Family Ducks, Geese, Swans (Anatidae)


Scaly-sided Merganser (Mergus squamatus)


French: Harle de Chine German: Schuppensäger Spanish: Serreta china

Mergus squamatus


, 1864,



Recent phylogenetic study found this species to be basal to M. merganser#R. Monotypic.


Breeds in extreme SE Siberia, NE China and N Korea. Winters mainly in C & S China (especially in R Yangtze catchment); also in SE Russia, Korea, Japan, occasionally Taiwan, Myanmar and Thailand.

Descriptive notes

52–62 cm; male 1125–1400 g, female 870–1100 g; wingspan 70–86 cm. Structurally intermediate between M. merganser and M. serrator.... read more


Generally silent but vocalizations much like those of M. serrator, though also makes deep... read more


During breeding season, inhabits well-forested, clear, fast-flowing mountain rivers and rapid... read more

Food and feeding

Until recently few data available, but several studies have now elucidated the species’ diet and foraging behaviour. Diurnal feeder,... read more


Little known until recently. During local spring: arrives on breeding grounds late Mar/early Apr, initially frequents lakes and larger... read more


Migratory (though true extent still not entirely known), mainly present on breeding grounds between... read more

Status and conservation

ENDANGERED. Fully protected in all range states. Poorly known, population probably quite small, but has been suggested that perhaps as many as 10,000 individuals survive,... read more

Recommended citation

Carboneras, C. & Kirwan, G.M. (2020). Scaly-sided Merganser (Mergus squamatus). 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 9 April 2020).