Using grids of acoustic recording devices to map the spatial distribution of bat activity

Abstract

Bats provide essential ecosystem services, such as insect pest control, which are particularly valuable in semi-rural and agricultural environments. Insect predation by bats is estimated to save the agricultural industry millions to billions of dollars annually in avoided pesticide use and crop damage. However, the removal of natural habitats for the creation and intensification of agricultural landscapes has had a detrimental effect on bat populations. Understanding how bats use various habitat features within modified landscapes is important for preventing a decline in species diversity and loss of beneficial bat foraging activity. Advancements in acoustic recording technology have made it possible to passively sample bat activity with numerous, inexpensive datalogging devices. In this thesis I test the novel application and configuration of a fine-scale grid of acoustic recording devices (AudioMoths) to record bat activity in a semi-rural environment. I explore how these data can be used to make interpolated heat maps that visualise bat activity in relation to fine-scale habitat features. Key variables such as detector density and interpolation settings were evaluated for their impact on heat map precision. Results showed that single detectors spaced 50 m apart effectively demonstrated fine-scale variations in bat activity. The created heat maps indicated that bat activity was significantly higher where trees were present but decreased within woodland and open paddocks, and that habitat relationships differed between different bat species. These findings have revealed that this novel grid sampling method can demonstrate fine-scale differences in bat activity across the entire sampled area and highlight how habitat features can influence this activity. This approach provides valuable insights for the development of effective habitat protection strategies to preserve bat populations and their services in semi-urban and agricultural ecosystems.

Date of Thesis submission	2025
Original language	English
Awarding Institution	Western Sydney University
Supervisor	Christopher Turbill (Supervisor), Leroy Gonsalves (Supervisor) & Brad Law (Supervisor)