The White-Thighed Sirili is arboreal and lives amongst the sub-montane forests and swamp areas of the Thai-Malay Peninsula, the Riau Archipelago and Sumatra. Their diet consists of seeds, fruits and leaf shoots. They have also been seen consuming flowers. They are characterized by the white patches located on the outside of their legs--which is what gives them their name-and they range from 41-69 cm tall and weighting 5-6.7 kg. They have a brown-grey fur coat on their backs, with white fur covering their bellies and dark fur on their head. Their tails--typically covered in dark fur--can extend roughly 58-85 cm. Compared to adults, infants are born with very light fur with crosses of dark fur along their arms and back. They live in small unimale-multifemale groups. After mating, females give birth to single infants to which the group of females care for. Due to their arboreal lifestyle, reliance on detection of predators is vital. Male group members are able to call or display a distraction for predators to protect group members. Their current status is near threatened. They are mainly affected by agriculture, harvesting of wood, as well as hunting. In regards to logging, the production of access roads into forests has increased the deforestation rate by 8% which reduces their habitat and creates a huge reduction of seeds, leaves and fruit available. To compensate for their lost food supply, they have been found to raid crops on the plantations--for instance, leaves of the oil palm--which increases reports of capturing and killing the primates. As well, they are sometimes kept as pets or used in the entertainment industry and that has led to their decimation in some regions of their domain.