Emission vocale de forte intensité chez Cercocebus galeritus agilis : structure, caractéristiques spécifiques et individuelles, modes d’émission

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Abstract
As most species of Cercopithecidae, C. galeritus has a high-intensity vocalization among its vocal repertoire which only adult males emit. Despite some similarity between this call and the one of C. albigena, a sympatric species, it has a complex structure and is specific of C. galeritus. Due to the combination of its time and frequency parameters, it may play a role in individual recognition from a distance. The call of a male increases the probability of occurrence of neighboring male responses, and contagion is evident. These vocalizations are most frequently given during the morning. Among the population of the Njadie river every vocalizer often has one or several neighbors and because of contagion, nearly all calls are given in the early morning. The vocalization is audible up to about 500-600 m and transmits informations regarding the location, the species and probably the identity of the vocalizing individual. It probably serves in spacing mechanisms, which is a typical function of these loud calls. A tendency to aggregate was observed among the vocalizers, everyone being inclined to stay within calling range of the others.