Blue Duck

(Hymenolaimus malacorhynchos)




Facts about this animal

The blue duck,or whio, is a unique threatened species of waterfowl endemic to New Zealand. It is believed to have appeared at a very early stage in evolutionary history and the species’ isolation in New Zealand has resulted in it acquiring a number of unique anatomical and behavioural features. It has, therefore, been designated a genus of its own and has no close relative anywhere in the world.

The whio is a medium-sized dabbling duck, about 53 cm long, the male with a body-weight of about 900 g, the female of about 750 g.

Bouldery rivers and streams within forested catchments which provide high water quality, low sediment loadings, stable banks and abundant and diverse invertebrate communities provide the habitat fir blue ducks. With such habitat requirements, blue duck are key indicators of river system health. The higher the number of breeding pairs of blue duck on a given stretch of river, the greater the life supporting capacity of that river.


Nest sites are variable, usually on ground under vegetation, in hollow logs etc., normally near water. Breeding season is from August to November. 4 to 9 pale-buff eggs are laid, which are incubated exclusively by the female for 31-32 days. The drake assists in tending the brood.


Males make a distinct whistling call (hence the Maori name “whio”) while females sound more like a rattle.

The whio’s food consists of insects, grubs and caddis fly larvae caught around boulders in the rapids.

Did you know?
that the blue duck is unique in various respects? It is unique to New Zealand, it appears unrelated to any duck elsewhere in the world and many of its habits are peculiar to the species, e.g., whereas most ducks eat plant material, the blue duck feeds on aquatic insects. In almost all ducks the male takes no part in raising the brood and may mate with a different duck each year but the male blue duck helps guard the ducklings and probably keeps the same mate.


Class AVES
Suborder ANSERES
Name (Scientific) Hymenolaimus malacorhynchos
Name (English) Blue Duck
Name (French) Canard bleu
Name (German) Saumschnabelente
Name (Spanish) Pato azul
Local names Maori: Whio
CITES Status Not listed
CMS Status Not listed



Photo Copyright by
Andrew Mc Millan



Range New Zealand
Habitat Rivers of medium to steep gradients with partial forest cover overhead, and vegetation to the water's edge
Wild population Approx. 2'000-2'400
Zoo population 6 reported to ISIS (2006)

In the Zoo

Blue Duck


How this animal should be transported

For air transport, Container Note 18 of the IATA Live Animals Regulations should be followed.


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Why do zoos keep this animal

The blue duck is endangered in the wild. Therefore, zoos in New Zealand keep blue ducks primarily to create awareness of the plight of the species, to build up an ex situ

reserve population and to produce birds for release to the wild programmes. The species is not kept by zoos outside the range country.