Family Ducks, Geese, Swans (Anatidae)

Least Concern

Smew (Mergellus albellus)


French: Harle piette German: Zwergsäger Spanish: Serreta chica

Mergus Albellus


, 1758,



Often placed in genus Mergus. Phylogenetic analysis, however, found that this species is closer to Bucephala than to Mergus#R. Known to hybridize in the wild with Bucephala clangula#R. Monotypic.


Breeds from Scandinavia E in band between about 55° N and Arctic Circle to E Siberia (Kamchatka). Winters in North and Baltic Seas and from C Europe E to Black and Caspian Seas, E China, Korea and Japan.

Descriptive notes

35–44 cm; male 540–935 g, female 510–650 g; wingspan 55–69 cm. Smaller than any species of Mergus. Unmistakable, especially mainly white male... read more


Vocalizes only infrequently, except during courtship or in alarm; in display, male gives soft but... read more


Freshwater lakes, pools, slow-flowing rivers and muskegs in taiga zone during breeding season, with... read more

Food and feeding

Aquatic invertebrates, mainly insects and their larvae, amphibians and some plant material (seeds, leaves and roots); also fishMale eating... read more


Starts Apr/May in S of range, or mid May to mid Jun in N. Seasonally monogamous, with pair-bonds forming mainly in late winter (late Dec... read more


Migratory; winters W & C Europe, E Mediterranean basin, Black Sea, S Russia, Middle East (... read more

Status and conservation

Not globally threatened (Least Concern). However, is considered Vulnerable in European context, where breeding populations are generally small, e.g. just 10–20 pairs in... read more

Recommended citation

Carboneras, C. & Kirwan, G.M. (2019). Smew (Mergellus albellus). 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 December 2019).