Arboreal Duck
| Arboreal Duck | ||||||||||||
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Hard arboreal duck ( Pteronetta hartlaubii ) |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Pteronetta | ||||||||||||
| Salvadori , 1895 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Pteronetta hartlaubii | ||||||||||||
| ( Cassin , 1859) |
The hard arboreal duck ( Pteronetta hartlaubii ) is a duck bird from the tribe of swimming ducks and the only representative of the genus Pteronetta . It occurs only in the African rainforest belt around the equator. It is named after the German ornithologist Karel Johan Gustav Hartlaub . Two subspecies were distinguished in the first half of the 20th century. The distinguishing feature was the size of the white spots on the face. However, this characteristic varies greatly throughout the population, so that it is not considered sufficient to distinguish between subspecies here.
Appearance
The hard arboreal duck has a body length of 56 to 58 centimeters. The females weigh an average of almost 800 grams, the males just under one kilogram. The body size of the hard arboreal duck roughly corresponds to that of the mallard . The hard arboreal duck is unmistakable in its natural range. The blue wing mirror is particularly noticeable in flight .
The species wears a year-round dress and has no conspicuous sexual dimorphism . The male's head and neck are black. There is a white spot on the front of the drake. In individual males this can extend to the head plate. The rest of the body fletching is reddish-brown in color. On the trunk, the longer shoulder feathers and on the tail it turns a darker brown. The light blue front wing cover contrasts strikingly with the olive brown of the arm wings. The underside of the wing is dark brown. The beak is black except for the front area. The front beak area is reddish gray. In the male, the base of the beak swells during the breeding season. The feet and legs are dark brown and can be tinged with yellow or green. The webbed feet are blackish. The iris is red-brown. The females are like the males. With them, however, the white patch of color on the face is smaller and with some females is even absent completely. Overall, they are slightly smaller in size, their plumage is slightly less contrasting. The red-brown of the iris is a bit more intense. The moulting process in wild arboreal ducks is unknown. The males whisper softly, while the females croak and snarle loudly.
Young birds are similar to females, but with them the feathers on the chest are brightly lined on the underside of the body. The chicks are blackish on the top and yellow on the underside. The chin, neck and face are tinged with orange. An eye stripe runs through the eye. There is a small black spot at each ear level. There are yellow spots on the wings, as well as on the back and trunk. The feet and beak are black. The chicks have sharp claws and are skilled at climbing.
Distribution and existence
The distribution area of the hard arboreal duck is the tropical rainforest of West and Central Africa. It ranges from Sierra Leone in western Africa to the southwest of Sudan . In the south it occurs to the south of the Democratic Republic of the Congo . The distribution area is now disjoint and is divided into two large distribution areas, as it is missing in the east of the Ivory Coast as well as in Togo and Benin . There are also gaps in the distribution within the two large distribution areas due to deforestation.
The population of this forest duck species is difficult to determine. The West African population is believed to be less than 1,000 individuals and appears to be in sharp decline. The decline in the population is particularly noticeable in Ghana , where the hard arboreal duck was still numerous in the 1970s. The population that lives in Central Africa still includes around 10,000 to 50,000 individuals. In Cameroon , the Republic of the Congo , Gabon and the Democratic Republic of the Congo , it is still quite numerous in forested regions. The population development in Nigeria is comparable to that in Ghana. This species is also comparatively rare in Sudan.
habitat
The arboreal duck is a resident bird that prefers to be found on small rivers and ponds in rainforests and gallery forests. In the coastal area and some inland regions, it also inhabits moist forest savannahs and mangroves . It often towers and is mainly observed individually, in pairs or in small groups. If there are more than 30 arboreal ducks, they are probably moulting groups. It does not socialize with other duck species.
Reproduction
So far, only a few observations from the wild have been made about the reproduction of the arboreal duck. As far as we know so far, the breeding season seems to fall predominantly in the rainy season. The couples presumably occupy territories all year round. Hard arboreal ducks kept in captivity show pronounced territorial behavior. The pair bond is apparently perennial.
In the case of hard arboreal ducks kept in captivity, the nest cavity was covered with gray down. The full clutch consisted of eight eggs on average. The shell of the eggs is cream-colored. They weigh an average of 68 grams and are laid by the female one day apart. The incubation period is 32 days. Newly hatched chicks weigh around 41 grams. The male is involved in the rearing of the chicks and the young birds fledge after 56 to 60 days.
Systematics
The classification of the arboreal duck to the swimming ducks is controversial. Analyzes of the DNA suggest that this species, together with the blue-winged goose, which only occurs in the Ethiopian highlands , could represent a separate subfamily of duck birds. This is also indicated by the pattern of wing coloration, which is an important classification criterion for ducks when classified solely on the basis of morphological features. The wing coloration characteristic of the hard arboreand the American blue-winged duck is unique among ducks.
Attitude in Europe
Until 1949 the hard arboreal duck was imported into Europe only three times. The British Wildfowl Trust began to keep this species in the 1950s and was able to start conservation breeding with this duck species from 1959, from which 60 young birds were raised by 1968. In Germany, the Berlin Zoological Garden kept this species of duck from 1960 and the Berlin Zoo from 1974. The first German breeding took place in 1977. Because of their territoriality, they are mainly kept in individual enclosures. You also need a shelter. Overall, they are rarely shown in zoos.
supporting documents
Individual evidence
- ^ Kear, p. 459
- ^ Kear, p. 459
- ↑ Kolbe, p. 170
- ^ Kear, p. 459
- ↑ Kolbe, p. 171
- ↑ Kolbe, p. 171
- ^ Kear, p. 460
- ^ Kear, p. 460
- ↑ Kear, p. 461
- ↑ Kolbe, p. 171
- ↑ Kear, p. 461
- ↑ Kevin P. Johnson, Sorenson, Michael D .: Phylogeny and biogeography of dabbling ducks (genus Anas): a comparison of molecular and morphological evidence . (PDF) In: Auk . 116, No. 3, 1999, pp. 792-805.
- ↑ Kolbe, p. 172
- ↑ Kolbe, p. 172
literature
- Janet Kear (Ed.): Ducks, Geese and Swans. Oxford University Press, 2005, ISBN 0-19-854645-9 .
- Hartmut Kolbe: The world's ducks. Ulmer Verlag 1999, ISBN 3-8001-7442-1
Web links
- Pteronetta hartlaubii inthe IUCN 2013 Red List of Threatened Species . Listed by: BirdLife International, 2012. Retrieved February 6, 2014.