A Molecular Analysis of Insectivory by Sympatric, Omnivorous Guenons (Cercopithecus ascanius, C. mitis) in Kibale National Park, Uganda
Insects and other arthropods are an important yet poorly understood food resource for many nonhuman primate species. Arthropods are generally high in proteins, lipids, and important micronutrients, and comprise a substantial part of the diet of most omnivorous primates. My overarching aim in this project was to examine variation in insectivory by sympatric primates to test the hypothesis that differential use of insects as a food resource facilitates coexistence of omnivorous species. As such, my primary research goal was to investigate the role of insectivory as a mechanism of coexistence through dietary resource partitioning. Secondary goals included the analysis of intra-specific and inter-seasonal variation in insectivory to increase our understanding of each study species’ feeding ecology. I achieved these goals by integrating advanced molecular methods and noninvasive field data collection to identify arthropod prey consumed by redtail (Cercopithecus ascanius) and blue monkeys (C. mitis) — two omnivorous primate species inhabiting Kibale National Park, Uganda. I used next-generation sequencing to identify arthropods consumed by redtail and blue monkeys over a six-month period encompassing one wet and dry seasonal cycle. Results of this research show that while overlap exists in the arthropod portion of their diets, 20-25% of taxa consumed are unique to each group. Additionally, redtail monkey fecal samples contained more arthropod taxa per sample than blue monkeys (p<0.05), while blue monkey samples contained a greater taxonomic diversity (p<0.05). This was reflected in the female redtail samples containing more arthropod taxa per sample and blue monkey female samples containing a greater diversity than their male contemporaries (p<0.05). Seasonal variation in arthropod abundance did not correspond to variation in consumption by the study groups. Indeed, overall arthropod abundance was higher during the wet season (p<0.05), but both study groups consumed more arthropods during the dry season (p<0.05). Our findings suggest that variation in arthropod intake may help decrease dietary niche overlap and hence facilitate coexistence of closely-related primate species and add to our understanding of the influences of ecological and life history variables on primate arthropod consumption.