Utilization of fruiting trees by monkeys as analyzed from feeding traces under fruiting trees in the tropical rain forest of Cameroon

Abstract

Individual trees of the food species of monkeys were identified by placing plastic tapes with an identification number on them in the tropical rain forest of Cameroon, West Africa. In order to determine the use of the feeding trees by monkeys, the ground under each of the trees was checked at least once a week to see if there were any fallen fruits or traces of feeding on fruits. Some fruit species were not fed on by either monkeys or large arboreal squirrels. Among the food species common to both the monkeys and large squirrels, a larger proportion in terms of quantity in each species was mainly eaten by the monkeys except in the case of super-abundantly fruit producing species. The monkeys and large arboreal squirrels were well segregated in their diets. Larger proportions (more than 85% for most of the monkeys' major foods) of fruits of larger sizes were made to fall on the ground by the monkeys and squirrels. The monkeys displayed a tendency to visit fruiting trees rather evenly (even rate of visit = even frequency of visit/duration of fruiting) not ignoring any area of the home range, although a small difference in this tendency was observed between the two study periods, one an abundant season and the other a poor fruiting season. On average, one associated polyspecific group of monkeys encountered only 14 fruiting trees per day. On the other hand, fruits were available all around the year, as the fruiting periods of different tree species were widely distributed around the year, or the fruiting periods of some species were very long. Although the monkeys are able to depend heavily on fruits, the quantity of fruits is not so great. The population size of monkeys is well balanced with the available food supply in the tropical rain forest of West Africa.