Nutritional content explains the attractiveness of cacao to crop raiding Tonkean macaques

Abstract

Abstract Nutritional ecology has been linked to crop raiding behavior in a number of wildlife taxa. Here our goal is to explore the role nutrition plays in cacao crop raiding by Tonkean macaques Macaca tonkeana in Sulawesi, Indonesia. From June – Sept. 2008 we collected fruit samples from 13 species known to be important Tonkean macaque foods and compared their nutritional value to that of cacao Theobroma cacao, an important cash crop in Sulawesi. Cacao pulp was significantly lower in protein, but lower in dietary fiber, and higher in digestible carbohydrates and energy content compared to forest fruits. These findings, combined with the fact that cacao fruits are spatially concentrated and available throughout the year, likely explain why Tonkean macaques are attracted to this cultivated resource. We use these data along with published feeding ecology data to propose strategies to minimize human-macaque conflict. Namely, we recommend the deliberate protection of Elmerillila tsiampaccca, Ficus spp. and Arenga pinnata, fruit species known to be regularly consumed and of considerable nutritional value. We also identify the A. pinnata palm as a potential buffer resource to curb cacao crop raiding by macaques. Cacao is a hard-to-process food because the pods have a thick outer skin that encases the seeds and pulp. Aren palm fruit, although lower in digestibility, is easier-to-process, higher in protein, and also available year round. In addition, because the palm has considerable cultural and economic significance for local people, the strategy of planting Aren palm in a buffer corridor is likely to garner local community support.