Olrog’s Gull feeds mainly on crabs and breeds along the Argentine coast. In winter it disperses north to Uruguay and southern Brazil.
Adult breeding plumage has a white body with a black back and wings. In nonbreeding plumage the head has dark markings, and the white tail has a broad black band.
It feeds mainly on crabs and relies heavily on them during breeding. Outside the breeding season it can also eat barnacles, fish and other foods.
An extinction-risk assessment has not been added yet.