Andaman white-throated duck
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Andaman white-throated duck ( Anas albogularis ) |
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| Anas albogularis | ||||||||||||
| ( Hume , 1873) |
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The Andaman white-throated duck ( Anas albogularis ) is a duck bird that is counted among the swimming ducks . Its species status is controversial, as some authors classify it as a subspecies of the Sunda white-throated duck. In any case, it is closely related to the Sunda white-throated duck and the Australian white-throated duck and is sometimes combined with them as a species group of white-throated ducks . The Andaman white-throated duck is an endemic species of duck of the Andaman Islands .
Appearance
The Andaman White-throated Duck has neither seasonal dimorphism nor pronounced sexual dimorphism . It largely resembles the Australian white-throated duck in its appearance, but is a little darker overall and the gray plumage is a bit browner overall.
The head of the Andaman white-throated duck is almost uniformly black. The species also has a white eye ring. White spots of color can also be on the face, throat, or front neck. The forehead is slightly arched, although the arch is not as pronounced as in the Sunda white-throated duck.
The moulting process has not yet been adequately described for this species of duck. However, it is probably comparable to that of the Australian white-throated duck.
The chicks of the Andaman white-throated duck are also very similar to those of the Australian white-throated duck. They are gray-brown on the top of the body and have a gray-white underside. The facial drawing is variable.
Distribution and existence
The Andaman white-throated duck occurs exclusively on the Andaman Islands. In the north it occurs there on two islands. It also colonizes the central Andaman Islands and the South Islands. It is absent on the nearby Nicobar Islands . The Andaman white-throated duck seldom reaches the coast of Myanmar as a stray visitor.
The population of Andaman white-throated ducks is estimated at 500 to 700 individuals. BirdLife International does not include the Andaman White-throated Duck in its Endangered Species List. This is due to the fact that it is considered here as a subspecies of the Sunda white-throated duck . Due to the small population and the relatively small area of distribution, however, it is classified as threatened by other organizations such as the Threatened Waterfowl Specialist Group. Besides hunting, the main threats are the draining of wetlands for road construction and agriculture.
Way of life
The Andaman white-throated duck occurs mainly in mangrove swamps on the coast. It also colonizes the few freshwater lagoons on the Andamen and also uses rice fields. Small forest ponds inland are also used as breeding grounds.
Very little is known about reproduction. The breeding season begins in early July. The nests are built both in tree hollows and on the ground. A full clutch probably contains fewer than ten eggs. The eggs are off-white and not shiny. Measuring 49 millimeters by 36.2 millimeters, they are large in relation to the size of the female. The chicks are led by both parent birds.
Keeping in human care
Like all white-throated ducks, the Andaman white-throated duck has relatively inconspicuous plumage. It therefore meets with relatively little interest from private owners. The London Zoo first bred Andaman white-throated ducks in 1909. The breeding was very successful in the beginning. In later years fewer juvenile ducks grew up than adult ducks died. The British Wildfowl Trust , which often plays a major role in the conservation breeding of rare duck species, succeeded in breeding in 1982. In 1983 and 1984, however, the entire offspring group died out. In 2005 there were no white-throated Andaman ducks outside of the Andaman Islands.
literature
- Janet Kear (Ed.): Ducks, Geese and Swans . Oxford University Press, 2005, ISBN 0-19-854645-9
- Hartmut Kolbe; Die Entenvögel der Welt , Ulmer Verlag 1999, ISBN 3-8001-7442-1