Adélie penguin foraging behaviour and krill abundance along the Wilkes and Adélie land coasts, Antarctica

The foraging behaviour of Adélie penguins Pygoscelis adeliae was studied simultaneously at Shirley Island (SI, 110°E) and at Petrel Island (PI, 140°E) in approximate conjunction with the ship-based krill survey conducted on board the RSV Aurora Australis. Acoustic and trawl data were collected near both study sites, albeit at the end of the penguins’ breeding season. The distances travelled by Adélie penguins from Shirley Island were significantly greater than those travelled by penguins from Petrel Island (SI 31–144 km; PI 6–79 km). Mean foraging trip durations and mean maximal distances travelled were also significantly different between colonies (duration: SI guard 55±32 h, crèche 113±17 h; PI guard 32±9 h, crèche 25±7 h; distance: SI guard 182±135 km, crèche 353±93 km; PI guard 100±42 km, crèche 86±28 km). All penguins foraged over the continental shelf or the shelf break and not in oceanic waters. The percentage distribution of dive depths was similar at both colonies; nearly 70% of all dives were to