About Larus atlanticus Olrog, 1958
Species Classification
Olrog's gull (scientific name Larus atlanticus Olrog, 1958) is a large gull species.
Adult Plumage - Core Body
Adults have white feathers on the head, neck, rump, breast, and belly. Their back and wings are black, with the exception of a white trailing edge along the wings.
Adult Plumage - Tail
The tail is white with a wide black band at its distal end.
Adult Soft Parts
The beak is yellow with a black band across it and a red tip. The eyes are brown, surrounded by a red orbital ring, and the legs and feet are dull yellow.
Size Measurements
This gull measures 50 to 60 cm (20 to 24 inches) in length, with a wingspan of 130 to 140 cm (51 to 55 inches). Males are slightly larger than females.
Juvenile Plumage
Juveniles have black heads and brownish plumage.
General Distribution Range
Olrog's gull is native to the Atlantic coast of Argentina, Uruguay, and southern Brazil.
Breeding Colony Locations
It breeds at only a very small number of colonies located between 38.49° and 45.11°S; roughly two-thirds of these breeding colonies are found in the estuary of the Bahia Blanca River.
Nesting Habits
It nests on the ground just above the high-water mark, on low islands and islets.
Non-Breeding Habitat
Outside of the breeding season, it can be found on rocky coasts, in harbours, on beaches, in coastal lagoons, in brackish water, and in estuaries.
