Vocal Recognition of Alarm Calls in Wild Putty-Nosed Monkeys, Cercopithecus Nictitans

Vocal recognition in social contexts is phylogenetically widespread and can be explained by kin and mate recognition or group coordination. It remains unclear why some species evolved alarm calls that also provide cues to signaller identity as the function of these calls is thought to predominantly serve predation avoidance. One hypothesis is that individually distinct alarms facilitate the detection of unreliable callers, which is in line with the idea of reputation-based mate choice. However, it remains unknown whether receivers use provided cues to identify the signaller and, if yes, how vocal signaller recognition impacts on their own behaviour during predation events. In many nonhuman primates, males provide risky antipredator services to the rest of the group while uttering conspicuous alarm calls. In putty-nosed monkeys, some male alarm types have been shown to be individually distinct and females have been shown to vocally recruit males for predation defence. Whether females are sensitive to the identity of the male supporting them in predation defence is unknown. We tested 16 groups of putty-nosed monkeys in the Nouabale Ndoki National Park (Republic of Congo) with different alarm types from different males. Specifically, we broadcast pyow, hack and kek calls from the group's own male, a neighbouring male and an unknown male, respectively, to each group. Female receivers were sensitive to signaller identity and consistently varied their own antipredator behaviour between different males for two call types but not for eagle-related hacks. We explored different possible explanations for male recognition based on risky male antipredator services and conclude that our results are strongly in line with the reputation-based mate choice hypothesis. (C) 2022 The Author(s). Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.