The well-studied species T. johnii inhabits upland forests and is more arboreal than is Semnopithecus entellus. It may shift its range in the course of a year, in response to the fruiting and flowering seasons of various plants. Population densities of 116-327 per sq km have been reported for T. vetulus, of Sri Lanka. No intergroup aggression has been noted in T. geei, but T. vetulus is highly territorial, and adult males defend the entire home range of 1-10 ha. In T. johnii, reported heterosexual group size is 6-30, and most units contain only a single adult male.
Additional males live alone or in small groups.
There is a strong, stable dominance hierarchy among the females, and they appear to be responsible for most group socialization. No seasonality has been reported for T. johnii or T. geei. In another area, where rainfall and food supplies were high all year, no reproductive peaks were observed. Normal interbirth interval is 2 years. Litter size is usually 1 in the genus, but twins are born occasionally.