Wind power and bats

In Finland, so far bat collisions have been studied to a lesser degree but based on observations, collisions seem to be quite rare although it is not possible to estimate turbine-specific fatalities due to the small amount of research data available. Bats are attracted to wind turbines, which may increase the risk of collision.

In addition to collisions, it is suggested that fatalities could also be caused by so-called barotrauma, i.e. ruptures in the bats’ lungs caused by a sudden change in air pressure behind a rotating blade. On the other hand, there are also research results indicating that only a small number of dead bats had signs of barotrauma, and therefore the significance of barotrauma in the wind turbine deaths of bats is still a disputable subject.

Based on research results, the harmful impacts of wind power on both birds and bats are smaller than the impacts of climate change and deterioration of the quality of habitats resulting from the burning of fossil fuels, wood, or peat. The impacts at the population level remain small with both species in comparison with the impacts of other human activities. (Ministry of Economic Affairs and Employment of Finland 2017)

Research

The University of Turku and the University of Helsinki published a study in 2023. on the impact of wind power on bats. The presence of bats was studied in large wind farms in the coastal areas of Western Finland. The analyses focused on the Northern bat (Eptesicus nilssonii) and the myotis, of which the most common in Finland are the Daubenton’s bat (Myotis daubentonii) and four other species.

The results of the study indicate that certain bat species avoid wind turbines. Both of the studied bat groups were nowhere to be seen near wind turbines. Northern bats were not found until at a distance of 800 metres from wind turbines, and with the myotis the distance may be even greater.

The study does not directly reveal the reason why there is a connection between the presence of bats and wind turbines. The avoidance may result from the wind turbines themselves or from wind turbine areas. In Finland, many wind turbines are built in forest areas and their construction requires an extensive road network. In addition, wind power areas form an opening in the forest.

According to studies, there is a need for further research because it is still not known why bats avoid wind turbine areas.

Review of impact on birds and bats

The Ministry of Economic Affairs and Employment commissioned a report on the impacts of wind power on birds and bats in 2017 (in Finnish). The impacts of wind turbines were assessed on the basis of international and domestic research literature and reports on impacts. According to the review, the number of birds and bats colliding with wind turbines varies a great deal between different species and sub-species. The siting of turbines plays a key part in the number of animal fatalities resulting from collisions.

On the basis of an estimate carried out by the Finnish Museum of Natural History for the Ministry of Economic Affairs and Employment, further construction of wind power is not likely to pose a significant threat to the bird and bat populations in Finland if the wind turbines are built in areas with a low density of species and where the likelihood of collisions is as low as possible. However, there is a need for further research in order to ensure that wind power construction will not pose a threat to the population sizes of species that are susceptible to collisions or disturbance.