I studied the activity budget of a group of a Tufted capuchin monkeys (Cebus apella) in the Colombian Amazon forest, during one year, in relation to the combined availability of fruits and arthropods. During the time period when fruits and arthropods were scarce, capuchins increased the percentage of time spent foraging and moving, while reducing time on activities such as resting and socially interacting. In this period, they also increased consumption of vegetative parts, but not of arthropods. These results suggest that the increase in foraging time is due not only to the fruit shortage, but also to the low abundance of arthropods that affected the distribution of time invested in different activities