Population dynamics management of invasive rock hyraxes, procavia capensis (Pallas, 1766), in the central Free State, South Africa

Abstract

Frequent reports of rock hyrax (Procavia capensis) invasions in residential areas prompted an investigation of this problem in order to identify possible solutions. From reports, problem areas in South Africa were identified, and sites within the Free State Province were selected for this study. At these sites, rock hyrax populations demonstrate an unusual annual increase. This increase has led to a food and habitat shortage, forcing individuals into residential areas in search of additional refuges and food sources. In order to manage populations, several preventive as well as control methods have been assessed and implemented. Population densities were determined using the Lincoln index and the Robson–Whitlock technique. Results obtained when both methods were used showed a positive correlation of R=0.88, calculated with Pearson’s correlation coefficient. Wild populations were included in the study for comparison purposes. Additional resources within residential areas have facilitated populations to grow much larger, in some instances exceeding the natural limits (30 – 40 individuals) by 175 - 225 %. This influx contributes to human–wildlife conflict. With the use of translocation, populations were reduced within three months. The introduction of natural predators for rock hyrax population control appears to have positive results, but will have to be monitored on a regular basis. Preventive measures have shown various levels of success. Different combinations of these measures proved to have different levels of effectiveness. A combination of wire fences higher than 1.8 m, an overhang at the top and dogs from the working and/or terrier groups seemed to be most effective. The strategy to capture and translocation individuals, for the rapid reduction of the population, has been successful. Results show that the establishment of translocated populations was not successful owing to high predation rates.