Effects of Human Management Events on Conspecific Aggression in Captive Rhesus Macaques (Macaca mulatta).

Conspecific aggression in outdoor-housed rhesus macaques (Macaca mulatta) at primate research facilities is a leadingsource of trauma and can potentially influence animal wellbeing and research quality. Although aggression between macaquesis a normal part of daily social interactions, human presence might affect the frequency of various behaviors and instigateincreases in conspecific aggression. We sought to determine how and which human management events affect conspecificaggression both immediately after an event and throughout the course of a day. From June 2008 through December 2009, werecorded agonistic encounters among macaques living in 7 social groups in large outdoor field cages. Behavioral data werethen synchronized with specific management events (for example, feeding, enclosure cleaning, animal catching) that occurredwithin or near the enclosure. By using an Information Theoretical approach, 2 generalized linear mixed models were developedto estimate the effects of human management events on 1) aggression after individual management events and 2) dailylevels of aggression. Univariate analysis revealed an increase in the rate of aggression after a management event occurred.The best predictor of aggression in a cage was the type of management event that occurred. Various factors including thenumber of daily management events, the total time of management events, the technicians involved, reproductive season,and their interactions also showed significant associations with daily aggression levels. Our findings demonstrate that humanmanagement events are associated with an increase in conspecific aggression between rhesus macaques and thus haveimplications regarding how humans manage primates in research facilities.