Current frontiers in the passive acoustic monitoring of bats
Charlotte Roemer, Alexandre Haquart, Adrià López‐Baucells, Aurélien Besnard
Abstract
Abstract Passive acoustic monitoring of bats is used in a growing number of studies in applied and basic research, from local to global scales. Despite the publication of good‐practice recommendations, several unsettled debates persist about the possibilities and limits offered by passive acoustic monitoring of bats. In this paper, we summarise and discuss these debates and invite the research community to invest efforts in resolving them. These debates include the correlation between acoustic bat counts and the actual number of individuals, the influence of weather and bat behaviour on acoustic detectability, the impact of prey size on bat activity counts and the influence of biogeography on bat call characteristics. We also shed light on promising metrics and models which, in spite of their potential, are not broadly used by ecologists and researchers. Indeed, some alternative acoustic metrics can be easily measured to quantify and qualify bat foraging activity, and several models have been developed to assess bat population sizes using passive acoustic monitoring. Such models and metrics have the potential to revolutionise how we interpret the results of passive acoustic monitoring. We strongly recommend that the community of bat researchers and practitioners progress in standardising the protocols for spatiotemporal analyses on large scales, such as estimating population trends and building species distribution models. We also insist on the importance of archiving and sharing data to make raw sound recordings available for re‐analysis, to adapt to the evolution of the technology, the metrics developed and the taxonomy.