Assessing fatality risk of bats at offshore wind turbines

Sep 18, 2026

Uploaded by Margaret

Guidance on assessing the fatality risk of bats at offshore wind turbines, motivated by evidence that bats occur offshore during migration and may be killed at sea. The report contrasts onshore carcass-search methods with the near-impossibility of systematic searches offshore, proposing model-based and empirical monitoring strategies. It details technologies such as radar, thermal cameras, ultrasonic bat detectors, and bird sound recorders, evaluates market systems, and outlines functional design considerations, advantages, and limitations.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages40

Reading Time1 h 41 min

AccessFree to download

Contents

Summary

1 Introduction

2 Bats and wind turbines

3 Model-based approach to estimate offshore fatalities

4 Automated monitoring techniques

5 Evaluated systems

6 Application design

7 Conclusions

8 Quality Assurance

References

Justification

Assessing fatality risk of bats at offshore wind turbines Author(s) : S. Lagerveld1, C.A. Noort1, L. Meesters2, L. Bach3, P. Bach3, S.C.V. Geelhoed1 Wageningen University & Research report C025/20 Assessing fatality risk of bats at offshore wind turbines Author(s): S. Lagerveld1, C.A. Noort1, L. Meesters2, L. Bach3, P. Bach3, S.C.V. Geelhoed1 1 Wageningen Marine Research 2 Wageningen Food & Biobased Research 3 Bach Freilandforschung Wageningen Marine Research Den Helder, March 2020 CONFIDENTIAL no Wageningen Marine Research report C025/20 Keywords: migratory bats, birds, offshore wind farms, fatalities, barotrauma, collision Client: RWS Water, verkeer en Leefomgeving (WVL) Attn. : Dhr. M. Platteeuw Postbus 17 8200 AA, Lelystad This report can be downloaded for free from [https://doi.org/10.18174/518591](https://doi.org/10.18174/518591)[ ](https://doi.org/10.18174/518591)Wageningen Marine Research provides no printed copies of reports Wageningen Marine Research is ISO 9001:2015 certified. Photo cover: Hans Verdaat © Wageningen Marine Research Wageningen Marine Research, an institute within the legal entity Stichting Wageningen Research (a foundation under Dutch private law) represented by Dr . M.C.Th. Scholten, Managing Director Wageningen Marine Research accepts no liability for consequential damage, nor for damage resulting from applications of the results of work or other data obtained from Wageningen Marine Research. Client indemnifies Wageningen Marine Research from claims of third parties in connection with this application . All rights reserved. No part of this publication may be reproduced and / or Contents Contents 3 Summary 4 1 Introduction 6 1.1 Background 6 1.2 Problem definition 7 1.3 Aim of this study 7 1.4 Project team 7 1.5 Reading guide 7 2 Bats and wind turbines 8 3 Model-based approach to estimate offshore fatalities 10 3.1 Carcass searches 10 3.2 Pre-construction acoustic bat activity 11 3.3 Post-construction acoustic bat activity 11 4 Automated monitoring techniques 13 4.1 Camera techniques 13 4.2 Radar 15 4.3 Lidar 15 4.4 Acoustics 16 4.5 Impact sensors 17 5 Evaluated systems 18 6 Application design 24 6.1 Functional requirements 24 6.2 Elaboration of the requirements 24 6.3 Conceptual design 27 6.3.1 Radar 27 6.3.2 Thermal cameras 27 6.3.3 Bat detector 28 6.3.4 Bird sound recorder 28 6.3.5 System integration 29 7 Conclusions 30 8 Quality Assurance 32 References 33 Justification 38 Summary Recent research shows that bats regularly occur offshore, in particular during the migration season . Atthe same, time land-based studies show that bats frequently become victim of wind turbines, and it is plausible that fatalities occur at sea as well. Given the fast development of the offshore wind sector it is urgently needed to determine the offshore fatality rate in order to assess the impact of offshore wind turbines on bat populations. On land the methodology for assessing the fatality rate is rather straightforward. This includes regular carcass searching under the wind turbines and adjusting the number of fatalities for causes of imperfect detection . Offshore, however, carcass searching is virtually impossible and therefore a model-based or technical solution may be a more appropriate approach, which may be also applicable for assessing bird fatalities. This report aims to provide guidance on how offshore fatalities could be monitored in the future. The first option is a model-based approach which assesses the offshore fatality rate by extrapolating onshore fatality rates based on the measured post-construction acoustic bat activity. The main advantages and disadvantages of this solution are: Advantages • Relatively easy to implement Disadvantages • Possibly biased results: o When wind turbines with different dimensions are used for the reference data o When reference data is gathere

FAQs

Why is estimating bat fatalities at offshore wind turbines difficult compared with onshore sites?

Carcass searching offshore is virtually impossible, unlike onshore where regular searches under turbines can be conducted. Therefore, technical or model-based alternatives are needed.

What model-based option does the report propose for estimating offshore bat fatality rates?

It proposes estimating the offshore fatality rate by extrapolating from onshore fatality rates using measured post-construction acoustic bat activity.

Which equipment combinations are suggested for an empirical monitoring approach?

The report suggests radar to detect approaching objects, thermal cameras to assess collisions and barotrauma and support species identification, an ultrasonic bat detector for echolocation/social calls, and a bird sound recorder for flight calls and bird species identification.

Sep 18, 2026

Uploaded by Margaret