Predator-prey dynamics and livestock production in human-occupied savannas: Can cattle be used to conserve declining wild ungulates?
Wildlife in human-occupied landscapes can be conserved if management is based on some understanding of mechanisms by which humans and livestock influence ecological processes. One such process critical to wildlife conservation is predator-prey dynamics. Our main management objective is geared towards maintaining diverse ungulate species populations such as hartebeest (Alcephalus busephalus jacksonii) while allowing the natural re-colonization of lions (Panthera leo) in Ol Pejeta Conservancy (OPC), Laikipia, Kenya. The project aims to determine whether livestock practices affect predator-prey dynamics and can be incorporated into conservation practices. In natural settings, hartebeest associate with zebra aggregations, which may lead them to incur higher rates of mortality due to their proximity to zebra, the primary prey for lions. In settings with livestock, zebra are attracted to grazing corrals while hartebeest are not. If hunting on the grazing lawns offers higher predation success for lions, they may prefer these habitats and predation pressure may decrease for hartebeest that prefer other foraging habitats.
This phase of the project was directed primarily to understand how lions impact hartebeest populations. Hartebeest decline had been documented as far back as 2004. A translocation of 170 individuals was carried out in 2009 to bolster the population, but abundance quickly dropped to pre-translocation levels. We compared the OPC hartebeest population to another population in an area with no lions, and found that in OPC, hartebeest seemed unable to reach a sustainable population size that could offset predation pressure. In addition, the proportion of adults was much higher at OPC, suggesting that predation on calves and subadults was affecting population demography. Finally, hartebeests continued to decline at OPC while the comparable population in the lion-free area was experiencing an increase in abundance.
We also radio-collared five lionesses and deployed camera traps to further investigate predation behavior. Using clusters of collar locations suggesting a kill site, we collected scat at the site to determine the predator species of the kill. Most kill sites were lion, followed by wild dog and cheetah. Further work with scat analysis will help to identify the dynamics of lions, other predators and their prey. Additional phases of the work will tease apart the alternative hypotheses regarding the effect of livestock grazing lawns to determine if cattle may in fact be part of a conservation strategy to bolster populations of hartebeest and other rare large herbivores on African savannas.
Finally, outreach efforts included completion and distribution of a practical manual on ways to reduce conflicts with lions; engagement of over 30 citizen scientists including local community members through Earthwatch; and numerous presentations throughout the region. Outreach efforts have identified that women are severely underrepresented in science and conservation in Laikipia, so future efforts will specifically focus on building capacity and working with local women’s groups to enhance livelihoods, build capacity and foster environmental ethics. ($7,930)