The blue duck or whio (''Hymenolaimus malacorhynchos'') is a member of the duck, goose and swan family

Anatidae The Anatidae are the biological family of water birds that includes ducks, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica. These birds are adapted for swimming, floating on ...

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 Anatinae are a subfamily of the family Anatidae (swans, geese and ducks). Its surviving members are the dabbling ducks, which feed mainly at the surface rather than by diving. The other members of the Anatinae are the extinct moa-nalo, a youn ...

, the dabbling ducks. The whio is depicted on the reverse side of the New Zealand $10 banknote.

Taxonomy

Captain James Cook James Cook (7 November 1728 Old Style date: 27 October – 14 February 1779) was a British explorer, navigator, cartographer, and captain in the British Royal Navy, famous for his three voyages between 1768 and 1779 in the Pacific Ocean and ...

saw the blue duck in

Dusky Sound Tamatea / Dusky Sound is a fiord on the southwest corner of New Zealand, in Fiordland National Park. Geography One of the most complex of the many fiords on this coast, it is also the largest at 40 kilometres in length and eight kilometre ...

, South Island, New Zealand, on his second voyage to the south Pacific. In 1777 both Cook and the naturalist

Georg Forster Johann George Adam Forster, also known as Georg Forster (, 27 November 1754 – 10 January 1794), was a German naturalist, ethnologist, travel writer, journalist and revolutionary. At an early age, he accompanied his father, Johann Reinhold F ...

mentioned the blue duck in their separate accounts of the voyage. A specimen was described in 1785 by the English ornithologist John Latham in his ''A General Synopsis of Birds''. Latham used the English name, the "soft-billed duck". When in 1789 the German naturalist Johann Friedrich Gmelin revised and expanded Carl Linnaeus's '' Systema Naturae'' he included the blue duck and placed it with all the other ducks in the genus ''

Anas ''Anas'' is a genus of dabbling ducks. It includes the pintails, most teals, and the mallard and its close relatives. It formerly included additional species but following the publication of a molecular phylogenetic study in 2009 the genus was s ...

''. He coined the

binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''Anas malacorhynchos'' and cited the earlier works. The blue duck is now the only species placed in the genus ''Hymenolaimus'' that was introduced specifically for the species by

George Robert Gray George Robert Gray FRS (8 July 1808 – 6 May 1872) was an English zoologist and author, and head of the ornithological section of the British Museum, now the Natural History Museum, in London for forty-one years. He was the younger brother ...

in 1843. The genus name combines the Ancient Greek ''humēn'', ''humenos'' meaning "skin" or "membrane" with ''laimos'' meaning "throat". The specific epithet ''malacorhynchos'' is also from Ancient Greek and combines ''malakos'' meaning "soft" with ''rhunkhos'' meaning "bill". The species has no close relatives. Its taxonomic relationships with other waterfowl species remains uncertain; DNA analysis has placed it as a sister to the South American dabbling ducks (Anatini), but with no close relative. As of 2013, it was commonly listed as ''

incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertaint ...

'' but likely within the

Anatinae The Anatinae are a subfamily of the family Anatidae (swans, geese and ducks). Its surviving members are the dabbling ducks, which feed mainly at the surface rather than by diving. The other members of the Anatinae are the extinct moa-nalo, a youn ...

and allied to the

. It was formerly thought to be related to the

shelduck The shelducks, most species of which are found in the genus ''Tadorna'' (except for the Radjah shelduck, which is now found in its own monotypic genus ''Radjah''), are a group of large birds in the Tadorninae subfamily of the Anatidae, the biolog ...

tribe. It is commonly known in

New Zealand English New is an adjective referring to something recently made, discovered, or created. New or NEW may refer to: Music * New, singer of K-pop group The Boyz Albums and EPs * ''New'' (album), by Paul McCartney, 2013 * ''New'' (EP), by Regurgitator, ...

by its

Māori Māori or Maori can refer to: Relating to the Māori people * Māori people of New Zealand, or members of that group * Māori language, the language of the Māori people of New Zealand * Māori culture * Cook Islanders, the Māori people of the Co ...

name Whio, pronounced , which is an

onomatopoeic Onomatopoeia is the process of creating a word that phonetically imitates, resembles, or suggests the sound that it describes. Such a word itself is also called an onomatopoeia. Common onomatopoeias include animal noises such as ''oink'', '' ...

rendition of the males' call. Other names may be known by are Mountain Duck or Blue Mountain Duck. Two subspecies are recognised: * ''H. m. hymenolaimus'' Mathews, 1937 – central, south North Island (New Zealand) * ''H. m. malacorhynchos'' (Gmelin, JF, 1789) – west South Island (New Zealand) Prior to 2022, the North Island and South Island whio were considered distinct but were not distinguished as subspecies; they were, however, treated as separate management units. However, the populations were defined as distinct subspecies by the International Ornithological Congress in 2022, based on strong genetic divergence and some plumage differences.

Description

The blue duck is long and varies in weight by sex. Females are smaller than males, weighing , whereas the males weigh . The plumage is a dark slate-grey with a greenish sheen on the head, a chestnut-flecked breast. The outer are tipped with white and the inner ones have black margins. The plumage of the two sexes are mostly the same, although the female has slightly less chestnut in the chest. The pinkish-white bill has fleshy flaps of skin hanging from the sides of its tip. The beak is green at hatching and develops its final colour eight hours later .

Song

The male's call is a high-pitched whistle. The female's call is a rattling growl or low-pitched grating notes.

Behaviour

This

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

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.

Diet

The blue duck feeds almost entirely on aquatic invertebrate larvae. A study of blue ducks on the Manganuiateao River in the central North Island found the most common prey items were

Chironomidae The Chironomidae (informally known as chironomids, nonbiting midges, or lake flies) comprise a family of nematoceran flies with a global distribution. They are closely related to the Ceratopogonidae, Simuliidae, and Thaumaleidae. Many specie ...

(midge) and cased

caddisfly The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the b ...

larvae, although cased caddisfly were less preferred and were only consumed so much because of their abundance.

Hydrobiosidae The Hydrobiosidae are a family of caddisflies in the insect order Trichoptera The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most ...

(free-living caddisfly) and '' Aphrophila neozelandica'' (

crane fly Crane fly is a common name referring to any member of the insect family Tipulidae. Cylindrotominae, Limoniinae, and Pediciinae have been ranked as subfamilies of Tipulidae by most authors, though occasionally elevated to family rank. In the mo ...

) larvae were also frequently eaten. Other prey included mayfly, '' Aoteapysche'' (net-building caddis) and

stonefly Plecoptera is an order of insects, commonly known as stoneflies. Some 3,500 species are described worldwide, with new species still being discovered. Stoneflies are found worldwide, except Antarctica. Stoneflies are believed to be one of the mos ...

larvae. The blue duck on occasion take berries and the fruits of shrubs.

Breeding

Blue ducks nest between August and October, laying 4–9 creamy white eggs. The female incubates the eggs for 31 to 32 days and chicks can fly when about 70 days old. Nesting and egg incubation of four to seven eggs is undertaken by the female while the male stands guard. Nests are shallow, twig, grass and down-lined scrapes in caves, under river-side vegetation or in log-jams, and are therefore very prone to spring floods. For this, and other reasons, their breeding success is extremely variable from one year to the next.

Captivity

Captive North Island whio are held and bred on both main islands of New Zealand, but the progeny are returned to their respective island. South Island whio are held and bred in captivity on the South Island only. All captives are kept by approved and permitted zoological and wildlife facilities as part of the national recovery plan. As part of this current ten-year plan (2009–2019) is the WHIONE program which works with specially trained nose dogs to locate nests. The eggs are removed, and the ducklings hatched and raised in captivity. Later they are conditioned for coordinated release. Blue ducks were presented to the International Waterfowl Association in the UK in the 1970s along with

New Zealand shoveler The Australasian shoveler (''Spatula rhynchotis'') is a species of dabbling duck in the genus ''Spatula''. It ranges from 46 to 53 cm. It lives in heavily vegetated swamps. In Australia it is protected under the National Parks and Wildl ...

s, New Zealand scaup, and

brown teal The brown teal (''Anas chlorotis''; mi, pāteke) is a species of dabbling duck of the genus ''Anas'' native to New Zealand. For many years it had been considered to be conspecific with the flightless Auckland and Campbell teals in ''Anas auckla ...

by The Wildlife Service of New Zealand. The species was maintained in the UK until at least 2012 before dying out; efforts to create the only

captive breeding Captive breeding, also known as captive propagation, is the process of plants or animals in controlled environments, such as wildlife reserves, zoos, botanic gardens, and other conservation facilities. It is sometimes employed to help species tha ...

population outside of New Zealand with these ducks ultimately failed when the last two male ducks formed a same-sex relationship with each other instead of with the female that was assigned to them. They have not been known to be exported and maintained anywhere else internationally.

Status

The blue duck is classified as Endangered by the IUCN due to its highly fragmented and shrinking population, and it is listed as Nationally Endangered in the

New Zealand Threat Classification System The New Zealand Threat Classification System is used by the Department of Conservation to assess conservation priorities of species in New Zealand. The system was developed because the IUCN Red List, a similar conservation status system, had some ...

. A 2010 census estimated a total population size of 2,500–3,000 individuals, with a maximum of 1,200 pairs. The blue duck is a very localised species now threatened by predation from introduced mammals such as

stoats The stoat (''Mustela erminea''), also known as the Eurasian ermine, Beringian ermine and ermine, is a mustelid native to Eurasia and the northern portions of North America. Because of its wide circumpolar distribution, it is listed as Least Conc ...

, competition for its invertebrate food with introduced trout, and damming of mountain rivers for hydroelectric schemes. Early recovery efforts by scientists, field workers and volunteers have been summarised in a project sponsored by Genesis Energy, the Central North Island Blue Duck Charitable Conservation Trust and the Royal Forest and Bird Protection Society in 2006. In 2009 the New Zealand Department of Conservation started a ten-year recovery programme to protect the species at eight sites using predator control and then re-establish populations throughout their entire former range. Female whio are especially vulnerable to stoats while nesting, and some populations are now 70 percent male. In one study area, clutches of eggs lasted an average of nine days before being destroyed by stoats, and the one brood that hatched was killed the next day. In 2011 the New Zealand Department of Conservation and Genesis Energy started the Whio Forever Project, a five-year management programme for whio. It will enable the implementation of a national recovery plan that will double the number of fully operational secure blue duck breeding sites throughout New Zealand, and boost pest control efforts.

References

External links

*ARKive
Images and movies of the Blue Duck (''Hymenolaimus malacorhynchos'')
* ttps://web.archive.org/web/20130428083454/http://www.doc.govt.nz/conservation/native-animals/birds/wetland-birds/blue-duck-whio/ Blue duck/Whioat the Department of Conservation
TerraNature , New Zealand ecology – Blue duck (Whio)Blue Duck Project Charitable TrustWhio Forever ProjectCentral North Island Blue Duck Trust
{{Taxonbar, from=Q420499

blue duck The blue duck or whio (''Hymenolaimus malacorhynchos'') 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 i ...

Tadorninae Endemic birds of New Zealand