Effects of age and sex on diet and activities of immature reintroduced western lowland gorillas.

Abstract

The juvenile life stage is crucial in primates, yet the behavior and diet of juveniles is an understudied area of primatology. Compared with adults, considerably less is known about wild juvenile primate development, particularly that of western lowland gorillas (Gorilla gorilla gorilla). While sex differences in diet and time budgets are well studied in adults, work remains to be done on how age and sex influence juvenile behavior. Here, we use data from nine immature reintroduced western lowland gorillas to fill some of this knowledge gap. We found that the immature gorillas spent most time feeding, followed by resting. Younger juveniles spent less time resting than older individuals, instead spending more time in self-play compared with older juveniles and more time in locomotion than subadults. The group had a varied diet as would be expected for western lowland gorillas; predominantly eating stems, flowers/leaves and fruit, with subadults eating more stems compared to younger individuals. Sex was found to have little influence on either behavior or diet. Additionally, behavioral and dietary diversity were calculated in order to describe the diversity of immature western lowland gorilla behavior. There were no age or sex differences found among this group of individuals, suggesting behavioral repertoire and diet may be influenced by those in their social group. The wider aim of this study is to provide insights into immature western lowland gorilla behavior and diet in the wild while also contributing to understanding of the post-release period for rehabilitated primates.