Abstract
1. Wind turbines negatively affect bats through mortality, which can be exacerbatedby attraction behaviours, and loss of habitat use caused by avoidance behaviours.However, potential mechanisms driving bat responses to wind turbines are stillpoorly understood. This is especially true of red aviation lighting, designed to preventaircraft collisions and implemented in many countries, that could be perceived bybats from a long distance and lead to a response at a large spatial scale.
2. We assessed the role of wind turbine red aviation lighting in the behavioural re-sponses (attraction and avoidance) of bats. To this end, we acoustically quanti-fied the activity of three functional bat guilds (long-, medium- and short- rangeecholocators) at three wind farms using a triplet sampling design: recordings wereconducted simultaneously at (i) wind turbines illuminated throughout the night,(ii) wind turbines equipped with the aircraft detection lighting system (ADLS) andilluminated an average of 12% of the night and (iii) control sites without nearbywind turbine. Thirteen and nine triplets were sampled at wooded edges ~250 mfrom the nearest wind turbine and in open habitats at the base of the turbine, re-spectively, during two consecutive nights in June 2021 in the Uckermark district(north-east Germany).
3. We found that acoustic activity was higher overall at sites near wind turbines il-luminated throughout the night than at control sites for all functional guilds andboth at wooded edges and in open habitats, indicating local attraction behaviourstowards wind turbines that might increase collision risks.
4. Activity at sites near wind turbines with ADLS was lower overall than at sitesnear wind turbines illuminated throughout the night, and similar to control sites,suggesting that part-night lighting could contribute to reducing bat attraction to-wards wind turbines.
5. Synthesis and applications. This study provides empirical evidence that attrac-tion behaviour of bats towards wind turbines is driven, at least partially, by red aviation lighting. We also demonstrate that smart lighting of wind turbines, suchas the ADLS, could cost-effectively help mitigate disruption of bat habitat useand the associated collision risks. Implementing adaptive lighting strategies couldtherefore represent a practical step towards balancing wind energy developmentwith bat conservation.