The mandarin duck (Aix galericulata ) is a perching duck species native to the East Palearctic. 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.
Mandarin ducks, called yuan-yang by the Chinese, are featured often in Oriental art and regarded as symbols of conjugal fidelity and affection. Adult males are striking and unmistakable, with a red bill, a large white crescent above his eye, and a reddish face with "whiskers". His breast is purple with double vertical white bars and his flanks are red and have two orange "sails" in the rear. During molting, the males resemble the females but their red bill is their point of difference. The female’s bill is pinkish and she is much less colorful than her mate. She is a pale beige with a thin white flank stripe and a white underbody and has a white eye-ring from where a stripe runs to the back of her head.
Mandarin ducks breed in eastern Siberia, Japan, and China, and winter in Japan and southern China. In Britain, there is a small number of these birds in a free-flying population, stemming from the release of captive-bred ducks. Mandarin ducks prefer to breed in the dense, shrubby forested edges of rivers and lakes. In winter, they may occur in marshes, flooded fields, and open rivers. While these ducks prefer fresh water, they may also be seen wintering in coastal lagoons and estuaries. In their introduced European range, they live in a more open habitat than in their native range, around the edges lakes, water meadows, and cultivated areas with woods nearby.
Mandarin ducks find food in as well as out of the water. They may feed by dabbling or walking on land. They forage among debris on banks, at the water’s edge, and while swimming, occasionally up-ending when seeking deeper submerged food. They feed mainly near dawn or dusk, perching in trees or on the ground during the day. Mandarin ducks are social birds outside the breeding season and will gather in flocks, sometimes of more than 60. They are agile flyers, using strong, rapid wing-beats, and can rise steeply from the water’s surface or land into the air. The male makes a nasal whistling, a grunting sound, and a bark, while the female makes a soft call.
Mandarin ducks are omnivores, but their diet changes seasonally: in the cold season they are mainly herbivores (granivores), they eat water plants and grains such as rice. When it's warm they eat insects, snails, small fish, and worms.
Mandarin ducks are monogamous and pair bonds may continue for many seasons. The courtship display of this species is very impressive, including mock drinking and shaking. It is the female who chooses the site for the nest but the male goes with her to find it. The nest is in a hole up to 30 feet off the ground in a tree. 9 to 12 white oval eggs are laid at daily intervals during April and May. Incubation is just by the female and is for 28 to 30 days. The eggs hatch within several hours of each other and when all the ducklings are hatched, their mother calls them from the ground and they crawl out of the hole and jump, to land unhurt on the ground and head to the nearest feeding ground. After 40-45 days when they can fly, they leave and join a new flock. Mandarin ducks become mature at one year of age.
Formerly abundant, Mandarin duck populations in their native countries in the Far East have declined as a result of habitat destruction (mainly logging), as well as over-hunting.
According to the IUCN Red List, the total Mandarin duck population size is around 65,000-66,000 individuals. National population estimates include: in China: 100-10,000 breeding pairs and fewer than 50 wintering individuals; in Taiwan: fewer than 100 breeding pairs and fewer than 50 wintering individuals; in Korea: 100-10,000 breeding pairs, and in Japan: 10,000-100,000 breeding pairs plus 1,000-10,000 wintering individuals. According to the Royal Society for the Protection of Birds (RSPB) resource, the total breeding population in the UK is 2,300 pairs and the wintering population is 7,000 birds. Overall, currently, Mandarin ducks are classified as Least Concern (LC), but their numbers today are decreasing.