A tree-dwelling species, the moustached guenon lives in groups ranging from 4 to 35 individuals, commonly comprising a single male, multiple females and their young. This species is mostly active during the day, foraging in the tree canopy for fruits, seeds and leaves, with insects, eggs and fledglings also taken when available (1) (2). As one of the smaller guenon species, the moustached guenon is particularly vulnerable to predation by birds of prey, such as the crowned hawk-eagle (Stephanoaetus coronatus), and therefore tends to forage where there is dense forest cover (6).
Communication between moustached guenon groups is usually carried out by means of loud booming calls produced by the males (2) (7). These calls may also be useful in mediating the intermingling that frequently occurs between groups of moustached guenon and other guenon species, such as the greater spot-nosed guenon (Cercopithecus nictitans) and crowned guenon (Cercopithecus pogonias) (7). The resulting large, mixed-species groups provide this species with protection from predation, enabling it to utilise open areas where food supplies are more abundant. In return, the moustached guenon provides information to the other species about the location of the best foraging sites (6).
Moustached guenon mating systems are usually polygynous, with the lone male in each group having exclusive breeding access to all the females (2) (8). While breeding may occur all year round (8), in Gabon, births peak from December to February, with the females giving birth to a single young after a gestation period of around six months (4).