Hardhead vs Brent Goose
Aythya australis 比較対象 Branta bernicla
Side-by-Side Comparison
| 属性 | Hardhead | Brent Goose |
|---|---|---|
| 学名 | Aythya australis | Branta bernicla |
| 目 | Anseriformes | Anseriformes |
| 科 | Anatidae | Anatidae |
| 保全状況 | Least Concern | Least Concern |
| 体長 | — | — |
| 翼開長 | 42.7 cm (16.8 in) | 63.9 cm (25.2 in) |
| 体重 | 803.75 g (28.35 oz) | 1335.0 g (47.09 oz) |
| 食性 | Dives for molluscs, crustaceans, and aquatic invertebrates in coastal habitats; diet shifts between invertebrate types … | Primarily herbivorous; grazes aquatic plants, grasses, and sedges; swans upend in shallow water for submerged … |
| 一腹卵数 | 6-18 | 1-10 |
| Population Trend | — | — |
Habitat Comparison
Hardhead
Deep freshwater lakes, rivers, and reservoirs across Australia and New Guinea. Nomadic in Australia, following seasonal inland flooding. Prefers deep water with submerged aquatic plants.
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
Hardhead
Male produces a deep, purring wheeze; female gives a grating quacking series. Calls closely resemble Common Pochard; the female's harsh notes carry far across Australian freshwater lakes.
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
Hardhead
Breeds in northern prairie potholes; winters along the Pacific coast of North America from British Columbia to Baja California.
Brent Goose
Breeds across boreal and subarctic Canada and Alaska; winters in the southern United States, Mexico, and Central America.
保全状況
Hardhead
Brent Goose
How to Tell Them Apart
Hardhead
Males dark chocolate-brown with white undertail and flanks. White eye conspicuous. Blue-gray bill with white band and black tip. Females similar but brown with brown eye. Bold white wing stripe …
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
Hardhead
オーストラリアンホワイトアイはオーストラリアとニュージーランドに分布する潜水性カモです。雄は栗色の頭部と赤い目が特徴的です。水草が豊富な深い湿地や湖に生息し、水に潜って水草の塊茎や根を採食します。オーストラリアでは比較的普通に見られる種です。
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。