Feeding Ecology of the Sanje Mangabey (Cercocebus sanjei): A Nutritional and Mechanical Perspective

The proposed doctoral dissertation research evaluates theoretically derived predictions about the role of fallback foods in the diet of the frugivorous Cercocebus sanjei mangabey, a primate which exhibits morphological traits presumed to have evolved in the context of critical reliance upon these foods, living in a seasonal environment with long periods of preferred food (fruits) scarcity. Fallback foods are abundant and easy to locate but hard to process, providing low rates of energy gain and may contain toxic tannins when compared to preferred foods such as ripe fruit (Marshall and Wrangham 2007). Fallback foods are however, assumed to be critical for many primates in sustaining the physiological maintenance of individuals during times of food scarcity. Behavioral and dietary data were collected over 12 months on a habituated group comprised of 31 adults, examining their responses to seasonal fluctuations in food availability. Results showed that food items such as plant stems (Afromomum species) contained 25%DM of protein, and hard dried seeds (Parinari excelsa) contained 49%DM of lipids. Both of these food items are important food items but Afromomum stems contains high levels of toxins (phenolics 16.36mg/L, condensed tannins 18.88% DM) and P. excelsa seeds, require over 500 kg of force to open. The data showed that the Sanje mangabey keep a constant energy balance between seasonal scarcity of food, relying on asynchronously fruiting lianas during periods of low food availability instead of fallback foods.