Gone with the wind (power): Onshore wind turbines reduce the habitat available for migrating bats in coastal areas

Many bat species seasonally migrate over long distances across Europe, using the coastline of the North Sea and the Baltic Sea as corridors. Coastal areas are also suitable locations for wind turbines, which can be fatal for bats. An investigation led by the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) on how common noctules use the air space in coastal regions shows that onshore wind turbines at the coast are increasingly restricting the habitat available to migrating bats. Therefore, the remaining refuges should be protected when deciding on areas designated for wind energy production, and new turbines should not be erected near foraging grounds or day roosts, the scientists conclude in the paper published in the "Journal of Environmental Management". Otherwise, the expansion of wind power in Germany will have negative consequences not only for native bats, but also for migrating bats from north-eastern Europe.

Many bats are true Europeans: they migrate, following the rhythm of the seasons, from summer habitats in north-eastern Europe, where they breed, to wintering areas in the Benelux countries, France and northern Spain. They travel up to 2,000 kilometres and are presumably carried by favourable winds. These winds, which blow strongly and steadily along the coast, are also particularly suitable for generating electricity by wind turbines. Analysing their spatial behaviour, a team of scientists led by the Leibniz-IZW now investigated the way in which common noctules (Nyctalus noctula) interact with wind turbines at coastal sites. Since migrating bats are strictly protected by German and European law, but frequently die at wind turbines, it is important to know how bats can be protected in such dense aggregations of wind turbine facilities – so that the conservation is not neglected in favour of climate protection.

The team led by PD Dr Christian Voigt and Dr Christine Reusch analysed the movement data of 11 common noctules captured in a coastal forest area and equipped with miniaturised GPS units. These units fall off the fluttering animals on their own after a few days. The analysis showed that most animals avoided wind turbines at a distance of several kilometres. “On the one hand, this is good news, because it prevents them from dying at the turbines,” says Voigt, head of the Department of Evolutionary Ecology at the Leibniz-IZW. “On the other hand, it also means that they lose a significant part of their habitats owing to the operation of the wind turbines. If wind energy production along the coastline is intensified, access to suitable habitats for bats will shrink and could become critical for these nomads of the air.”

The movement paths of the tracked bats showed that some animals also approached the wind turbines. They did this particularly frequently when the turbines were placed next to a daytime roost, farmhouses or waterbodies. Especially farmhouses outside towns and waterbodies seemed to attract them to areas close to wind turbines, probably because of the many insects they could hunt there. Large wind turbines were approached by bats significantly more often than small ones, but this could be a special effect of the underlying landscape structure and the location of the wind turbines relative to roosts and hunting areas. The comparatively higher activity at large wind turbines could, however, be a major disadvantage for the animals, as the intended expansion of wind energy production is to take place primarily via large turbines with a high energy output.

“Our overall recommendation for the coastal zone is to erect new turbines only at a sufficient distance from roosts and hunting grounds,” explains Christine Reusch, who carried out the project, funded by the Deutsche Bundesstiftung Umwelt, as postdoc. “We need to consider how we can use the valuable resource 'airspace' for both wind energy production and nature conservation. In important migration corridors, such as the coastline of northern Germany is for both birds and bats, the placement and operation of wind energy production must be carefully and thoughtfully carried out. The density of the turbines should not be too high in order to leave some space and habitat for migrating animals.”

With its central geographical location in Europe, Germany plays an important role in the protection of migratory and resident bat species. Bats are strictly protected under German and EU law. Furthermore, as a signatory to the relevant UN convention, Germany is committed to the protection of migratory animals. The expansion of wind energy production along the coastline could lead to significant habitat loss for migrating bats and thus impede their migration. So far, habitat degradation as indicated by bats avoiding turbines is not assessed or even compensated for during the planning process. In order to follow the existing legislation, this habitat loss would have to be included in the approval procedures and in the planning process for areas suitable for wind farms, the scientists conclude. The fact that bats as well as birds die at wind turbines in notable numbers is an obstacle to the expansion of wind energy production. As biodiversity conservation and climate protection are recognized as equally important goals this must be thought about and implemented together.

Publication

Reusch C, Lozar M, Kramer-Schadt S, Voigt CC (2022). Coastal onshore wind turbines lead to habitat loss for bats in Northern Germany. Journal of Environmental Management. DOI: 10.1016/j.jenvman.2022.114715

Contact

Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) in the Forschungsverbund Berlin e.V.
Alfred-Kowalke-Str. 17, 10315 Berlin, Germany

PD Dr Christian Voigt
Head of the Department of Evolutionary Ecology
phone: +49(0)30 5168 511
email: voigt@izw-berlin.de

Jan Zwilling
Science Communication
phone: +49(0)30 5168121
email: zwilling@izw-berlin.de