Personality and social dynamics of zoo-housed western lowland gorillas (Gorilla gorilla gorilla)

Western lowland gorillas are among the most studied nonhuman primates. However, managing them in captivity is not without its challenges. Understanding individual differences between gorillas, as well as differences in group dynamics, may be of high value in these apes' more efficient captive management. Predicting behaviour may be especially useful, particularly in terms of affiliative and aggressive behaviours. For these reasons, we designed a brief study that investigates the relationship between gorillas' personality and social dynamics. Our study was conducted in Paignton Zoo Environmental Park (UK), in May 2015. Behavioural observations were carried out on an all-male gorilla group, comprising one silverback and four maturing blackbacks. Behaviour was recorded using scan sampling, with an instantaneous recording technique. During the same time, we used all occurrence sampling to record social behaviours of interest: affiliative behaviour (social resting, social playing) and agonistic behaviour (displacement, aggressive behaviour), with the initiator and the recipient recorded for each event. Additionally, the main gorilla keeper rated each gorilla on the Gorilla Behavior Index (GBI), a personality assessment instrument that identifies four personality factors - Extroverted, Dominant, Fearful, and Understanding. Gorillas with higher scores on the Extroverted factor had higher proportions of social behaviour in their activity budgets, and were also more likely to be chosen to rest near. Individuals with higher Dominant scores were less likely to be displaced, while higher Understanding scores were correlated to a lesser likelihood of initiating aggressive interactions, and a higher proportion of solitary behaviour. To better understand the relationship between gorillas' personality and behaviour, we recommend the use of a hierarchical approach to studying personality in the future. We anticipate that a higher level of specificity will enable more accurate prediction of behaviour, thereby providing useful tool for gorillas' captive management