Savanna herbivore populations may respond to various aspects of global change, including a possible increase in the incidence of drought. Droughts induce widespread and catastrophic mortality among savanna herbivores, and as such, effective conservation of these herbivores depends on considering the strategies that diverse herbivores employ to mitigate mortality during drought. Seasonal herbivore strategies may contribute, including diet switching and migration, or herbivore drought-responses strategies may instead depend on other contributors to herbivore behavior (e.g., body size) or may vary independently of well established axes of herbivore differentiation. To evaluate how herbivores responded strategically to drought, we compared herbivore diet and landscape use in Kruger National Park, South Africa during and after a severe drought.
Results/Conclusions
We found that only the two mixed feeder taxa sampled in this study, elephants (N=166, F=36.02, p < 0.0001) and impala (N=151, F=30.27, p < 0.0001), significantly changed their diets during the drought; grazer and browser diets were remarkably constant. Meanwhile, only grazers (N=2478, F=22.43, p < 0.0001) and megaherbivores (N=2478, F=45.35, p < 0.0001) moved significantly, altering their patterns of landscape use during the drought. These results suggest that herbivore responses may be constrained by their body size and feeding ecology. Grazer conservation in semi-arid savannas, especially, may depend on development of reserves that are sufficiently large to allow grazer movement in the face of increasing climate variability.