Influence of livestock density on vigilance behavior of wild prey in a dangerous grazed ecosystem

Background/Question/Methods Presence of human settlements along with livestock is a common occurrence in many protected areas in developing countries. Large and vulnerable livestock act as preferred prey for many large carnivores.Traditionally ecological research on interactions between wild and domestic prey were mainly focused on direct competition for limited resources (grazing) and or resulting man- animal conflicts. However the presence of livestock can result in indirect interactions between them and the common native wild prey via shared predator. Indirect interactions like apparent competition can occur where presence of one prey species increases the mortality risk for the other prey by causing positive functional and numerical response of their shared predator in the patch.  However, this enemy mediated indirect effect on a focal prey can be influenced by the alternative prey densities, vulnerability, or preference by the shared predator. Higher densities, vulnerability, and predator preference towards one prey can reduce the functional responses towards other prey due to switching or satiation by the predator. This can result in apparent mutualism where one prey benefits  due to the presence of another. Thus, the presence of livestock can result in mixed indirect density-dependent interactions with common native prey that promote their coexistence.  We explored these effects by studying vigilance of native chital deer living in areas of low versus high densities of large domestic prey in Acacia-Zizhypus forests where deer and livestock share a common large predator (Asiatic lions). Data on livestock population and their mortality rates in these two areas were evaluated for trends in lion predation rates

Results/Conclusions  Prey vigilance was higher in areas with low livestock densities than in high-density areas.  This unexpected indirect interaction occurs because lion predation rates on livestock were twice as great where livestock were abundant than where livestock densities were low.  Cheetal deer’s lower vigilance level when coexisting in high livestock density areas suggest that it experiences lower predation risk, as lions switch more towards taking livestock as their main prey. This suggests that a positive indirect effect via shared predation takes place for chitals at higher densities of livestock. It is thus apparent that conservation managers must anticipate a variety of indirect interactions especially in protected areas dominated by human and livestock population.