Comparison of the diet of the blue-eyed shag Phalacrocorax atriceps by the analysis of pellets and stomach contents

A total of 45 pellets from the blue-eyed shag Phalacrocorax atriceps were collected in January 1994 at Duthoit Point, Nelson Island, South Shetland Islands. The analysis showed fish as the main prey, followed by octopods, polychaetes and gastropods. Notothenia coriiceps formed the bulk of the diet, but Harpagijer antarcticus was the most frequent and important fish in number. The prey represented in the pellets were consistent with those observed in stomach contents sampled simultaneously in the same colony; however, they differed in importance. A daily mean of 0.7 pellets per bird was collected, representing 255 g of fish. Correction factors previously estimated in a feeding trial were applied to this value, and suggested that the average daily amount of food ingested by an adult shag during the sampling period was 1325 g, which fall into the range observed by the analysis of stomach contents. Other aspects related to the feeding behavior of this bird are also discussed.