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.

The species were 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.

Compared to other ducks, mandarins are shy birds, preferring to seek cover under trees such as overhanging willows, and form smaller flocks but may become bolder as a result of becoming tame from frequent interaction with humans.

The Chinese refer to Mandarin ducks as yuanyang (simplified Chinese: 鸳鸯; traditional Chinese: 鴛鴦; pinyin: yuānyāng), where 'yuan' (鴛) and 'yang' (鴦) respectively stand for male and female mandarin ducks. In traditional Chinese culture, mandarin ducks are believed to be lifelong couples, unlike other species of ducks. Hence they are regarded as a symbol of conjugal affection and fidelity, and are frequently featured in Chinese art.

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