Long-term bioacoustic monitoring of arid-zone bats: the boom and bust

Arid regions cover approximately 45% of the global land surface and are characterised by extreme climatic variability, with wildlife populations subject to dramatic boom-and-bust cycles driven by episodic rainfall. In Australia, native fauna must also contend with introduced mammalian predators, resulting in the widespread use of fenced predator-free reserves as a conservation tool. Despite this, little is known about how highly mobile species such as bats respond to drought conditions or benefit from fenced reserves. Using seven years of bioacoustic monitoring data from an arid-zone fenced reserve, we examined bat activity in relation to the fenced reserve, during drought, and post-drought recovery. Bat activity was near zero during drought conditions, suggesting local population collapse or abandonment of the area. Long-term vegetation productivity was the strongest predictor of activity across all species, with no detectable effect of short-term rainfall or the fenced reserve. Recovery dynamics were consistent with recolonisation from local or regional refugia once long-term conditions improve, rather than localised irruptive breeding. Together, these results add to the growing evidence that some arid-zone bats may sit towards the irruptive-nomadic end of the movement ecology continuum, tracking spatially and temporally variable resources rather than maintaining residency in a fixed area.