Personality Dimensions and Their Behavioral Correlates in Wild Virunga Mountain Gorillas (Gorilla beringei beringei)

Studies of animal personality improve our understanding of individual variation in measures of life history and fitness, such as health and reproductive success. Using a 54 trait personality questionnaire developed for studying great apes and other nonhuman primates, we obtained ratings on 116 wild mountain gorillas ( Gorilla beringei beringei) monitored by the Dian Fossey Gorilla Fund's Karisoke Research Center in Rwanda. There were 8 raters who each had more than 1.5 years of working experience with the subjects. Principal component analyses identified 4 personality dimensions with high interrater reliabilities-Dominance, Openness, Sociability, and Proto-Agreeableness-that reflected personality features unique to gorillas and personality features shared with other hominoids. We next examined the associations of these dimensions with independently collected behavioral measures derived from long-term records. Predicted correlations were found between the personality dimensions and corresponding behaviors. For example, Dominance, Openness, Sociability, and Proto-Agreeableness were related to gorilla dominance strength, time spent playing, rates of approaches, and rates of interventions in intragroup conflicts, respectively. These findings enrich the comparative-evolutionary study of personality and provide insights into how species differences in personality are related to ecology, social systems, and life history.