クロワカモメ Larus delawarensis

Fairly small gull, common and widespread throughout most of North America. Breeding adults are white-headed with a bold black ring around the bill; nonbreeding adults have smudgy brown markings on the head. Note pale eye and yellow legs. Immatures are mottled brownish overall; note pink bill with black tip. Found along lakes, rivers, ponds, and beaches. More common inland than most other gull species, and quite fond of parking lots and urban areas. Often in flocks. Most similar to Short-billed Gull, but larger and larger-billed. Immatures of the two species are especially difficult to differentiate, but Ring-billed is usually more coarsely mottled.