Abstract: The African wild dog is a highly endangered canid that occurs at low densities across only a fraction of its former range, with most remaining populations living in or around protected areas. Wild dog populations are limited by a number of human-caused threats such as disease, habitat loss, and direct persecution. They are also strongly limited by interference competition with African lions and spotted hyenas, and they occur at much lower population densities than their dominant competitors under natural conditions. Wild dogs coexist with dominant competitors by utilizing areas with few competitors, which also forces them to use areas of low prey density, and prior studies have shown that wild dog population density is inversely related with prey density. Prey depletion is an emerging threat that is negatively impacting many protected areas throughout Sub-Saharan Africa, effecting the entire large carnivore guild and substantially reducing densities of dominant competitors such as lions. Our recent research has shown that, contrary to mesopredator release theory, wild dog populations do not increase when lion populations are reduced as a result of prey depletion; instead, wild dogs decrease to critically low levels, in parallel with their dominant competitors. However, the mechanisms that drive this response are unknown. By fitting dynamic Brownian Bridge Movement Models to 5 years of movement data, we investigated the interplay of naturally occurring competitive effects from dominant competitors and humans on the movement and space-use of wild dogs in a prey depleted system. Our results show that even when lion population density is reduced greatly by prey depletion, wild dogs continue to show changes in movement patterns as a result of both short- and long-term exposure to the risk of encountering lions. Initial investigations also show that wild dogs avoid areas that are heavily used by lions (which also hold high prey densities), even when lion density is low. In ecosystems that suffer from prey depletion, our results suggest that competitive limitation of subordinate carnivores remains strong, despite the low absolute density of dominant competitors. This result has immediate implications for the conservation of carnivore guilds in ecosystems suffering from prey depletion in Sub-saharan Africa, and around the world.
