Mentawai Langur

The Mentawai langur (golden-bellied Mentawai langur) is a primate endemic to the Mentawai Islands in Indonesia, found on Sipora and the Pagai islands; the Siberut population is now treated as a separate species, the Siberut langur. Infants are born with white fur, which begins to darken after two to three weeks as the face becomes darkly pigmented, starting along the back and head; after three months the belly and chest are dark red (Wikipedia, general species account).