White-headed Ruddy Duck
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Ruddy Duck ( Oxyura leucocephala ), male |
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| Oxyura leucocephala | ||||||||||
| ( Scopoli , 1769) |
The white-headed Ruddy Duck ( Oxyura leucocephala ) is a species from the duck family . She is a representative of the rowing ducks .
The populations of the white-headed rudder ducks, especially in southern Europe and North Africa, are threatened by hybridization with black-headed rudder ducks. It is one of the rarest breeding birds in Europe and one of the most endangered species of ducks in the world. For this reason, extensive protective measures have been introduced in Europe.
Relatively little is known about the way of life of this duck. Many details are only known from zoo management, which began to be used increasingly from the 1970s to preserve the species.
Appearance
body shape
Like all rowing ducks, the white-headed rudder is characterized by a head that is noticeably thick in relation to its body with a broad, somewhat distended beak . The body is about 46 cm long, and the tail is long and feathery, as is typical of rowing ducks. It is often used by both sexes outside the courtship season . Despite the small, curved wings, white-headed rudders are known to be skillful and fast fliers. Both sexes weigh around 700 grams.
In comparison to other ducks that do not belong to the rowing ducks, the legs are set very far back on the body. You are thus well behind the body's center of gravity. The white-headed rudder duck is able to swim and dive very powerfully. On land it seems rather clumsy.
Breeding and resting plumage of the male
As with most duck species, there is also a pronounced sexual dimorphism in the white-headed rudder . In the male in the brood dress, the head sides are white, on the head plate and on the neck there is a black plumage, which is differently pronounced in the individual individuals. This head coloration is also the easiest way to distinguish the White-headed Ruddy Duck from the closely related North American Ruddy Duck. In this case, only the cheek area is white; their body fletching is also a more intense chestnut brown.
The body plumage of the White-headed Ruddy Duck is red-brown with very fine black markings. The bright, light blue beak is striking during the courtship and breeding season.
When resting, the body plumage of the male is a little paler red-brown, the beak is then dark gray.
The males wear their brood and courtship dress from late February, early March to September.
Plumage of the female
In the female, however, the beak is dark gray and much less raised. Their body plumage is darker all year round than that of the male. In the lower cheek field it is also feathered white, and below the eye there is a slightly curved, white stripe under the eyes. With this body plumage, the female resembles that of the Ruddy Duck. The stripe under the eyes is more straightforward in the female of the black-headed duck.
Down dress and youth dress
The chicks have dark sepia-brown plumage on the top of the body. The chest and stomach, on the other hand, are creamy white. The head drawing is noticeable. The chicks have a sepia-brown stripe on the cheeks, which is bordered by a light cream-colored stripe under the eyes and beard. When young, the young ducks of both sexes resemble the females. In the young pelvis the blue-colored beak appears as early as autumn; they wear the full, splendid dress for the first time shortly before they are one year old.
Voice and instrumental sounds
The white-headed rudder duck is a largely silent species of duck. Occasionally she can hear hard and deep creaking, grunting and happy sounds. During the courtship, the male emits a rhythmically hard "krr-krr-k ..." as well as high-pitched whistling sounds that can be onomatopically described as "düdü". On the other hand, a deep “gagaga…” and a short, soft “go” can be heard from the female. A noisy, loud splash of water also belongs to courtship.
Occurrence
Distribution area
White-headed Ruddy Ducks are breeding birds that have a very disjoint breeding area in Northwest Africa, in Middle and East Asia and in places in South and Southwest Europe. This species of duck can be found in parts of Russia , Kazakhstan , Uzbekistan , Mongolia , Armenia , Azerbaijan , Iran , Afghanistan , Turkey , Albania , southern Spain , Algeria and Tunisia .
In autumn and winter the white-headed ducks gather in larger bodies of water. They are then occasionally kept with other diving ducks and are more often in open water than during the breeding season. While the Spanish breeding birds are predominantly resident birds, the breeding birds in southeastern Europe are migratory birds. The steppe lakes in Kazakhstan and the Burdur lake in Turkey are among the important wintering areas .
Apart from Hungary, there are only sporadic breeding records for Central Europe. The most recent observations are likely to involve refugees in prison.
habitat
White-headed Ruddy Ducks prefer to live on shallow lakes with distinct reed areas . They prefer slightly brackish salty water to pure fresh water . The white-headed duck, on the other hand, does not breed on more salty lakes because there are no reed thickets. The breeding areas are also all in regions that have a high summer temperature and intense solar radiation.
Stock situation
Duration
Although no population figures are available for this duck from earlier centuries, it is believed that the species was much more common in southern Europe in the past and that their numbers have declined due to drainage projects and expansion of agricultural production. White-headed ducks rely on shallow waters. However, these have been continuously drained in the 19th and 20th centuries, so that this type of habitat is increasingly lacking. This also explains the island-like occurrences in southern Europe and North Africa. The declines in the Asian range are due to loss of habitat and hunting.
Hartmut Kolbe estimated the population after 1990 to be around 19,000 animals, 80% of which breed in Kazakhstan and Russia and the majority of which overwinter on a few lakes in Anatolia . The wintering area of the remaining birds is concentrated in lakes in Pakistan . According to Kolbe's estimate, the population of the white-headed rudder duck in southern Spain , Algeria and Tunisia was 1,000 white-headed rudder ducks around 1992. The populations in Hungary had meanwhile died out. An attempt was made to reintroduce the species there in the 1980s, but has not yet been able to build a stable breeding population.
In 2003 the British government estimated the number of European white-headed ducks at 2,700 individuals and assumed a worldwide population of 10,000 adult birds. The IUCN , which keeps the international red list of endangered species , has classified the white-headed rudder duck as an endangered species since 2004. The reason for this classification is that the population has declined by a total of 60% in the last 10 years . Since the Spanish population in particular has recovered, the IUCN assumes that the population loss will be less dramatic in the coming years. The white-headed rudder has benefited greatly from the intensive protective measures. In the Valencia region, for example, the population rose from four breeding pairs in 1994 to 190 breeding pairs in 2000. In 1997, Morocco was repopulated.
Stock threat from hybridization
The closely related North American Ruddy Duck has been kept as an ornamental fowl since the 1950s, particularly in Great Britain . By the 1960s at the latest, birds escaped from the keeping and multiplied as so-called captive refugees. In 1993, their population comprised 3,500 animals that brooded in Europe and spread to southern Europe and northwestern Africa. In 2003 there were 6,000 individuals of this species in Great Britain alone, which means that they already have a greater population density than the white-headed Ruddy Duck native to Europe. In many areas there has been intermingling with resident white-headed Ruddy Ducks, so that their relict-like populations in Europe are threatened and endanger attempts at reintroduction. The males of the black-headed rudder ducks are more aggressive than those of the white-headed rudders, so that they can drive the white-headed rudders out of the breeding ground and force copulations with their females. Reproductive hybrids emerge from the pairings . Many bird conservationists fear that the black-headed rudder will ultimately displace the white-headed duck completely if far-reaching measures are not taken.
Population threat from climate change
A research team that, on behalf of the British Environment Agency and the RSPB, examined the future development of the distribution of European breeding birds on the basis of climate models, indicates that the populations of the white-headed rudder duck may disappear in Europe in the course of the 21st century solely due to global warming. In the simulations of the investigating team, no region of Europe of this type offered more habitats that would meet the specific climatic requirements.
Reproduction
Courtship
The courtship begins with the return to the breeding areas in April. The courtship of the drake includes, among other things, a jerky straightening of the tail and the bobbing up and down of the head. This behavior alternates with two forms of demonstration swimming. In one form, the drake swims quickly around the duck in wide circles and lies high on the water. The tail lies horizontally on the water, the head of the drake is often turned towards the duck. In the second form, the drake swims up and down near the duck, deeply submerged, with its head resting on its back.
The female duck often shows no noticeable behavior during this courtship of the drake. However, it occasionally lapses into a noticeable cleaning behavior.
Nest and clutch
The nests are preferably created in the reed thicket. The nesting islands of frequently Coot and diving ducks used. When the Wildfowl Trust began the conservation breeding of the species in the 1970s, it was learned that courting duck pairs only reproduced if they were artificially offered such nesting aids in their aviary .
The clutch consists of about six to thirteen eggs with a rough shell, which are initially light green and then increasingly take on a dirty white color. The duck incubates the clutch on its own. In the event of a malfunction, the duck dives into the water directly at the nest and only reappears at a great distance from the nest. She stays under water for up to two minutes. It often comes to the surface again near the drake. As ducks were rarely observed on the nest due to this escape behavior, the literature occasionally still claims that white-headed rudder ducks only incubate the eggs for a few days and that they "finish incubating" due to their own warmth. Experience from the zoo has refuted this view.
The drake stays near the nest when the chicks hatch. He then leaves the area and forms moulting groups with other drakes.
The chicks
The chicks hatch after about 23 to 25 days. You will only be guided by the duck, which stays with its offspring along the reed zone during the day. In the evenings she can occasionally be seen with the chicks in the open water.
The chicks are able to fly after about 60 days. The young birds are sexually mature in their second year of life.
food
White-headed ducks mainly live on aquatic plants, from which they eat both the young greens and the seeds. Small organisms are only picked up by chance. The chicks and young ducks, on the other hand, eat almost exclusively aquatic insects, small crabs and water snails.
Human and White-headed Ruddy Duck
White-headed ducks as ornamental poultry
White-headed rudders are not typical ornamental poultry . For a long time, only the North American Ruddy Duck was kept in zoos and private breeders, which were easier to obtain due to their frequency.
In the 1960s, a zoo in Spain raised the first two wild-caught chicks. The first breeding of this species, however, only succeeded in 1973 by the Wildfowl Trust, which had full-grown ducks caught in Pakistan for this purpose. The offspring were given to numerous zoos for maintenance purposes. The Wuppertal Zoo is one of the zoos that have been successfully breeding white-headed ducks for a long time . This species is now also kept by private breeders; however, rearing chicks is considered difficult.
Protective measures
Since 1993 there has been an extensive protection program to preserve the white-headed rudder ducks, in which the British Wildfowl Trust, among others, are involved. In Spain, among other things, all hybrids are specifically shot down. Numerous European zoos, such as the Cologne Zoo, have given up keeping black-headed ducks and are participating in the conservation breeding of white-headed ducks. Reintroduction programs are trying to reintroduce this species of duck to France , Hungary and Italy .
The protective measures also include the fact that the wild black-headed Ruddy Ducks are specifically shot down in Great Britain. These shooting measures led to extensive discussions about animal welfare programs in Great Britain after almost a third of the animals living there were deliberately hunted in 2002. The Royal Society for the Protection of Birds (RSPB) was seen as the driving force behind the shooting down of the rudder duck and many of the members resigned as a protest against the measure supported by the society. Andrew Tyler, director of the British animal welfare organization Animal Aid , described the killing of the Ruddy Duck as grotesque and absurd during these discussions. He saw hybridization with the more robust black-headed rudder as an opportunity for the white-headed rudder to survive in the long term. Many conservationists do not share this view. For them, the displacement of the white-headed rudder by a human-imported neozoa is an irretrievable loss of biodiversity .
supporting documents
literature
- T. Bartlett: Ducks And Geese - A Guide To Management. The Crowood Press, Ramsbury 2002, ISBN 1-85223-650-7
- 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 .
- Dominic Couzens : Rare Birds - Survivors, Evolution Losers and the Lost. Haupt Verlag, Bern 2011, ISBN 978-3-258-07629-4 .
- John Gooders and Trevor Boyer: Ducks of Britain and the Northern Hemisphere . Dragon's World Ltd, Surrey 1986, ISBN 1-85028-022-3
- Brian Huntley, Rhys E. Green, Yvonne C. Collingham, Stephen G. Willis: A Climatic Atlas of European Breeding Birds , Durham University, The RSPB and Lynx Editions, Barcelona 2007, ISBN 978-84-96553-14-9
- Hartmut Kolbe: The world's ducks . Verlag Eugen Ulmer, Stuttgart 1999, ISBN 3-8001-7442-1
- Erich Rutschke: Europe's wild ducks - biology, ecology, behavior . Aula Verlag, Wiesbaden 1988, ISBN 3-89104-449-6
Web links
- Animal Aid British animal welfare organization for the shooting of black-headed rudders to protect the white-headed rudders
- International Species Action Plan for the White-headed Ruddy Duck (DOC, 3.2 MB)
- Oxyura leucocephala in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2006. Retrieved on January 24 of 2009.
- Videos, photos and sound recordings for Oxyura leucocephala in the Internet Bird Collection
Individual evidence
- ^ 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. 32
- ↑ Protection of endangered bird species and their habitats Activities of the registered association Naturschutzbund Deutschland (NABU) in Azerbaijan.
- ↑ Mostly in the Karavasta lagoon .
- ^ Huntley et al., P. 99
- ↑ Gooders and Boyder, p. 172
- ↑ Bauer et al., P. 37
- ↑ Gooders and Boyer, p. 173
- ↑ Bauer et al., P. 38
- ^ Huntley et al., P. 99
- ↑ Couzon, pp. 154-155
