The relation between herbivore density and relative resource density at the landscape level: kudu in semi-arid savanna

Abstract

Ecological theory can help range scientists to understand the determinants of ecological animal density or, in range management terms, 'carrying capacity'. The relation between the relative density of resources and herbivore density is illustrated by regressions of the ecological density of kudu (Tragelaphus strepsiceros) on the relative density of habitat patches within landscapes for a semi-arid savanna. Habitat suitability models were used to isolate patches of suitable kudu habitat for each landscape. The habitat suitability models were used to classify a proportion of randomly located circular plots as kudu habitat. The relative density of habitat patches within the respective landscapes was thus determined. The relation between kudu density and the relative density of habitat patches in each landscape was significant, with exponential models producing more significant statistics than linear models. Regressions of resource density against animal density are useful to understand 'carrying capacity' for wild herbivores, and additionally provide insights into temporal fluctuations in animal numbers. The usefulness of the approach depends on correctly defining the size of a habitat patch and selection an appropriate scale of study.

Keywords: carrying capacity; foraging theory; habitat; habitat suitability model; herbivores; kudu; landscape ecology; landscapes; management; models; range management; relative density; resource dispersion hypothesis; resources; savanna; semi-arid savanna; south africa; theories; tragelaphus strepsiceros; ungulates

African Journal of Range & Forage Science, Vol. 11(1), pp. 7-10