Whistling geese
| Whistling geese | ||||||||||
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| Dendrocygninae | ||||||||||
| Reichenbach , 1849 | ||||||||||
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The whistling geese (Dendrocygninae) form a subfamily of the goose birds (Anseriformes) family of ducks (Anatidae). They got their German name because of the high-pitched whistling calls they use to communicate with one another. Its generic scientific name, dendrocygna , translates as tree swan, and several features are actually swan-like. Whistling geese, like swans and geese, only change their plumage once a year. Although they are not tied to trees in their way of life, all species spend part of their time building up in small groups on trees floating in the water.
Appearance
Their external appearance, which is considered to be comparatively primitive within the duck birds, i.e. is regarded as characteristic of the common ancestor of these birds, is reminiscent of both real geese (Anserini) and ducks (Anatinae), which is why they are also "whistling ducks" in English. , so called "wigeons". The white-backed goose ( Thalassornis leuconotus ) has numerous anatomical peculiarities that can be regarded as an adaptation to the food procurement through diving, which is characteristic for this species, and which sets it apart from the other species.
The body of the whistling geese is relatively small and stocky, which can easily hide the very upright posture. Characteristic are the long neck, which is stretched far forward when flying, and the also quite long legs, which are placed backwards in flight. The wings are broad but short and colored black from below; Otherwise, the plumage is not very conspicuously patterned and mostly kept in shades of brown, gray or beige, but the flank feathers are often magnificently enlarged. Presumably because some species like to stay in trees, the toe pointing back is elongated compared to other ducks.
The Kuba Whistling Goose, which lives in the forest swamps in the Caribbean, is the largest of its kind and reaches a body length of up to 60 cm. Males and females usually do not differ in body size. However, the females are often heavier than the males during the breeding season. This occurs relatively rarely within the duck family. Both parent birds breed, which is also an exception within this bird family.
Diet and Lifestyle
Whistling geese feed on vegetable food, mostly aquatic plants, but also grass and seeds. Many species are nocturnal and rest or preen their plumage during the day. Some, but not all, like to sit on trees, which has given them their Latin name Dendrocygninae, which translates as "tree swans".
Outside of the breeding season, they usually live gregariously in large flocks, in which they also commute between resting areas and feeding grounds every day. They communicate through the characteristic whistling sounds that are generated during flight by the vibrations of their outer primary feathers and that sound a little deeper in the female.
Whistling geese move skilfully and quickly on both land and water. Occasionally, and in the case of the white-backed goose, very often, they also dive for food. The flight is powerful but quite slow.
distribution
Whistling geese live in tropical and subtropical areas around the world . The Kuba Whistle Goose is native to the Caribbean. The autumn whistling goose and yellow whistling goose occur from the southern USA to northern Argentina , the latter also being native to sub-Saharan Africa and South Asia . The widow whistle goose from South America and Black Africa is also very widespread . The white-backed whistling goose is also native to large parts of Africa . The pygmy whistle goose is native to South Asia, South East Asia, and island India . Island India also there is the spotted whistling duck and the wandering whistling duck . The piper goose is also part of the fauna of Australia, together with the sickle whistle . This means that 3 species are widespread in the Australis , 4 in the Oriental , 3 in the Afrotropic and 4 in the Neotropical . Several species occur simultaneously on several continents and in several fauna regions . They prefer warmer lowland areas where they can stay all year round, but migratory behavior has also been reported outside the tropics .
Reproduction
Whistling geese mate for life, although there are reports of communities of three (two males and one female or vice versa). The bond between the partners is considered to be very close and is regularly strengthened by mutual plumage care.
After copulation has taken place, the couples perform a special ritual in which the wing sides facing the partner are periodically raised. The nests are made in tall reeds , grass or camouflaging bushes on the ground, more rarely on trees, and sometimes lined with down feathers. The latter happens less often when the male is breeding, which is very often the case.
The female lays between ten and fifteen whitish eggs ; if several females are in the same nest, a behavior that is often encountered, it can even be up to a hundred. The young hatch after about four to four and a half weeks and are able to fly after about nine weeks. Almost always both partners take care of the common brood , which is aggressively defended by sibilants, loud whistles and also active attacks.
Danger
None of the species is currently considered endangered in its entirety, but this does not apply to subspecies or local populations. Offspring in captivity are usually unproblematic.
Systematics
There are nine species of whistling geese in two genera :
- Whistling geese in the narrower sense ( Dendrocygna )
- Spotted Whistler Goose ( Dendrocygna guttata )
- Plumed Whistling Duck ( Dendrocygna eytoni )
- Peregrine Whistle Goose ( Dendrocygna arcuata )
- Yellow-breasted Whistler Goose ( Dendrocygna bicolor )
- Kuba Whistler Goose ( Dendrocygna arborea )
- Pygmy Whistling Goose ( Dendrocygna javanica )
- Widow Whistling Goose ( Dendrocygna viduata )
- Autumn Whistling Goose ( Dendrocygna autumnalis )
- White-backed Whistling Geese ( Thalassornis )
- White-backed Whistling Goose ( Thalassornis leuconotus )
The exact relationships between the species can be seen in the following diagram:
| Whistling Geese (Dendrocygninae) |
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Individual references, literature and web links
Individual evidence
- ^ Kear, p. 187
- ↑ Kubapfeifgans on the VZI website ( Memento from November 30, 2010 in the Internet Archive )
- ^ Kear, p. 187
literature
- T. Bartlett: Ducks And Geese - A Guide To Management. The Crowood Press, 2002, ISBN 1-85223-650-7
- 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
