Père David's deer (Elaphurus davidianus), also known as the milu (Chinese: 麋鹿; pinyin: mílù) or elaphure, is a species of deer that are mostly found in captivity. This semiaquatic animal prefers marshland, and is native to the subtropics of China. It grazes mainly on grass and aquatic plants. It is the only extant member of the genus Elaphurus. Based on genetic comparisons, Père David's deer is closely related to the deer of the genus Cervus, leading many experts to suggest merging Elaphurus into Cervus, or demoting Elaphurus to a subgenus of Cervus.
According to Chinese legend, when the tyrant King Zhou of Shang ruled the land more than 4,000 years ago, a horse, a donkey, an ox and a deer went into a cave deep in the forest to meditate and on the day the King executed his virtuous minister Bigan, the animals awoke from their meditation and turned into humans. They entered society, learned of the King's heinous acts and wanted to take recourse against the King, who was powerful. So they transformed themselves into one creature that combined the speed of the horse, the strength of the ox, the donkey's keen sense of direction and the nimble agility of the deer. This new animal then galloped to the Kunlun Mountains to seek the advice of the Primeval Lord of Heaven. The Lord was astonished at the sight of a creature that had antlers of a deer, hooves of an ox, face of a horse and tail of a donkey. "It's unlike any of four creatures!" he exclaimed. Upon learning of the animal's quest, Lord gave his blessing and dispatched the creature to his disciple the sage Jiang Ziya, who was battling the King. Jiang Ziya rode the creature to victory over the King and helped found the Zhou Dynasty. After fulfilling its vow, the milu settled in the lower reaches of the Yangtze River. The animal became a symbol of good fortune and was sought by later emperors who believed eating the meat of the milu would lead to everlasting life.