Water dependence structures predation risk for large herbivores in insular protected areas

Predator avoidance strategies vary across the ungulate guild. Population-level responses to the presence of large predators to a large extent depend on how well ecological conditions suit the particular predator avoidance strategies of a species. Predation risk from ambush predators, e.g. lions negatively correlates with distance from surface water, but only at scales comparable to the foraging range of lions. Prey species with low surface water requirements spend less time close to surface water, and their predator avoidance revolves around selecting predator-free zones. Arguably, spatial segregation would be further encouraged by competition from water-dependent conspecifics. The scarcity of predator-free zones in confined spaces raises the expectation that they are exposed to a high predation risk relative to species more dependent on surface water. Based on this premise, we argue that lion introductions to insular conservation areas of limited size, compromise diverse ungulate communities. We do an across-species comparison of the long-run population growth of a selection of prey species across fourteen small conservation areas. Study areas are categorised according to those harbouring apex predators (lions) and those that do not. Our findings suggest species differentially respond to the presence of lions, with negative responses biased towards species with low surface water requirements. In smaller conservation areas harbouring lions, reducing surface water frequency might prove key to the successful conservation of water-independent large herbivores.