Summer food of the Great and Double-crested Cormorants on the Magdalen Islands, Quebec

Abstract

This study of the food of the Great Cormorant (Phalacrocorax carbo) and the Double-crested Cormorant (P. auritus) on the Magdalen Islands, Quebec, is based on regurgitations and pellets collected on nesting sites during the summers of 1977 and 1978. Both species generally ate flatfishes (especially the winter flounder, Pseudopleuronectes americanus), American sand lances (Ammodytes americanus) and cunners (Tautogolabrus adspersus). Relatively more Great Cormorants than Double-crested Cormorants ate flatfishes and cunners during both summers, while relatively more Double-crested Cormorants fed on American sand lances during the summer of 1977. These fishes and other prey taken in lesser extent were mostly bottom-associated species; however both cormorants, especially the Double-crested Cormorant, take advantage of Capelin (Mallotus villosus) and Atlantic Herring (Clupea harengus harengus) schools which come spawning close to the seashore. Great and Double-crested cormorants appear to be opportunistic feeders since their diet varies with the availability of prey.