Frugivory in Chimpanzees (Pan Troglodytes Schweinfurthii) as Influenced by Fruit Nutrient Composition in Kalinzu Forest Reserve, South Western Uganda

Chimpanzees are frugivorous primates that eat fruit in large quantities compared to other foods. To find suitable fruit, they must navigate through the available fruit resource that constitute varying concentrations of nutrients, toxins, and digestion inhibitors. In this study, two year all-day follows coupled with faecal analysis were done to record the fruits eaten by chimpanzees (Pan troglodytes schweinfurthii) of Kalinzu Forest Reserve. A total number of fifteen (15) fresh fruits were collected and analysed for their macronutrient and antifeedant content to determine whether nutrient composition had an influence on chimpanzees' pattern of frugivory. Fruit nutrient content was determined by analyzing freeze dried fresh samples using standard techniques. Musanga leo-errerae (76.14%) and Ficus spp (66.05 %) constituted the most commonly eaten fruits while other eaten fruits constituted the remaining 18.68% (N = 2683). With the exception of Musanga leo-errerae, Uvariopsis congoensis, and Aframomum angustifolium, fruit consumption generally increased for fruits with total phenols and tannins less than 1% per gramm. Only calcium, tannins, crude fat, protein, and energy content significantly predicted 76.86% of consumption, according to multiple regression analysis (R2 = 76.86%; P = 0.019). However, the fact that some of the most eaten fruits like Aframomum angustifolium and Musanga leo-errerae were recorded to have the highest amounts in tannins shows that chimpanzees have other behavioural feeding strategies they use to deal with such antifeedants. According to this study, Musanga leo errerae alone provided 10253 mg per kilogram of calcium consumed per day. Therefore, Chimpanzees in Kalinzu forest have adequate calcium intake and its nutritional benefits like healthy strong bones and teeth. Other than fruit availability, consideration of effect of fruit size and handling within the existing models of chimpanzees’ diet could hence enhance further the understanding of other fruits consumed by chimpanzees.