in large numbers along the southeastern shores of the Antarctic and on some of the surrounding islands. Colonies of Adelie penguins tend to be confined to rocky zones.
The penguins start arriving and assembling in these ares at the beginning of the southern spring, at the end of October. Pairs of penguins return punctually every year to the same spot in the colony. In many cases the colony seems to consist of a single huge assembly of breeding pairs, sometimes formed into individual small groups situated at various distances from one another. In the sea, they dusplay a degree of speed and agility surpassing that of many fishes. Penguins literally "fly" in the water with powerful strokes of their wings. They can swim 15 miles an hour over long distances and can go twice as fast for short periods when pursuing prey or escaping from enemies. To breathe, penguins break the surface periodically.
Huge flocks of Adelie penguins may gather near the edge of the Antarctic pack ice. As many as 100,000 gragarious Adelies may cluster in one rookery, perhaps finding safety in numbers from skuas and other birds that prey on eggs and chicks.
Breeding & Raising Young
It is usually the male who comes back to take possession of his territory and begins building the nest even before his mate emerges from the sea. The territorial instinct is very pronounced and fierce fights often break out among the males, even if one of them is merely trying to make his way through the maze of occupied sites. Adelie Penguin
The first egg is laid a few days after mating, and as a rule a second egg appears, 3-4 days later. By the time egg laying is completed more than three weeks will have elapsed since the birds returned to the colony. At this point, the females, weakened by their breeding activities leave the nests en mass and head for the sea, there to feed on krill. When the female returns to the colony after ten days or so in the sea, it is the turn of the males to quit the nests and go off to find food, having fasted for more than a month.
The eggs are incubated on a crude nest of stones (the only available nesting material) for 34-36 days. When they are almost ready to hatch they are tended by both parents. During the first stage of the chock's development, both adults take turn to plunge into the sea, remaining there for some 24 hours at a time. When they get back to the nest, they feed the young who have no difficulty in swallowing a quantity of food equivalent to their own weight.
As soon as they have acquired their complete plumage, the young Adelie penguins set off together toward the sea. The adults remain for another couple of weeks in the sea, feeding and putting on large amounts of fat that helps them to survive during the weeks or months when they are forced to remain on land to complete their molt.