Wind power and birds

Wind power and birds

The impacts of wind turbines on birds mainly come from the disturbing effect of the operating noise and the blade movement on nesting and searching for food, as well as from the risk of birds flying into the blades. The impacts depend on the size and number of wind turbines and their technical solutions and geographical location, the shape of the surrounding terrain, as well as on the composition of bird species in the region and the distances between turbines.

It is possible to prevent birds from flying into wind turbines, for example, with a bird radar. A bird radar has been installed in the first offshore wind farm in Finland, Tahkoluoto in Pori, collecting information about the behaviour and number of birds. The radar can also stop a turbine when a bird of an endangered species is flying towards it.

Radar observations carried out in Tahkoluoto have indicated that birds do not fly right past the wind turbines even if the birds have previously used that particular route. No changes have been observed in the total number of flights or in the direction where birds set off from nesting islets for hunting and where they are feeding. All in all, the impacts of wind turbines on birds would seem to be small and more minor than predicted.

Photo: Markku Saiha

Bird monitoring study 

The summary of a Finnish bird monitoring study covering a period of several years was completed in summer 2019. The monitoring was carried out during spring and autumn migration in the area of onshore wind farms on the North-Eastern coast of the Bay of Bothnia. This area has a lot of wind power and is a significant migratory route for birds.

Based on the monitoring results, migratory birds primarily aim to avoid wind farms; therefore, the impacts of wind turbines on migratory birds and on the nationally important migratory routes of birds have remained low. No changes resulting from wind turbines were detected in the location of resting and feeding areas. Agricultural activities carried on in the area and the timing of their different work stages have a bigger impact on the location of areas that are useful for birds.

Modern wind turbines are spaced so far apart that they do not prevent bird movement even in the area of wind farms, and therefore the building of wind farms has not cut nationally important main migratory routes of birds even in migratory bottleneck areas. Based on implemented studies, the number of collisions of birds with wind turbines has remained clearly lower than estimated in the project planning stages and in environmental impact assessments (EIA). Actual verified collisions have mainly taken place among local species.

Extensive bird monitoring was carried out in the spring and autumn: a total of 324 field work days in the Simo and Ii regions and a total of 120 field work days in the Kalajoki and Pyhäjoki regions. In addition to the migration watch, birds that have flown into wind turbines were also sought in the monitoring. In the area of wind farms, surveys on nesting birds have been carried out and, for example, feeding flights of different species have been monitored.

The study was published in the BirdLife Finland yearbook 2018, and articles on the subject have been published in the Tuulivoima online magazine (in Finnish).

Wind power and large birds of prey 

The need to protect the nesting sites of large birds of prey, such as white-tailed eagles, golden eagles, greater spotted eagles, ospreys, and northern eagle owls, as well as endangered medium-sized birds of prey, such as European honey buzzards and common buzzards, must be taken into account in the planning of wind power construction. According to previous guidelines, special requirements for studies concerning large birds of prey in the planning of wind power construction arise when the planning zone is located within about two kilometres of the nesting sites of large birds of prey and regular feeding areas in the winter period. However, the limit of two kilometres is not always sufficient. It is advisable on a case-by-case basis to investigate the impacts on an area wider than this as, in many cases, taking account of impacts over an area wider than two kilometres may have impacts on the prevention of harmful effects.

As of yet, there has been very little research data available concerning the impacts of wind turbines on large birds of prey in Finland. However, further information will be available over the next few years with regard to eagles as a result of the WINDLIFE project, which was launched in 2023 (see Chapter Land Mammals,  In addition, in 2022 Metsähallitus published guidelines for the assessment of impacts on golden eagles in support of the planning of wind power projects. The Finnish-language publication includes examples that highlight good practices with regard to the impacts to be assessed in connection with wind power planning concerning golden eagles in the nesting areas. The methods have been compiled from actual impact assessments of wind power projects, added by further development.

The Centres for Economic Development, Transport and the Environment (ELY Centres) have knowledge of eagle nesting sites. Although this knowledge is confidential, an ELY Centre will provide wind power developers with preliminary information at an early stage whether there is a nest in the area. If there is a nest in the area or its vicinity, the ELY Centre will tell how close to the planned project area the nest is located, in which case the project operator can decide whether or not to go ahead with the project in the area.

If the ELY Centre has no knowledge of an eagle’s nest in the area, it is still possible to enquire from WWF whether the area is of the type that according to observations there may be a new nest, the accurate location of which may not be known yet to WWF or the ELY Centre. If this is the case, an eagle’s nest can be sought in the most likely places before investing in further surveys.

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.