Claire Bear's Thoughts

The first eggs are laid in early November; if the incubating egg is left unattended for more than an hour or two, it will cool and become infertile. When nests are abandoned the eggs are easy prey for skuas, which are the Adelie penguin's main enemy on land. Males and females take turns incubating the eggs. Within hours of laying the eggs, the female returns to the sea, leaving the male to stand alone for up to ten days while his partner feeds. Most pairs produce two eggs separated by an interval of two to three days, and incubation takes about thirty days. While the two chicks hatch almost simultaneously, inevitably one chick is stronger and consequently better able to win food from its parents.

The chicks are fed from the crop of whichever parent is present at the time. The chicks are brooded closely by their parents for the first two to three weeks and their appetite is considerable. Growing rapidly, the chicks soon develop a thick woolly gray down and quickly become almost as large as their parents. During the third or fourth week they join other chicks in crèches or nursery groups. This leaves both parents free to go to sea to feed themselves in order to satisfy their chicks' increasing demands for food.

A parade of adults can regularly be seen moving between the colony and the sea. The birds congregate in large numbers at the water's edge waiting for the appropriate moment to take the plunge. The Adelie's main oceanic predators are the leopard seals which often lie in wait beneath the ledges to snare the first penguin into the water. By late March most Adelies have left the colonies to spend the winter in the comparative warmth of the offshore pack ice.
Adelie penguins provided generations of early explorers with entertainment, palatable eggs, and tough but tasty meat. Through detailed studies of the birds's breeding and eating behavior, scientists today use the Adelie as an indicator species to monitor the abundance of krill, so important to the web of Antarctic life.

Emperor penguins are the most biologically interesting of the southern species. They have been recorded diving to a depth of more than 1500 feet (450 m) for up to 18 minutes, although the usual depth and duration of their dives is much less. But it is their unique breeding behavior that differentiates the Emperor from other penguin species.

Rather than breeding during the warmer, lighter summer months, Emperors breed through the cold, dark winter. The female lays a single egg in May after a 63-day gestation period, and then passes the egg over to her mate and goes to sea to feed. When the male takes over the incubation, he fasts for 9 weeks, all the while balancing the egg on his feet, where it is insulated by a thick roll of skin and feathers. During this period the males huddle together for added warmth and protection against the bitter winds and sub-zero temperatures. By the time the female returns the male will have lost up to one third of his body weight; she takes over feeding the now-hatched chick for a six week period, while the male makes another long trek over the ice -- up to 60 miles (100 kms) to find food.

Once the young are about seven weeks old, they join other chicks in a crèche, which is protected by a few adults. By January the sea-ice begins to break out, but by this time the chicks have begun to shed their soft down and are able to fend for themselves. The Emperors are believed to have developed this winter breeding pattern to allow the chick to grow to independence at a time when food is most plentiful. The large size of the adults means they can store enough fat to withstand the long winter weeks without regular feeding.

Gentoo Penguins (Pygoscelis papua)