Cap saw
| Cap saw | ||||||||||||
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Cap saws, females in front, males behind |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Lophodytes | ||||||||||||
| Reichenbach , 1853 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Lophodytes cucullatus | ||||||||||||
| ( Linnaeus , 1758) |
The Hooded Merganser ( Lophodytes cucullatus ) is a kind from the family of ducks . Within this family he is sometimes assigned to the genus Mergus . Even Carl Linnaeus , who for the first time scientifically described the Hooded Merganser in 1758, still ranked him as Mergus cucullatus to the sawyers. Ludwig Reichenbach placed it in its own genus in 1853, called Lophodytes , the only representative of which is the cap saw .
The conspicuous feather hollow gives the bird its name . It is present in both sexes, but in the adult male it is conspicuously black and white.
In Europe the cap saw is a very rare wanderer. It is mostly observed in Great Britain and Ireland. There are no unequivocal observations of wild birds for Central Europe. Almost all of the observations are based on the assumption that they are prisoners .
Distribution area
Breeding area
The cap saw is a breeding bird of the coniferous forest belt of North America , also known as the northern boreal zone . It can be found there on lakes surrounded by forest, in swamp and floodplain areas as well as on the banks of calm flowing rivers. Settlement density within these areas is low, which is attributed to the fact that he uses tree hollows for breeding and competes for these with other species such as wood duck , golden blue duck , buffalo head duck and goosander . It can be observed in the breeding area from April to September.
Wintering areas
The cap saw winters in the estuary areas and in the large bays of the Atlantic and Pacific coasts of North America. It can be observed there from September to mid-February. Cap saws belong to the migratory birds that only cover a relatively short distance on their migration. During their migration, they mostly stay on rivers.
Nevertheless, it does occasionally happen that cap saws get lost on their way to Europe . Since this species is now often kept as an ornamental fowl in Europe, cap sawmills are generally considered refugees in captivity . Only if it can be determined from any ringing that they are North American wild birds are they classified as stray migratory birds.
Duration
According to data from 2002, the IUCN estimates the total population of the cap saw at 270,000 to 390,000 animals and classifies the species as "not endangered".
Appearance
As with many other species from the duck family, the plumage shows a strong sexual dimorphism . The female is inconspicuously feathered with its gray-brown plumage and the short, reddish-brown feather cover. The iris is red-brown, the beak yellowish gray. Females weigh an average of around 550 grams, making them lighter than males, who reach an average weight of around 650 grams.
In the breeding plumage, the male has a very large feathers on the head, which consists of predominantly white feathers that are black on the outside. Two feathers on the inner arm wings are also elongated into black and white decorative feathers. The breast plumage is clearly set off in black and white, while the flanks have a red-brown plumage. The beak is yellowish gray at its base, the iris is yellow. When resting, the male cap saws resemble the females and can be easily distinguished from them by the different iris color and the white breast plumage. Males start moulting in June and change back to their splendid plumage as early as October.
Reproduction
Courtship
The courtship between males and females begins in February in the winter resting areas, shortly before the birds begin their migration to the breeding grounds. Mating already occurs in the winter area. If the birds arrive in the breeding area in April, the courtship intensifies, with the fight for nesting holes.
Brood
Cap saws prefer to use tree hollows for breeding, which can be up to eight meters above the ground. The start of laying depends on the respective territory conditions. In the southernmost area of distribution, the ducks begin to lay as early as the end of April. In the northern distribution area this happens in June. The clutch consists of six to 12 round, shiny white eggs. They are incubated for about 30 days.
The chicks
The chicks are looked after by the female, who stays with them mainly in the shallow water area along the outer vegetation fringes. The downy dress of the chicks is dark brown and has a light throat spot. In their juvenile dress, the young birds resemble the female, although their den is significantly shorter. The young birds are able to fly after about 70 days. They are then abandoned by the female, who retreats to the larger areas of water to moult . Young cap saws reach sexual maturity at around two years of age. The male birds only show a fully developed breeding or splendid dress from the age of three.
food
Cap saws mainly eat small fish, small crustaceans and, during the summer months, also aquatic insects. They prey on them by diving underwater.
Cap sawmills also eat a small amount of aquatic plants.
The cap saw as an ornamental fowl
Cap saws have only been kept as ornamental poultry for a relatively short time . The first breeding took place in the USA in the 1950s. From there, birds were given to the British Wildfowl Trust ; the first breeding successes in Germany did not take place until the 1970s. The Hooded Merganser is now relatively often kept in European zoos and often maintained by private ornamental poultry farmers, as this species is to keep as simple as the remaining merganser species.
Individual evidence
- ↑ Hans-Günther Bauer, Einhard Bezzel and Wolfgang Fiedler (eds.): The compendium of birds in Central Europe: Everything about biology, endangerment and protection. Volume 1: Nonpasseriformes - non-sparrow birds , Aula-Verlag Wiebelsheim, Wiesbaden 2005, ISBN 3-89104-647-2 , p. 141
literature
- T. Bartlett: Ducks And Geese - A Guide To Management. The Crowood Press, 2002, ISBN 1-85223-650-7 .
- Hartmut Kolbe: The world's ducks. Ulmer Verlag, 1999, ISBN 3-8001-7442-1 .
Web links
- Lophodytes cucullatus in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed January 30 of 2009.
- Feathers of the cap saw