The Javan langur is a diurnal and arboreal primate (5). It feeds mainly on leaves, fruit, flowers, flower buds, and insect larvae and, like other members of the Colobinae subfamily, has evolved a specialised stomach to digest plant material more efficiently (3). This species also has enlarged salivary glands to assist it in breaking down food (5).
This langur lives in social groups of around seven individuals, with one or two adult males in the group (5). Adult Javan langur females are aggressive towards females from other groups, and have been observed looking after the offspring of other mothers, as well as their own. It is thought that juveniles are brightly coloured because this alerts females to their presence and ensures that they will always be noticed and protected (3) (5). Mating occurs throughout the year and females produce one offspring at a time (5).