Using diet and plant resources to set wildlife stocking densities in African savannas

The concept of carrying capacity originally was developed for domestic grazers and does not make provision for the wide variety of diets found in wild African herbivores. In the African savannas, herbivores are classified into 4 basic dietary classes: low-selective grazers, high-selective grazers, mixed feeders, and browsers. Given these conditions, a more appropriate approach was needed than the agricultural method based on livestock units to determine stocking rates for wildlife. Consequently, a new approach was developed that recognizes plant resource variation at the plant community level and differentiates between the grazing and browsing component in the diet of herbivores in the African savannas. The model used to calculate the grazing and browsing capacity on wildlife ranches provides for rainfall variability, quality and quantity of available grazing and browse, dietary requirements of each type of wildlife, and availability of suitable habitat. In this model the conventional conversion of wildlife to a Large Stock Unit has been replaced by a Grazer Unit, which is the equivalent of a 180-kg blue wildebeest (Connochaetes taurinus), and a Browser Unit, which is the equivalent of a 140-kg greater kudu (Tragelaphus strepsiceros). By separating the grazing and browsing components in the diet of wildlife for stocking density calculation, the diversity in the vegetation resources is optimally utilized. This concept is exemplified with an actual case study of a wildlife ranch in a South African savanna. In doing so, quantitative and clearly defined parameters are provided on which to base wildlife management decisions.