Feeding aggregation and diets of seabirds at Gerlache Strait, Antarctica

FAVERO M & N R CORIA

ACTA ZOOLOGICA SINICA

Año: 2007 vol. 53 p. 425 - 430

0001-7302

Foraging associations between flying seabirds and penguins were studied from December 1997 to February 1998 at Cierva Point, Antarctic Peninsula. Observations were complemented with diet information from main species observed in aggregations. An average of 35.6 ± 37.0 flying birds per aggregation was observed, almost all of them associated to Chinstrap penguin (Pygoscelis antarctica) groups. The most common species were the Kelp gulls (Larus dominicanus), South polar skuas (Catharacta maccormicki), Pintado petrels (Daption capensis) and Southern giant petrels (Macronectes giganteus). The number of associations observed per sampling unit decreased as the season progressed, in some species accordingly with particular stage of their phenology. Antarctic krill (Euphausia superba) was particularly important in the diet of most abundant flying bird species in assemblages. The overlap index for krill sizes consumed give highest values in the comparisons between Kelp gulls and Chinstrap penguins. The foraging behaviour of flying birds suggested that prey was available near the surface for short time periods, likely facilitated by movements of krill avoiding penguin predation.