Male Barbary macaques eavesdrop on mating outcome: a playback study

Female copulation calls have been viewed as being addressed to the mating partner, to ensure male protection and mate guarding or, alternatively, to other males, to incite male competition. In a previous study, we found that copulation calls of female Barbary macaques, Macaca sylvanus ; given during ejaculatory matings differed from those given during nonejaculatory matings and hence provided potential information about mating outcome to listeners. In this playback study, we tested whether this variation is salient to male listeners. In addition, we assessed the influence of cues from other modalities that are related to female receptivity on male responses to copulation calls. The study was conducted on Barbary macaques living in the enclosure ‘La Foret des Singes’, at Rocamadour, France. Males responded more rapidly and more strongly, and spent more time walking and in the vicinity of females, after playbacks of calls given during ejaculatory copulations than after those given during nonejaculatory copulations. Responses, however, were not influenced by the cycle stage of the female whose calls were played back. The results suggest that male Barbary macaques appear to discount contextual information in favour of information related to mating outcome when allocating their mating effort.