Uncommon to locally fairly common; often found with flocks of Black-headed Gulls and Mew (Common) Gulls. Slightly larger than Black-headed Gull, more similar to Mew Gull in size and shape but bill stouter. Adult is distinctive, the only small gull with snow-white wingtips; breeding plumage has black hood. Nonbreeding and immature have distinctive, dark horizontal face mask. Juvenile has mottled brownish back, which molts to pale gray by winter.