Sensitivity of Africa’s larger mammals to humans

Abstract

Habitat loss and overexploitation are driving differential declines in vertebrate taxa but variation in responses means it is often difficult to determine where to place conservation effort. Here we present an easy-to-use method to rank the relative sensitivities of the larger mammals of savanna Africa to human activities in order to prioritize conservation activities. We first made coarse predictions about susceptibility based on species’ intrinsic ecological traits. Next we determined actual presence of these species using transect surveys within the heavily impacted Wami-Mbiki Wildlife Management Area in Tanzania, by conducting interviews outside this protected area, and monitoring changes in populations within both of these zones. Finally we used these combined data to derive a sensitivity measure that we compared to prior predictions about the susceptibility. Our empirical measure of sensitivity to humans was positively correlated with species’ body mass, and home range size. The empirical data allowed us to categorize these species into those that are very sensitive to humans (species in danger), sensitive to humans (human avoiders), moderately common species (human adapters), and those that are positively impacted by people (human exploiters). Conservation efforts aimed at human avoiders and species in danger are likely to have disproportionate payoffs in protecting larger mammal assemblages in Africa as these more sensitive species likely act as focal species (sensu Lambeck, 1997) for management efforts. Our measures combine easy-to-conduct transect data with interview data, and evaluate temporal changes to reach conclusions about how sensitive large mammals are to humans. These methods can be applied in other regions where studies are beginning to examine wildlife declines outside protected areas.