Three decades later in the Northern Kruger National Park: multiple acoustic and capture surveys may underestimate the true local richness of bats based on historical collections.

Abstract

The Kruger National Park (KNP) is considered an important biodiversity hotspot, with insectivorous bats representing about twenty percent of the total mammalian diversity of South Africa. Historically, 40 bat species have been documented in the northern region of the Park between 1960 and 1990. However, it has been three decades since the last comprehensive assessment. To aid the long-term monitoring of bats within KNP, our study re-surveyed the bat community of northern KNP over two years , incorporated the latest acoustic technologies, compared changes in bat species richness with historical data, and tested the use of an automated classifier for the acoustic data. We captured bats and recorded echolocation calls at 26 sites ), between March and October in 2017 and 2018. Kaleidoscope Pro software was used to identify each bat call series recorded. To enhance the accuracy of this tool, a northern KNP-specific classifier was developed. We recorded 27 distinct species during this study, of which 13 were live-captured. The historical data therefore show a much higher richness of bat species within the study area (40 species) than recorded during our study (27 species), although the former were collected over a much longer period of time during numerous collecting trips by staff of the former Transvaal Museum (Ditsong National Museum of Natural History). Total sample effort, environmental effects, biological aspects and overall study limitations likely contributed to the observed differences. The classifier tool had a relatively high percentage accuracy (80%) but manual identification was required to avoid the misidentification of rare species and to detect new species not previously recorded. Future studies should focus more effort on live-capturing, given the high species richness of the region and the limitation of bat detectors to record high frequency and low intensity echolocation calls, which are common in many southern African species.