A continental-scale tool for acoustic identification of European bats
Article first published online: 6 AUG 2012
© 2012 The Authors. Journal of Applied Ecology © 2012 British Ecological Society
Journal of Applied Ecology
Volume 49, Issue 5, pages 1064–1074, October 2012
How to Cite
Walters, C. L., Freeman, R., Collen, A., Dietz, C., Brock Fenton, M., Jones, G., Obrist, M. K., Puechmaille, S. J., Sattler, ., Siemers, B. M., Parsons, S., Jones, K. E. (2012), A continental-scale tool for acoustic identification of European bats. Journal of Applied Ecology, 49: 1064–1074. doi: 10.1111/j.1365-2664.2012.02182.x
- Issue published online: 20 SEP 2012
- Article first published online: 6 AUG 2012
- Manuscript Accepted: 28 JUN 2012
- Manuscript Received: 17 FEB 2012
- NERC. Grant Number: NE/H525003/1
- The University of Auckland
- Leverhulme Trust
- The Darwin Initiative. Grant Numbers: 15033, EIDPO036, EIDPR075
- acoustic monitoring;
- ensembles of artificial neural networks;
- indicator species;
- species identification
- 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 Europe to ensure objective, consistent and comparable species identifications. We selected 1350 full-spectrum reference calls from a set of 15 858 calls of 34 European species, from EchoBank, 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 European species, and an estimate of classification error for each species.
- These classifiers were packaged into an online tool, iBatsID, which is freely available, enabling anyone to classify European calls in an objective and consistent way, allowing standardized acoustic identification across the continent.
- Synthesis and applications. iBatsID is the first freely available and easily accessible continental-scale bat call classifier, providing the basis for standardized, continental acoustic bat monitoring in Europe. This method can provide key information to managers and conservation planners on distribution changes and changes in bat species activity through time.