Aspects of the home range ecology of the leopard tortoise in the semi-arid central Karoo: An area threatened with fracking

Abstract

Whilst fracking is used globally, impact studies on wildlife are limited. The semi-arid Karoo, South Africa, a large ecosystem with a high degree of endemism, is targeted for fracking. We investigated how adult leopard tortoises (Stigmochelys pardalis) use their environment by determining individual and seasonal variation in home range and effects of weather factors on these pre-fracking. Data were obtained from Global Positioning System (GPS) transmitters placed on leopard tortoises (n = 11) on private livestock farms near Beaufort West, South Africa for a year. Kernel density estimation (KDE) was used to estimate home range. Individuals had a mean (±SE) home range of 121.86 ± 28.12 ha, (range 40.53–258.52 ha) with a core area of 76.55 ± 17.33 ha (range 21.22–83.89 ha). No difference was found between annual male and female home ranges. Two telemetered individuals were excluded from analysis because they exhibited apparent nomadic behaviour. Several individuals did not visit permanent water sources, possibly suggesting that dietary water intake was sufficient. Generalised Linear Mixed Models were used to explain monthly home range estimates (95% KDEhref) in regards to biologically significant predictor variables. A single top model (ΔAICc < 2) was produced, indicating importance of individual variability (sex, body mass) and weather (temperature, rainfall) variables. Our results provide baseline data pre-fracking in the region, and as such, should be repeated following commencement of fracking.