The Grey Gull, Leucophaeus modestus, is found along the Pacific coast of South America. Unusual among gulls, it only breeds in the extremely arid Atacama Desert in northern Chile, although it is present as a non-breeding visitor throughout most of the Chilean coast, and the coast of Peru and Ecuador.
These photos were taken at the Los Pantanos de Villa Preserve near Lima, Peru.
It has a distinctive dark body, white head and black bill and feet.