Bioacoustic monitoring of aggression in group-housed rhesus macaques

Many captive primate facilities house rhesus macaques in multimale-multifemale social groups in large enclosures that simulate the natural social and environmental features characteristic of the species, enhancing their reproductive performance as well as their psychological well-being, yet one of the most difficult management problems in socially housed macaques is their propensity for exhibiting spontaneous bouts of deleterious aggression. To address this management problem, an automated bioacoustic monitoring system might be developed that is capable of detecting and forecasting problematic patterns of contact aggression. To evaluate the utility of this approach, this study examined the magnitude of aggression and the co-occurrence of certain vocalization types and aggression in 10 groups of rhesus macaques. The data confirmed aggression as a significant problem in rhesus groups and indicated that certain patterns of vocalizations are indicative of the type or level of aggression. The detection and classification of these vocalization types need further research to eventually design and implement an efficacious bioacoustic system for monitoring aggression in rhesus macaques.