Dietary Resource Partitioning in Large Mammal Herbivores: The Intra- and Interspecific Diet Variation in Kafue National Park, Zambia

Abstract

Kafue National Park is the fifth largest protected area within African and is host to a highly biodiverse ecosystem of both herbivores and carnivores. Despite Kafue National Park’s regional importance, relatively little research exists to describe the wildlife community assemblages found within the park especially for large mammal herbivores, and the factors that influence species coexistence and ecosystem stability. We used DNA metabarcoding to quantify the diet composition of 10 of the most abundant large mammal herbivore species within Kafue National Park and to compare the role of intraspecific and interspecific variation of the functional dietary niche partitioning. Puku and impala are the two most abundant species found within the park and occur syntopically. Therefore, both species diets were compared and overlap of their niche’s determined. Food resource use is one of the most important elements of the niche and multiple species characteristics constrain herbivore diets. Thus, the influence of species characteristics, such as body size, muzzle width and population density, was investigated in terms of its effect on the degree of among-individual variation. The large mammal herbivore community distinctly partitioned their niches, with minimal overlap amongst grazers and clear separation of the puku and impala dietary niches. Overall our results suggest that large mammal herbivores within a stable and diverse ecosystem manage coexistence through the partitioning of their niches so as to mitigate interspecific competition, while their diets are constrained by body size, muzzle width and population density. Increased intraspecific diet variation correlated with total niche width indicative of the Niche Variation Hypothesis. These results have substantial implications for conservation effort and management of protected areas.