Black-headed Duck vs Smew
Heteronetta atricapilla compared with Mergellus albellus
Side-by-Side Comparison
| Attribute | Black-headed Duck | Smew |
|---|---|---|
| Scientific Name | Heteronetta atricapilla | Mergellus albellus |
| Order | Anseriformes | Anseriformes |
| Family | Anatidae | Anatidae |
| Conservation Status | Least Concern | Least Concern |
| Length | — | — |
| Wingspan | 34.7 cm (13.7 in) | 37.5 cm (14.8 in) |
| Weight | 528.5 g (18.64 oz) | 658.75 g (23.24 oz) |
| Diet | Parasitic; adults may feed on aquatic plants, seeds, and invertebrates in South American marshes. Diet … | Dives for small fish, aquatic insects, and crustaceans in freshwater and coastal habitats. Uses serrated … |
| Clutch Size | 2 | 5-11 |
| Population Trend | — | — |
Habitat Comparison
Song & Call Comparison
Black-headed Duck
Male gives a soft, raspy peeping note; female produces a muted quack. An obligate brood parasite with reduced vocalizations; subdued calls suit its secretive lifestyle among Argentine reeds.
Smew
Male gives a soft, crow-like krr note; female produces a grating, rasping call. Both sexes are relatively quiet; the male's harsh, crow-like call is surprisingly low for such a small …
Geographic Range & Migration
Black-headed Duck
Resident in southern South America from southern Brazil and Bolivia south to Argentina and Chile. Found on lakes and marshes in open lowlands.
Smew
Breeds in boreal forests of northern Europe and Siberia. Winters on large lakes and coasts from western Europe east to Japan and China.
Conservation Status
Black-headed Duck
Smew
How to Tell Them Apart
Black-headed Duck
Male has distinctive jet-black head and neck, warm chestnut-brown back, and pale buff underparts; blue-grey bill with red base. Female is streaked brown above with pale supercilium and whitish underparts.
Smew
Male is largely white with black eye patch, black lines on back, and fine black lines on flanks creating a cracked-ice pattern. Female has chestnut-red head, white cheeks, and grey …
About These Birds
Black-headed Duck
A small diving duck (~530 g) of South America, family Anatidae, and the sole member of genus Heteronetta. Inhabits freshwater marshes and lakes in Argentina, Bolivia, Brazil, Chile, and Uruguay. Unique among waterfowl as an obligate brood parasite, laying eggs in nests of coots and other waterbirds. Feeds on seeds and aquatic invertebrates. Least Concern.
Smew
A small merganser (~660 g) in family Anatidae, males predominantly white with fine black markings and a small crest. Breeds in boreal forests of northern Eurasia near rivers and lakes, nesting in tree holes; winters on freshwater and coastal waters in central and western Europe. Feeds on small fish and aquatic invertebrates. Least Concern.