コカモメ Larus brachyrhynchus

Small dainty gull. Dark-eyed and long-winged with a rounded head. Breeding adults are white-headed with an unmarked bill; non-breeding adults are smudged on the head and bill. Younger birds are brownish, with black-tipped pink bills. Occurs in western North America, primarily breeding in Alaska and Canada and wintering to Baja. Breeds in wetlands, meadows, and beaches; winters in waterside habitats and fields. Does not frequent large urban centers as much as some other gulls.