Macro-ecological patterns of a prey-predator system: rodents and snakes in West and Central Africa

Optimal foraging theory predicts that in animals both the sizes of prey consumed and the range of prey sizes eaten should increase with increasing predator size. Rodent prey and rodent-eating snakes (their predators) can provide a useful model for testing the ecological correlates of these predictions. In this study, we explore the relationships between species richness of these predators and prey and the prey size and predator size relationships. The analysis was performed at the level of the whole of West and Central Africa. Distribution data and body size for each genus within both rodents and snakes were obtained from the literature, and mapped using the World Map program. Numbers of rodent and snake genera by cell increased significantly from North to South, this being consistent with typical macro-ecological patterns. Snake mean body size per cell and mean rodent body size per cell were not significantly correlated; however, when the same analysis was restricted to only rodent-eating snakes, this relationship became statistically significant. Cell vegetation type significantly affected the mean body size of both snakes and rodents, with body sizes being smaller in dry savannah cells than in Guinea savannah and forests cells.