Acoustic Monitoring Reveals Patterns of Insectivorous Bat Diversity and Activity in South and North Nandi Forests, Kenya

Abstract

Understanding how habitat degradation affects insectivorous bats is essential for guiding tropical forest conservation. This study employed passive acoustic monitoring to investigate patterns of insectivorous bat diversity and activity across three habitat types: matrix, edge, and interior in South and North Nandi Forests, western Kenya. Recordings were collected between June 2019 and July 2020 using ultrasonic detectors, and call sequences were manually verified using Kaleidoscope Pro to the species level. A total of 24 species representing 8 families and three foraging guilds were identified from over 60,000 validated bat passes. Overall, bat activity and species richness were highest in forest interiors and lowest in matrices, indicating sensitivity to habitat simplification and anthropogenic disturbance. Edge- and open-space foragers such as Mops pumilus and Tadarida spp. dominated the degraded habitats, whereas clutter-adapted species, including Nycteris spp., Myotis tricolor, and Kerivoula spp., were confined to forest interiors. Canonical Correspondence Analysis revealed that tree density, along with indicators of disturbance such as cut stumps and footpaths, significantly influenced bat assemblage composition. These findings demonstrate that structurally complex habitats support higher acoustic activity and greater species diversity, underscoring the importance of conserving interior forest habitats within fragmented landscapes. The study provides a valuable reference for using acoustic monitoring in long-term biodiversity assessments and highlights the potential of insectivorous bats as sensitive indicators of forest ecosystem integrity across tropical forests.