Windräder: Lethal for non-native bats

German plants also endanger migratory bats from neighboring countries

Bat killed by a wind turbine © Christian Voigt / IZW
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Rotating death traps: Wind turbines are not only a deadly threat to bats, they actually lure them. Not only bats from the surrounding area are dying, but also many who are on their way to their winter quarters and come from far away. This is now confirmed by a study of German biologists. Especially fatal: Most of the dead are females and young and thus those who are important for the preservation of the species.

Wind turbines deliver clean electricity and are important for the energy transition. But they too have dark sides. One of them: For many birds and bats, the rotor blades are a deadly danger. If the facilities are not shut down during the night - the time when the bats are most active - then an estimated 300, 000 bats at wind turbines in Germany could crash every year, such as Linn Lehnert from the Leibniz Institute for Zoo and Wildlife Research (IZW) and their colleagues to report.

For their study, the biologists examined deaths of large noctule-nests (Nyctalus noctula), a migratory species of bat on wind algae. These bats are among the most common victims of wind farms installed in northern Germany. To determine their origin, the researchers analyzed the ratio of heavy to light hydrogen in keratin of the hair. Both hydrogen forms are absorbed by the water and preserved in the hair. Because their relationship varies with ambient temperature and latitude, it tells where an animal came from.

A quarter of the dead were just passing through

As it turned out, more than a quarter of the bats did not come from the vicinity of the wind farms. Instead, they were animals on their way to their winter quarters in Germany or south-western Europe. They came from the northeastern distribution area, which extends from the Baltic States over Russia and Belarus to Poland. Germany is exactly on the migration route of these bats when they move to warmer areas for the winter, for example to Germany, or further to Switzerland or to southern France.

Areas of origin (red) of the large noctule found dead at the German wind turbines (white dots). Lehnert et al. / PLOS ONE, doi: 10.1371 / journal.pone.0103106

For these populations, a loss is particularly dramatic, as they are unlikely to proliferate in adverse climatic conditions in some years anyway, as the researchers explain. If many other bats on German wind turbines then fail, the stock is likely to be vulnerable. The study shows that in Germany we not only bear responsibility for the conservation of native bat species, but also migrant bats from distant countries due to their central location as a transit country, emphasizes bat expert Christian Voigt from the IZW. display

It especially affects females and juveniles

In addition Windr der are particularly fatal because they really attract the bats. The pull time is also mating time, then the bats fall right into the buzzing in the truest sense of the word. And that's what happens most in landscape-striking structures such as rocks, church towers, or wind turbines. As the study showed, particularly many female and young animals die on the wind turbines. This is particularly critical for the population, as one female does not have any potential kittens in the next generation.

"We are still a long way from knowing the population size, demographic parameters and consequences of such threats to the survival of bat populations, " the researchers said. However, the large number of bats killed every year at the wind farms shows that there is an urgent need for action at national and international level.

Consistent enforcement of bat protection urgently needed

Voigt is surprised that only a few measures are taken against these deadly traps: Featherers are protected under both national and EU law and are migrating bats They are also protected by a UN convention signed by Germany. Who kills a single bat, can be prosecuted. In the wind turbines, however, looked away generously. KlimThere, climate protection and species protection are played off against each other but they would have to go hand in hand in the sense of comprehensive environmental protection.

Windmills and bats actually fit together well: bats do not like strong winds. They are only active at wind speeds of a maximum of six to eight meters per second. That's where Windr ders first start producing energy properly. If the plants were only able to run in strong winds, collisions could be avoided - including those between climate and species divers. (PLOS ONE, 2014; doi: 10.1371 / journal.pone.0103106)

(Forschungsverbund Berlin eV, 14.08.2014 - NPO)