While plant foods such as seeds and nuts, berries , fungi and fruit comprise the bulk of their food, chipmunks will also eat insects and their larvae and other small organisms including small birds, frogs and snakes. Their mouth pouches make handy carrying basket for transporting large quantities of food back to their burrows. Beech nuts are a special favorite and nests have been found to contain 5,000-6,000 nuts by the beginning of autumn.