Seasonal utilization of habitat by large grazing herbivores in semi-arid Zimbabwe

The factors determining habitat utilization among a large grazing herbivore community on Malilangwe Estate, southeastern Zimbabwe, were investigated. Gross vegetative structure, herbaceous composition and topographic features thought likely to determine herbivore distribution were measured and analysed using a single multivariate technique. Seasonal variation in resource distribution was considered and research extended over an entire year. Herbivore distribution and niche separation were explained by several environmental variables, and potential interspecific competition inferred. Ungulates showed a large degree of niche overlap in both the hot-wet season and the cool-dry season. Ecological separation between grazers was pronounced in the hot-dry season. Herbivore distribution was associated most closely with distance from water, grass sward height, time since last burn, woody plant density and by the presence of the predominant grasses Urochloa mossambicensis, Panicum maximum, Heteropogon contortus and Digitaria eriantha. Management options are considered. The findings of the study provide a better understanding of ecological separation, and possible competitive interactions, among members of the large grazing herbivore community on Malilangwe Estate.