Belcher's Gull

Belcher's gull, also known as the band-tailed gull, is a bird in the family Laridae found along the Pacific coast of South America. It formerly included the very similar Olrog's gull as a subspecies, but that bird occurs on the Atlantic coast of South America and is now accepted as a separate species Larus atlanticus. Belcher's gull is a medium-sized gull with a blackish mantle, white head and underparts, a black band on the otherwise white tail, and a yellow bill with a red and black tip. Non-breeding adults have a brownish-black head and a white eye-ring. The name commemorates the British explorer Sir Edward Belcher, who performed survey work on the Pacific coast of South America.

Source: Wikipedia