OPTIMAL FORAGING AND INTRASPECIFIC COMPETITION IN THE TUFTED PUFFIN

Diets of Tufted Puffin (Fratercula cirrhata) chicks and breeding and nonbreeding adults were compared between two years during the breeding season at Kodiak Island, Alaska. Fish dominated the diet of all groups. Nonbreeders ate more invertebrates than did breeders, and chicks were fed the lowest proportion of invertebrates of any group. Nonbreeders consumed more pelagic prey (e.g., cephalopods, euphausiids), than did breeders, which ate more inshore prey (osmerids, ammodytids). Chicks were fed the largest prey and prey with highest protein and energy values. These data are consistent with central place foraging and optimal foraging theory.