Vocal Quavering: A Basis for Recognition in Forest Guenons
Résumé
Cercopithecus nictitans and C. cephus (Cercopithecinae), two guenons of West African tropical forests, are characterized by a tendency to live together in mixed troops (Gautier and Gautier-Hion 1969). In such sympatric troops, individuals of the two species vocalize in common vocal bouts regardless of the context of emission: alarm situations, troop progression, intertroop spacing, etc. The acoustic structure of most of their calls is so similar that species are very often difficult to identify by an observer relying on calls only. In fact, loud calls given by adult males are the only sounds which allow unambiguous species recognition (Gautier 1975).