The small penguin species include the Adelie Penguin Pygoscelis adeliae, the Gentoo Penguin Pygoscelis papua, and the Chinstrap Penguin Pygoscelis antarctica.
Named after the wife of the French explorer Admiral Durmont d’ Urville, the Adelie is probably
the most commonly studied of all the penguin species. Counts of Adelie penguins are being used
to monitor changes to the Antarctic environment.
A rare visitor to the New Zealand
mainland, the Adelie penguin inhabits the Antarctic continent and the surrounding waters
within the limits of pack ice. Adelie penguins spend their lives, outside of the breeding season, at sea, resting on ice floes. Their diet is primarily krill with some fish.
Adelie penguins nest in large colonies of up to half a million birds. The breeding season is from November to February. Nests are small depressions lined with pebbles
that are carefully selected and brought to the nest site. Nests are started by males at the beginning
of the season and then added to by both birds after the pair is formed. Usually two eggs are laid, in
rare cases, three. The incubation period of the first egg is 35 - 37 days; chicks hatch asynchronally.
Both male and female parent share incubation and chick rearing duties. The downy grey and black chicks
are fed regurgitated krill. Young are independent of the parents at about two months of age.
Skuas prey on eggs and chicks on land whilst Leopard seals are the primary predators of adult birds. Following films that have recorded Adelie penguins leaping en masse from the edge of the ice with Leopard seals lurking in the water below, researchers have found that adults are at greater risk when returning from trips out to sea. Gordon S. Court has written: “For long suspenseful moments, the chase of one Adelie continued underwater; rapid changes in the direction of the bubbles indicated that the seal was in hot pursuit. Suddenly, the zigzag changed to a straight line, an all-out test of speed with both animals rising, arcing, and resubmerging in syncrony. An Adelie penguin on land is an ungainly thing, but in water, it moves like a salmon and, when traveling fast, clears the surface every few seconds to breathe. To see an eleven–foot–long leopard seal, weighing perhaps 800 pounds, match this performance, stroke for stroke, is spectacular. The chase lasted for some minutes, long enough for four scientists working in different parts of the penguin rookery to look out to sea and watch the Adelie successfully outdistance the seal.” Source: Natural History, August 1996 (Gordon S. Court)
Visit penguinscience.com, population ecology of Adelie Penguins in the Ross Sea, Antarctica.
