Does wind power disrupt local food webs?


Bat strike victim under a wind turbine. © Christian Voigt/ Leibniz-IZW

Wind power is important for the energy transition, while collisions with rotors kill thousands of birds and bats every year. Researchers in Brandenburg have investigated the consequences of the latter for the local food chains. The stomach contents of noctule bats (Nyctalus noctula) killed at wind turbines suggest that these bats have a major impact on local insect life. Their loss could therefore upset the balance of food webs.

Energy production from wind power is an important component of the energy transition and climate protection. It contributes to the phase-out of fossil fuels and is therefore almost indispensable for a climate-friendly power supply in Germany. However, wind turbines are also highly controversial because they can run counter to local conservation efforts. The reason: birds and bats often collide with the rotors. According to estimates, up to 14 bats per wind turbine per year die as a result in Central Europe, which adds up to several million animals per year for the approximately 30,000 onshore wind turbines in Germany.

Which insects are on the bat menu?

But what does the death of bats mean for local food webs? Until now, only guesses could be made because of the lack of data. That is why Carolin Scholz and Christian Voigt from the Leibniz Institute for Zoo and Wildlife Research (IZW) in Berlin have examined this in more detail using the example of rotor strike victims in Brandenburg. For their study, they analyzed the stomach contents of 17 noctule bats (Nyctalus noctula) that died there at wind turbines. Using DNA analyses, they determined which insects these bats had eaten shortly before they died.

The evaluation revealed: “We found DNA barcodes from 46 species of insects from nine orders, most of them beetles and moths,” says Scholz. “The insect species could be assigned to a large number of different habitats, from arable land to grassland to forests and wetlands.” Twenty percent of the insect species consumed by bats are considered pests or nuisances in agriculture and forestry, including the buck (Spondylis buprestoides) , the chestnut borer (Curculio elephas) ​​or the oak moth (Cydia splendana). A complementary literature review confirmed that bats play an important role in insect pest control and can even suppress local outbreaks.

Disruption of local food webs

According to the scientists, these results underline that bats can play an important role in the natural regulation of insect populations and that they thus provide valuable “services” for agriculture and forestry. If the local bat populations decline due to the rotor strike, this could also have consequences for the insect populations and thus the balance of the local food webs. “Not only are individuals disappearing from the landscape, but potentially their interactions in complex food webs are also being lost,” explains Scholz.

In addition, because many bat species only have low reproduction rates, it is difficult for them to compensate for the losses caused by the victims. In extreme cases, this could mean that there are permanently fewer bats in a region. The research team suspects that the loss of bats and their influence on food chains would then also make ecosystems more susceptible to disturbances. “We still need to understand much more precisely how the energy transition will affect biodiversity in the affected habitats,” says Voigt. However, he also emphasizes that wind turbines clearly contribute to protecting the climate and also to preserving biodiversity

Turn off when bat activity is high

The solution is therefore not so much abandoning wind power as adapting wind turbines and their operation. For example, newer systems are now switched off temporarily during periods of high bat activity to prevent the bats from colliding with the rotor blades. This can reduce the number of animals killed to one or two individuals per year per wind turbine. However, three quarters of all wind turbines in Germany are older and are operated without these shutdown devices – that has to change, according to Voigt and Scholz.

A first important step towards preserving bats and their functional role in their habitats would therefore be a mandatory shutdown of wind turbines at times of high bat activity. For this purpose, the approval practice of old plants must be reconsidered.

Source: Leibniz Institute for Zoo and Wildlife Research (IZW) in the Research Association Berlin eV; Umbrella article: Conservation Science and Practice, doi: 10.1111/csp2.12744

Recent Articles

Related Stories