The diet of the blue-eyed shag Phalacrocorax atriceps during summer at Nelson Island, Antarctica: temporal variations and consumption rates

One hundred and thirty nine stomach contents of the blue-eyed shag Phalacrocorax atriceps were sampled at Nelson Island, Antarctica, between 1 December 1994 and 2 February 1995. Fish were by far the main prey, followed by octopods, gammarids, euphausiids and polychaetes. Notothenia coriiceps, predominated in frequency (56%) and in mass (55%), whereas Harpagifer antarcticus was the most important by number (60%). The mean mass of the stomach contents was 220 g, whereas the mean number of fish was 7.4 (range 1-34). Eight hundred and sixty four bird h-1 of observations on 5-7 nests showed that the adults averaged 1.7 trips day-1 during incubation, 2.0 trips day-1 in early rearing and 4.6 trips day-1 during late rearing period. The estimated daily intakes reached 352, 462 and 1017 g respectively.