Prey preferences of the chimpanzee (Pan troglodytes)

Abstract

The common chimpanzee Pan troglodytes is the closest extant relative of modern humans and is often used as a model organism to help understand prehistoric human behavior and ecology. Originally presumed herbivorous, chimpanzees have been observed hunting 24 species of birds, ungulates, rodents, and other primates, using an array of techniques from tools to group cooperation. Using the literature on chimpanzee hunting behavior and diet from 13 studies, we aimed to determine the prey preferences of chimpanzees. We extracted data on prey-specific variables such as targeted species, their body weight, and their abundance within the prey community, and hunter-specific variables such as hunting method, and chimpanzee group size and sex ratio. We used these data in a generalized linear model to determine what factors drive chimpanzee prey preference. We calculated a Jacobs’ index value for each prey species killed at two sites in Uganda and two sites in Tanzania. Chimpanzees prefer prey with a body weight of 7.6 ± 0.4 kg or less, which corresponds to animals such as juvenile bushbuck (Tragelaphus scriptus) and adult ashy red colobus monkeys (Piliocolobus tephrosceles). Sex ratio in chimpanzee groups is a main driver in developing these preferences, where chimpanzees increasingly prefer prey when in proportionally male-dominated groups. Prey preference information from chimpanzee research can assist conservation management programs by identifying key prey species to manage, as well as contribute to a better understanding of the evolution of human hunting behavior.