Drought-Response Strategies of Savanna Herbivores

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Carla Staver
Essay Abstract: 
Savanna herbivore populations are threatened by possible increases in the incidence of drought with climate change, and as such, understanding the behaviors they utilize to mitigate the effects of drought is vital to their conservation. Herbivores employ two strategies to navigate seasonal variability in savannas, namely diet switching and migration, and these behaviors thus represent potential responses of herbivores to drought as well. To evaluate whether herbivores utilized these strategies in the face of drought, we compared herbivore diet and landscape use in Kruger National Park, South Africa during and after a severe drought. 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, while 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, while herbivores can respond to drought behaviorally, their responses are constrained by their body size and feeding ecology. This highlights our need to craft conservation schemes that recognize these constraints and which likewise facilitate the diverse responses of herbivores to drought.