[order] ANSERIFORMES | [family] Anatidae | [latin] Thalassornis leuconotus | [authority] Eyton, 1838 | [UK] White-backed Duck | [FR] Erisamture a dos blanc | [DE] Weissrucken-Pfeifgans | [ES] Pato Dorsiblanco | [NL] Witrugeend | [copyright picture] Jan Harteman
The White-backed Duck (Thalassornis leuconotus) is a waterbird of the family Anatidae. It is distinct from all other ducks, but most closely related to the whistling ducks in the subfamily Dendrocygninae, though also showing some similarities to the stiff-tailed ducks in the subfamily Oxyurinae. It is the only member of the genus Thalassornis.
Head and neck buff speckled with brown, heavies speckling on crown, with foreneck and sides of neck plain buff. White patch near bill. Breast, underparts and upperparts buff with black barring, broader barring on flanks than breast and dusky on abdomen. Scapulars brown with buff barring. Rump and uppertail coverts black with white tipping. Lower back white, not visible when wings folded.
Wing coverts dark brown with buff and white markings. Flight feathers paler brown.
Listen to the sound of White-backed Duck
Copyright remark: Most sounds derived from xeno-canto
Africa : widespread. White-backed Ducks live in southern Africa, especially between Senegal and Chad in the west and Ethiopia and South Africa in the east.
Their habitat consists of lakes, ponds, swamps and marshes where they are well camouflaged against predators.
The nest is constructed of vegetation either floating on or up to 45 cm above water amongst reedbeds or papyrus beds rarely with down or feather lining, or on the ground in waterside vegetation on small islands. Usually well concealed from above. The species will occasionally use the abandoned nests of grebes or coots as nest bases. Clutch size is 4-10 eggs which are incubated for about 4-5 weeks. The young are brooded for another 2-3 months. Both sexes construct the nest. Sometimes nest in small groups with several nests close together. Both sexes incubate, with the male performing most of the incubation and also actively defending his mate and nest. Newly-hatched are brooded on the nest. Both parents care for the ducklings.
The species breeds in solitary pairs or loose groups, dispersing after breeding (as water levels drop) to gather in small flocks of 20 to 100 individuals on more permanent lakes and marshes. The species is crepuscular and obtains its food almost solely by diving. Although the species is predominantly herbivorous (taking the seeds and leaves of aquatic plants such as water-lilies Nymphaea spp. and Polygonum spp.) the young may feed on Chironomid insect larvae.
copyright: Josep del Hoyo
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size may be moderately small to large, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The species is threatened by the modification of wetlands especially where the native aquatic flora is affected, e.g. through the introduction of herbivorous fish, the introduction of exotic plants, deterioration in water quality as a result of deforestation and soil erosion in catchment areas, and pollution. The species has also declined in Madagascar due to hunting and trapping, and its large eggs are especially prized as food by people living near wetlands. A distinctive species placed in its own genus, it was formerly considered to be closer to stifftails (tribe Oxyurini), but is now usually regarded as an atypical whistling duck and included in tribe Dendrocygnini. Some isolate it in its own tribe (Thalassornini) or even subfamily (Thalassorninae).
This species is partially migratory or semi-nomadic, making local dispersive movements during the rainy season to take advantage of temporary wetlands. The timing of breeding varies geographically although it generally coincides with periods of higher or more stable water levels.