Over 65% of the original wildlife habitat in Africa has been lost (Kiss, 1990) as a result of agricultural expansion, deforestation, and overgrazing, which have been fuelled by rapid human population growth and poverty. As a result, protected areas are becoming increasingly ecologically isolated while wildlife on adjacent lands is actively eliminated (Newmark and Hough, 2000). Invasive alien species pose additional dangers to biodiversity in protected areas in east and southern Africa.