Exploration versus exploitation: a field study of time allocation to environmental tracking by foraging chipmunks

Abstract

When food sources change unpredictably in time and space, animals may improve their foraging rate if they devote some of their foraging time to locating and assessing the quality of alternative sites, even after they have already discovered and begun to use one site. To test the hypothesis that the amount of time allocated to exploration would increase as the quality of the presently exploited patch decreased, experiments were performed on five wild eastern chipmunks, Tamias striatus, hoarding sunflower seeds from artificial patches. When seed density was high, chipmunks returned promptly to the patch as soon as they had deposited each load. As seed density was reduced, chipmunks spent progressively more time exploring before returning to the patch. When seed density again increased, exploration times declined. Our experimental design also permitted a test of central place foraging theory. As predicted, chipmunks had longer collecting bouts but took smaller numbers of seeds per load when seed density was low than when it was high.