Editing Blue duck (section)

==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}}