Predator-prey research : Assessments of non-lethal effects of predation

If you have been visiting Welgevonden Game Reserve recently you may have come across a vehicle with massive speakers mounted on the back.

If you happen to have been close by heard the speakers bellowing wolf howls, lion roars, classical music, etc. from their spheres.

This is a part of a research project run by Fred Dalerum and associate researchers studying the non-lethal effects of predation.

Assessments of non-lethal effects of predation:
Large terrestrial carnivores such as leopard, lion and hyaena are not only charismatic species with a wide public appeal; they are also important components in their respective ecosystems.

Predators can have multiple ecological effects, primarily through the impact they have on their prey. The most obvious of these is that they need to kill prey to feed on. However, equally important, but perhaps less obvious is that anti-predator responses of prey may also impose negative implications on them such as decreased number of offspring and increased disease load. This can, for instance, be caused by potential prey being forced to inhabit low-quality habitat to avoid being killed.

Because they have large requirements, often occur at low population densities and frequently end up in conflict with humans, many large carnivores have become globally or locally extinct, and many remaining populations have become threatened.

As a consequence of this, there is currently large conservation and recovery programs to restore carnivore populations into areas they previously used to inhabit. However, although recent work has highlighted the ecological importance of apex predators, little attention has been given to the non-lethal effects of these reintroductions on resident prey.

We are quantifying the effects of lions (Panthera leo) on the time budget of foraging groups of ungulate prey as well as on glucocorticoid stress hormone levels using comparable data from Welgevonden Private Game Reserve and from Lapalala Wilderness, where lions have been extinct for decades.

In addition, data from North America and Europe suggest that large ungulates very rapidly loose the ability recognise predators and hence fail to exhibit appropriate anti-predator behaviour when exposed to introduced carnivores. Such failure in predator recognition can therefore have quite severe impacts on the ecological effects of introduced or restored carnivores. We are therefore also examining the behavioural response to lions in populations of impala, wildebeest and warthog in Welgevonden Game Reserve and in Lapalala Wilderness.

This work is primarily done through the Centre for Wildlife Management and the Mammal Research Institute, University of Pretoria, but we also have an enrolled BSc Honours student from University of Tasmania conducting field work during 2012.

Fredrik Dalerum, Research Fellow, Centre for Wildlife Management, University of Pretoria.