Redhead
| Redhead | ||||||||||||
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Redhead ♂ ( Aythya americana ) |
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| Scientific name | ||||||||||||
| Aythya americana | ||||||||||||
| ( Eyton , 1838) |
The redhead duck ( Aythya americana ) is a diving duck from the duck bird family . It is a North American breeding bird. In its plumage it resembles the giant pochard, which also breeds in North America, and the pochard that is native to Europe . However, the three species can be distinguished by their beak color. The giant pochard has a consistently dark gray bill. The forehead also slopes down flat, making its profile look like that of the eider duck. The pochard has a black beak base so that the beak has a light gray band in the middle. In the redhead, on the other hand, only the tip of the beak is dark gray to black.
features
The males of the red headed duck reach a body length between 44 and 54 centimeters when fully grown. The females are slightly smaller and have a body length between 41.5 and 51.5 centimeters. The weight of this species of duck averages 972 grams. The ducks reach their wintering areas in an emaciated condition and reach their maximum weight shortly before returning to the breeding areas. They then weigh an average of 1110 grams.
Redheads are similar to pochards , but have a rounder head and a slightly darker body. Like many other ducks, redheads show a pronounced sexual dimorphism . The male has a red-brown head, a black chest and a silver body. The male's beak is light gray. The color of the iris is yellow and occasionally even orange.
The female is gray-brown in color. It is characterized by the darkest small plumage in the species group of diving ducks. Their beak is darker gray with a black tip compared to that of the male. The iris is dark brown.
The chicks are strikingly light. The headstock, neck and back are light olive brown. The forehead, face and underside of the body and individual spots on the sides of the body are yellow.
Distribution, existence and habitat
The redhead breeds in western North America and Alaska . Their habitat are lakes and swamps in grasslands. As a migratory bird, it migrates in winter to areas further south of the USA , to Mexico and the Caribbean . It is rare to find refugees in prison in Europe . As Irrgast the redhead appeared so far on in Iceland, the United Kingdom, in Siberia, in Japan, Hawaii and Guam.
No significant change in the population of the red headed duck can be determined. The breeding bird population includes an average of around 601,000 individuals. However, habitat changes have resulted in the wintering locations shifting somewhat. The number of winter guests on the Atlantic coast has declined, while more redheads hibernate on the Gulf of Mexico. A change in vegetation in the Chesapeake Bay and similar coastal areas is suspected to be the cause . There, the underwater vegetation has largely died, which in the giant pochard, a closely related species to the red-headed duck, led to a diet change from vegetable to animal food. The redhead seems to have reacted differently here and to go to other wintering locations.
Reproduction
Redheaded ducks are one of the few duck species in which laying parasitism occurs. The ducks lay their eggs in the nests of other redheaded ducks as well as in the nests of alien ducks. It is particularly common to parasitize giant table ducks. Most nests of this species have at least one redhead egg. Red-headed ducks follow three laying strategies: Part of the population lays the eggs in self-constructed nests, semi-parasitic red-headed ducks lay eggs in the nests of foreign and similar ducks in addition to their own clutch, and the third part of the females does not incubate at all and restricts themselves to their eggs to be deposited in other nests.
The redhead is a basically monogamous species, but it mates anew every year. The mating season begins in mid-winter and intensifies until they return to the breeding areas. It appears that all females are mated, but that yearlings in particular have not yet brood. This tends to increase when the breeding area has poor water conditions.
behavior
Food is aquatic plants and small animals.
supporting documents
Individual evidence
literature
- T. Bartlett: Ducks And Geese - A Guide To Management. The Crowood Press, 2002, ISBN 1-85223-650-7
- John Gooders and Trevor Boyer: Ducks of Britain and the Northern Hemisphere. Dragon's World Ltd, Surrey 1986, ISBN 1-85028-022-3
- 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
- WP reports. Dutch Birding 6/2017: 396.
Web links
- Aythya americana in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed January 31 of 2009.
- Videos, photos and sound recordings of Aythya americana in the Internet Bird Collection