Habitat selectivity influences the reactive responses of African ungulates to encounters with lions

Abstract

Prey mortality depends on the likelihood of encountering a predator and of being killed following such an encounter. While the proactive responses of large herbivores to the risk of predation have been well documented, the reactive responses of prey following encounters have been less well studied and restricted mostly to northern temperate ecosystems. We postulated that the reactive response should depend on the habitat selection of the prey species as well as the hunting tactic (cursorial versus stalking) of the predator. We investigated the reactive responses of a selective grazer, the blue wildebeest, Connochaetes taurinus, and a generalist grazer, the plains zebra, Equus quagga, to encounters with lions, Panthera leo, their main predator, in Kruger National Park. We used simultaneous global positioning system (GPS) locations of prey and predators to identify encounters and assess their frequency and characteristics (e.g. time of day). We compared both the immediate response (stay or flee) and subsequent movement (remain in the habitat patch or relocate) of the two ungulate species following encounters with lions. Despite being more predictably located in open short grass areas, wildebeest encountered lions no more frequently than zebra. However, being more selective for these particular habitat types, wildebeest more often stayed near the encounter site than zebra. Specifically, wildebeest were less likely to leave when located in more open areas with short grass providing both high-quality food and little concealment for stalking lions. We suggest that this is because wildebeest incur higher risks and greater feeding costs than zebra should they relocate, owing to their narrower preference for areas of short grass. Our findings show how the adaptive responses of wildebeest and zebra following encounters with their major predator depend on their habitat requirements.