Liancheng white duck. Darkmouth water duck, known as Liancheng White Duck, is an excellent local duck species in China. It was originally called Baiyu Duck and Darkmouth Duck. Liancheng White Duck is produced in Liancheng County, Fujian Province, and Liancheng is also named the hometown of Liancheng White Duck in China, which is protected by geographical indications. Liancheng white duck has a long and narrow body, a small head, a slender neck, a shallow chest, a drooping abdomen, flexible movements, strong foraging ability, nervousness and tight white feathers. The beak is black. Tibia and webbed feet are grayish black or dark red. Because of the sharp contrast between their black and white feet and heads, they are also called black girls locally.