Males keep a look out for predators, keeps the group together and patrols the territory. In good weather, they sleep outside, but during cold winters, they shelter in caves. Other species are in serious danger in some parts of their distribution due to habitat destruction and hunting. Francois' leaf monkey populations in Vietnam also suffered during the Vietnam War. One young, twins are rare.
Newborns are bright yellow or orange red with pink faces.
They turn into the adult greyish within 6 months. They are born full furred and active. Dense forests with tall trees. Rainforest, deciduous forest, temperate forests. Those in colder areas live near rocky outcrops where they shelter in caves during cold winters.