White-backed Duck
Encyclopedia
The White-backed Duck 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 duck
s in the subfamily Oxyurinae
. It is the only member of the genus Thalassornis.
These bird
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
. From danger, they also escape preferentially by diving; hence, the namesake white back is hardly visible in life.
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.
There are two subspecies, Thalassornis leuconotus leuconotus and Thalassornis leuconotus insularis. The latter lives entirely on Madagascar
and is considered to be endangered by hunting, habitat loss and the introduction of competing exotic species.
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 (2006) 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 (Delany & Scott, 2002) may be too optimistic. Its African population may be in the range of 10,000 to 25,000 birds (Kear, 2005)." (Johnsgard, 2010)
Anatidae
Anatidae is the biological family of birds that includes ducks, geese and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica and on most of the world's islands and island groups...
. It is distinct from all other ducks, but most closely related to the whistling ducks in the subfamily Dendrocygninae
Dendrocygninae
The whistling ducks or tree ducks are a subfamily, Dendrocygninae of the duck, goose and swan family of birds, Anatidae. In other taxonomical approaches, they are either considered a separate family "Dendrocygnidae", or a tribe "Dendrocygnini" in the goose subfamily Anserinae The whistling ducks or...
, though also showing some similarities to the stiff-tailed duck
Stiff-tailed duck
The stiff-tailed ducks are part of the Oxyurinae subfamily of ducks. All have, as their name implies, long stiff tail feathers, which are erected when the bird is at rest. All have relatively large swollen bills.These are freshwater diving ducks...
s in the subfamily Oxyurinae
Oxyurinae
Oxyurinae is a subfamily of the duck, goose and swan family of birds, Anatidae. It has been subject of considerable debate about its validity and circumscription. Most of its members have long stiff tail feathers which are erected when the bird is at rest, and relatively large swollen bills...
. It is the only member of the genus Thalassornis.
These bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
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
Nymphaeaceae
Nymphaeaceae is a family of flowering plants. Members of this family are commonly called water lilies and live in freshwater areas in temperate and tropical climates around the world. The family contains eight genera. There are about 70 species of water lilies around the world. The genus...
. From danger, they also escape preferentially by diving; hence, the namesake white back is hardly visible in life.
White-backed Ducks live in southern Africa, especially between Senegal
Senegal
Senegal , officially the Republic of Senegal , is a country in western Africa. It owes its name to the Sénégal River that borders it to the east and north...
and Chad
Chad
Chad , officially known as the Republic of Chad, is a landlocked country in Central Africa. It is bordered by Libya to the north, Sudan to the east, the Central African Republic to the south, Cameroon and Nigeria to the southwest, and Niger to the west...
in the west and Ethiopia
Ethiopia
Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...
and South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
in the east. Their habitat consists of lakes, ponds, swamps and marshes where they are well camouflaged against predators.
There are two subspecies, Thalassornis leuconotus leuconotus and Thalassornis leuconotus insularis. The latter lives entirely on Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
and is considered to be endangered by hunting, habitat loss and the introduction of competing exotic species.
The White-backed Duck is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA
AEWA
The Agreement on the Conservation of African-Eurasian Migratory Waterbirds is the largest of its kind developed so far under the Bonn Convention. It was concluded on 16 June 1995 at The Hague, the Netherlands and entered into force on 1 November 1999 after the required number of at least fourteen...
) applies.
Woolaver and Nichols (2006) 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 (Delany & Scott, 2002) may be too optimistic. Its African population may be in the range of 10,000 to 25,000 birds (Kear, 2005)." (Johnsgard, 2010)