Using acoustic monitoring to assess insectivorous bat richness and activity in a Sub-Tropical Savanna.

Abstract

Understanding insectivorous bat diversity and activity is crucial for conservation efforts, particularly in under-researched regions like sub-tropical savannas. Our study assessed bat species richness and seasonal activity (i.e., number of passes) in MalaMala Game Reserve, located within the south-western region of the Greater Kruger National Park (KNP), South Africa, a hitherto unsampled site. We conducted acoustic monitoring using ultrasonic detectors over two distinct seasons: the wet season (January to March) and the dry season (June to August) in 2022. Our findings revealed 16 species from six families, representing 40% of the bat species known in KNP. The Molossidae family was the most dominant, followed by Vespertilionidae, while the Hipposideridae family recorded the fewest calls, likely due to their high-frequency echolocation calls, which attenuate rapidly, or possibly because these bats were less active in our study area, or a combination of both factors. Seasonal variations in bat activity were observed, with significantly higher activity during the wet season, likely due to increased insect abundance and reduced thermoregulatory costs. By targeting a previously unsurveyed region and incorporating seasonal comparisons, our study addresses a critical spatial and temporal knowledge gap and provides a valuable foundation for the development of long-term, standardized bat monitoring across the Greater KNP landscape.