DISSERTATION RESEARCH: Can avoidance behavior and landscape complexity explain patterns of predator coexistence in mammalian carnivores?

This project explores the population dynamics of large African predators, asking how spotted hyenas, leopards, and cheetahs are able to live with lions, given that lions frequently harass and kill these smaller predators. Investigators will integrate data from surveys of lions with data from camera traps to determine how hyenas, leopards, and cheetahs distribute themselves across the landscape with respect to lions, and how differences in habitat use enable these species to coexist with and without lions. Understanding how predators coexist is important for understanding how large ecosystems function. Recent research has emphasized the profound effects that top predators can have on ecosystems; disrupting predator populations can destabilize natural systems in unexpected ways. The ability to predict how and why destabilization occurs is a necessary first step to preventing the ecological collapse of ecosystems with many types of predators. This project will engage the public through a citizen science platform (www.SnapshotSerengeti.org) in which members of the public help identify wild animals in photographs taken by camera traps. As anthropogenic change drives the continued decline of large predators around the world, research on ecosystem stability becomes increasingly relevant, as does public engagement in research.

More specifically, this study will test predictions from an ongoing predator study in the Serengeti by comparing distributions and population sizes of spotted hyenas, leopards, and cheetahs across two South African reserves with and without lions. For example, without lions, leopard numbers may higher or hyenas may occupy prime riverine habitats. This type of response is expected because overlap between mammalian predators is typically minimal; instead, suppression appears to be mediated primarily through direct aggression and a large-scale avoidance response that displaces subordinate species from large portions of the landscape. In traditional predator-prey systems, this non-consumptive effect (NCE) of predation risk creates a 'landscape of fear' that can be more important for predator-prey dynamics than actual predation. It can, for example, be the driving force behind trophic cascades. However, the role of NCEs in driving population dynamics has been almost exclusively investigated in small scale predator-prey systems. This project investigates the role of NCEs in driving apex-mesopredator coexistence in a guild of large African carnivores. The research has two aims: (1) to compare effects of large-scale displacement in driving lion-mesopredator coexistence, and (2) to evaluate the role of landscape structure and behavioral avoidance at multiple spatial and temporal scales in mediating lion-mesopredator coexistence. It is predicted that complex landscapes will facilitate fine-scale partitioning and thus coexistence by minimizing large-scale displacement.