Olrog's gull 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. Nonbreeding 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 has rated it as being "near threatened".
Region
Southwestern Atlantic coast of South America
Typical Environment
Breeds in coastal estuaries and islands along the Buenos Aires Province of Argentina, especially around Bahía Blanca and Bahía Anegada. Outside the breeding season it disperses north along the coast to Uruguay and southern Brazil. It favors mudflats, saltmarshes, tidal channels, and sheltered bays where crabs are abundant. Birds are seldom found far inland and typically remain close to low-lying coastal wetlands.
Altitude Range
Sea level to 50 m
Climate Zone
Temperate
Ease of Keeping
Beginner friendly: 1/5
Olrog's gull is a South Atlantic coastal gull that specializes on intertidal crabs, an unusual level of dietary specialization among gulls. It was formerly treated as a subspecies of Belcher’s gull but is now recognized as distinct, with a characteristic black tail band and yellow legs. The species breeds mainly in Argentine estuaries and disperses north to Uruguay and southern Brazil outside the breeding season. Habitat loss, disturbance, and fisheries interactions have led to a global assessment near threatened.
South Brazil
Temperament
social and alert
Flight Pattern
strong flier with steady wingbeats; often cruises low over surf and mudflats
Social Behavior
Breeds colonially on low islands and saltmarsh edges, forming small to medium colonies. Pairs are monogamous within a season and both sexes incubate and feed chicks. Outside the breeding season it roosts and forages in flocks, often associating with other gulls.
Migratory Pattern
Partial migrant
Song Description
Vocalizations are typical harsh gull calls, including yelping kek-kek notes and rattling cackles. During displays it gives a prolonged, nasal long-call with head-tossing, especially at colonies.
