Abstract # 47:

Scheduled for Thursday, June 21, 2007 05:00 PM-07:00 PM: Session 7 (South Main Hall) Poster Presentation

Bioacoustic Monitoring of Aggression in Group-housed Rhesus Macaques (Macaca mulatta)

B. McCowan1,2 and I. Rommeck2,3
1Department of Population Health & Reproduction, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616, USA, 2California National Primate Research Center, 3Animal Biology Graduate Group, University of California, Davis
     In many captive primate facilities, rhesus macaques are housed in multimale-multifemale social groups in large enclosures 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. This study examined the magnitude of aggression and the co-occurrence of certain vocalization types and aggression in ten groups of rhesus macaques over three months using an event sampling regime. Data were collected on both contact (e.g., hit, slap, bite, shove) and no-contact aggression (e.g., head bob, open mouth, direct stare, lunge, chase) and three patterns of vocalizations (screams, threat barks, multiple vocalizations) The data collected represents 65 hours of observations and over 770 aggressive/vocal events. Results 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. Eighty-two percent of aggressive events occurred with aggressive vocalizations, 11% of aggressive events occurred without aggressive vocalizations and only 7% of aggressive vocalization events occurred without aggressive behavior. Categorical outcomes (contact or no-contact aggression) were analyzed by rates of vocalizations by type using multinomial logistic regression. Multiple vocalizations representing a combination of threat barks and screams were produced almost twice as often under conditions of contact aggression than no-contact aggression [Multinomial Logistic Regression, a=0.05]. These results could be used in the development of an automated bioacoustic monitoring system that is capable of detecting and forecasting problematic patterns of contact aggression in rhesus macaques.