Territorial behaviour in the green monkey, Cercopithecus sabaeus: Seasonal defense of local food supplies

Abstract

Territorial behaviour among green monkeys (Cercopithecus sabaeus) was studied for 15 months in Senegal, West Africa. Intergroup relations were quantified, as well as the distribution and availability of resources in the heterogeneous habitat. Intergroup encounters varied seasonally in their location and frequency. Green monkeys did not specifically engage in territorial ‘patrols’, bur rather, areas of range-overlap with neighbouring groups were exploited for specific resources they contained. Neighbours showed flexible responses to seasonally variable competition for these resources. Four types of encounter were quantified, varying in intensity and duration, with descriptions of the ecological context underlying each: chance, ritual, one-sided, and intense encounters, varying according to the relative net benefit to each group to defend specific resources. This depended on the relative availability and distribution of these resources, and the degree to which they could be depleted. Comparisons were made with other populations of C. aethiops. A higher frequency of encounters was associated with higher population density at one site, and with monkeys living in ranges small enough to be economically defendable.