Authors: Lucy A Bates Richard W Byrne
Publish Date: 2009/08/25
Volume: 64, Issue: 2, Pages: 247-255
Abstract
Most social primates live in cohesive groups so travel paths inevitably reflect compromise decision processes of individuals are obscured The fission–fusion social organisation of the chimpanzee however allows an individuals movements to be investigated independently We followed 15 chimpanzees eight male and seven female through the relatively flat forest of Budongo Uganda plotting the path of each individual over periods of 1–3 days Chimpanzee movement was parsed into phases ending with halts of more than 20 min during which individuals fed rested or engaged in social activities Males lactating or pregnant females and sexually receptive females all travelled similar average distances between halts at similar speeds and along similarly direct beeline paths Compared to lactating or pregnant females males did travel for a significantly longer time each day and halted more often but the most striking sex differences appeared in the organisation of movement phases into a days path After a halt males tended to continue in the same direction as before Lactating or pregnant females showed no such strategy and often retraced the preceding phase returning to previously visited food patches We suggest that female chimpanzee movements approximate an optimal solution to feeding requirements whereas the paths of males allow integration of foraging with territorial defence The ‘continually moving forwards’ strategy of males enables them to monitor their territory boundaries—border checking—whilst foraging generally avoiding the explicit boundary patrols observed at other chimpanzee study sitesWe thank all the staff of the Budongo Forest Project especially Kakura James Fred Babweteera and Vernon Reynolds For permission to work in Uganda we thank the Uganda National Council for Science and Technology the Presidents Office the Uganda Wildlife Authority and the Uganda Forest Authority This research was supported by a studentship from the Biotechnology and Biological Sciences Research Council 01/A1/S/07457 The paper has benefited from helpful comments from two anonymous referees
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