Black-headed Duck vs King Eider
Heteronetta atricapilla compared with Somateria spectabilis
Side-by-Side Comparison
| Attribute | Black-headed Duck | King Eider |
|---|---|---|
| Scientific Name | Heteronetta atricapilla | Somateria spectabilis |
| Order | Anseriformes | Anseriformes |
| Family | Anatidae | Anatidae |
| Conservation Status | Least Concern | Least Concern |
| Length | — | — |
| Wingspan | 34.7 cm (13.7 in) | 53.3 cm (21.0 in) |
| Weight | 528.5 g (18.64 oz) | 1507.5 g (53.18 oz) |
| Diet | Parasitic; adults may feed on aquatic plants, seeds, and invertebrates in South American marshes. Diet … | Dives for sea urchins, molluscs, and crustaceans in Arctic coastal waters. Shifts to freshwater invertebrates … |
| Clutch Size | 2 | 1-16 |
| 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.
King Eider
Male produces a melodious, ascending ooo-wuh cooing; female gives a guttural grunt. The male's haunting, dove-like call is one of the most atmospheric sounds of the High Arctic in spring.
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.
King Eider
Circumpolar High Arctic breeder in North America, Greenland, Svalbard, and Russia. Winters at sea in the North Atlantic and Bering Sea.
Conservation Status
Black-headed Duck
King Eider
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.
King Eider
Male has bluish-grey crown, pale greenish cheeks, vivid orange-red frontal shield, black back and wings, and white breast patch. Female is warm rufous-brown with dark crescentic barring throughout.
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.
King Eider
A large sea duck (~1.5 kg) of the family Anatidae, males adorned with an ornate orange frontal shield and vivid plumage. Inhabits Arctic coasts and tundra, migrating to subarctic seas in winter. Dives up to 25 m to forage on mussels, clams, and sea urchins. Least Concern; circumpolar breeding population remains stable.