Notes on the Incubation of an Adelie Penguin Egg by a pair of South Polar Skuas

Abstract

In most rookeries of the Adelie Penguin Pygoscelis adeliae, the South Polar Skua Catharacta maccormicki is the only terrestrial predator, preying on the eggs and young chicks of the penguins. CRAWFORD (1974) observed a South Polar Skua which was incubating an Adelie Penguin's egg at a rookery near the U.S. Hallett Station, Antarctica. It is an interesting question whether a predatory skua would incubate a penguin egg and feed the chick if it were hatched successfully. On 29 November 1978 we found an undamaged egg of the Adelie Penguin which was taken from a nest by a skua and left on the ground, in the rookery on Cape Bird, Ross Island, Antarctica. We placed it in a nest of the South Polar Skua under our observation. This nest was built around November 20. The pair laid two eggs a few days later, but one of the eggs was carried away by another skua on November 28, one day before we put in the penguin egg.