Abstract
Behavioral plasticity is a key mechanism by which animals buffer themselves against environmental change. The degree to which behavioral plasticity is constrained by morphological and physiological traits, and the factors that drive such relationships, have strong implications for animal fitness yet remain poorly understood. In an effort to derive overarching mechanisms that underpin behavioral trade-offs in complex natural environments, I examined how morphological and physiological traits shape the behavior and performance of large mammals across three ecologically important contexts: foraging, reproduction, and post-disturbance. First, I evaluated physiological traits mediating individual dietary specialization in an African antelope (bushbuck, Tragelaphus sylvaticus). I found that animals in better nutritional condition have narrower diets because they invest more time in searching for nutritious foods. These findings are consistent with predictions from optimal foraging theory about the energetic underpinnings of individual specialization, suggesting a potentially generalizable framework for understanding how individual’s diets are constrained by behavior and physiology. Next, I evaluated whether individual behaviors buffer climatic constraints on reproductive success in an endangered carnivore (African wild dog, Lycaon pictus). We find that (1) packs that use favorable thermal environments, which reduce energetic constraints of heat dissipation on the pregnant female, produced larger litters, and (2) fecundity is constrained by competition among packs wherein larger packs exclude smaller ones from thermally favorable. Our study is among the first to elucidate the mechanistic underpinnings of thermal constraints on reproductive success in a wild population of large mammals and suggests that thermal refugia are a key component of habitat quality that will likely increase in importance as the climate warms. Finally, I quantified the responses of a large-mammal community to an extreme tropical cyclone to identify mechanisms underlying animal robustness to disturbance. In March 2019, the worst tropical cyclone on record in the southern hemisphere, Cyclone Idai, passed directly over Gorongosa National Park. Utilizing multiple data streams for 13 ungulate species and 2 carnivores, I found that small species are most vulnerable to cyclones due to limited mobility, which increased likelihood of death during the flood and constrained animals’ capacity to withstand food shortage afterwards. This study is the first to identify individual-level mechanisms that underpin community-level responses to severe disturbance and suggests a general trait-based theory for predicting the impacts of extreme climatic events.