Hawaiian Duck vs Brent Goose
Anas wyvilliana compared with Branta bernicla
Side-by-Side Comparison
| Attribute | Hawaiian Duck | Brent Goose |
|---|---|---|
| Scientific Name | Anas wyvilliana | Branta bernicla |
| Order | Anseriformes | Anseriformes |
| Family | Anatidae | Anatidae |
| Conservation Status | Vulnerable | Least Concern |
| Length | — | — |
| Wingspan | 44.0 cm (17.3 in) | 63.9 cm (25.2 in) |
| Weight | 573.25 g (20.22 oz) | 1335.0 g (47.09 oz) |
| Diet | 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 … |
| Clutch Size | 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.
Conservation Status
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
A medium-sized duck resembling a female Mallard, with mottled brown plumage and green speculum. Endemic to Hawaii; hybridizes with feral Mallards, threatening its genetic integrity. Found on freshwater wetlands of Kauai and other islands. Endangered; conservation focus on reducing hybridization.
Brent Goose
A small dark-bodied goose with a black head and neck, small white neck patches, and pale grey belly. Migrates between high-Arctic breeding grounds and temperate coastal wintering areas. Feeds on eel-grass and saltmarsh vegetation in winter. Three subspecies differ in belly coloration.