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Providing evidence to improve practice

Individual study: Reduktion des Kollisionsrisikos von Fledermäusen an Onshore-Windenergieanlagen (RENEBAT II)

Published source details

Behr O., Brinkmann R., Korner-Nievergelt F., Nagy M., Niermann I., Reich M. & Simon R. (2016) Reduktion des Kollisionsrisikos von Fledermäusen an Onshore-Windenergieanlagen (RENEBAT II). Umwelt und Raum Bd. 7, 368 S., Institut für Umweltplanung, Hannover report.


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Automatically reduce turbine blade rotation when bat activity is high Bat Conservation

A replicated, paired sites study in 2012 at eight pairs of wind turbines in Germany (Behr et al. 2016) found that using automated ‘bat-friendly’ operating systems that reduced turbine blade rotation speed resulted in fewer bat fatalities than at normally operated wind turbines. Total bat fatalities and average collision rates were lower at automated turbines (total 2 bat fatalities, 0.01 fatalities/turbine/night) than at normally operated turbines (total 21 bat fatalities, 0.06 fatalities/turbine/night). At automated turbines, predictive models identified periods of high fatality risk and low energy yield from bat activity and wind speed data. During these periods, rotor blades were moved parallel to the wind to reduce rotation speed according to a target bat fatality rate (0.01 fatalities/turbine/night). Normally operated turbines rotated freely. At each of eight sites, automated and normal operating modes were alternated weekly between two paired turbines over 14 weeks in July–October 2012. Carcass searches were carried out daily. If applied to all turbines, it was estimated that automated operation would result in annual energy losses of 2.1%.

(Summarised by Anna Berthinussen)