Increased folivory in brown spider monkeys Ateles hybridus living in a fragmented forest in Colombia

Abstract

Brown spider monkeys Ateles hybridus are one of the most threatened primates in the Neotropics. Most of the remaining populations of this species already live either in forest fragments or in areas that face imminent anthropogenic disturbance. Understanding how these animals cope with the challenge of living in small fragments, while at the same time being a large, frugivorous mammal is crucial to design effective conservation and management strategies. We studied the diet of wild A. hybridus and measured forest productivity in a small (~65 ha) fragment in the Magdalena Region of northern Colombia over a period of 26 mo. Spider monkeys at this site spent far less time feeding on fruits than reported in previous studies of Ateles spp. living in less fragmented sites. Moreover, we registered a high consumption of leaves in every month (on average 37% of their feeding time) as well as the consistent inclusion of decayed wood in the diet. Ficus trees can be considered staple feeding items, as they were present in high proportions in the monkeys' diet throughout the study. Although wild populations of spider monkeys can have flexible diets that include large proportions of leaves over long periods of time, they may also be exposed to a suboptimal diet which may have negative implications for their reproduction and well-being in the long run, further compromising the viability of wild populations living in disturbed habitats.