idw – Informationsdienst Wissenschaft
Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
idw - Informationsdienst
Wissenschaft
A research team led by the Museum für Naturkunde presents the first evidence that several bat species produce courtship songs in the immediate rotor-swept zone of wind turbines while circling around the nacelle. Data from over 80,000 audio recordings at nacelle height from six German sites, together with stereo-thermal 3D reconstructions of bat flight trajectories, document both bat song and elevated bat density in the rotor-swept zone. Both lines of evidence suggest that, under certain circumstances, bats actively approach wind turbines and provide an explanation for why collision risk may increase during the mating season.
Male bats, similar to songbirds, sing to attract females and deter rivals, and they often fly around prominent landscape features while doing so. In homogeneous, structurally poor landscapes such as arable fields, wind turbines may constitute attractive structures that males use as “song perches.” In doing so, they not only put themselves at risk — their relatively far-carrying songs can also draw females to the turbines.
The researchers detected bat song at all study sites and throughout the entire study period, indicating that this is not a local phenomenon or a one-off. Remarkably, songs of the common noctule (Nyctalus noctula) and Nathusius’ pipistrelle (Pipistrellus nathusii) were recorded most frequently. These are also the two species that collide most often with wind turbines in Germany — a clear behavioral link to the known fatality patterns.
“From a study our colleagues in the north-west German coastal region, we know that during the mating season more female than male Nathusius’ pipistrelles are found dead beneath wind turbines.””, says Martina Nagy, the study’s lead author. “Our results offer a coherent possible explanation for the high proportion of females among the fatalities.”
From the duration of the recorded songs, the detection range of the microphones used, and existing knowledge about species-specific flight speeds, the researchers inferred that bats did not simply sing while flying past the turbines; instead, they circled around the nacelles or the tower. Consistent with this, song amplitude often fluctuated periodically (louder/softer), as would be expected when circling around a stationary microphone.
The 3D reconstructions generated with two thermal cameras likewise produced a very clear picture. The density of detected bats decreased sharply with increasing distance from the nacelle. This points to an active approach of bats to the turbine structure itself. It has been suspected in the past that bats may approach wind turbines while searching for roosts or food. The new findings now show that wind turbines are also of interest to bats ready to mate.
The researchers hope that these new insights can be translated into more effective mitigation strategies. “Wind energy is vital for climate protection, but it must not come at the expense of species conservation”, says Mirjam Knörnschild, the study’s senior author. “If we understand why bats deliberately approach wind turbines, operators can apply more precise and more species-sensitive curtailment to minimize fatalities.”
https://doi.org/10.1038/s42003-026-09882-7
Criteria of this press release:
Journalists
Biology, Environment / ecology, Zoology / agricultural and forest sciences
transregional, national
Research results, Scientific Publications
English
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