Bog duck
| Bog duck | ||||||||||||
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Moor duck ( Aythya nyroca ), left ♀, right ♂ |
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| Scientific name | ||||||||||||
| Aythya nyroca | ||||||||||||
| ( Güldenstädt , 1770) |
The Ferruginous Duck ( Aythya nyroca ) is a bird art from the family of ducks . It is one of the so-called diving ducks . It is the only European species of duck that has only weak sexual dimorphism . The bog duck is a breeding bird of moderate latitudes, which breeds only sporadically with a few breeding pairs in Western and Central Europe. Its main area of distribution is the steppes and semi-desert zones of Ukraine . In some areas, however, the bog duck is a wintering guest in small numbers. Captive refugees of this easy-to-breed species are also increasingly being observed in the wild .
features
Characteristics of adult bog ducks
The bog duck is the smallest diving duck of the genus Aythya . They reach a body length of 38 to 42 centimeters. Bog ducks weigh an average of around 560 grams.
The breeding dress of the moor duck pelvis is bright maroon with white eyes. The female is similar but paler in color and has brown eyes. In females, the contrast between the color of the back and the rest of the body is less noticeable. Both sexes have white shining under tail-coverts that stand out strikingly against the black-brown of the back. The long beak is dark gray to blue-black in color with a black beak nail; the tip of the beak is lightened, but this is not noticeable in all adult birds. In the plain dress the colors and the color distribution are unchanged from the splendid dress. As with the female in breeding plumage, however, the colors are less bright and noticeable. A clear white wing stripe can be seen in flight.
The voice of the bog duck is hardly noticeable. It is similar to those of the other Aythya species. During the mating season, which falls between January and May, the male calls out a slight wräijö . The call can only be heard within a few meters. The call of the female is a voiceless, rasping rerrr rerrr and can also be heard in flight.
Appearance of the chicks and fledglings
The chick's downy dress is dark brown on the top of the body. The chest, the front and side necks and the sides of the head are yellow and sharply set off from the brown skull and neck. Conspicuous facial signs, however, are missing. The rear torso and thighs are brown. The chicks also have yellowish wing bands and yellowish spots on the upper flanks. The iris is blue.
In newly hatched chicks, the upper bill is initially dark gray-blue. The edges of the beak are flesh-colored to pink. The nail is reddish brown and the lower mandible is flesh-colored. Legs and toes are dark gray to almost black-gray, the webbed feet are black. In the growing bog ducks, the beak brightens. The iris changes color to a pale gray-blue.
distribution
Bog ducks are found in the steppes and semi-deserts of Asia and in Eastern Europe , especially in Hungary , Bulgaria , Romania and the Ukraine . Large populations are also found in Inner Mongolia and on the Tibetan plateau. In Germany it has not appeared as a breeding bird for a long time. Since 1999, however, it has been breeding again in the Saxon - Brandenburg border area and on Lake Constance (Germany 2005: 2–9 breeding pairs), and since 2010 in Mecklenburg-Western Pomerania . In Austria you can find them regularly on Lake Neusiedl . In France, the bog duck breeds sporadically in the region between La Dombes and Lyon . In the south it is found in the Mediterranean area. It occurs in large parts of Asia Minor and Southwest Asia and reaches the eastern limit of its range in the Tibetan highlands.
The wintering areas of the bog duck are mainly found on the Black Sea, the Caspian Sea and the Aral Sea. In extreme weather conditions, the bog ducks move on and then overwinter in Greece, Turkey, Italy and North Africa. Only a very small part of the population crosses the Sahara and winters in Senegal, the Niger Delta and Sudan. The eastern populations move towards Iraq, Iran and also reach Pakistan and northern India. Moor ducks stay in the wintering quarters from the end of October to March. The retreat to the breeding areas lasts from March to April.
habitat
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The preferred habitat of the bog duck is found where the reed forest is replaced by floating leaf plants. It prefers shallow and silting waters with an extensive silting zone, the eutrophication of which is not yet so advanced that a species-rich underwater vegetation is missing. In Hungary it breeds at the soda lakes, among other places. In the desert and steppe zones of Central Asia, it occurs mainly in alkaline waters. On the other hand, they avoid deep waters and fast flowing rivers and streams.
Unlike most other diving duck species, the bog duck is not a very sociable species, even in winter. Troops of several hundred bog ducks are very rare and only occur where the bog duck is generally very common. Usually no more than half a dozen bog ducks can be seen together.
food
Compared to other diving ducks , the bog duck lives mainly vegetarian. The animal component of their food - mainly snails - is taken in together with the plant parts. However, it also eats free-swimming aquatic insects, small crabs as well as tadpoles and young frogs. The vegetable diet consists of green parts of the underwater vegetation and the floating leaf zone as well as seeds, rhizomes and tubers. Foraging includes diving, gudging, or feeding in which the bog duck swims with its neck submerged. Moor ducks spend about fifty percent of their time foraging for food.
Reproduction
The courtship of the bog duck has elements that can also be observed in other diving ducks. Species-specific elements are nodding swimming, in which the head and neck are nodding, and the kinked neck, in which the neck is severely bent. To what extent the mating is already taking place in the wintering places cannot yet be precisely estimated. But since large parts of the courtship only take place in the breeding area, this is an indication that a large part of the population arrives there unmated.
Moor ducks only breed once a year. The nest is created well hidden in the herbaceous vegetation. It can be found either directly on the water or in the immediate vicinity of the shore. Often a passage covered by vegetation leads from the nest to the water. The nest is a thick hollow with parts of the surrounding plants, down and feathers. The nest down that is found in the hollow is brownish-gray and has a small, light center.
The clutch comprises seven to eleven eggs. The eggs are creamy yellow to dark reddish cream in color. Their shape is elliptical to spindle-shaped and measures an average of 52.3 × 38.2 millimeters. They weigh an average of 43 grams. The eggs are laid every 24 hours and the female begins incubating as soon as the clutch is complete. The female breeds alone. At the beginning of the breeding phase, the male remains near the nest and then moves to the moulting area. After the clutch has been lost, the second brood only has about five eggs. However, a second clutch only occurs if the first clutch is lost early during the breeding season. The incubation period is 23 to 27 days. The young fledged after two months.
Duration
At the beginning of the 20th century, the bog duck was one of the most common species within its range. Since then, their numbers have decreased dramatically in some cases. The area she inhabits has also shrunk. In the 1960s, the population in the Ukrainian region from Dniestr to Dniepr and the Moldova region was around 65,000 breeding pairs. The same applies to Spain, where 500 breeding pairs were still breeding at the beginning of the 20th century and now a maximum of four breeding pairs are found annually. The global population is believed to be 40,000 to 100,000 individuals. Reliable population figures are difficult to determine, however, as insufficient information is available, especially from the eastern breeding areas, and this species lives very hidden.
BirdLife International estimated 17,400 to 30,100 breeding pairs for Europe in 2015. The largest numbers of breeding pairs of 6,000 to 15,000 breeding pairs were in Romania, 1,000 in Hungary, 1,000 in Moldova and 500 in Russia. There are also regular broods in Poland, Lithuania, Belarus, Slovakia and several Balkan countries. The species has been breeding sporadically in Switzerland, the Czech Republic, the Netherlands, France and Spain since 1975. The first new broods have been recorded in Germany and Austria since the 1990s. However, it is not always certain whether this is a recovery of the remaining stocks due to intensive protective measures or whether prisoner refugees have settled. The bog duck is often bred because it is easy to breed and also looks attractive. Because of the ban on cropping the wings since 2006 by the Animal Welfare Act in Germany, ducks keep escaping from captivity. The ecological protection station Steinhuder Meer and NABU Lower Saxony carried out a resettlement project at Steinhuder Meer from 2012 to 2015 and released 237 bred bog ducks. There have been broodings in the wild since 2015. In the city of Leipzig , moor ducks are released from the Leipzig Zoo .
In Germany the bog duck is classified as critically endangered (cat. 1) in the red list of threatened breeding bird species.
supporting documents
Individual evidence
- ↑ Kear, p. 659
- ↑ Rutschke, p. 257
- ↑ Hans-Heiner Bergmann; Hans-Wolfgang Helb; Sabine Baumann; The voices of the birds of Europe - 474 bird portraits with 914 calls and chants on 2,200 sonograms , Aula-Verlag, Wiesbaden 2008, ISBN 978-3-89104-710-1 , p. 62
- ↑ Collin Harrison and Peter Castell: Field Guide Bird Nests, Eggs and Nestlings , HarperCollins Publisher, revised edition from 2002, ISBN 0007130392 , p. 76
- ↑ Collin Harrison and Peter Castell: Field Guide Bird Nests, Eggs and Nestlings , HarperCollins Publisher, revised edition from 2002, ISBN 0007130392 , p. 76
- ^ Kear, p. 660
- ↑ Stübing, S. Remarkable Brutvorkommen 2010. In: Sudfeldt, C., R. Dröschmeister, T. Langgemach & J. Wahl (Eds.): Birds in Germany - 2010. DDA, BfN, LAG VSW, Münster. P. 48
- ↑ Gooders and Boyer, p. 95
- ↑ Rutschke, p. 257
- ↑ Gooders and Boyer, p. 96
- ↑ Rutschke, p. 257
- ↑ Gooders and Boyer, p. 96
- ↑ Gooders and Boyer, p. 95
- ↑ Rutschke, p. 259
- ↑ Rutschke, p. 259
- ↑ Collin Harrison and Peter Castell: Field Guide Bird Nests, Eggs and Nestlings , HarperCollins Publisher, revised edition from 2002, ISBN 0007130392 , p. 76
- ^ Kear, p. 660
- ↑ Horst Zimmermann: Moor duck Aytha nyroca . Contributions to the Avifauna Mecklenburg-Western Pomerania, H. 3/2019: 15–22
- ↑ Christoph Grüneberg, Hans-Günther Bauer, Heiko Haupt, Ommo Hüppop, Torsten Ryslavy, Peter Südbeck: Red List of Germany's Breeding Birds , 5 version . In: German Council for Bird Protection (Hrsg.): Reports on bird protection . tape 52 , November 30, 2015.
literature
- 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 .
- Bezzel, Einhard (1995): BLV Handbuch Vögel. BLV Verlagsgesellschaft, Munich
- Glutz v Blotzheim, NN / Bauer, KM (1966–1993): Handbook of the birds of Central Europe. 13 volumes, Aula-Verlag, Wiesbaden
- John Gooders and Trevor Boyer: Ducks of Britain and the Northern Hemisphere , Dragon's World Ltd, Surrey 1986, ISBN 1-85028-022-3
- Madge, Steve; Burn Hilary (1989): Water Fowl. Paul Parey, Hamburg
- Janet Kear (Ed.): Ducks, Geese and Swans. Oxford University Press, 2005, ISBN 0198546459 .
- Erich Rutschke: The wild ducks of Europe - biology, ecology, behavior , Aula Verlag, Wiesbaden 1988, ISBN 3-89104-449-6
Web links
- Aythya nyroca 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 nyroca in the Internet Bird Collection
- Feathers of the bog duck