Personality traits and their correlation with behavior in the bonnet macaque (Macaca radiata) in southern India

The purpose of our research was to identify the primary personality traits of bonnet macaques using an observer-based questionnaire and to assess the accuracy of this method in predicting behavior. Additionally, we examined the relationship between personality traits and variables such as sex, age, and rank. We rated 25 males and 38 females on 50 personality questionnaire items using a 7-point scale, with reliable ratings and good agreement among raters (the lowest of the calculated ICC (3:k) index ≥ 0.62). Behavioral observations of 38 females over two-years were analyzed. Exploratory factor analysis revealed five traits: Friendliness, Aggression, Playfulness, Fearfulness, and Opportunism. Every trait correlated with a certain number of observed behaviors. Our results suggest that the questionnaire-based method is sufficiently valid as it confirmed high behavioral convergence with Fearfulness, Playfulness and Aggressiveness. Further studies are needed to understand the functional value of behaviors associated with Friendliness and Opportunism. Our study confirmed a tolerant social style of bonnet macaques, characterized by similar Aggression levels in both males and females, and lack of difference in Aggression level between subadult and adult males. Moreover, we identified a species-characteristic trait Opportunism which, unlike in other studied macaques, did not involve aggression-related characteristics.