Hierarchy of fear: experimentally testing ungulate reactions to lion, African wild dog and cheetah

Impalas, elephants, and other ungulates demonstrate a "hierarchy of fear" toward their predators, most fearing the "King of Beasts" (lions). Quantifying how fearfully prey react to one predator versus another is critical to fully comprehend each predator's impact on the ecosystem, but this has proven difficult to predict. Using automated camera-speaker systems, we demonstrate the ready feasibility of experimentally quantifying the fear the African ungulate community manifests toward lions, African wild dogs, and cheetahs. Experiments have begun demonstrating that the fear (antipredator behavioral responses) large carnivores inspire in ungulates can shape ecosystem structure and function. Most such experiments have focused on the impacts of either just one large carnivore, or all as a whole, rather than the different impacts different large carnivores may have in intact multi-predator-prey systems. Experimentally testing the relative fearfulness ungulates demonstrate toward different large carnivores is a necessary first step in addressing these likely differing impacts. We tested the fearfulness ungulates demonstrated to playbacks of lion (Panthera leo), African wild dog (Lycaon pictus), cheetah (Acinonyx jubatus) or non-predator control (bird) vocalizations, in Greater Kruger National Park, South Africa. Ungulates ran most to lions, then wild dogs, and then cheetahs, demonstrating a very clear hierarchy of fear. Those that did not run looked toward the sound more on hearing large carnivores than controls, looking most on hearing lions. Notably, prey species-specific population level kill rates by each predator did not predict the patterns observed. Our results demonstrate that different large carnivores inspire different levels of fear in their ungulate prey, pointing to differing community-level impacts, which we discuss in relation to the ongoing worldwide decline and loss of large carnivores.