View source for Blue duck

{{short description|Species of duck endemic to New Zealand}}
{{About|the bird native to New Zealand|other uses|Blue Duck (disambiguation)}}
{{Redirect|Whio||WHIO (disambiguation){{!}}WHIO}}
{{Use dmy dates|date=December 2019}}
{{Use New Zealand English|date=December 2016}}
{{speciesbox
| name = Blue duck
| status = EN
| status_system = IUCN3.1
| status_ref = <ref name=iucn>{{cite iucn |author=BirdLife International |year=2022 |title=''Hymenolaimus malacorhynchos'' |page=e.T22680121A214275489 |doi=10.2305/IUCN.UK.2022-2.RLTS.T22680121A214275489.en}}</ref>
| image = Whio (Blue Duck) at Staglands, Akatarawa, New Zealand.jpg
| image_caption = Blue duck at Staglands, [[Akatarawa Valley]]
| genus = Hymenolaimus
| parent_authority = [[George Robert Gray|G.R. Gray]], 1843
| species = malacorhynchos
| authority = ([[Johann Friedrich Gmelin|Gmelin, JF]], 1789)
| subdivision_ranks = Subspecies
| synonyms = ''Anas malacorhynchus'' ([[protonym]])
| subdivision = See text
| range_map = Hymenolaimus malacorhynchos - distribution map.svg
| range_map_caption = {{leftlegend|#008100|Extant}}{{leftlegend|#DBD56E|Probable original distribution where the blue duck is extinct}}
}}

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

The whio is depicted on the reverse side of the [[New Zealand ten-dollar note|New Zealand $10 banknote]].

== Taxonomy ==
[[James Cook|Captain James Cook]] saw the blue duck in [[Dusky Sound]], South Island, New Zealand, on his [[Second voyage of James Cook|second voyage]] to the south Pacific. In 1777 both Cook and the naturalist [[Georg Forster]] mentioned the blue duck in their separate accounts of the voyage.<ref>{{cite book | last1=Cook | first1=James | author1-link=James Cook | last2=Furneaux | first2=Tobias | author2-link=Tobias Furneaux | date=1777 | title=A Voyage Towards the South Pole, and Round the World : Performed in His Majesty's ships the Resolution and Adventure, in the Years 1772, 1773, 1774, and 1775 |volume=1 | location=London | publisher=W. Strahan and T. Cadell | edition=2nd | pages=[https://archive.org/details/b30413953_0001/page/72/mode/1up 72], [https://archive.org/details/b30413953_0001/page/97/mode/1up 97]}}</ref><ref>{{Cite book | last=Forster | first=Georg | author-link=Georg Forster | date=1777 | title=A Voyage Round the World, in His Britannic Majesty's Sloop, Resolution, Commanded by Capt. James Cook, During the Years 1772, 3, 4, and 5 | volume=1 | location=London | publisher=B. White, P. Elmsly, G. Robinson | page=157 | url=https://archive.org/details/b30413849_0001/page/157/mode/1up}}</ref> A specimen was described in 1785 by the English ornithologist [[John Latham (ornithologist)|John Latham]] in his ''A General Synopsis of Birds''. Latham used the English name, the "soft-billed duck".<ref>{{cite book | last=Latham | first=John | author-link=John Latham (ornithologist) | year=1785 | title=A General Synopsis of Birds | volume=2, Part 2 | publisher=Printed for Leigh and Sotheby | location=London | page=522 | url=https://www.biodiversitylibrary.org/page/40079343 | access-date=1 July 2022 | archive-date=1 July 2022 | archive-url=https://web.archive.org/web/20220701155958/https://www.biodiversitylibrary.org/page/40079343 | url-status=live }}</ref> 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]]''. He coined the [[binomial name]] ''Anas malacorhynchos'' and cited the earlier works.<ref>{{cite book | last=Gmelin | first=Johann Friedrich | author-link=Johann Friedrich Gmelin | year=1789 | title=Systema naturae per regna tria naturae : secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis | edition=13th | volume=1, Part 2 | language=Latin | location=Lipsiae [Leipzig] | publisher=Georg. Emanuel. Beer | page=526 | url=https://www.biodiversitylibrary.org/page/2656019 | access-date=1 July 2022 | archive-date=29 June 2022 | archive-url=https://web.archive.org/web/20220629151751/https://www.biodiversitylibrary.org/page/2656019 | url-status=live }}</ref> The blue duck is now the only species placed in the genus ''Hymenolaimus'' that was introduced specifically for the species by [[George Robert Gray]] in 1843.<ref>{{cite journal | last=Gray | first=George Robert | author-link=George Robert Gray | date=1843 | title=Some remarks on the soft-billed duck of Latham | journal=Annals and Magazine of Natural History | volume=11 | issue=71 | pages=369–372 [370] | doi=10.1080/03745484309445317 | url=https://www.biodiversitylibrary.org/page/2287123 | access-date=1 July 2022 | archive-date=20 June 2022 | archive-url=https://web.archive.org/web/20220620165014/https://www.biodiversitylibrary.org/page/2287123 | url-status=live }}</ref><ref name=ioc>{{cite web | editor1-last=Gill | editor1-first=Frank | editor1-link=Frank Gill (ornithologist) | editor2-last=Donsker | editor2-first=David | editor3-last=Rasmussen | editor3-first=Pamela | editor3-link=Pamela Rasmussen | date=January 2022 | title=Screamers, ducks, geese & swans | work=IOC World Bird List Version 12.1 | url=http://www.worldbirdnames.org/bow/waterfowl/ | publisher=International Ornithologists' Union | access-date=1 July 2022 | archive-date=1 October 2017 | archive-url=https://web.archive.org/web/20171001165500/http://www.worldbirdnames.org/bow/waterfowl/ | url-status=live }}</ref> 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".<ref>{{cite book | last=Jobling | first=James A. | year=2010| title=The Helm Dictionary of Scientific Bird Names | publisher=Christopher Helm | location=London | isbn=978-1-4081-2501-4 | pages=[https://archive.org/stream/Helm_Dictionary_of_Scientific_Bird_Names_by_James_A._Jobling#page/n198/mode/1up 198], [https://archive.org/stream/Helm_Dictionary_of_Scientific_Bird_Names_by_James_A._Jobling#page/n239/mode/1up 239]}}</ref>

The species has no close relatives.<ref>{{cite web |title=Habitat loss > Hymenolaimus malacorhynchos (blue duck, whio) > Taxonomy |url=http://www.nhm.ac.uk/nature-online/species-of-the-day/biodiversity/loss-of-habitat/hymenolaimus-malacorhynchos/taxonomy/index.html |archive-url=https://web.archive.org/web/20140814100421/http://www.nhm.ac.uk/nature-online/species-of-the-day/biodiversity/loss-of-habitat/hymenolaimus-malacorhynchos/taxonomy/index.html |archive-date=14 August 2014 |access-date=5 December 2014 |website=NHM.ac.uk |publisher=[[Natural History Museum, London]]}}</ref> Its taxonomic relationships with other waterfowl species remains uncertain; DNA analysis has placed it as a sister to the South American [[dabbling duck]]s (Anatini), but with no close relative. As of 2013, it was commonly listed as ''[[incertae sedis]]'' but likely within the [[Anatinae]] and allied to the [[Anatini]].<ref>{{cite book |last1=Howard |first1=Richard |title=A complete checklist of the birds of the world |last2=Moore |first2=Alick |year=2013 |edition=4th}}</ref> It was formerly thought to be related to the [[shelduck]] tribe.<ref>{{cite book |last=Kear |first=J. |title=Bird families of the world: Ducks, geese and swans |publisher=Oxford University Press |year=2005 |location=Oxford}}</ref><ref name="Livezey">{{cite journal |author=Livezey, Bradley C. |year=1986 |title=A phylogenetic analysis of recent anseriform genera using morphological characters |url=http://sora.unm.edu/sites/default/files/journals/auk/v103n04/p0737-p0754.pdf |journal=[[Auk (journal)|Auk]] |volume=103 |issue=4 |pages=737–754 |doi=10.1093/auk/103.4.737 |jstor=4087184 |access-date=29 May 2016 |archive-date=17 February 2020 |archive-url=https://web.archive.org/web/20200217030730/https://sora.unm.edu/sites/default/files/journals/auk/v103n04/p0737-p0754.pdf |url-status=live }}</ref>

It is commonly known in [[New Zealand English]] by its [[Māori language|Māori]] name Whio, pronounced {{IPAc-en|'|f|i|ɔ:}} {{respell|FEE|oh}}, which is an [[onomatopoeic]] rendition of the males' call.<ref name=":1">{{Cite book|author=Lindsey, Terence |url=https://www.worldcat.org/oclc/776539108|title=Collins field guide to New Zealand wildlife|date=2011|publisher=HarperCollins|author2=Morris, Rod |isbn=978-1-86950-881-4 |location=Auckland |oclc=776539108}}</ref><ref name=":2">{{Cite web|title=Blue Duck|url=http://nzbirdsonline.org.nz/species/blue-duck|access-date=26 September 2020|archive-date=30 May 2022|archive-url=https://web.archive.org/web/20220530180355/https://nzbirdsonline.org.nz/species/blue-duck|url-status=live}}</ref>  Other names it may be known by are Mountain Duck or Blue Mountain Duck.<ref name=":2" />

Two [[subspecies]] are recognised:<ref name=ioc/>
* ''H. m. hymenolaimus'' [[Gregory Mathews|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.<ref>{{cite report |title=Broad-scale genetic population structure in blue duck Hymenolaimus malacorhynchos. Pilot study of mitochondrial genetic variation |last1=Robertson |first1=B. C. |last2=Paley |first2=R. |publisher=New Zealand Department of Conservation |volume=112 |pages=12 |last3=Gemmell |first3=N. J. |year=2003 |series=DOC Science Internal Series}}</ref> However, the populations were defined as distinct subspecies by the [[International Ornithologists' Union|International Ornithological Congress]] in 2022, based on strong genetic divergence and some plumage differences.<ref name=ioc/>

==Description==
[[File:Hymenolaemus malacorhynchus, Gmelin. Whistling of Mountain Duck. "Wio.".jpg|thumb|left| 1888 illustration of the beak and head of the blue duck]]
[[File:Whio potrait MTL.jpg|alt=Image of blue duck|right|thumb|244x244px|Blue duck, Mikonui River]]
The blue duck is {{cvt|53|cm}} long and varies in weight by sex. Females are smaller than males, weighing {{cvt|680|-|870|g|}}, whereas the males weigh {{convert|820|-|970|g}}.<ref name=hanzab>{{cite book | year=1990 | chapter=''Hymenolaimus malacorhynchos'' Blue Duck | editor1-last=Marchant | editor1-first=S. | editor2-last=Higgins | editor2-first=P.G. | title=Handbook of Australian, New Zealand & Antarctic Birds. Volume 1: Ratites to ducks; Part B, Australian pelican to ducks | location=Melbourne, Victoria | publisher=Oxford University Press | isbn=978-0-19-553068-1 | pages=1255–1260 | chapter-url=http://nzbirdsonline.org.nz/sites/all/files/022_Blue%20Duck.pdf | access-date=1 July 2022 | archive-date=9 August 2022 | archive-url=https://web.archive.org/web/20220809064636/https://nzbirdsonline.org.nz/sites/all/files/022_Blue%20Duck.pdf | url-status=live }}</ref> The plumage is a dark slate-grey with a greenish sheen on the head, a chestnut-flecked breast. The outer {{birdgloss|secondaries}} 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.<ref name="hbw">{{cite web |last1=Carboneras |first1=K. |last2=Kirwan |first2=G.M. |editor1-last=del Hoyo |editor1-first=Josep |editor2-last=Elliott |editor2-first=Andrew |editor3-last=Sargatal |editor3-first=Jordi |editor4-last=Christie |editor4-first=David A. |editor5-last=de Juana |editor5-first=Eduardo |year=2017 |title=Blue Duck (''Hymenolaimus malacorhynchos'') |work=Handbook of the Birds of the World Alive |url=https://www.hbw.com/species/blue-duck-hymenolaimus-malacorhynchos |publisher=Lynx Edicions |location=Barcelona, Spain |access-date=5 December 2017 |url-access=subscription |archive-date=4 April 2023 |archive-url=https://web.archive.org/web/20230404013319/https://birdsoftheworld.org/bow/species/bluduc1/cur/introduction |url-status=live }}</ref> 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.<ref name=":1" /><ref name=":2" /> The female's call is a rattling growl or low-pitched grating notes.<ref name=":1" /><ref name=":2" /><ref name="Madge">{{cite book|last1=Madge|first1= Steve |last2= Burn|first2= Hilary |year=1987|title=Wildfowl: an identification guide to the ducks, geese and swans of the world|publisher=[[Helm Identification Guides|Christopher Helm]]|location=London|isbn =978-0-7470-2201-5}}</ref>

{{listen|filename=Blue duck whio song.ogg|title=Blue duck recording|description=Recording of adult pair in a stream communicating and answering tape recorded calls.|pos = right}}

==Behaviour==
This [[species]] is an [[endemic (ecology)|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 [[larva]]e. A study of blue ducks on the Manganuiateao River in the central North Island found the most common prey items were [[Chironomidae]] (midge) and cased [[caddisfly]] larvae, although cased caddisfly were less preferred and were only consumed so much because of their abundance. [[Hydrobiosidae]] (free-living caddisfly) and ''[[Aphrophila neozelandica]]'' ([[crane fly]]) larvae were also frequently eaten. Other prey included [[mayfly]], ''[[Aoteapysche]]'' (net-building caddis) and [[Plecoptera|stonefly]] larvae.<ref>{{cite journal |last1=Veltman |first1=C. J. |last2=Collier |first2=K. J. |last3=Henderson |first3=I. M. |last4=Newton |first4=L. |date=1995 |title=Foraging ecology of blue ducks ''Hymenolaimus malacorhynchos'' on a New Zealand river: implications for conservation |journal=Biological Conservation |volume=74 |issue=3 |pages=187–194 |doi=10.1016/0006-3207(95)00029-4|bibcode=1995BCons..74..187V }}</ref> The blue duck on occasion take berries and the fruits of shrubs.<ref name=iucn/>

===Foraging===
The foraging behaviour of the blue duck is characterised by its reliance on benthic invertebrates in fast-flowing riverine environments. Blue ducks primarily engage in dabbling behaviour where they feed by scouring rocks rather than up-ending or dabbling at the water's surface. Observations indicate that territorial males and females dabble approximately 96% of the time, with juvenile ducks dabbling 86% of the time. During the diurnal cycle, territorial birds exhibit higher foraging in the early morning and late evening, while non-territorial birds tend to forage more at midday. The decrease in dabbling during midday corresponds with an increase in diving behaviour in deeper pools. This pattern suggests that blue ducks capitalise on invertebrate resources that vary in availability throughout the day.<ref name="Eldridge">Eldridge, J. L. (1986). Territoriality in a river specialist: the blue duck. Wildfowl, 37(37), 123-135.</ref> Diving behaviour was seen most frequent in March and July when water levels are higher and prey living on stones and boulders above the water-surface would have been inaccessible using alternative foraging methods.<ref>Veltman, C. J., Collier, K. J., Henderson, I. M., & Newton, L. (1995). Foraging ecology of blue ducks Hymenolaimus malacorhynchos on a New Zealand river: implications for conservation. Biological Conservation, 74(3), 187-194.</ref> Blue ducks’ foraging activities peak during early morning and late afternoon, coinciding with the diurnal activity patterns of invertebrate drift. The reliance on these temporal patterns allows blue ducks to exploit a resource that is continuously recolonising denuded areas in the river.<ref name="Velt">Veltman, C. J., Triggs, S., Williams, M., Collier, K. J., McNab, B. K., Newton, L., ... & Henderson, I. M. (1991). The blue duck mating system: are river specialists any different? Acta XX Congressus Internationalis Ornithologici, 860-867.</ref> Ducks can be seen feeding at other times but often the day and night is spent in hiding or resting.<ref name="Kear">Kear, J., & Burton, P. J. K. (1971). The food and feeding apparatus of the blue duck Hymenolaimus. Ibis, 113(4), 483-493.</ref> Feeding behaviour is influenced by the type of prey available, requiring both tactile and visual foraging techniques. While foraging, blue ducks primarily glean invertebrates from rock surfaces using visual cues for mobile prey such as mayfly larvae. They have forward facing eyes that indicate this visual foraging use, typical of diving ducks, some attribute the evolution of this feature to the special absence of predators.<ref name="Kear"/> Blue ducks also utilise tactile cues to scrape small chironomid larvae from submerged surfaces. <ref name="Martin">Martin, G. R., Jarrett, N., & Williams, M. (2007). Visual fields in Blue Ducks Hymenolaimus malacorhynchos and Pink‐eared Ducks Malacorhynchus membranaceus: visual and tactile foraging. Ibis, 149(1), 112-120.</ref> Changes in water clarity can therefore significantly affect foraging efficiency, particularly for mobile prey. Territoriality in blue ducks is closely linked to the availability of food resources. Although blue ducks occupy large territories, the size is not primarily determined by food abundance; rather, it reflects the overlapping life cycles of benthic invertebrates, which exhibit minimal seasonal variation. <ref name="Velt"/> This indicates that while food resources are critical for blue duck distribution and population structure, they do not necessarily dictate territorial size.<ref name="Godfrey">	Godfrey, J. D., Bryant, D. M., & Williams, M. (2003). Energetics of blue ducks in rivers of differing physical and biological characteristics. Science for Conservation, 214, 35-68.</ref>

===Territoriality===
Blue ducks display territorial behaviours, they are known for their year-round territoriality, with territories typically ranging from 0.5 to 1.5 kilometres along river habitats characterised by alternating pools and rapids. The size and boundaries of these territories depend on resource availability, environmental conditions, and competition with other blue ducks.<ref name="Velt"/><ref name="Eldridge"/> During the breeding season, territory defence becomes critical as breeding pairs protect their territories from intruders. This behaviour secures access to essential resources and optimal breeding sites, enhancing reproductive success.
Both male and female blue ducks cooperate to defend their territories, using a variety of behaviours to deter intruders. Defensive behaviours include head bobbing, vocalisations, and aggressive confrontations. These behaviours communicate their presence and resolve conflicts over territory.<ref name="Eldridge"/><ref name="Williams">Williams, M. (1991). Social and demographic characteristics of blue duck ''Hymenolaimus malacorhynchos''. Wildfowl, 42, 65-86.</ref> The intensity of these interactions varies based on several factors, including the presence of a female during confrontations. When females are present, aggressive behaviours may escalate, highlighting the significance of mate guarding in territory defence. This interaction shows social and environmental factors shaping territorial behaviour.<ref name="Eldridge"/> Territoriality in blue ducks is linked to habitat quality. Research indicates that pairs in higher-quality environments expend less energy on territorial defence, allowing for greater foraging opportunities and improved reproductive fitness.<ref name="Godfrey"/> While pairs defend their territories, extensive areas between them may remain unprotected. Juvenile and unpaired blue ducks exploit these undefended spaces for foraging, indicating that territoriality does not completely limit resource availability for non-breeding individuals.<ref name="Eldridge"/> After the breeding period, blue ducks may adjust their territorial size in response to resource availability, often reducing their territory to focus on the most productive areas. As the breeding season progresses, interactions between neighbouring pairs can intensify, particularly with increasing competition for shared resources. Most aggressive confrontations involve males defending territories against foraging intruders, highlighting male-male competition's role in shaping blue duck social dynamics.<ref name="Eldridge"/><ref name="Williams"/>

===Mating===
Blue ducks exhibit a complex social structure characterised by strong pair bonds and monogamous behaviour, integral to their reproductive success and territory defence in riverine habitats. Typically, blue ducks maintain permanent year-round territories defended by mated pairs, emphasising the significance of monogamy for the successful rearing of offspring. <ref name="Velt">Veltman, C. J., Triggs, S., Williams, M., Collier, K. J., McNab, B. K., Newton, L., ... & Henderson, I. M. (1991). The blue duck mating system: are river specialists any different? Acta XX Congressus Internationalis Ornithologici, 860-867.</ref> Pair members rarely stray far from each other, with individuals often remaining in close proximity throughout the year.<ref name="Williams"/> In blue ducks, synchronous behaviours further enhance the stability of pair bonds, as pairs coordinate their activities, particularly during periods of brood dispersal and moulting. Pairs often forage together, displaying high synchronisation rates during various behavioural activities, which can range from 62% during moult to 81% in the pre-laying phase. <ref name="Velt"/> This synchronised behaviour is said to likely improve foraging efficiency and reduces vulnerability to predation, reinforcing the significance of the social bonds. During incubation, males shift their foraging habits to support female partners and their offspring, highlighting a collaborative approach to parental care. <ref name="Williams"/> Although blue ducks generally exhibit monogamous pair bonding, instances of extra-pair mating may occur, particularly when environmental pressures or territory dynamics shift. <ref name="Velt"/>

===Breeding===
[[File:Blue Ducks.JPG|thumb|Blue duck family in Hawke's Bay]]
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.<ref name=hanzab/>

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.<ref name="r8">{{cite web|url=http://www.doc.govt.nz/conservation/native-animals/birds/birds-a-z/blue-duck-whio/|title=Blue duck/whio|website=New Zealand Department of Conservation – Te Papa Atawhai|access-date=13 March 2015|archive-url=https://web.archive.org/web/20150302200701/http://www.doc.govt.nz/conservation/native-animals/birds/birds-a-z/blue-duck-whio/|archive-date=2 March 2015|url-status=dead}}</ref>

==Captivity==
[[File:Whio pair Iris Burn Stevage.jpg|thumb|left|A breeding pair in the wild, in Fiordland National Park (2017).]]
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 programme 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]]s, [[New Zealand scaup]], and [[brown teal]] by The Wildlife Service of New Zealand. The species was maintained in the UK until at least 2012<ref>{{cite web|website=WWT.org.uk|publisher=Wildfowl & Wetlands Trust|title=Ducky companion saves blue Jerry from a lonely life|date=5 March 2012|url=http://www.wwt.org.uk/news/all-news/2012/03/wwt-arundel-news/ducky-companion-saves-blue-jerry-from-a-lonely-life/|archive-url=https://web.archive.org/web/20141209012553/http://www.wwt.org.uk/news/all-news/2012/03/wwt-arundel-news/ducky-companion-saves-blue-jerry-from-a-lonely-life/|archive-date=9 December 2014|access-date=5 December 2014}}</ref> before dying out; efforts to create the only [[captive breeding]] population outside of New Zealand with these ducks ultimately failed when the last two male ducks formed a [[Homosexual behavior in animals|same-sex relationship]] with each other instead of with the female that was assigned to them.<ref>{{Cite web|last=Lite|first=Jordan|title=Gay ducks derail repopulation plan|url=https://blogs.scientificamerican.com/extinction-countdown/gay-ducks-derail-repopulation-plan/|access-date=2021-12-04|website=Scientific American Blog Network|language=en|archive-date=4 December 2021|archive-url=https://web.archive.org/web/20211204182527/https://blogs.scientificamerican.com/extinction-countdown/gay-ducks-derail-repopulation-plan/|url-status=live}}</ref> They have not been known to be exported and maintained anywhere else internationally.<ref>{{Cite web |title=Blue Duck |url=https://www.waterfowl.org.uk/wildfowl/true-ducks/blue-duck/ |access-date=2022-03-05 |website=British Waterfowl Association |language=en-GB |archive-date=5 March 2022 |archive-url=https://web.archive.org/web/20220305221628/https://www.waterfowl.org.uk/wildfowl/true-ducks/blue-duck/ |url-status=live }}</ref>

==Status==
The blue duck is classified as [[endangered species|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]]. A 2010 census estimated a total population size of 2,500–3,000 individuals, with a maximum of 1,200 pairs.<ref name=iucn/>

The blue duck is a very localised species now threatened by predation from introduced mammals such as [[stoats in New Zealand|stoats]], 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.<ref>{{Cite book|title=Whio : saving New Zealand's blue duck|last=Young|first=David|date=2006|publisher=Craig Potton Publishing|isbn=9781877333460|location=Nelson, N.Z.|oclc=166312805}}</ref> 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.<ref>{{cite book |last1=Glaser |first1=Andrew |last2=Andrew |first2=Paul |last3=Elliott |first3=Graeme |last4=Edge |first4=Kerri-Anne |title=Whio/blue duck (''Hymenolaimus malacorhynchos'') recovery plan 2009–2019 |url=http://csl.doc.govt.nz/upload/documents/science-and-technical/tsrp62.pdf |series=Threatened Species Recovery Plan 62 |date=December 2010 |publisher=Department of Conservation |location=Wellington, N.Z. |isbn=978-0-478-14841-1 |access-date=21 November 2011 |archive-url=https://web.archive.org/web/20120425235214/http://csl.doc.govt.nz/upload/documents/science-and-technical/tsrp62.pdf |archive-date=25 April 2012 |url-status=dead }}</ref> Female whio are especially vulnerable to stoats while nesting, and some populations are now 70 percent male.<ref name=":0">{{Cite journal|last=Hansford|first=Dave|date=July–August 2018|title=The first test|url=https://www.nzgeo.com/stories/the-first-test/|journal=New Zealand Geographic|volume=152|pages=74–91|access-date=5 August 2018|archive-date=6 August 2018|archive-url=https://web.archive.org/web/20180806060121/https://www.nzgeo.com/stories/the-first-test/|url-status=live}}</ref> 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.<ref name=":0" />

In 2011 the New Zealand Department of Conservation and [[Genesis Energy Limited|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==
{{Reflist}}

==Further reading==
{{refbegin}}
*{{cite web|url=http://www.doc.govt.nz/upload/documents/science-and-technical/tsrp22.pdf|title=Blue duck (Whio) ''Hymenolaimus malacorhynchos'' recovery plan 1997–2007|first1=J.|last1=Adams|first2=D.|last2=Cunningham|first3=J.|last3=Molloy|first4=S.|last4=Phillipson|year=1997|publisher=Department of Conservation|location=Wellington, New Zealand|access-date=7 November 2007|ref=none|archive-date=14 October 2012|archive-url=https://web.archive.org/web/20121014094609/http://www.doc.govt.nz/upload/documents/science-and-technical/TSRP22.pdf|url-status=live}}
*{{Cite journal| doi = 10.1016/j.biocon.2008.08.013| volume = 141| issue = 11| pages = 2784–2794| last1 = Whitehead| first1 = A.
| first2 = K. |last2=Edge|first3=A.|last3=Smart|first4=G.|last4= Hill|first5=M.|last5=Willans| title = Large scale predator control improves the productivity of a rare New Zealand riverine duck| journal = Biological Conservation| year = 2008 | bibcode = 2008BCons.141.2784W| ref=none }}
*{{Cite journal| doi = 10.1111/j.1442-9993.2009.02079.x| volume = 35| issue = 7| pages = 722–730| last1 = Whitehead| first1 = A.
| first2 = G. |last2=Elliott|first3=A.|last3=McIntosh| title = Large-scale predator control increases population viability of a rare New Zealand riverine duck| journal = Austral Ecology| year = 2010 | bibcode = 2010AusEc..35..722W| ref=none}}
{{refend}}

==External links==
*ARKive: [https://web.archive.org/web/20060422093654/http://www.arkive.org/species/GES/birds/Hymenolaimus_malacorhynchos/ Images and movies of the Blue Duck (''Hymenolaimus malacorhynchos'')]
*[http://www.birdlife.org/datazone/search/species_search.html?action=SpcHTMDetails.asp&sid=422&m=0 BirdLife Species Factsheet.]
*[https://web.archive.org/web/20130428083454/http://www.doc.govt.nz/conservation/native-animals/birds/wetland-birds/blue-duck-whio/ Blue duck/Whio] at the Department of Conservation
*[http://www.terranature.org/duckBlue.htm TerraNature | New Zealand ecology – Blue duck (Whio)]
*[http://www.wceet.org.nz/blue-duck-project-charitable-trust/ Blue Duck Project Charitable Trust]
*[https://web.archive.org/web/20120415134013/http://www.whioforever.co.nz/whio%2Dforever/ Whio Forever Project]
*[http://www.genesisenergy.co.nz/generation/our-generation-sites/tongariro-power-scheme/environmental-mitigation/central-north-island-blue-duck-trust/central-north-island-blue-duck-trust.cfm Central North Island Blue Duck Trust] {{Webarchive|url=https://web.archive.org/web/20130516214849/http://www.genesisenergy.co.nz/generation/our-generation-sites/tongariro-power-scheme/environmental-mitigation/central-north-island-blue-duck-trust/central-north-island-blue-duck-trust.cfm |date=16 May 2013 }}

{{Birds of New Zealand}}
{{Odontoanserae|B.|state=collapsed}}
{{Portal bar|Birds|New Zealand}}
{{Taxonbar|from=Q420499}}

[[Category:Ducks]]
[[Category:Tadorninae]]
[[Category:Endemic birds of New Zealand]]
[[Category:Birds described in 1789]]
[[Category:Taxa named by Johann Friedrich Gmelin]]