Brent Goose vs Knob-billed Duck
Branta bernicla 比較対象 Sarkidiornis melanotos
Side-by-Side Comparison
| 属性 | Brent Goose | Knob-billed Duck |
|---|---|---|
| 学名 | Branta bernicla | Sarkidiornis melanotos |
| 目 | Anseriformes | Anseriformes |
| 科 | Anatidae | Anatidae |
| 保全状況 | Least Concern | Least Concern |
| 体長 | — | — |
| 翼開長 | 63.9 cm (25.2 in) | 64.2 cm (25.3 in) |
| 体重 | 1335.0 g (47.09 oz) | 1817.5 g (64.11 oz) |
| 食性 | Primarily herbivorous; grazes aquatic plants, grasses, and sedges; swans upend in shallow water for submerged … | Dabbles for seeds and aquatic invertebrates; diet shifts toward invertebrate prey in spring breeding season; … |
| 一腹卵数 | 1-10 | 6-20 |
| 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.
Knob-billed Duck
Freshwater lakes, marshes, floodplains, and forested wetlands across sub-Saharan Africa and South and Southeast Asia from India to southern China. Nests in large tree hollows near 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.
Knob-billed Duck
A low, grunting 'wuk' or soft, nasal 'krank'. Similar to Comb Duck in call quality. Generally quiet; calls are not loud or distinctive compared to other large African waterfowl.
Geographic Range & Migration
Brent Goose
Breeds across boreal and subarctic Canada and Alaska; winters in the southern United States, Mexico, and Central America.
Knob-billed Duck
Breeds on sub-Arctic tundra; winters on the Atlantic coast of North America from Labrador to Florida and the Gulf Coast.
保全状況
Brent Goose
Knob-billed 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.
Knob-billed Duck
Males have white head with black spots; iridescent dark blue-black back and wings; white underparts with gray flanks. Large black fleshy knob atop bill. Females smaller, brown, and lack the …
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。
Knob-billed Duck
ノブビルダックはアフリカ、南アジア、南米に広く分布するカモです。雄の嘴の根元にある肉質のコブが特徴的です。木の洞に営巣し、湿地、川、池に生息します。季節的な移動をすることがあります。水草、種子、農作物を採食します。