Rose-eared duck
| Rose-eared duck | ||||||||||||
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Rose-eared Duck ( Malacorhynchus membranaceus ) |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Malacorhynchus | ||||||||||||
| Swainson , 1831 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Malacorhynchus membranaceus | ||||||||||||
| ( Latham , 1802) |
The rose-eared duck ( Malacorhynchus membranaceus ), also called spatula-billed duck , is a small, very numerous species from the duck- bird family , which belongs to the fauna of Australia . It is able to colonize suitable habitats very quickly and leaves them again just as quickly when the environmental conditions change. Therefore, in temporarily favorable habitats, mass gatherings of this duck species occur very quickly. In Australia it is one of the game birds , but it is shot relatively rarely compared to other game birds.
What is striking about this duck is the unusually large, spatula-shaped beak. With this beak, the duck is perfectly adapted to a way of life in which the water is sifted through for the smallest particles of food.
Appearance
Rose-eared ducks have a wing length of 15.2 centimeters (females) to 21.3 centimeters (males). The males weigh between 290 and 480 grams; the females are comparably heavy with a weight between 272 grams and 423 grams. The total body length is between 36 and 45 centimeters. The wingspan is 57 to 71 centimeters. The sexual dimorphism is not very pronounced. The males are only slightly larger and more contrasting in color than the females. However, they can be distinguished by their voice. The male emits high single tones, the female, on the other hand, short, deep series of calls.
The rose-eared duck is a small, pale-colored duck with a conspicuously large, spatula-shaped beak. The face is white. The eye is surrounded by a large dark brown spot. The chin and throat are white. The flanks, the chest and the lower neck area are striped. The color scheme of this duck is identical in its splendor and rest dress. The feet and legs are dark gray. The eyes are brown.
Adult rose-eared ducks go through their full moults after breeding has ended. In Australia this falls between October and February. Young birds, on the other hand, molt their small plumage and control feathers during the first year of life. Then they go through a full moult and change into old age clothes.
Newly hatched chicks of the rose-eared duck are light brown on the upper side of the body. A strong black-brown eye streak runs through the face. Otherwise, the face as well as the chest, the underside of the body, the rear edge of the wing and small spots on the beaks and the rump sides are light gray to white. The beak is light blue-gray and is already broadened like a spatula when it hatches. This distinguishes the chicks, among other things, from those of the Australian shoveler , in which the typical beak only develops with increasing age. The youth dress is similar to the old age dress, however, it is less strictly banded and overall somewhat paler and more brownish.
Rose-eared ducks can be seen either in pairs or in small to very large flocks. They typically occur in relatively shallow inland waters and are rarely seen on the coast. Typical for them is resting on trees or on low branches above or in the water. They always swim very high on the water, while foraging for food their beak is immersed in the water up to their eyes. They very rarely bottom and never dive. They fly with fast flapping wings and, when startled, circle high or low above the water. They often also fly during the night; humans can then hear them through their calls.
The rose-eared duck can hardly be confused with any other species due to its beak, eye-catching eye spot and white eye ring. Only the Australian shoveler has a similarly striking beak, but the head shape is different. The beak and forehead run in one line in this species, while the rose-eared duck has a more noticeable side profile. The two species also differ significantly in their plumage.
distribution and habitat
The rose-eared duck is an endemic species of Australia. It is found in wetlands across the continent and is only absent in the arid zone that runs through western Australia. Its main area of distribution is the inland wetlands; it only reaches the coast where more than 400 millimeters of rain falls annually. She usually prefers shallow, standing water and avoids strong currents and clear water. It also uses sewage lakes or lakes polluted by sewage. During their migrations they can occasionally be found in habitats that are unusual for them, such as mountain lakes, mangrove swamps and estuaries.
The stock numbers fluctuate very strongly. The ornithologist Hartmut Kolbe , who specializes in ducks , described the red-eared duck as the most extreme invasive anatids in Australia. In places where ecologically favorable conditions prevail, this type of mass accumulates very quickly. Due to the seasonal distribution of rainfall, however, their migration is somewhat predictable.
Inland and brackish water lakes and flooded grasslands are ecologically beneficial. In regions where there has been heavy local rainfall, large numbers of these birds arrive very quickly. If the flooded areas offer them suitable living conditions, they immediately begin courtship and mating. With the falling water levels, their preferred food - namely zoo and phytoplankton - is concentrated in ever smaller bodies of water. Most of the time the young birds have hatched by this time. During these mass gatherings, they are often socialized with Australian white-throated ducks .
Just as quickly as it arrived, the rose-eared duck also leaves certain regions as soon as the vital waters have dried up. In Eastern Australia, the average population size is regularly 370,000 individuals. In good years, more than 750,000 birds can be found in this region alone.
food
Rose-eared ducks mainly eat invertebrates, but they also eat seeds. Most of the food is found by sifting through the water. The water is sucked in at the tip of the beak and pressed out again through the side lamellas. Rose-eared ducks usually stand in shallow water while they are feeding. They often look for food in dense groups. The rose-eared ducks at the end of a flock catch the invertebrates that have been scared off by the ducks in front. Occasionally they put their heads completely under the surface of the water. At regular intervals they raise their heads to examine the surroundings.
Reproductive biology
Rose-eared ducks are monogamous birds and may be in a relationship until one of the birds dies. Only the female breeds, but both parent birds lead the young birds. The courtship behavior is triggered by suitable habitat conditions and is not tied to any particular season. In northern Australia, they typically breed after the summer rains in March to May. The nest is usually located above the surface of the water in a tree hole or a fork in a branch. They also use post ends, tree trunks lying in the tree or tree stumps protruding from the water and also accept nesting aids or use abandoned nests of other bird species. Usually the nest is about a meter above the surface of the water. The nesting density can be very high. In New South Wales, nests have been found every 14 to 18 meters along the shoreline of a watercourse. When there is a lack of breeding space, it often happens that several females lay their eggs in one nest. Such nests can then have forty to sixty eggs. The breeding season is about 26 days.
Systematics
Similar to the split-footed goose , the barnacle goose , the monkey goose , the mane goose and the ragged duck , the rose-eared duck also belongs to the avifauna of Australia, which has no close relatives to a species native to other continents.
Human and rose-eared duck
The rose-eared duck is one of the species that came to Europe from Australia very late. It was not until 1979 that 40 chicks came to England from Perth, which formed the breeding basis for the rose-eared ducks kept in West and later also in North America. However, the species is very sensitive to cold spells.
swell
literature
- PJ Higgins (Ed.): Handbook of Australian, New Zealand & Antarctic Birds , Volume 1, Ratites to Ducks, Oxford University Press, Oxford 1990, ISBN 0195530683
- Hartmut Kolbe; Die Entenvögel der Welt , Ulmer Verlag 1999, ISBN 3-8001-7442-1
- Janet Kear (Ed.): Ducks, Geese and Swans. Oxford University Press, 2005, ISBN 0198546459 .
Individual evidence
- ↑ Higgins, p. 1249
- ↑ Kolbe, p. 145
- ↑ Higgins, p. 1247
- ↑ Kolbe, p. 145
- ↑ Higgins, p. 1247
- ↑ Higgins, p. 1248
- ↑ Higgins, p. 1247
- ↑ Higgins, p. 1249
- ↑ Higgins, p. 1250
- ↑ Kolbe, p. 145 f.
- ↑ Kear, p. 443
- ↑ Higgins, p. 1250
- ↑ Higgins, p. 1252
- ↑ Higgins, p. 1253
- ↑ Kolbe, p. 146
- ↑ Kolbe, p. 146 f
Web links
- Malacorhynchus membranaceus 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 Malacorhynchus membranaceus in the Internet Bird Collection