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New Zealand Blue duck (Whio)

Hymenolaimus malacorhynchos

Blauwe eend / Saumschnabelente / Canard blue de Nouvelle-Zélande


The blue duck (Whio) is a member of the family Anatidae and  the only member of the genus Hymenolaimus.

Two subspecies are recognized: 


  • H. m. malacorhynchos (J. F. Gmelin, 1789) – W South I, New Zealand.
  • H. m. hymenolaimus Mathews, 1937 – C & S North I, New Zealand.

A genetic assessment of Blue Duck concluded that the North Island and South Island populations show a level of lineage separation and should be treated as separate management units for conservation purposes (Robertson et al. 2007).


This species is an endemic resident breeder in New Zealand, nesting in hollow logs, small caves and other sheltered spots. It is a rare duck, holding territories on fast flowing mountain rivers. It is a powerful swimmer even in strong currents, but is reluctant to fly. It is difficult to find, but not particularly wary when located.


Blue ducks are listed as Endangered (IUCN, 2013) because it has a very small and severely fragmented population which is undergoing a rapid decline owing to a variety of factors, most notably the effects of introduced predators. A national survey estimated the population to number at least 1,200 mature individuals, roughly equivalent to 1,800 individuals in total.


Two co-ordinated management programmes are underway involving Hymenolaimus malacorhynchos, Operation Ark and Whio Operation Nest Egg (WHIONE) (Glaser et al.2010). Operation Ark was initiated in 2003 to target a suite of species occurring in Nothofagus forests, including this species. Initially this focused on establishing five viable populations (of fifty pairs each) with an extensive network of predator traps at each site (Williams 2006). WHIONE is a programme where breeding pairs are closely monitored and eggs removed for hatching in captivity before being returned once the chicks are at a lower risk of predation, and has proven very effective at rapidly increasing numbers (Glaser et al. 2010). Both of these programmes occur alongside large-scale control of predators in the release locations. Numbers in managed areas had increased three-fold after 4 years (Bain 2008). A captive population has been established on the North Island (Whio Forever Project) and c.20 young are reared each year (Anon 2004). In 1987 and 1991, 12 birds were released at Egmot National Park on Mt Taranaki and further releases have been carried out annually (43 birds released up to 2005) (Caskey and Peet 2005), breeding occurred for the first time in 2005-2006 when five pairs nested rearing two young (Hutchinson 1998, Biswell 2006). Intensive predator control is now carried out in the release area, this has led to the loss of no birds between 2004 and 2006 (Biswell 2006). Recreational activities have been reduced or stopped in some sensitive areas. Modifications to river flow regimes appear to have improved productivity and increased population sizes in certain areas (Adams et al. 1997). Research is on-going to determine factors that most influence distribution. Genetic analyses of population fragments have been completed (Triggs et al. 1992).


More information: 

No Blue ducks are currently being kept in aviculture outside of New Zealand/ Australia, the last bird in Arundel (UK) died in 2015. 



Above: New Zealand blue ducks at Arundel Wetland Centre, UK. Photo by Paul Rose (2006)



Above: New Zealand blue duck at Arundel Wetland Centre, UK. Photo by Paul Rose



Above: Blue duck aviary at Arundel Wetland Centre, UK. Photo by Paul Rose.



Above: New Zealand blue duck at Arundel Wetland Centre, UK. Photo by Paul Rose.



Above: New Zealand blue duck at Arundel Wetland Centre, UK. Photo by Paul Rose.


Whio chick rearing at the Isaac Conservation and Wildlife Trust. from WestCoastFilm on Vimeo.

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