Olrog's gull (Larus atlanticus) is a species of gull found along the Atlantic coast of southern Brazil, Uruguay and northern Argentina. It was formerly considered a subspecies of the very similar L. belcheri. It is a large gull with a black back and wings, white head and underparts, a black band in the otherwise white tail, and a yellow bill with a red and black tip. Non-breeding adults have a blackish head and a white eye-ring. The species is named after Swedish-Argentine biologist Claes C. Olrog.It has a rather restricted breeding range and is threatened by habitat loss, and the IUCN rate it as being "Near Threatened".