Never found west of the Mekong River. One captive Leaf Monkey lived for 28 years and 3 months. Mainly leaves and some flowers and fruits. The troop sleeps outside in mild weather and in caves for shelter in cold winters. Major habitat alteration, including increased agriculture, fuelwood harvesting, logging, warfare and severe hunting for food and medicinal purposes.
Support needs to be given to the development and maintenance of reserves.
There were 55 individuals in 11 collections in 1992, most were presumed to be bred in captivity. There are six or seven subspecies within the francoisi group, all may be distinct species. Pate, D.E. 1991. Francois' Languar Studbook Presbytis francoisi francoisi North American Region . Metro Washington Park Zoo, Oregon.