The white-backed duck (''Thalassornis leuconotus'') is a

waterbird A water bird, alternatively waterbird or aquatic bird, is a bird that lives on or around water. In some definitions, the term ''water bird'' is especially applied to birds in freshwater ecosystems, although others make no distinction from seabi ...

of the family

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

. It is distinct from all other ducks, but most closely related to the whistling ducks in the subfamily

Dendrocygninae The whistling ducks or tree ducks are a subfamily, Dendrocygninae, of the duck, goose and swan family of birds, Anatidae. In other taxonomic schemes, they are considered a separate family, Dendrocygnidae. Some taxonomists list only one genus, ...

, though also showing some similarities to the stiff-tailed ducks in the subfamily Oxyurinae. It is the only member of the genus ''Thalassornis''.

Description

These

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

s are well adapted for diving. On occasions they have been observed to stay under water for up to half a minute. They search especially for the bulbs of waterlilies, but also seeds and leaves of waterlilies and other water plants and the young feed on lake flies larvae as well. From danger, they also escape preferentially by diving; hence, the namesake white back is hardly visible in life. File:White-backed Duck RWD1.jpg File:Weißrückenente Thalassornis 050501.jpg File:White-backed Duck RWD3.jpg File:Thalassornis leuconotus 5zz.jpg File:Thalassornis leuconotus 2zz.jpg

Distribution and habitat

White-backed ducks live in Africa, especially between

Senegal Senegal, officially the Republic of Senegal, is the westernmost country in West Africa, situated on the Atlantic Ocean coastline. It borders Mauritania to Mauritania–Senegal border, the north, Mali to Mali–Senegal border, the east, Guinea t ...

and

Chad Chad, officially the Republic of Chad, is a landlocked country at the crossroads of North Africa, North and Central Africa. It is bordered by Libya to Chad–Libya border, the north, Sudan to Chad–Sudan border, the east, the Central Afric ...

in the west,

Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...

in the east, and

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

in the south. Their habitat consists of lakes, ponds, swamps and marshes where they are well camouflaged against predators.

Subspecies

There are two subspecies, ''Thalassornis leuconotus leuconotus'' and ''Thalassornis leuconotus insularis''. The latter lives entirely on

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

and is considered endangered as a result of hunting, habitat loss and the introduction of competing exotic species.

Conservation

The white-backed duck is one of the species to which the ''Agreement on the Conservation of African-Eurasian Migratory Waterbirds'' ( AEWA) applies. Woolaver and Nichols conducted a nesting survey of the Madagascar race in 2001 at Lake Antsamaka in western Madagascar. They found a total of 37, indicating the significance of this single site for the conservation of this insular subspecies. Young, et al. (2006) suggested that an earlier population estimate of 2,500–5,000 total birds in Madagascar by Delany and Scott may be too optimistic. Its African population may be in the range of 10,000 to 25,000 birds.Johnsgard, P. 2010

Notes

References

* Kear, J. 2005. ''Ducks, Geese and Swans.'' 2 vol. Oxford, UK: Oxford Univ. Press. * Woolaver. L., and R. Nichols. 2006. Nesting survey of the white-backed duck at Lake Antsamaka in western Madagascar. ''TWSG News'' 15:34–37. * Young, H. G., R. Safford, F. Hawkins, R. Rabarisoa, & F. Razafindrajao, 2006. Madagascar whitebacked duck: What is its true status? ''TWSG News'' 15:38–40. *Delany, S., & D. A. Scott. 2006. ''Waterfowl Population Estimates.'' 4th ed. Netherlands: Wetlands International. * Johnsgard, P. 201
"The World’s Waterfowl in the 21st Century: A 2010 Supplement to Ducks, Geese, and Swans of the World"

External links

Species text in The Atlas of Southern African Birds
{{Taxonbar, from=Q529857 white-backed duck Birds of Sub-Saharan Africa white-backed duck white-backed duck