African savannas are home to the world’s last great megafaunal communities, but despite ongoing declines, we only poorly understand constraints on savanna herbivore abundances. Seasonal diet shifts (except migration) have received little attention, despite a diversity of possible dietary strategies. Here, we first formulate two simple models (one discrete time model that allows more complete analysis and a second consumer-resource model in continuous time), and then test predictions across a dataset of herbivore diets and herbivore population densities across Southern and East African savanna parks.
Results/Conclusions
Models consistently predict that both mixed feeding and migratory grazing will increase population sizes. These predictions are borne out in comprehensive data across African savanna parks: mixed feeders are indeed the most abundant herbivores in Africa, although migratory (but not stationary) grazers also achieve high population densities. Mixed feeder dominance may reflect a historical pattern or may instead mirror a general global decline in specialist species. Regardless, mixed feeders dominate today’s savanna.