Black duck

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Black duck
Black duck

Black duck

Systematics
Order : Goose birds (Anseriformes)
Family : Duck birds (Anatidae)
Subfamily : Anatinae
Tribe : Swimming ducks (anatini)
Genre : Actual ducks ( Anas )
Type : Black duck
Scientific name
Anas sparsa
Eyton , 1838
Yellow-billed ducks, which are among the most common ducks in the open African savannah landscapes, can be identified by their different beak colors

The black duck ( Anas sparsa ) is a duck bird that is assigned to the swimming ducks. The species occurs exclusively in Africa. There are two subspecies. The nominate form is the South African black duck ( Anas sparsa sparsa ), which is widespread in southern Africa. A distinction is also made between the significantly lighter and smaller Abyssinian black duck ( Anas sparsa leucostigma ). The form formerly known as West African black duck ( Anas sparsa maclatchyi ) is no longer regarded as a subspecies, but is an isolated rainforest variant of the Abyssinian black duck .

Appearance

General characteristics and possibilities of confusion with other ducks

The black duck is a dark brown duck with striking white or cream-colored markings on the upper body. It reaches a body length between 50 and 55 centimeters. The males weigh an average of 1086 grams, the females 914. It can be confused with the yellow-billed duck . The body of the black duck looks more elongated due to the slightly longer tail. The black duck also has a shorter neck than the yellow-billed duck. However, the most striking distinguishing feature between these two African duck species is the color of the beak. While the yellow-billed duck has a bright yellow beak, the beak of the black duck is dark. The blue-green wing mirror with the white border can also be clearly seen in the flight image .

Feather dress of adult black ducks

The species has no sexual dimorphism . The ducks also wear a year-round dress. The plumage is predominantly soot-brown. The underside of the body is predominantly brown, but because some feathers have a pale hem, they can also appear spotted on the underside. Some black ducks also have white spots on their chin and neck. The upper wing covers and the upper tail cover have a white transverse banding. The tail feathers also have two rows of white spots. The spotting of the upper side of the body is otherwise very different from one individual to another. The two subspecies can be distinguished by the color of the beak. The beak of the South African black duck is slate gray. In the Abyssinian black duck, the beak at the beak root is partially pink, as is the lower bill. The beak nail is black in both subspecies. The Abyssinian black duck has overall lighter plumage that is more gray-brown. With her, the white transverse ligament is also narrower and sparse. The full moult of the black ducks in South Africa occurs between October and December. After shedding the feathers, the tail and small plumage moults follow. They are unable to fly for a period of 25 to 26 days during the moulting season. Another small plumage moult occurs in the months of February to May.

Chick's plumage

The chicks are black on top and have three pale yellow spots on each side of the body. They are white on the underside of the body. A white chest band runs at the level of the upper chest. The chin, head and forehead are also white. The face has black and pale yellow stripes. The stripe around the eyes, on the other hand, is whitish, and a black bridle runs over the eye. The beak is black, the legs are light gray.

Distribution and existence

Black ducks colonize sub-Saharan Africa. Their distribution area extends from Ethiopia in the east of the African continent to the southern tip of the African continent. There are isolated populations in Gabon and Cameroon . The species is rare in Angola and Namibia and in western Equatorial Africa . The South African black duck has its northernmost distribution area in southern Zimbabwe . The Abyssinian black duck is common in Gabon, Cameroon, Angola, the Democratic Republic of the Congo , East Africa, Sudan, and Ethiopia.

Their habitat requirements and the occupation of large areas by individual couples limit the population. The population is estimated at 1,000 to 5,000 individuals for Gabon, 100 for the Conakry highlands and 1,000 to 5,000 for the Cameroon highlands. Around 2,000 to 10,000 black ducks live in the highlands of Ethiopia. In East Africa the population is between 10,000 and 25,000 black ducks and the population of South African black ducks in southern Africa is between 20,000 and 50,000 ducks.

habitat

The black duck can be found mainly on shallow rivers with strong water movement. It mainly inhabits rivers in the highlands and in wooded regions. In contrast to the New Zealand black-billed duck or the South American torrent , it shows no morphological adaptations to a life in fast-flowing waters. Occasionally, it is also found on quieter sections of the river and in still waters near the river. In South Africa it predominantly populates bodies of water that are between 3 and 14 meters wide and one meter deep. In Abyssinia it reaches an altitude of up to 4,000 meters above sea level.

In waters with rich bank vegetation and overhanging banks, it is often hardly to be seen because of its inconspicuous plumage. The black duck is a very territorial duck during the breeding season that occupies and actively defends a stretch of river. The couple checks the entire length of the river on a daily basis. The pair bond is strong, but it weakens a little outside of the breeding season. But it is very likely that the pair bond exists over several reproductive periods. Black ducks are resident birds that stay in their territory all year round. Only during the moulting season do they occasionally form small flocks with other black ducks occupying neighboring territories.

Food and diet

Black ducks take their food from the surface of the water. But they also dig with their beak, head or head and neck submerged when examining rocks in rapids. Adult black ducks also occasionally dive for seeds. It is an omnivorous species of duck that also looks for plant seeds on the banks of the river. However, the largest portion of the diet is made up of small organisms such as water snails and insects, as well as fish and terrestrial invertebrates. The duck is diurnal. Food intake alternates with feathers cleaning and resting on stones in the water. During the day, couples look for feeding grounds throughout their territory. You alternate between the individual places on the fly and follow the watercourse.

Reproduction

Black ducks lack the extensive courtship ritual that is characteristic of many other swimming ducks. The breeding season varies from region to region. In the extreme south of Africa, the breeding season falls from July to December and has its peak in September. In Zimbabwe and Zambia, they breed from May to August.

The nests are usually built on the bank. Exceptionally, however, it also breeds in hollow trees. The nesting trough is covered with plenty of down. The eggs are pale yellow and shiny. They are very large in relation to the size of this duck. The full clutch consists of four to eight eggs. The laying interval is 24 hours. The female breeds alone. The incubation period is 25 days. The chicks are also led by the female alone. The young ducks can fledge at nine to ten weeks.

Keeping in human care

Black ducks first came to the Netherlands from Natal in 1914 . The world's first breeding in human care took place in 1916. A more intensive keeping took place only after the 1960s. The species is shown more often in large zoos. Since it is sensitive to cold, it may need a shelter.

supporting documents

Individual evidence

  1. ↑ Kolbe, p. 205
  2. ↑ Kear, p. 507
  3. ↑ Kolbe, p. 206
  4. ↑ Kolbe, p. 206
  5. ↑ Kear, p. 507
  6. ↑ Kear, p. 507
  7. ↑ Kolbe, p. 206
  8. ↑ Kear, p. 507
  9. ↑ Kolbe, p. 207
  10. ↑ Kear, p. 509
  11. ↑ Kolbe, p. 207

literature

Web links