Blue-billed Duck
Australian duck (Oxyura australis)
The Australian duck (Oxyura australis) is a small species of the subfamily of the rudder ducks. BirdLife International has this kind at the early warning Near Threatened. This means that with continued population decline this type must be classified as threatened. The greatest threat to this species is based on the draining of wetlands. Further adverse developments are changing the biodiversity of these habitats by introduced fish species, grazing cattle on the periphery of wetlands, their salinity and the lowering of the groundwater table. The stock is currently estimated at 12,000 mature individuals.
Description
The Australian headed duck is a small ruddy duck with a body length of an average of 40 centimeters. In the male head and neck are drowned out black and sooty brown slightly. The body plumage is reddish brown very dark. Like some other types of rudder ducks also has the male of the Australian Rowing Duck in breeding plumage a striking blue beak. In English usage, the duck is therefore also Blue -bill duck called to German blue -billed duck. A few males display their plumage throughout the year ..
In plumage males and females have a slate-gray beak. The plumage is then inconspicuous gray-brown. In the male the head is only slightly darker and the edges are slightly more interspersed brown.
When swimming the Australian headed duck is very low in the water. The tail is usually flat on the water surface. The birds are excited, it will be stiff spread upwards. These features are also found in other rowing ducks.
Immature young birds resemble the female, but are colored somewhat brighter.
Typical behaviors
Outside the breeding season, keep Australian rowing ducks are typically found in large teams on large, clear lakes. During the breeding season they live, however, in densely vegetated swamps, which have a high water level. In the coastal regions, these are primarily swamps, which are densely covered with Myrtenheiden. The flight of the Australian headed duck is very fast, it can be clearly heard as an instrumental sound flapping noise. In contrast, Australian rowing ducks do not call in flight. On land, they spend only very rarely. However, you climb occasionally on tree trunks, swimming in the water to clean themselves there. However, you will spend the rest phases floating on the water. The individual dives take 10 to 30 seconds. A large part of the food intake takes place in the day.
Possible confusion
In the used by the Australian headed duck habitats also Australian Ferruginous Duck, duck cloth and Coot occur. Especially outside the breeding season, these species are often associated with each other.
The Coot has a similar body size, but looks floating higher than the Australian headed duck, as it floats higher in the water. The head is compared to the Australian Ruderente significantly smaller. Due to the bright and differently shaped beak and the white forehead shield of the coot, the two species are not to be confused with each other in good visibility. The movement sequences differ significantly, so that the two species are well tell apart from a distance. The coot leads immersions one with a plunge, the Australian rowing duck dives under the other hand, with a smooth motion of the floating position. On the water flying up coots and ducks Australian rowing require long start-ups, but the start-up of the coot is longer, the single step movements are striking. Both species are similar in their flight pattern, often fly in small groups and low over the water, so that the two species are difficult to tell apart in flight.
The Australian Ferruginous Duck has a similar plumage coloration. The males have conspicuous white eyes and a pale beak stripes. They are basically larger than the Australian headed duck, have a longer and slimmer neck. Floating Australian Ferruginous Ducks are relatively high in the water. Also Australian Ferruginous Ducks conduct their dives through a characteristic header, which does not occur in the Australian Ruderente so.
The cloth duck is significantly larger than the Australian headed duck with a body length of up to 66 centimeters in males and 55 cm in females. The plumage coloration, however, is similar to the Australian Ferruginous Duck, and especially young birds of the duck cloth can be confused with the Australian headed duck. However, the beak of the duck cloth is much stronger, and Australian rowing Ducks have a concave head profile that lacks the rag ducks.
Distribution, habitat and way of life
The Australian headed duck is an endemic species of temperate climate zones of Australia. It is found in southern Queensland through New South Wales and Victoria to Tasmania. Widespread is the kind in the South West of Western Australia. Very numerous, it is along the river system of Murray and Darling. The extent to which Australian ruddy duck is a migratory bird, is controversial. While some authors see a seasonal migrant movement, represented other ornithologists agree that this is to young birds that create the periphery of the distribution area their breeding grounds. Adult birds with established breeding grounds hold against it the whole year round on in their breeding grounds.
The Australian headed duck is tied up in their way of life very strongly to the water. It is occasionally observed on land. Due to the very far back on the body recognized legs but her gait looks awkward. Outside the breeding season, the Australian rowing ducks congregate in groups. Winter flocks of over 1,000 individuals are from New South Wales known .. During the breeding season, however, they lead a very hidden life and are very difficult to observe. In case of danger they usually fly not, but dive away.
Reproduction
The courtship ritual the male is long and complicated with very specific movements. To this end, rubbing the cheeks on the back feathers or dipping the head belongs in the water while the feet water is splashed. After the courtship and a resolute pursuit copulation takes place in the water. The female is completely submerged. Australian rowing ducks are polygamous. In captive Australian rowing ducks usually one dominant male was mated with three females. The dominant males defended these females against other males and prevented a mating ritual of the other also on the waters situated males.
The breeding habitat is found in regions with permanent water-bearing and interspersed with lush vegetation Swamplands. The female chooses the nest site and builds the nest. The male usually leaves the female at the time of oviposition. An average clutch consists of about five to six eggs. The eggs have a greenish- white color. The Brut, which usually begins with the laying of the last ice is 24 to 26 days. The young birds are from the female parent birds independently at least four to five weeks. It often comes after very quickly at a second nest.
Sexual maturity achieve Australian rowing ducks about a year.
Food
The Australian headed duck eats both seeds, buds and fruits of aquatic and marsh plants and microorganisms. Much of the plant food originates from Algenfarn and milfoil. The animal in the diet makes up about 43 percent. The food is immersed taken on water surface. The Australian Ruderente can stay up to ten seconds under water.
Protection measures
The main cause of the population decline in the Australian Ruderente measures for drainage and for the regulation of lowland waters are seen. The Australian Environmental Protection Agency has therefore taken several measures to protect the habitat of these Ruderentenart. These include the conservation of a sustainable water flow in such regions, measures against a progressive salinization and regulations applicable to such grazing grounds.