The white-winged duck or white-winged wood duck (Asarcornis scutulata) is a large species of duck, formerly placed in the genus Cairina with the Muscovy duck (Cairina moschata) and considered allied to the dabbling ducks. However, two genetic studies have indicated that the anatomical similarity to the Muscovy duck is deceiving, with the species appropriately placed in a monotypic genus, as Asarcornis scutulata; it proved evolutionarily closest to a clade containing the diving duck genera Netta and Aythya, while Cairina resolved as close to the genus Aix in a very different part of the family tree.
Description
This is one of the largest living species of duck next only to the steamer ducks which are heavier. The Muscovy duck also attains sizes that nearly rival the white-winged duck, but may average a bit smaller in a wild state. Length is and wingspan is . Males weigh , while females weigh . The most noticeable feature on adult birds is the dark body contrasting with a whitish head and neck. Males have a mostly dull yellowish bill, blackish mottling on the head and upper neck, white lesser median coverts and inner edges of tertials, and bluish-grey secondaries. In flight, white wing-coverts contrast with the rest of the wings. Females are smaller and usually have more densely mottled head and upper neck. The juvenile is duller and browner.
This secretive species feeds mainly at dawn and dusk when moving between daytime roosts and feeding sites. It has been described as omnivorous, regularly consuming pondweed, small fish, aquatic snails, spiders and insects. The white-winged duck is the state bird of Assam.
Conservation status
In the October 2024 IUCN Red List update (version 2024-2), the white-winged duck was uplisted from Endangered to Critically Endangered under criteria A2bcde+3bcde+4bcde and C1+2a(i), reflecting a global decline of an estimated 70–90% over the past three generations (26 years; 1997–2023).
Conservation actions
The species is listed on CITES Appendix I and on CMS Appendix II, and is legally protected in most range states; in India it is listed in Schedule I of the Wildlife Protection Act, 1972.
In 2023, the Wildlife Trust of India and partners published a species action plan for Assam, Call of the Divine Duck, recommending strengthening of protected-area enforcement, restoration of forest wetlands through de-siltation and weed control, mitigation of disturbance, and community-engagement programmes; a species-recovery project is now underway. The European and North American captive lines descend from ten birds collected in Assam in 1969–1970.