Nomascus siki

The body length is 45-62 cm and the weight is 7-10 kg. The legs are short, the palms are longer than the soles of the feet, and the knuckles are long; the body is slender, with broad shoulders and narrow hips; it has long canine teeth. The body hair is long and rough. The male is mainly black with a faint silver color, but there is a patch of white or yellow hair on each side of the cheek from the corner of the mouth to the top of the ear. The female's body hair is orange to creamy white, and there is no black hair on the abdomen, which distinguishes it from the black-crested gibbon.
The characteristic of this species is that the fur has different colors at different stages of its growth. The hair of weaned babies is light yellow to white; juveniles are black for both sexes; when they reach adulthood, females return to light yellow to white, with black stripes on the crown or neck. Males remain black and have a wide, thick, arc-shaped, eye-catching white cheek whiskers around t