The diet of the Antarctic shag during summer at Nelson Island, Antarctica.

FAVERO, M.; CASAUX R.,; SILVA, P.; BARRERA-ORO E.; CORIA N.

THE CONDOR

COOPER ORNITHOLOGICAL SOC

Año: 1998 vol. 100 p. 112 - 118

0010-5422

Abstract. Analysis of 139 stomach contents of the Antarctic Shag (Phalacrocorax bransjeldensis)collected at Nelson Island, Antarctica, showed that fish were the main componentin the diet, followed by octopods, gammarids, euphausiids, and polychaetes. The fish Nototheniacoriiceps predominated in frequency (56%) and in mass (49%), whereas Harpagtferantarcticus was the most important by number (58%). The sizes of N. coriiceps and H.antarcticus taken by males were significantly larger than those caught by females. Thisdietary difference is probably due to differential prey selection related to shags’ sexualdimorphism, temporal prey availability, and/or different foraging depths/areasO. bservationsat nests showed that females mainly foraged in the morning, whereas males foraged in theevening. No significant differences were observed between the number of daily foragingtrips made by males and females, averaging 1.7 during incubation, 2.0 in early chick-rearing,and 4.6 during the late chick-rearing period. The estimated daily food intakes were 321,315, and 758 g for females, and 421, 582, and 1,288 g for males during incubation, earlyand late chick-rearing, respectively