Insectivorous bat diversity in relation to proximity and type of water source at two sites in the Limpopo Valley, South Africa

Abstract

Water availability plays an important role in the habitat requirements of bats. Previous studies have shown that water bodies (both natural and artificial) are used by bats and other animals for drinking water and foraging. I collected my data in the semi-arid landscape of the Venetia Nature Reserve (VNR) and the Mapungubwe National Park (MNP) which is bordered by the Limpopo River. I sampled bats acoustically for 25 nights in total at VNR and MNP, and in three austral seasons (autumn, winter and summer). A total of 21030 bat echolocation calls were recorded, and 23 different species were identified. These species represented the families Vespertilionidae, Molossidae, Emballanuridae, Miniopteridae and Rhinolophidae. Mops condylurus, Chaerephon pumilus, Rhinolophus smithersi were the most commonly recorded species at MNP, while Neoromicia capensis and Mops condylurus were the most commonly recorded species at VNR. Rarefaction analysis showed no significant differences in the estimated richness/diversity between MNP and VNR. However, VNR sites near artificial water bodies had a higher species richness and diversity compared to sites 500-750 m away. No such trend was evident at MNP, likely because all sampling sites were not more than two kilometers away from riparian habitats along the Limpopo river. These results show both the importance of riparian habitats (contributing to higher diversity and activity associated with proximity to the Limpopo River) and how important artificial water bodies are for bats in semi-arid habitats. My results illustrate that MNP has higher overall bat activity compared with VNR, probably because of its proximity to the Limpopo river. Sampling season and moon phases were also important predictors of bat activity and species richness in this study; there was more activity in autumn than in summer and winter, while winter had the lowest activity. VNR and MNP are protected areas where future research about the biology, morphology and behaviour of bats which are biological indicators should take place in order to improve the understanding of challenges faced such as climate change.