Feeding behavior of the Kelp Gull (Larus dominicanus) during the non-breeding season at sandy beaches of Península Valdés, Argentina

Abstract

Birds that feed in intertidal areas exploit resources that often are distributed in patches, and which become available during regular intervals that depend on the tidal cycle. The quality of foraging patches depends on prey species composition, prey density, prey size distribution, and prey availability to predators. We analyzed the feeding behaviour of Kelp Gulls (Larus dominicanus) on intertidal sectors with different densities and sizes of prey on a sandy beach at Península Valdés, Chubut Province, Argentina. Gulls fed along the tide line by foot paddling, and their diet was mostly composed of sand burrowing clams, Tellina petitiana and Darina solenoides. Average sizes of both clams identified in Kelp Gull pellets were larger than those found in beach sediments. Feeding activity was concentrated in areas of high clam density and with larger sizes of both clam species. Even though Kelp Gulls are foraging generalists that use a wide spectrum of food items, these results show that they can also be selective in their choice of prey.