Quantifying Sexual Partitioning in Diet and Habitat Use in Wild Mandrills in a Dynamic Rainforest Savannah Landscape

As natural habitats are confronted with substantial environmental change, we urgently need more information on the resilience of at-risk populations in the face of disturbance. How will species react to the decreased resources levels and increased uncertainty in resources that future environments promise? Will populations adjust their usage of space to compensate for local reductions in environmental quality, or will they adjust their diet to make the best of what is available in altered habitats? Historically, our efforts to predict how organisms will respond to environmental stress has been hampered because of challenges in studying both how wild animals exploit space and what they eat. This PhD studentship will contribute to an ongoing project that brings movement ecology and nutritional ecology together in one coherent framework to study animal resilience in the face of environmental change. Sexually dimorphic species can shed light on factors affecting resilience. Although habitat and dietary choices differ substantially across species, drawing inferences on how these factors affect resilience to change is quite difficult because different taxa vary in many characters in addition to habitat and diet. Intraspecific sexual differences in functional traits also have dramatic effects on how individuals acquire and use environmental resources. Species with strong dimorphism are therefore ideal for studying how functional traits affect resilience to disturbance. The extreme sexual dimorphism of Mandrills (Mandrillus sphinx) presents an opportunity to study plasticity in diet and habitat use within the same species, a sharp contrast that isolates spatial and dietary differences from other variables including differences due to phylogenetic background.Mandrills are the most sexually dimorphic primates(Fig. 1). In addition to the remarkable ornaments that are important for sexual signalling, males weigh three times as much as females and take much longer to reach sexual maturity. Both ornamental traits and size have strong links with resource availability, and may at least partly explain observations of sexual differences in space use within Lopé NP in Gabon, where members of our team have been observing mandrills for many years (Fig. 2). Whatever the proximate cause of differences in space use, females exploit a wider range of habitats, and travel within very large groups, while mature males range less and spend much of the year outside of the group.