females, half of the time for each. To solicit mating, the mantled guereza will walk near its potential partner and make low-intensity mouth clicks or tough-smacks. During copulation, the males hold on the female's ankles and body. Most matings take place between individuals of the same group but copulations outside of the group have been recorded. In multi-male groups, more than one male may mate with the females. The gestation period lasts 158 days with a 16–22 month interbirth interval. The newborn guereza relies on its mother for support and must cling to her. As they grow older, infants can move on their own but keep returning to their mothers. The infants take up most of the attention in the groups. The other females in a group may handle an infant although the latter are only comfortable with their mothers. The males normally don't pay much attention to infants until they are four to five weeks old. Infants can eat solid food at about eight to nine weeks and by fifty weeks they are fully weaned and no longer need to hold on to their mothers. Communication The most notable vocalization of the mantled guereza is the "roar", which is made mainly at night or dawn by males. The sound of a roar can be carried for up to a mile. It is normally the dominant male who roars when there are multiple males in the group. Roars are used for long-distance communication and can regulate inter-group spacing without direct, physical contact while foraging. When one male starts roaring, neighboring males will start to roar as well. Often, the mantled guereza will respond to calls regardless of "caller identity," focusing more on the collective vocal displays and not the familiarity of the caller. There is variation in the roars of males which could signal the status of their group and fighting ability. With a roar, a male can advertise his body size; both actual and exaggerated. Other vocalizations are made as well. Males may snort, possibly as an alarm call. "Purrs" are made before group movements. Females and infants may "caw" when under mild distress. When in more serious distress, like if an infant is in danger, females and sub-adults will squeak or scream. "Tongue-clicking" is made during mild aggression. In addition to vocalizations, the mantled guereza communicates with several different body postures and movements, displaying of fringe fur, facial