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

Abstract

Western lowland gorillas are among the most studied non-human 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 behavioural instances. For these reasons, we designed a short study that investigates the relationship between gorillas' personality profiles and their 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, and social playing) and agonistic behaviour (displacement, and aggressive behaviour), with the initiator and the recipient recorded for each event. Additionally, the main gorilla keeper rated each of the gorillas on the Gorilla Behavior Index (GBI), a personality assessment instrument that identifies four personality factors - Extroverted, Dominant, Fearful, and Understanding.

Our results show that 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, as well as a higher proportion of solitary behaviour. To better understand the relationship between gorillas' personality and behaviour, we advise a hierarchical approach to studying personality. We anticipate that a higher level of specificity will enable more accurate predictions of behaviour, thereby providing useful tool for gorillas' captive management.