Acoustic Characterisation of Bats on Penang Island, Malaysia: First Call Descriptions for Biodiversity Monitoring (Early view)

Abstract

The bat diversity on Penang Island is increasingly threatened by deforestation, agricultural expansion and urbanisation. Although acoustic monitoring is widely used in bat research and conservation, the acoustic diversity of the island's bat fauna remains poorly understood. This study characterises and compares echolocation calls of 12 bat species on Penang Island. Species from families Vespertilionidae, Megadermatidae, Emballonuridae and Coelops frithii from Hipposideridae produce frequency-modulated calls, and the remaining Hipposideridae species alongside all species from Rhinolophidae produce constant-frequency calls. Principal component analysis based on frequency parameters well cluster samples by species, with bandwidth and lowest frequency particularly informative for species discrimination. Comparisons with published mainland data reveals variation in call frequencies among certain species, although these differences should be interpreted cautiously due to limited sample sizes and the absence of molecular validation. This study provides baseline acoustic information to support future bat monitoring and conservation efforts on Penang Island.