Black-headed Duck vs Steller's Eider
Heteronetta atricapilla comparado con Polysticta stelleri
Side-by-Side Comparison
| Atributo | Black-headed Duck | Steller's Eider |
|---|---|---|
| Nombre científico | Heteronetta atricapilla | Polysticta stelleri |
| Orden | Anseriformes | Anseriformes |
| Familia | Anatidae | Anatidae |
| Estado de conservación | Least Concern | Vulnerable |
| Longitud | — | — |
| Envergadura | 34,7 cm (13.7 in) | 40,7 cm (16.0 in) |
| Peso | 528,5 g (18.64 oz) | 815,75 g (28.77 oz) |
| Dieta | Parasitic; adults may feed on aquatic plants, seeds, and invertebrates in South American marshes. Diet … | Eats molluscs, crustaceans, and aquatic invertebrates; dives in shallow coastal and estuarine habitats; diet invertebrate-dominated. |
| Tamaño de la puesta | 2 | 3-10 |
| Population Trend | — | — |
Habitat Comparison
Steller's Eider
Breeds on low-lying coastal tundra in Arctic Russia and occasionally Alaska. Winters on shallow rocky sea coasts, kelp beds, and sheltered bays in the Baltic Sea and Pacific coast of Alaska. Listed as Vulnerable.
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.
Steller's Eider
Male produces a low, soft cooing note; female gives a guttural, grunting purr. Quieter than other eiders; the male's gentle cooing is unlike the louder calls of the Common Eider.
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.
Steller's Eider
Breeds in boreal Canada and Alaska; winters along Pacific and Atlantic coasts and on large interior lakes of the US.
Estado de conservación
Black-headed Duck
Steller's 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.
Steller's Eider
Males have white head with green nape spot, black eye patch and chin; orange-buff underparts; black back with white wing patches. Females mottled dark brown with blue speculum bordered white. …
About These Birds
Black-headed Duck
El pato cabeza negra es un pequeño pato buceador (~530 g) de América del Sur, familia Anatidae, y el único miembro del género Heteronetta. Tiene la cabeza negra en el macho y cuerpo marrón. Parásita de nido obligada: pone sus huevos en los nidos de otras aves acuáticas, especialmente fochas y pollas de agua. Habita en lagos y lagunas con vegetación emergente de Argentina, Bolivia, Brasil, Chile, Paraguay y Uruguay. No cría su propia cría nunca.
Steller's Eider
El eider de Steller es el más pequeño de los eiders, con el macho de color blanco y negro con el pecho y los flancos de color canela-naranja. Cría en la tundra costera del norte de Siberia y Alaska, y pasa el invierno en costas marinas del norte del Pacífico y el norte del Atlántico. Está clasificado como vulnerable, con declives de población en Alaska.