Brent Goose vs Spectacled Duck
Branta bernicla 比較対象 Speculanas specularis
Side-by-Side Comparison
| 属性 | Brent Goose | Spectacled Duck |
|---|---|---|
| 学名 | Branta bernicla | Speculanas specularis |
| 目 | Anseriformes | Anseriformes |
| 科 | Anatidae | Anatidae |
| 保全状況 | Least Concern | Near Threatened |
| 体長 | — | — |
| 翼開長 | 63.9 cm (25.2 in) | 52.4 cm (20.6 in) |
| 体重 | 1335.0 g (47.09 oz) | 1248.25 g (44.03 oz) |
| 食性 | Primarily herbivorous; grazes aquatic plants, grasses, and sedges; swans upend in shallow water for submerged … | Eats aquatic plants, seeds, and invertebrates; dabbles in shallow water; diet varies widely between seasons … |
| 一腹卵数 | 1-10 | 4-9 |
| Population Trend | — | — |
Habitat Comparison
Brent Goose
Breeds on high-Arctic tundra; winters on estuaries, coastal mudflats, saltmarshes, and sea-grass beds along Atlantic and Pacific coastlines. One of the most strictly coastal wintering geese.
Spectacled Duck
Clear fast-flowing rivers and streams in temperate forest from central Chile and adjacent Argentina south to Tierra del Fuego. Requires cold turbulent mountain rivers with riparian forest. Avoids slow or muddy water.
Song & Call Comparison
Brent Goose
A low, guttural 'rronk' or 'ronk-ronk' from flocks. Soft nasal calls in feeding groups. A subtle, understated call for a goose — less loud than most Anser geese.
Spectacled Duck
Emits deep, guttural quacking notes; alarm is a loud, repeated honking bark. Calls are resonant and powerful, carrying far along fast-flowing Patagonian rivers.
Geographic Range & Migration
Brent Goose
Breeds across boreal and subarctic Canada and Alaska; winters in the southern United States, Mexico, and Central America.
Spectacled Duck
Breeds in wetlands from Iceland to Siberia; winters in temperate and subtropical Asia, Europe, and North Africa.
保全状況
Brent Goose
Spectacled Duck
How to Tell Them Apart
Brent Goose
Small; mostly black head, neck, and breast. Small white neck-patch on adults. Back dark brownish-gray; belly pale gray to white depending on subspecies. White undertail coverts. Sexes similar.
Spectacled Duck
Dark brown body with fine pale speckling. Distinctive white 'spectacle' rings around eyes. Iridescent greenish-bronze speculum. Underparts pale buff-brown. Bill grayish; legs orange. Andean and Patagonian streams.
About These Birds
Brent Goose
北極圏で繁殖し、北半球の海岸で越冬する小型のガン（体長55〜66cm）。黒い頭・首・胸に短い白い首輪が特徴。Branta bernicla（コクガン）は主にアマモなどの海草を食べ、干潟や浅い入り江を好む。日本でも北海道・東北の海岸で越冬する姿が見られ、個体数は比較的少ない。Anatidae科。
Spectacled Duck
A large dark brown duck with distinctive white spectacle-like eye-rings, a pale buff face, and a prominent white speculum. Found in fast-flowing forest rivers of southern South America. Shy and elusive; inhabits clear rushing rivers through temperate forest. Also known as the Bronze-winged Duck.