White-backed Duck Thalassornis leuconotus Scientific name definitions

38–43 cm (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); male 650–790 g, female 625–765 g (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Black rump and uppertail-coverts with narrow white barring; mid back black. Sexes alike (2 Safford, R. J., and A. F. A. Hawkins, Editors (2013). The Birds of Africa. Volume 8. The Malagasy Region. Christopher Helm, London, UK. Close ). Juvenile darker with smaller loral spot, less distinctively patterned with black-spotted sides of face and neck. Race insularis  is smaller and more vividly marked, with darker crown and crest, blacker upperparts with more cinnamon-brown (less buffy) barring and lacks pale underparts (2 Safford, R. J., and A. F. A. Hawkins, Editors (2013). The Birds of Africa. Volume 8. The Malagasy Region. Christopher Helm, London, UK. Close ), sometimes recalling juvenile of nominate race (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); also reported to be slightly smaller (2 Safford, R. J., and A. F. A. Hawkins, Editors (2013). The Birds of Africa. Volume 8. The Malagasy Region. Christopher Helm, London, UK. Close ).

Editor's Note: This article requires further editing work to merge existing content into the appropriate Subspecies sections. Please bear with us while this update takes place.

Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Favours a variety of quiet freshwater lakes , pools, lagoons, marshes and swamps, even suburban dams (3 Dowsett-Lemaire, F., and R. J. Dowsett (2006). The Birds of Malawi: An Atlas and Handbook. Tauraco Press & Aves, Liège, Belgium. Close ) and slow-flowing rivers (4 Ash, J. S., and J. Atkins (2009). Birds of Ethiopia and Eritrea: An Atlas of Distribution. Christopher Helm, London, UK. Close ), provided they are characterized by shallow waters and abundant floating vegetation  , especially water lilies  (Nymphaea) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); prefers forested lakes in Madagascar (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Not usually found in open waters. Recorded to at least 1300 m in Madagascar (though perhaps only formerly) (2 Safford, R. J., and A. F. A. Hawkins, Editors (2013). The Birds of Africa. Volume 8. The Malagasy Region. Christopher Helm, London, UK. Close ), to 1800 in Uganda (5 Carswell, M., D. Pomeroy, J. Reynolds, and H. Tushabe (2005). The Bird Atlas of Uganda. British Ornithologists’ Club and British Ornithologists' Union, Oxford, UK. Close ) and Zambia (6 Dowsett, R. J., D. R. Aspinwall, and F. Dowsett-Lemaire (2008). The Birds of Zambia. Tauraco Press & Aves, Liège, Belgium. Close ), and to 3000 m in Kenya (7 Lewis, A. D., and D. E. Pomeroy (1989). A Bird Atlas of Kenya. A. A. Balkema, Rotterdam, the Netherlands. Close ).

Mostly sedentary, with some local or semi-nomadic movements largely related to availability of water and perhaps more general post-breeding dispersal, at least on Madagascar, as water levels drop, when tends to congregate on more stable and permanent waterbodies (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). In Zambia, a ringed bird moved 180 km NE from its original trapping site (6 Dowsett, R. J., D. R. Aspinwall, and F. Dowsett-Lemaire (2008). The Birds of Zambia. Tauraco Press & Aves, Liège, Belgium. Close ) and pair of vagrants collected in S Somalia (late Jun 1901) were some distance from known range (8 Ash, J. S., and J. E. Miskell (1998). Birds of Somalia. Pica Press, Robertsbridge, UK. Close ), as were other wandering individuals recorded in Mauritania, Burkina Faso, Togo and N Cameroon (9 Borrow, N., and R. Demey (2001). Birds of Western Africa. Christopher Helm, London, UK. Close ). Concentrations of up to 550 birds recorded in non-breeding season in Malawi (3 Dowsett-Lemaire, F., and R. J. Dowsett (2006). The Birds of Malawi: An Atlas and Handbook. Tauraco Press & Aves, Liège, Belgium. Close ). Seldom flies during day.

Eminently vegetarian, principally seeds and leaves of aquatic plants, especially water lilies (Nymphaea) and floating hearts (Nymphoides) (2 Safford, R. J., and A. F. A. Hawkins, Editors (2013). The Birds of Africa. Volume 8. The Malagasy Region. Christopher Helm, London, UK. Close ); stomach contents of two birds in Malawi contained seeds of Paspalidium geminatum, Nymphaea spp., Aeschynomene pfundii, among others (3 Dowsett-Lemaire, F., and R. J. Dowsett (2006). The Birds of Malawi: An Atlas and Handbook. Tauraco Press & Aves, Liège, Belgium. Close ). Young feed mainly on insect larvae (Chironomidae), aquatic invertebrates (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ) and Polygonum seeds. Virtually all food obtained by diving in shallow waters, and appears to most active early morning and evening (9 Borrow, N., and R. Demey (2001). Birds of Western Africa. Christopher Helm, London, UK. Close ).

Considered to be usually silent, although both sexes give whistled calls, e.g. “whit-wee” or “si-wee-wheet” (9 Borrow, N., and R. Demey (2001). Birds of Western Africa. Christopher Helm, London, UK. Close ) and a double-noted “curwee”, as well as soft, flute-like trills around nest, which is defended using a hissing note (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); flight calls regarded as similar to those of some Dendrocygna (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ).

Season variable according to locality, generally coincides with period of higher and more stable water levels: Dec in Senegal (10 Condamin, M. (1991). Nouvelle observation sur la nidification de l’Érismature à dos blanc Thalassornis leuconotus au Sénégal. Alauda. 59(3): 182. Close ), Sept in Ethiopia (4 Ash, J. S., and J. Atkins (2009). Birds of Ethiopia and Eritrea: An Atlas of Distribution. Christopher Helm, London, UK. Close ), Jul in Congo-Kinshasa (11 Demey, R., P. Herroelen, and T. Pedersen (2000). Additions and annotations to the avifauna of Congo-Kinshasa (ex-Zaïre). Bulletin of the British Ornithologists' Club 120(3):154–172. Close ), Apr in Uganda (5 Carswell, M., D. Pomeroy, J. Reynolds, and H. Tushabe (2005). The Bird Atlas of Uganda. British Ornithologists’ Club and British Ornithologists' Union, Oxford, UK. Close ), Apr–Aug in Malawi (3 Dowsett-Lemaire, F., and R. J. Dowsett (2006). The Birds of Malawi: An Atlas and Handbook. Tauraco Press & Aves, Liège, Belgium. Close ), Dec–Aug (mainly Apr–Jun) in Zambia (6 Dowsett, R. J., D. R. Aspinwall, and F. Dowsett-Lemaire (2008). The Birds of Zambia. Tauraco Press & Aves, Liège, Belgium. Close ), and Feb–May in Madagascar (2 Safford, R. J., and A. F. A. Hawkins, Editors (2013). The Birds of Africa. Volume 8. The Malagasy Region. Christopher Helm, London, UK. Close ) and South Africa (where nests recorded virtually all months) (12 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ). Not territorial, but pairs remain together for several seasons (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). In single pairs or loose groups (e.g. 37 nests at c. 150-ha L Antsamaka in Madagascar) (2 Safford, R. J., and A. F. A. Hawkins, Editors (2013). The Birds of Africa. Volume 8. The Malagasy Region. Christopher Helm, London, UK. Close ), with nests sometimes just 10 m apart (12 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ); nest built (by both sexes) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ) with weeds, usually lined with fine vegetable matter, rarely with some down or feathers (30–34 cm wide and 11–25 cm deep) (12 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ), hidden amidst reedbeds or Juncus, in water up to 1·5 m deep (3 Dowsett-Lemaire, F., and R. J. Dowsett (2006). The Birds of Malawi: An Atlas and Handbook. Tauraco Press & Aves, Liège, Belgium. Close ), or on small islands of vegetation, often with a canopy (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ) and ramp leading to water; two nests in Madagascar were constructed below those of Purple (African) Swamphens (Porphyrio porphyrio madagascariensis) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Clutch generally 4–10 (occasionally fewer) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ) chocolate-brown eggs (colour unique among ducks) (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ), laid at one-day intervals (12 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ), size 55–68·8 mm × 44·9–51·7 mm (nominate race), mass 77–94 g (captivity), unusually large for size of adult (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); incubation  29–33 (mean 32) days (12 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ), by both sexes (male mainly by day, female at night) (2 Safford, R. J., and A. F. A. Hawkins, Editors (2013). The Birds of Africa. Volume 8. The Malagasy Region. Christopher Helm, London, UK. Close ); downy chicks  have olivaceous-buff upperparts, with blackish-grey underparts and crown, weigh mean 53·8 g when one day old (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ) and capable of swimming and diving within < 1 day of hatching (2 Safford, R. J., and A. F. A. Hawkins, Editors (2013). The Birds of Africa. Volume 8. The Malagasy Region. Christopher Helm, London, UK. Close ); fledging c. 55 days and cared for by both sexes (12 Tarboton, W. (2001). A Guide to the Nests and Eggs of Southern African Birds. Struik Publishers, Cape Town, South Africa. Close ). No data concerning breeding success, adult survival or longevity in wild, but captive male lived 12 years (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ).

Not globally threatened (Least Concern). Still locally common, but has declined in parts of range (e.g. Uganda) (5 Carswell, M., D. Pomeroy, J. Reynolds, and H. Tushabe (2005). The Bird Atlas of Uganda. British Ornithologists’ Club and British Ornithologists' Union, Oxford, UK. Close ) due to agricultural development and locally (in Malawi) the spread of water hyacinth (Eichhornia crassipes) (3 Dowsett-Lemaire, F., and R. J. Dowsett (2006). The Birds of Malawi: An Atlas and Handbook. Tauraco Press & Aves, Liège, Belgium. Close ), despite some level of adaptability to changed conditions (provided is not persecuted) and loss of habitat (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Mass mortality in gill-nets reported at L Naivasha, Kenya (7 Lewis, A. D., and D. E. Pomeroy (1989). A Bird Atlas of Kenya. A. A. Balkema, Rotterdam, the Netherlands. Close ). Difficult to census as fairly solitary, but apparently very scarce; W African population, apparently isolated from other populations, may be near extinction and suspected to number < 1000 individuals at start of present century (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). Only records from Benin (13 Dowsett, R. J., and F. Dowsett-Lemaire (2011). The avifauna of Benin: additions and corrections. Bulletin of the African Bird Club 18(2):148–167. Close ) and (perhaps) Niger are apparently historical (14 Cheke, R.A. (1996). Historical records of birds from the Republic of Benin. Malimbus. 18(1): 58–59. Close ). Elsewhere, census figures give 500 birds at L Naivasha, Kenya, and also at Kafue Flats, Zambia (in May–Jun) (6 Dowsett, R. J., D. R. Aspinwall, and F. Dowsett-Lemaire (2008). The Birds of Zambia. Tauraco Press & Aves, Liège, Belgium. Close ), with the overall population in E & S Africa estimated most recently (2002) at 10,000–25,000 birds (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ). In South Africa , frequent to uncommon, but presence and numbers unpredictable. Race insularis widespread throughout Madagascar except on High Plateau; formerly quite common, but now rather rare, and by 1989 thought to be extinct at L Aloatra and Vohémar (2 Safford, R. J., and A. F. A. Hawkins, Editors (2013). The Birds of Africa. Volume 8. The Malagasy Region. Christopher Helm, London, UK. Close ); only fairly common now in marshes at Soalala, with largest recent count 118 at L Andranolava (2 Safford, R. J., and A. F. A. Hawkins, Editors (2013). The Birds of Africa. Volume 8. The Malagasy Region. Christopher Helm, London, UK. Close ) and total population most recently estimated at 2500–5000 birds (1 Kear, J., Editor (2005). Ducks, Geese and Swans. Volume 1: General chapters, and Species accounts (Anhima to Salvadorina). Oxford University Press, Oxford, UK. Close ); this decline attributed to trapping and hunting, although species reputed to make rather bad eating.