Cuckoo duck
| Cuckoo duck | ||||||||||
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Cuckoo Duck ( Heteronetta atricapilla ) |
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| Systematics | ||||||||||
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| Scientific name of the genus | ||||||||||
| Heteronetta | ||||||||||
| Salvadori , 1865 | ||||||||||
| Scientific name of the species | ||||||||||
| Heteronetta atricapilla | ||||||||||
| ( Merrem , 1841) |
The cuckoo duck ( Heteronetta atricapilla ) is a South American species that belongs to the subfamily of rowing ducks. It is the only real brood parasite among ducks and the only brood parasite whose chicks flee the nest. Its brood parasitic behavior has been known since 1918, but for a long time the cuckoo duck was thought to be an optional brood parasite that only occasionally lays eggs in the nests of other bird species. It was only towards the end of the 1960s that it was recognized that the cuckoo duck is an obligatory brood parasite that never raises its offspring itself. Another unusual feature of this species of duck is that the females are significantly larger than the males. This characteristic is also not found in any other species of duck.
Within the subfamily of rowing ducks, this species is considered to be the most primitive. The duck has more shape features of a diving duck . It lacks the stiff tail feathers and the chunky beak characteristic of rowing ducks.
The stock situation of the cuckoo duck is indicated with 
(= least concern - not endangered).
description
The males of the cuckoo ducks weigh an average of 512 grams, the females are on average 10 percent heavier and weigh 562 grams.
The drakes of the cuckoo ducks wear an annual dress in which the head and neck are black and the chin and throat are feathered with white spots. The back plumage is black-brown. The beak is black in the nail and ridge area. The sides are light blue. The base of the beak is red during the breeding season.
Female cuckoo ducks have a dark gray skull. The head sides are gray-white; A light stripe runs over the eye area. The lower sides of the head, the chin and the throat are of a light gray-white. The beak nail and the ridge are black as in the male. The beak sides are gray-blue. Fledglings resemble the female.
The cuckoo duck does not call often, the calls are mostly limited to soft quick quwick quwick calls. When disturbed, they fly up very quickly, unlike other rowing ducks, and fly with rapid wing flapping in a way that is reminiscent of swimming ducks.
Habitat and way of life
Cuckoo ducks live in pairs or in small groups on the edge of the reed belt of small pools and swamps in regions with few trees. The largest population density of cuckoo ducks is in the province of Buenos Aires and in Córdoba in Argentina . Cuckoo ducks are basically resident birds. There are hikes during dry seasons.
Kuckuck ducks are bound to fresh water and use such waters to the shore seams sealed with ledges are passed, as well as on the water-free flooding water plant such as Lemna have. Outside the breeding season, they can also be found on larger lakes and in moats along roads. They then also occasionally use flooded fields and reservoirs.
The diet of the cuckoo ducks is mainly vegetable.
Reproduction
Weller argued that the reverse weight difference between male and female cuckoo ducks, which is unusual for ducks, was not clearly due to the development of brood parasitism in this species. However, the larger body mass enables the female to lay a comparatively large number of eggs.
The breeding season depends on the breeding seasons of the host birds. In the region around Buenos Aires, for example, the breeding season in spring falls from September to mid-December and thus corresponds to that of the Peposaka duck , one of the main host bird species. The eggs are oval and white to isabel in color. They can hardly be distinguished from those of the Peposakaente.
The peposaka duck and coots , ibises , gulls and chimango carakaras are parasitized when they breed on the ground. Weller counted a total of 14 different host bird species. The most important host birds are the yellow-billed coot , the red-fronted coot and the peposaka duck. In these species, the brood parasitism has no negative influence on the reproductive rate of the host parents or reduces it only slightly. Unlike many brood parasitic bird species, cuckoo ducks do not remove an egg from the host bird's nest. The chicks flee the nest within a day or two and do not compete with their nesting siblings for food. Weller therefore referred to the cuckoo duck as the brood parasite who perfected brood parasitism.
It is comparatively unusual for a brood parasite that, according to current knowledge, the cuckoo duck lays several eggs in the nests of host birds. Numerous brood parasitic species limit this to one egg - in these, the nestlings compete with their nesting siblings for food. It is also noticeable that the cuckoo duck also repeatedly lays eggs in nests of species in which little success insists that the chicks successfully leave the nest. Both the Maguaristorch and the Chimangokarakara are among the species that are predators of cuckoo chicks. Cuckoo ducks prefer to lay their eggs in nests that previously only contained one egg. In a single study, this was the case for 73 percent of all nests parasitized by the cuckoo duck. But it also happens that they lay eggs in clutches in which the brood is already well advanced, so that there is little chance that the egg will hatch. Cuckoo chicks hatch after a breeding period of 24 to 25 days. The two coot species, which are the preferred host bird species, breed from the beginning of the first egg-laying 28 to 29 days and around 25 days after the last egg is laid.
While Peposakaenten show no defense behavior against the brood parasitism by the cuckoo ducks, this can be found in the two more frequently parasitized coot species. The two species of coot, which are among the main host birds, cover the eggs in their nests with nesting material or lay their eggs on a layer of cuckoo duck eggs.
In cuckoo ducks kept in human care, their laying behavior could be observed more closely: The drake swims quickly and threateningly towards a nest, so that the host duck leaves the nest. The female of the cuckoo duck then lays her egg in the nest within a few minutes. Eggs were only ever laid when host birds were nesting in the facility. Hatching chicks of the cuckoo ducks leave the nest and join a female duck who is leading the chicks. It does not matter which species the female duck belongs to.
Attitude in Europe
The first cuckoo ducks that came to Europe were acquired by Hagenbeck's zoo in 1957 . The world's first breeding was achieved in 1977 by the British Wildfowl Trust . The first German offspring took place in 1986 in Wuppertal Zoo and Berlin Zoo . Overall, however, very few cuckoo ducks were kept in Europe up to the turn of the millennium.
literature
- T. Bartlett: Ducks And Geese - A Guide To Management. The Crowood Press, 2002, ISBN 1-85223-650-7 .
- NB Davies: Cuckoos, Cowbirds and Other Cheats . T & AD Poyser, London 2000, ISBN 0-85661-135-2 .
- Paul A. Johnsgard: The Avian Brood Parasites - Deception at the Nest . Oxford University Press, Oxford 1997, ISBN 0-19-511042-0 .
- Hartmut Kolbe: The world's ducks. Ulmer Verlag 1999, ISBN 3-8001-7442-1
- MW Weller: The breeding biology of the parasitic black-headed duck , Living Bird 7: 169-208.
Web links
- Heteronetta atricapilla onthe IUCN Red List of Threatened Species .
- Videos, photos and sound recordings of Heteronetta atricapilla in the Internet Bird Collection
- Cuckoo duck calls in Xeno-canto
Individual evidence
- ↑ a b c Johnsgard: The Avian Brood Parasites . P. 111
- ↑ Davies: Cuckoos, Cowbirds and Other Cheats. P. 24.
- ^ McCracken, Kevin G .; Harshman, John; McClellan, David A. & Afton, Alan D .: Data set incongruence and correlated character evolution: An example of functional convergence in the hind-limbs of stifftail diving ducks; . Systematic Biology 48 : 683-714. PDF full text ( Memento of the original from June 14, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Heteronetta atricapilla in the endangered Red List species the IUCN ., Called on September 3, 2016.
- ^ A b Johnsgard: The Avian Brood Parasites . P. 112.
- ↑ Cuckoo Duck's Calls on Xeno-canto , accessed on September 3, 2016
- ↑ Johnsgard: The Avian Brood Parasites . P. 113.
- ↑ a b c d e f Johnsgard: The Avian Brood Parasites . P. 114.
- ^ A b Weller: The breeding biology of the parasitic black-headed duck , Living Bird 7: pp. 169-208.
- ^ Kolbe, p. 86
- ^ A b Johnsgard: The Avian Brood Parasites . P. 115.
- ↑ Kolbe, p. 89
