How have drought and climate change influenced rare antelope declines?
a study of ungulate competition in the Kruger National Park, South Africa
a study of ungulate competition in the Kruger National Park, South Africa
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View a video of my 2023 talk on this topic here!
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Herbivore diets have a huge impact on their movements and interactions with other species. This much is clear even by looking at body shape and size: A squat hippo and a tall giraffe live in entirely different worlds, with entirely different habits and diets. These differences in morphology and diet affect more than just their eating habits, though. Because grasses and trees hold different amounts of nutrients and water, and respond differently to rainfall patterns, the animals that eat them must have different strategies to cope during times of less water. A browser like a giraffe meets much of its water needs through juicy leaves; grass is relatively dry, however, so a grazer like a hippo might need to roam to greener pastures to take refuge.
Grazers and browsers might not compete much for the same food resources, but a third group of savanna herbivores do cross this divide. Recent studies (e.g. Abraham, Hempson, and Staver 2019) have found that herbivores with diets spanning both grasses and leaves (called 'mixed feeders') are likely to supplement scarce water resources during drought by switching their diets from abundant (but dry) grasses to more water-rich trees and forbs (herbaceous non-grasses). This diet-switching behavior can have indirect effects on their fellow herbivores: Might this increased competition for browse challenge the otherwise well-off browser guild? And could diet-switching by mixed feeders relax competition on grazing mammals for those greener pastures? I explore these patterns through the use of a Generalized Joint Attribute Model ('GJAM'--more here), to understand how these animals interact with each other, other large herbivores, and other environmental factors that drive spatial heterogeneity of forage and water availability across the park. With this analysis, I can then start to answer even bigger questions, like: How will these interactions change in the future? In a climate that's growing ever-drier with climate change, what will this community look like in 20 or 50 years? 
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