Listening in the dark: acoustics indices reveal bat species diversity in a tropical savannah

ABSTRACT

Surveying biodiversity using bioacoustics has become increasingly common worldwide, although it is mostly concentrated in temperate regions. The variety of automatic recorders, the development of free analytical tools, and several acoustic indices have increased the number of studies worldwide. The bioacoustic approach is essential for application in poorly surveyed regions with the pressure of human activities, such as the Brazilian cerrado. We tested the association of four bat diversity metrics (taxonomic, phylogenetic, and two functional diversity metrics, being one based on morphological and the other on acoustical traits, with five commonly used acoustic indices. We used a dataset of 608.4 h obtained from 30 sampling points in three protected areas in Central Brazil. Using Flexible Discriminant Analysis, we identified 21 bat species used in our subsequent analysis. The Entropy index was the best predictor of taxonomic and phylogenetic diversity, whereas the Acoustic Complexity Index was the best predictor of functional morphological diversity. We concluded that acoustic indices are suitable for estimating the diversity of insectivorous bats in the cerrado. However, we registered only part of the bat community, and bats can vary seasonally masking the real diversity of the study area; thus, this method should be used parsimoniously.

KEYWORDS:

• Chiroptera
• bioacoustics
• cerrado
• phylogenetic diversity
• functional diversity
• taxonomic diversity

Acknowledgements

We thank the Jardim Botânico de Brasília, Fazenda Água Limpa -UnB and Reserva do Roncador - IBGE for their permission to conduct the work in their areas.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethical statement

This study followed the institutional and national ethical guidelines for scientific research with licenses number 27719–25, 27719–30, 21172–1 given by SISBIO/ICMBIO.

Supplementary material

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Additional information

Funding

This work was supported by the PPBIO-CNPq trough the project PELD/AGCV #307303/2017-9; CNPq personal research grant to LMSA # 304989/2019-3 and RBM # 304221/2019-8; and FAPDF [process # 00193.00001525/2019-24].