Bat Conservation Trust supports the development of wind and other sustainable energy, but stresses the importance of carrying out ecological impact assessments for wind farm development to avoid and reduce negative impacts on bats. Bats, and other wildlife like birds, should be considered before choosing a location for a wind turbine or farm, as appropriate siting is the first step in avoiding negative ecological impacts.

How do wind turbines impact bats?

Wind turbines impact bats when placed on bat flight lines or migration routes, or near to roosts, foraging areas and swarming sites.

Bats are directly impacted by onshore wind turbines through collision with the turbine blades or injuries from air pressure changes around the blades. Indirectly, bats are impacted by onshore wind farm development through loss and fragmentation of their habitats. The impacts of offshore wind on bats foraging offshore or migrating across the sea are less well known; further research is a high priority.

How can impacts on bats from wind turbines be avoided or reduced?

A suitably qualified ecologist can carry out a desk study and ecological surveys to inform an impact assessment. They will then design measures to avoid or reduce impacts on bats and other wildlife where needed. These measures should be monitored to inform future development.

Planning conditions can be used to capture impact avoidance and reduction measures and monitoring.

Proven techniques are available to avoid or reduce bats colliding with operational wind turbines onshore. These include adjusting the angle of the blades (feathering) so that they don't turn at low wind speeds, or stopping operation (curtailment) during the times of the year or night when bats are likely to be at risk. These methods are being constantly refined and their success monitored, but have been shown to cause fewer bat fatalities and minimal losses in power generation onshore. This method could potentially also be used offshore.

The construction of smaller, individual wind turbines and repowering of existing onshore wind farms also require ecological impact assessment. We would ideally like to see monitoring of existing onshore wind turbine sites and remedial action where any issues are identified.

What evidence, information and guidance is available for the UK?

Bat Conservation Trust was part of a collaboration of organisations involved in research into the impacts of wind farms on bats in the UK, see Understanding the Risk to European Protected Species (bats) at Onshore Wind Turbine Sites to inform Risk Management.

This research led to guidance being produced for UK onshore development, see Bats and Onshore Wind Turbines: Survey, Assessment and Mitigation.

What about bats and offshore wind?

In 2022, the Department for Business, Energy and Industrial Strategy undertook a public consultation on their Offshore Energy Strategic Environmental Assessment 4 (OESEA4) Report. Bat Conservation Trust's response to the OESEA4 report consultation highlighted significant evidence gaps in our knowledge about bats offshore and provided recommendations for further work. The Government then published a response to the OESEA4 report consultation, which acknowledged that bat migration, particularly of Nathusius' pipistrelle in the southern North Sea, represents a key sensitivity and that more research is required.

Bat Conservation Trust completed a Natural England-funded project on Bat Migration and Offshore Wind in spring 2024, which involved a literature search and series of stakeholder workshops. The report will be available in due course.

Where else can I get information?

Bat Conservation Trust also contributes to the work of the Eurobats Intersessional Working Group on Wind Turbines and Bat Populations, see Eurobats Resolutions, Reports and Publications (including guidance).

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