White-headed duck

{{Short description|Species of bird}} {{Speciesbox | name = White-headed duck | image = Witkopeend - white-headed duck - Oxyura leucocephala 3.tif | image_caption = Breeding male, Andalusia, Spain | image2 =Female white headed duck.JPG | image2_caption= Female | status = EN | status_system = IUCN3.1 | status_ref = <ref name="iucn status 12 November 2021">{{cite iucn |author=BirdLife International |date=2017 |title=''Oxyura leucocephala'' |volume=2017 |article-number=e.T22679814A119403602 |doi=10.2305/IUCN.UK.2017-3.RLTS.T22679814A119403602.en |access-date=12 November 2021}}</ref> | status2 = CITES_A2 | status2_system = CITES | status2_ref = <ref>{{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=2022-01-14|website=cites.org}}</ref> | genus = Oxyura | species = leucocephala | authority = (Scopoli, 1769) | range_map = OxyuraLeucocephala.png | range_map_caption = ''Oxyura leucocephala'' range {{leftlegend|#008000|Breeding|outline=gray}} {{leftlegend|#00FF00|Resident|outline=gray}} {{leftlegend|#007FFF|Non-breeding|outline=gray}} {{leftlegend|#00FFFF|Passage|outline=gray}} {{leftlegend|#FF00FF|Vagrant (seasonality uncertain)|outline=gray}} {{leftlegend|#FF8080|Probably extinct|outline=gray}} }}

The '''white-headed duck''' ('''''Oxyura leucocephala''''') is a small diving duck some {{convert|45|cm|in|abbr=on}} long. The male has a white head with black crown, a blue bill, and reddish-grey plumage. The female has a dark bill and rather duller colouring. Its breeding habitat is lakes with open water and dense vegetation at the margin. It dives under water and feeds on aquatic vegetation as well as some animal matter. It is more likely to swim away from a perceived threat than to fly. This duck is known from Spain, North Africa, Western Asia and Central Asia. Populations are declining, mostly due to loss of habitat and pollution, and the International Union for Conservation of Nature has rated the bird's status as "endangered".

== Taxonomy and systematics == The white-headed duck was originally described as ''Anas leucocephala'' by Giovani Antonio Scopoli in 1769. It is currently in the genus Oxyura. Other generic synonyms used in the past include ''Erismatura'', ''Cerconectes'', ''Gymnura'', ''Undina'', ''Bythonessa'', ''Plectrura'', and ''Pervicauda''. Other junior synonyms for the species include ''Anas mersa'', ''Anas vindila'', ''Anas ruthenica'', and ''Oxyura unifasciata''. Its scientific name comes from the Greek ''Oxyura'' (from ''oxus'', "sharp", and ''oura'', "tail") and ''leucocephala'' (from leukos, "white" and ''kephalos'', "head".<ref>{{Cite book|last=Jobling|first=James|title=The Helm Dictionary of Scientific Bird Names|publisher=ChristopherHelm|page=223}}</ref> The common name white-headed duck, like the specific name, refers to its white head.<ref name=":0">{{Cite journal|last1=Salvador|first1=Alfredo|last2=Amat|first2=Juan A.|last3=Green|first3=Andy J.|editor1-first=Shawn M|editor1-last=Billerman|editor2-first=Brooke K|editor2-last=Keeney|date=2020-12-18|title=White-headed Duck (Oxyura leucocephala)|url=https://birdsoftheworld.org/bow/species/whhduc1/cur/introduction|journal=Birds of the World|doi=10.2173/bow.whhduc1.02|language=en|url-access=subscription}}</ref>

It interbreeds with other species in its genus, such as the ruddy duck. The hybrids are fully fertile and capable of having viable offspring with both parent species.<ref name=":0"/>

The species is monotypic. Different populations of the white-headed duck do not display significant genetic differences. However, some studies have found that they do display morphological differences, with western populations being larger in size, having darker ventral coloration, and males having more yellow feathers on their back. Dark phase birds have only been found in the western populations.<ref name=":0" />

In the genus Oxyura, it is generally thought to be related most closely to Maccoa duck. Some studies have also found that these two species form a clade with the blue-billed duck, although this is disputed and species relations between Oxyura ducks are unresolved.<ref name=":0" />

==Description== Adult males have a grey and reddish body, a blue bill and a largely white head with a black cap and neck. Adult females have a grey-brown body with a white face and a darker bill, cap, and cheek stripe. Length is {{convert|43|–|48|cm|in|abbr=on}} and weight is {{convert|580|–|750|g|lb|abbr=on}}. thumb|left|Male in winter

==Distribution and habitat== [[File:Oxyura leucocephala MWNH 1036.JPG|left|thumb|Egg, collection Museum Wiesbaden]] This duck breeds in Spain and North Africa, with a larger population in western and central Asia. Their breeding habitat is large tracts of open water, such as lakes and ponds including artificial water bodies, with dense stands of aquatic plants to provide shelter and nesting sites.<ref>{{usurped|1=[https://web.archive.org/web/20170530115057/http://www.abcc-am.org/white-headed-duck.html White-headed Duck (''Oxyura leucocephala'') in Armenia.]}} 2017. In online publication: "The State of Breeding Birds of Armenia". TSE NGO, Armenian Bird Census Council. Retrieved on 10 October 2017.</ref> Individuals are fairly frequently reported well north of their breeding range, but as with many wildfowl, the status of these extralimital records is clouded by the possibility of escapes from collections.

== Behaviour and ecology ==

=== Diet === These birds dive and swim under water. They are omnivorous, with vegetable matter predominating. They are reluctant to fly, preferring to swim for cover.

==Conservation== This duck is considered endangered due to a large reduction in populations in the last 10 years. Most of this decline is due to habitat loss and hunting, but interbreeding of the Spanish population with the introduced ruddy duck (''Oxyura jamaicensis'') is a more recent threat. This has led to the attempted eradication of the American species from western Europe.

The white-headed duck is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies, and the International Union for Conservation of Nature has rated the bird's conservation status as being "endangered".<ref name="iucn status 12 November 2021" />

==References== {{Reflist}}

==Further reading==

* Gantlett, Steve (1993) The status and separation of White-headed Duck and Ruddy Duck ''Birding World'' 6(7): 273-281

==External links== {{Commons|Oxyura leucocephala}} *ARKive - [https://web.archive.org/web/20060506212006/http://www.arkive.org/species/GES/birds/Oxyura_leucocephala/ images and movies of the white-headed duck ''(Oxyura leucocephala)''] *[http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=359&m=0 BirdLife Species Factsheet]

white-headed duck white-headed duck Category:Birds of Europe Category:Birds of Azerbaijan Category:Birds of Central Asia Category:Birds of West Asia white-headed duck Category:Endangered Fauna of China