Aix is a genus that contains two species of ducks: the Wood Duck (Aix sponsa), and the Mandarin Duck (Aix galericulata). The genus belongs to the family Anatidae in the waterfowl order Anseriformes. They were formerly placed in the “perching ducks”, a paraphyletic group somewhat intermediate between shelducks and dabbling ducks, and it is not quite clear whether they should be placed in the Anatinae (dabbling duck) or Tadorninae (shelduck) subfamily. The two species are generally considered to be very attractive, particularly the multi-coloured drakes. Wood Ducks are a North American species, occurring mainly in the eastern half of the United States, and from southern Canada to northern Mexico. Mandarin Ducks are an Asian species mainly in Japan and China, but there is an important feral population in the United Kingdom. Both species migrate from the northern parts of their respective ranges to winter in the south of the range. They inhabit quiet wooded streams and ponds. The genus shows marked sexual dimorphism (differences between the sexes), with the females being smaller and less colorful.
The wings of Wood Ducks are highly characteristic. The primary wing feathers, which are the 10 outermost flight feathers attached to the wing beyond the wrist, are dark in colour. The outer vanes of these feathers look as if they have been sprayed with aluminum paint. The Wood Duck is the only North American duck so marked.
In most cases it is possible to distinguish immature from mature ducks and to tell males from females by their wings alone. In the Wood Duck, as in other ducks, the feathers of that year’s young are finer, more pointed and worn, and less colourful than those of adults. Females show a few small feathers on the upper surface of the wing that are purplish and have the same lustre as oil on water. These feathers are absent in males. The white tips on the feathers along the trailing edge of the wing are usually teardrop-shaped in the female, but either straight or V-shaped in the male. By studying the wings of ducks taken by hunters, biologists can determine the ratio of young to adult ducks in the population and thereby measure waterfowl production.
The Wood Duck is a distinctively North American species. Its only close relative is the Mandarin Duck of eastern Asia. Evidently the Wood Duck originated in North America, as fossil remains have been found only in widely scattered locations in the eastern part of the continent.
Listen to the sound of Wood Duck
Copyright remark: Most sounds derived from xeno-canto
Upon hatching, usually in June in eastern Canada, the young use their sharp claws to climb up the inside of the nesting cavity to its entrance, then jump and flutter to the ground, generally landing unharmed. The female guides them to the nearest water, where they will spend the next eight to nine weeks hunting for food together.
Shortly after the female begins incubation the male loses interest in family affairs and spends more time away from the nest. He joins other males, which eventually form large groups. As mid-summer approaches, the males begin the move to remote, undisturbed, sheltered places to moult, or shed old feathers. To reach these areas, they may travel great distances; many thousands migrate to southeastern Canada from breeding grounds in the northern states. On arrival the moult begins, and by August the brilliant spring feathers of the male have been replaced by a plumage similar to that of the female. Then, all at once, the flight feathers are moulted, leaving the male flightless for approximately four weeks while new feathers grow in.
Soon after the ducklings have fledged, or taken their first flight, usually by mid-August in eastern Canada, the females leave their broods, move a short distance, and undergo their moult. Like the males, they too seek out remote, undisturbed swamps and marshes and become flightless for a short period.
In late summer and early autumn, the young with their newly acquired powers of flight and the adults with their recently replaced flight feathers move in a leisurely way about the northern parts of their range. Their principal concern is to store up energy, in the form of fat, in preparation for the soon-to-come fall migration.
Ducklings require a high protein diet for rapid growth. Invertebrates such as dragonflies, bugs, beetles, and spiders are important foods during the first few weeks of life, so high populations of these small creatures are essential in habitats where the young will hatch and develop.
Video Wood Duck
In Canada, the Wood Duck nests in scattered locations in the southern parts of all provinces; however, there is only one breeding record for Newfoundland and Labrador. The most extensive breeding ranges are in Ontario, Quebec, New Brunswick, and British Columbia. This duck occurs over a much wider area in late summer and early autumn, as a result of post-breeding dispersal. Although most Wood Ducks migrate to the United States, a few may spend the winter in extreme southern Ontario and southeastern British Columbia.
The Wood Duck is much more widely distributed in the United States, where it nests in areas east of the Mississippi River, along the lower Missouri River into South Dakota, in eastern Texas, along the Pacific coast, and in a few other places. It winters mainly along the Atlantic coast from New York south, along the Gulf coast into central Texas, to the lower Mississippi River valley and western California. A few winter in Mexico south to Distrito Federal. In Europe all sightings are of escaped birds.
By the first severe frost, usually in late September or early October in eastern Canada, Wood Ducks begin to head for the southeastern United States. Southern populations of Wood Ducks, particularly females, are less migratory. Populations in the interior of British Columbia migrate to the west coast, whereas Wood Ducks that live on the coast do not migrate at all. Has occurred Bermuda (regular), Azores and Alaska. Many sightings from Europe, presumed escapes.