Analysis of the stomach content in the blue-eyed shag Phalacrocorax atriceps bransfieldensis at Nelson Island, South Shetland Islands

Forty stomach contents of the blue eyed shag Phalacrocorax bransfieldensis were sampled at Nelson Island, South Shetland Islands, in January 1994. The analysis of the diet showed that fish were by far the main component, followed by octopods, polychaetes and gammarids. Notothenia coriiceps, predominated in frequency (58%) and in weight (65%), whereas Nototheniops nudifrons was the most important by number (47%) . The comparison with data published on pellets analysis of shags from the same colony gave similar results. However, although the methodology used in the present study requires more time in the field, it reduces the errors arose from the examination of regurgitated casts, like erosion by digestion or loss of the otoliths through the gastrointestinal tract. The analysis of the stomach contents is complemented with information on shags’ foraging trips, obtained in the field by film records.