Apex Predators in the Anthropocene: African Large Carnivore Ecology at the Human-Wildlife Interface

Deep Blue (University of Michigan)2023

Abstract

As anthropogenic pressures expand to permeate landscapes worldwide, sometimes with synergistic impacts, wildlife must navigate human-dominated landscapes and novel environmental regimes to survive. In this dissertation, I examine how complex human-caused environmental changes alter wildlife distributions, behaviors, and interactions, as well as the consequences of these changes for wildlife conflict with human communities. I focus on African large carnivores because of their ecological and conservation importance, using insights from ecological theory to contextualize large carnivore interactions with other wildlife, livestock, and people. Large carnivores are particularly at risk from human pressures due to long life histories, high energetic requirements, and the harm they can inflict on human livelihoods. Avoiding the risks posed by humans leads large carnivores to modify their ecological roles as top-down ecosystem regulators, potentially causing cascading impacts that restructure community processes. In Chapter II, I explore the spatiotemporal responses of three large carnivores and their prey to human use of a protected area in West Africa. Overall, wildlife avoided humans by changing the timing of their daily activity. By conducting a novel analysis on an extensive camera survey dataset, I found that human presence disrupted the overlap between predators and their prey, which could change prey selection and subsequent ecosystem processes. However, human presence is just one aspect of human-caused changes to wildlife habitats. In Chapter III, I synthesized the spatiotemporal responses of African lions (Panthera leo) to the multi-faceted effects of human disturbance across their range using a systematic meta-analysis of 23 studies across 30 sites. I found that lions consistently avoided the pressures of human-dominated landscapes in space and time, limiting lions’ spatiotemporal niche and likely reducing their ecological impacts as predators. However, the risks of human encounters appeared to be outweighed by lions’ metabolic needs, resulting in increased overlap with human-dominated areas when primary resources were scarce. Additionally, lions avoided human disturbance more strongly at sites with high livestock production, signaling that livestock presence displaces wildlife or that lions are using behavioral strategies to target livestock as prey. To better understand the tangible impacts of how changing resource availabilities cascade to influence human-carnivore conflict, Chapter IV combines remotely sensed environmental measures with empirical data on prey availability and livestock depredation by lions in the Makgadikgadi Pans ecosystem in northern Botswana. I found that the incidence of livestock depredation by lions was highest at times of primary resource scarcity, including reduced primary production and water availability. Though changes in prey availability are commonly used to explain links between primary resources and livestock depredation, we did not find a direct link between wild prey availability and livestock depredation rates despite prey availability being strongly driven by primary productivity in the study area. The results of Chapter IV suggest that livestock depredation may be more strongly influenced by livestock and lion responses to resource availabilities, a process that was highlighted as a likely contributor to conflict in Chapter III but is overlooked in most human-carnivore conflict studies. By examining bottom-up drivers of conflict at fine temporal scales, Chapter IV expands our understanding of the fundamental role of global change in driving human-lion conflict across Africa. Overall, my dissertation thoroughly examines the consequences of human pressures on the ecological roles of lions and other large carnivores, highlighting how humans directly and indirectly modify their behaviors and interspecific interactions.

Abstract

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