Unusual Coastal Breeding in the Desert-Nesting Gray Gull (Leucophaeus modestus) in Northern Chile

Abstract

Abstract. The Gray Gull (Leucophaeus modestus) has the unique habit among gulls of nesting in the interior Atacama Desert, up to 100 km from the coast. During the 2014–2015 austral breeding season, two breeding colonies were recorded on the coast within 90 m of the shoreline in the Antofagasta Region, northern Chile. The new colonies ranged in size from 40 (Playa Grande) to 150 (Playa Brava) nests. Egg laying was synchronous in both colonies and most likely occurred in late November 2014, coinciding with egg laying in desert colonies. The colony at Playa Brava was successful, but the one at Playa Grande was deserted due to feral dog (Canis familiaris) attacks. The habitat used by Gray Gulls resembled that reported for desert colonies, with flat plains covered with small rocks, which provide protection to chicks from intense solar radiation. This unusual coastal nesting behavior could result in the modification of certain life history and behavioral traits in the Gray Gull (e.g., chick growth rates, energy...