The blue duck or whio is a member of the duck, goose and swan family Anatidae endemic to New Zealand. It is the only member of the genus Hymenolaimus. Its exact taxonomic status is still unresolved, but it appears to be most closely related to the tribe Anatini, the dabbling ducks.
Region
New Zealand
Typical Environment
Occurs on clear, fast-flowing rivers with boulder and cobble beds in forested and alpine foothill catchments. It is strongly tied to whitewater habitats, using riffles and rapids more than slow pools. Nests are placed in bankside cavities, under logs, or among rocks close to the water. The species avoids degraded or sediment-choked streams and relies on high water quality.
Altitude Range
0–1500 m
Climate Zone
Temperate
Ease of Keeping
Beginner friendly: 1/5
Also called the whio, the blue duck is a river specialist found only in New Zealand and the sole member of its genus. Its pale bill has a distinctive soft, leathery 'lip' that helps it scrape aquatic invertebrates from slippery rocks. Pairs defend long stretches of fast-flowing rivers year-round. The male’s sharp whistled call gives the species its Māori name.
1888 illustration of the beak and head of the blue duck
Blue duck, Mikonui River
Blue duck family in Hawke's Bay
A breeding pair in the wild, in Fiordland National Park (2017).
Temperament
solitary and territorial
Flight Pattern
short rapid wingbeats, low and fast over water
Social Behavior
Usually seen as territorial pairs that hold linear river territories year-round. Monogamous; nests in concealed sites near water with the female incubating and the male guarding territory. Broods are precocial and navigate strong currents soon after hatching.
Migratory Pattern
Resident
Song Description
The male gives a high, clear whistle “whio” used in contact and display. The female responds with lower, rasping growls and grunts. Vocal exchanges are frequent during territory defense.
