Fragmentation reduces vesper bat abundance and evenness in a southern Appalachian forest

Abstract

Habitat fragmentation alters biodiversity through changes in habitat patch size, structure, and increasing distance between patches. However, if species regularly move across distances greater than those between patches, the effect of distance may approach zero. More studies of highly mobile species such as vesper bats (Vespertilionidae) are needed to clarify how such species respond to fragmentation. This study examines the impact of forest fragmentation on vesper bat community diversity in the Southeastern United States. Using mobile acoustic surveys, bats were monitored along forest transects in the Cherokee National Forest and in surrounding farmlands containing widely spaced forest fragments. The same nine vesper bat species were recorded and identified in both habitat types. Results indicate a 43% decline in vesper bat abundance in the farmland when compared to intact forest, with eight species having a higher abundance within the intact forest. Notably, Seminole bats, (Lasiurus seminolus) maintained similar abundance across habitats, suggesting species-specific responses to fragmentation. Despite identical species richness, diversity indices such as the Shannon diversity index and {beta}Shannon identified lower biodiversity in the farmland when compared to the forest. Our results indicate that despite being highly mobile, vesper bats exhibit a largely negative response to habitat fragmentation and loss. This could be due to the change of the core to edge habitat ratio, emphasizing the importance of conserving core forest habitat to sustain bat biodiversity. Observed species-specific responses to habitat fragmentation indicate a need for further research to elucidate the complexities of managing bat communities in human-modified ecosystems.