A continental‐scale tool for acoustic identification of <scp>E</scp>uropean bats

Abstract

Summary Acoustic methods are used increasingly to survey and monitor bat populations. However, the use of acoustic methods at continental scales can be hampered by the lack of standardized and objective methods to identify all species recorded. This makes comparable continent‐wide monitoring difficult, impeding progress towards developing biodiversity indicators, trans‐boundary conservation programmes and monitoring species distribution changes. Here we developed a continental‐scale classifier for acoustic identification of bats, which can be used throughout E urope to ensure objective, consistent and comparable species identifications. We selected 1350 full‐spectrum reference calls from a set of 15 858 calls of 34 E uropean species, from E cho B ank, a global echolocation call library. We assessed 24 call parameters to evaluate how well they distinguish between species and used the 12 most useful to train a hierarchy of ensembles of artificial neural networks to distinguish the echolocation calls of these bat species. Calls are first classified to one of five call‐type groups, with a median accuracy of 97·6%. The median species‐level classification accuracy is 83·7%, providing robust classification for most E uropean species, and an estimate of classification error for each species. These classifiers were packaged into an online tool, i B ats ID , which is freely available, enabling anyone to classify E uropean calls in an objective and consistent way, allowing standardized acoustic identification across the continent. Synthesis and applications . i B ats ID is the first freely available and easily accessible continental‐scale bat call classifier, providing the basis for standardized, continental acoustic bat monitoring in E urope. This method can provide key information to managers and conservation planners on distribution changes and changes in bat species activity through time.