Family Ducks, Geese, Swans (Anatidae)

Critically Endangered

Brazilian Merganser (Mergus octosetaceus)


French: Harle huppard German: Dunkelsäger Spanish: Serreta brasileña

Mergus octosetaceus


, 1817,





Isolated populations in SE Brazil in Bahia, Tocantins, Goiás, Minas Gerais and Paraná (species is believed extinct in Mato Grosso do Sul, Rio de Janeiro, São Paulo and Santa Catarina), and NE Argentina (Misiones). May still survive in E Paraguay (Alto Paraná).

Descriptive notes

49–56 cm; 600–700 g. Head, neck and upperparts dark brown with greenish iridescence and long crest; upperwing blackish, secondaries and greater wing-coverts white... read more


Usually silent, vocalizations being mainly heard during breeding season or when threatened, but... read more


Rapid, torrential streams and fast-flowing rivers usually fringed by dense tropical forest,... read more

Food and feeding

Mostly fish (of 6–19 cm length, characids, cichlids, pimelodids and hemiodontids), complemented with molluscs and insects and their... read more


Few data available until recently. Season apparently starts Jun/Jul (dry season), with first ducklings hatching in early Jul and young... read more


Mostly sedentary, with only small-scale movements recorded, with genetic structure in... read more

Status and conservation

CRITICALLY ENDANGERED. Small, little-known population, estimated at just 50–249 mature individuals by BirdLife International, widely scattered over range (of 32,600 km2... read more

Recommended citation

Carboneras, C., Kirwan, G.M. & Sharpe, C.J. (2020). Brazilian Merganser (Mergus octosetaceus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from on 28 January 2020).