Miniature GPS tags reveal extensive movements by a threatened narrow-space bat and highlight sensitivity to forest clearing

Abstract

An understanding of fine-scale movements made by animals is critical for assessing localized habitat preferences and informing the scales over which land management should be applied. However, for cryptic species such as insectivorous bats that are highly mobile and active at night, it is difficult to collect these data. Nyctophilus corbeni serves as a case study for narrow-space species as it is listed as threatened and nothing is known about its localized habitat preferences. We used miniature GPS tags to assess fine-scale movements across three sites and 2 years (autumn 2020 and 2021) in the Pilliga forests in northwest New South Wales. Each site consisted of a mosaic of forest disturbances (e.g. timber harvesting / thinning regrowth, prescribed fires and wildfires, and cleared farmland). Bats made large movements in the non-maternity season, with a maximum of ~21 km recorded as a one-way movement on a given night. On average, the maximum distance travelled by tagged bats was 6.2 ± 1.4 km per night. Short-term home (9884 ha) and core (2157 ha) ranges were extensive, but varied by sex, with ranges of females ~15 times larger than males. Bats crossed cleared land that was within close proximity (<2.3 km, but typically <~600 m) of large forest blocks (>100 ha). Based on availability of habitat types, bats selected for older regrowth and burnt forest and avoided cleared areas with scattered trees and also thinned forest, though the availability for the latter was low (<3 %). Flight speeds and the lack of clustering of GPS fixes in cleared landscapes suggest that limited foraging may occur there. Overall, our results highlight the sensitivity of the species to forest clearing and potentially to thinning, but also demonstrate the importance of maintaining large areas of forest and where possible, reforesting cleared areas that occur between smaller, more isolated forest blocks.