4-12-2015 JURONG, SINGAPORE - MANDARIN DUCK (MALE) (Aix galericulata)

The mandarin duck (Aix galericulata) is a perching duck species native to the East Palearctic. It is sexually dimorphic, males showing a dramatic difference from the females. It is medium-sized, at 41–49 cm (16–19 in) long with a 65–75 cm (26–30 in) wingspan. It is closely related to the North American wood duck, the only other member of the genus Aix. 'Aix' is an Ancient Greek word which was used by Aristotle to refer to an unknown diving bird, and 'galericulata' is the Latin for a wig, derived from galerum, a cap or bonnet. Outside of its native range, the mandarin duck has a large introduced population in the British Isles and Western Europe, with additional smaller introductions in North America.

The mandarin duck is among the more diminutive types of waterfowl, with a shorter height and smaller overall body size than the dabbling ducks, and is slightly smaller than its American wood duck relatives. The adult male has a petite, red bill, large white crescent above the eye and reddish face and "whiskers". The male's breast is purple with two vertical white bars, the flanks ruddy, and he has two orange feathers at the back (large feathers that stick up similar to boat sails). The female is similar to the female wood duck, with a grayish-lavender tone to her plumage, and a white eye-ring and stripe running back from the eye. The female is paler on the underside, has a small white flank stripe, and a pale tip to its bill.

Both the males and females have crests, but the purple crest is more pronounced on the male.

Like many other species of ducks, the male undergoes a moult after the mating season into eclipse plumage. When in eclipse plumage, the male looks similar to the female but can be distinguished by its bright yellow-orange or red beak, lack of any crest, and a less-pronounced eye-stripe.

Mandarin ducklings are almost identical in appearance to wood ducklings, and very similar to mallard ducklings. The ducklings can be distinguished from mallard ducklings because the eye-stripe of mandarin ducklings (and wood ducklings) stops at the eye, while in mallard ducklings it reaches all the way to the bill.

The species was once widespread in East Asia, but large-scale exports and the destruction of its forest habitat have reduced populations in eastern Russia and in China to below 1,000 pairs in each country; Japan, however, is thought to still hold some 5,000 pairs. The Asian populations are migratory, overwintering in lowland eastern China and southern Japan.

Specimens frequently escape from collections, and in the 20th century, a large, feral population was established in Great Britain; more recently, small numbers have bred in Ireland, concentrated in the parks of Dublin. Now, about 7,000 are in Britain with other populations on the European continent, the largest of which is in the region of Berlin. Isolated populations exist in the United States. The town of Black Mountain, North Carolina, has a limited population, and a free-flying feral population of several hundred mandarins exist in Sonoma County, California. This population is the result of several ducks escaping from captivity, then reproducing in the wild. In 2018, a single bird, dubbed Mandarin Patinkin, was seen in New York City's Central Park.

The habitats it prefers in its breeding range are the dense, shrubby forested edges of rivers and lakes. It mostly occurs in low-lying areas, but it may breed in valleys at altitudes of up to 1,500 m (4,900 ft). In winter, it additionally occurs in marshes, flooded fields, and open rivers. While it prefers fresh water, it may also be seen wintering in coastal lagoons and estuaries. In its introduced European range, it lives in more open habitat than in its native range, around the edges of lakes, water meadows, and cultivated areas with woods nearby.