Hawaiian Duck vs Brent Goose
Anas wyvilliana 比較対象 Branta bernicla
Side-by-Side Comparison
| 属性 | Hawaiian Duck | Brent Goose |
|---|---|---|
| 学名 | Anas wyvilliana | Branta bernicla |
| 目 | Anseriformes | Anseriformes |
| 科 | Anatidae | Anatidae |
| 保全状況 | Vulnerable | Least Concern |
| 体長 | — | — |
| 翼開長 | 44.0 cm (17.3 in) | 63.9 cm (25.2 in) |
| 体重 | 573.25 g (20.22 oz) | 1335.0 g (47.09 oz) |
| 食性 | Fish-diving duck of South American rivers; uses serrated bill to catch fish and aquatic invertebrates; … | Primarily herbivorous; grazes aquatic plants, grasses, and sedges; swans upend in shallow water for submerged … |
| 一腹卵数 | 9-13 | 1-10 |
| Population Trend | — | — |
Habitat Comparison
Hawaiian Duck
Freshwater marshes, rivers, reservoirs, and taro fields on Kauai and other Hawaiian islands. Nests in dense vegetation near water. Threatened by hybridization with domestic or feral Mallards.
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.
Song & Call Comparison
Hawaiian Duck
Female produces a raspy, descending quacking series; male gives a soft, nasal sound. Calls similar to Mallard but higher-pitched; alarm is a rapid-fire quacking rattle.
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.
Geographic Range & Migration
Hawaiian Duck
Ranges across sub-Saharan Africa in open grasslands and wetland edges. Locally nomadic following seasonal rainfall patterns.
Brent Goose
Breeds across boreal and subarctic Canada and Alaska; winters in the southern United States, Mexico, and Central America.
保全状況
Hawaiian Duck
Brent Goose
How to Tell Them Apart
Hawaiian Duck
Mottled brown plumage; males may show slight green gloss on head but reduced compared to Mallard. Iridescent blue-purple speculum with white borders. Orange bill. Females similar to males; pale buff …
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.
About These Birds
Hawaiian Duck
ハワイガモはハワイ諸島固有の絶滅危惧種のカモです。マガモに近縁で、雄は緑色の頭部を持ちますが、より地味な外見をしています。湿地や川、池などに生息し、水生植物や無脊椎動物を食べます。外来捕食者や生息地の喪失が主な脅威となっています。
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。