There are usually several adult males and about 1.5-3 times as many adult females. One group of 75-80 individuals included 10 adult males and 21 adult females. There were also solitary animals, mostly immature males driven out of groups by older males. There is a pronounced dominance hierarchy within a group, expressed by priority access to food, space, and grooming. Most mating is done by the highest-ranking male.
Rank order is maintained by aggressive interaction, but actual physical fighting is rare.
Infants are handled by the mother alone until they are 1-3.5 months old. Red colobus have a great variety of vocalizations, perhaps the most outstanding of which is the alarm bark of the adult males. Reported group home range size has varied from about 8.5 to 132.1 ha. There is no territoriality, but the area being used at a given time may be defended through aggressive displays and vocalizations. Reproductive seasonality has not been reported.