Blue-winged duck
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Blue-winged duck ( Spatula discors ) |
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| Spatula discors | ||||||||||||
| Linnaeus , 1766 |
The blue-winged duck ( Spatula discors , Syn .: Anas discors ) is a small species of duck native to North America. It is the counterpart to occur in the Old World teal ( Spatula querquedula ), which like these shallow waters preferably with lush vegetation. The stocks have indeed declined due to the conversion of part of their habitats into agricultural land. However, the species is still very common. The population is estimated at around five million individuals.
In Europe, stray visitors are found almost every year, especially in the Atlantic area. The increase in observations in the last few decades can, however, be partly traced back to prisoner refugees. In 1986 breeding blue-winged ducks were observed for the first time in Denmark.
Mark
Blue-winged ducks are relatively small ducks. Their body length is between 37 and 41.5 centimeters. Males weigh between 318 and 544 grams. Females are slightly lighter and weigh between 227 and 500 grams fully grown with an average weight of 377 grams.
The adult male has a grayish-blue head with a white, crescent-shaped face. The body is gray-brown and has a white spot at the rear end. The chest and belly are spotted dark. The duck's tail is black. The female is inconspicuously speckled with brown. Both sexes have a blue wing spot, which gave the species its name. The feet are yellow. When resting, the male resembles the female, but the sides of the head are a little more dull in color.
Most likely, the females of this species are other small ducks as Garganeys or teals to be confused, but the yellow feet are a safe differentiator. In flight, the characteristic head markings in the male are the most certain distinguishing feature from other ducks. Females, on the other hand, cannot be clearly identified in flight. Blue-winged ducks often fly in dense flocks. The frequent change of direction is noticeable.
Distribution area
The breeding area of the blue-winged duck extends over large parts of the temperate and cold climate zone of North America. It reaches Alaska in the north and extends in an easterly direction to the mouth of the St. Lawrence Current. In the south it stretches from northern Nevada via Texas and Louisiana to the coast of California . The main distribution area is in the Prairie Pothole region of southern Canada and the northern United States.
The wintering areas of the blue-winged duck range from Baja California and Mexico via Central America to Colombia and Venezuela . Evidence of wintering is also available from Chile , Argentina and Uruguay . A small fraction of the population also overwinters in the southern United States. This includes the coastal areas of Texas, Louisiana, Florida, and South Carolina, and to a much lesser extent Arkansas , Mississippi , Alabama , Georgia , North Carolina , Missouri , Tennessee , Oklahoma, and New Mexico . Blue-winged ducks are therefore distinctive migratory birds in which breeding and wintering areas almost do not overlap. Occasionally wanderers are sighted in Cuba , the Bahamas , Haiti and Puerto Rico . Occasional specimens reach Europe and North Africa on their trains . The migration to the wintering areas takes place in swarms and runs very quickly. Blue-winged ducks return to their breeding grounds as early as January. The retreat movement is slow and only completed in April.
Way of life
The blue-winged duck is a very sociable duck that can be seen in schools from early autumn until retreating to the breeding areas. It also socializes with other ducks such as the dark duck , the cinnamon or the pintail . Similar to the teal duck, the blue-winged duck searches for food in shallow waters. She seldom founds. Plant foods make up the majority of their food intake. It also eats molluscs and crustaceans.
Breeding areas are wetlands and ponds in North America . Blue-winged ducks usually return to the breeding areas already paired. They are seasonally monogamous and mate with new partners in the wintering areas. The breeding season starts very later. Nest building begins at the earliest in late April and ends in mid-July. Most of the nests are built around mid-May. The nest consists only of a small dent in the floor, which is padded with grass and down. It is found no more than 400 meters from the shore line. The eggs are laid about a day apart. A clutch usually consists of nine to thirteen yellow-brown eggs. The female breeds alone. Breeding begins when the eggs are laid. The males initially stay near the nest. However, they leave the breeding area before the dune chicks hatch and go to the moulting area. The chicks can fledge after about 42 days.
Systematics
The monotypical blue-winged duck is closely related to the cinnamon , with which hybridization occasionally occurs. However, the breeding areas overlap to a large extent, so that the two species do not form superspecies with each other.
supporting documents
Individual evidence
- ↑ Kear, p. 549.
- ↑ 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. 102.
- ↑ 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. 102 and p. 103.
- ↑ a b Kear, p. 546.
- ↑ Kear, p. 548.
- ↑ Christopher S. Smith: Field Guide to Upland Birds and Waterfowl. Wilderness Adventure Press, Belgrade (Montana) 2000, ISBN 1-885106-20-3 , p. 64.
- ↑ Gooders and Boyer, p. 69.
- ↑ Kear, p. 348
- ↑ 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. 102.
literature
- Janet Kear (Ed.): Ducks, Geese and Swans. Oxford University Press, 2005, ISBN 0-19-854645-9 .
- Hartmut Kolbe: The world's ducks. Ulmer Verlag, 1999, ISBN 3-8001-7442-1 .
- John Gooders, Trevor Boyer: Ducks of Britain and the Northern Hemisphere. Dragon's World Ltd, Surrey 1986, ISBN 1-85028-022-3 .
Web links
- Spatula discors in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed on December 18 of 2008.
- Videos, photos and sound recordings of Spatula discors in the Internet Bird Collection