Unknown to South Georgia and the South Sandwich Islands.
South-central Chile and Uruguay south to Tierra del Fuego and Falkland Is; probably also south-eastern Brazil (Rio Grande do Sul). Winters north to northern Chile and central-eastern Brazil.
 
Population
Estimated population is 100,000 - 1,000,000 (2010).
Brown-hooded Gull (Chroicocephalus maculipennis) [XC44339]
by Andrew Spencer from Estero Caulin, Chiloe Island, X Region, Chile (call)
Brown-hooded Gull (Chroicocephalus maculipennis) [XC48636]
by Alvaro Jaramillo from Estancia Las Vinchucas_Altona_Tapalque_Buenos Aires, Argentina (call)
Subspecies
Sometimes treated as a subspecies of Black-headed Gull (Larus ridibundus). Morphometric analysis links it most closely with Brown-headed Gull (Larus brunnicephalus) or Silver Gull (Larus novaehollandiae).