Assessing population performance of hunted impala and wildebeest in Simanjiro Plains, Northern Tanzania

Abstract

Human exploitation of wildlife is driving some species to severe population decline but, few studies examine the combined effect of hunting, environmental variability and demographic traits on population dynamics of hunted species, making it difficult to design sustainable hunting practices. In this study forty-five model scenarios defined by varying levels of hunting, female breeding and mortality rates, were used under Vortex population viability modelling program to assess performance of impala and wildebeest populations and to explore the management options to improve their population persistence. The resident impala population was predicted to suffer severe decline under most hunting scenarios when >2% per year of its population is killed, resulting in local population extinction within 15 years. In contrast, the wildebeest population did not decline at 5% current hunting rates due perhaps to its migratory behaviour that buffers the hunting impact but could go extinct within just 40 years when hunting rate in increased. Further, <10% environmental variability associated with the female breeding and mortality rates had considerable impacts on the population change and size under most hunting scenarios. Improving habitats and reducing hunting could improve female breeding rates thus ensuring the long-term survival of the ungulates in the Simanjiro plains, Tanzania.