Habitat use by sympatric wild and domestic herbivores in an African savanna woodland: the influence of cattle spatial behaviour.
Abstract
The spatial distribution of two wild ungulates, impala (Aepyceros melampus) and kudu (Tragelaphus strepsiceros), and of domestic cattle, was monitored across seasons in a 9400 ha ranch of the 'highveld' of Zimbabwe. Habitat use, preference, selectivity and overlap were estimated. Predation was negligible and the study concentrated on interspecific competition. Cattle were contained in paddocks, and were moved regularly, while wild ungulates moved freely. Wild ungulate habitat use, preference and selectivity between paddocks with and without cattle were compared, as was the variation in broad diet, group size and densities. All herbivores were selective, with a marked preference for the nutrient-rich Acacia/Dichrostachys vegetation type. Terminalia communities were almost completely avoided. Selectivity increased as the dry season progressed. Habitat overlap was always high. Interspecific competition occurred between cattle and impala, especially during the wet season and the hot dry season. Impala showed a switch in habitat preference and an increase in selectivity and started to concentrate on 'refuge habitat'. Some also switched in their diet composition. During the hot dry season, when resources were at their lowest, most impala stopped using paddocks with cattle. Kudu seemed relatively unaffected by the presence of cattle: the variations observed in kudu spatial behaviour may have been caused by competition with impala.