Bats and offshore wind: Closing the knowledge gap

The overlooked frontier of biodiversity monitoring

Understanding offshore bats and wind farm ecology

When wind and wildlife are discussed together, the focus usually falls on birds. But as offshore wind expands, another group of highly mobile species is drawing attention: bats.

Traditionally, bat research has centred on terrestrial and nearshore environments, from roosting caves to migration corridors and foraging habitats. Yet growing evidence shows that bats are not confined to land. Migratory species such as Nathusius’ pipistrelle, noctules, and parti-coloured bats are now being detected far offshore, in some cases tens of kilometres from the coast.

While offshore detections remain limited, the trend is clear: bats are active over open water, and understanding their movement is critical to how offshore wind farms are planned, permitted, and operated.

Why bats at sea matter for offshore wind

What offshore wind developers need to know about bats at sea

In recent years, scientific and regulatory attention has grown around bats as an overlooked receptor group for offshore wind. A combination of studies now point to three main themes:

Bats migrate across open water, sometimes following favourable winds and warm air currents. Acoustic monitoring in the North Sea, the Baltic, and along the U.S. eastern seaboard confirms that several species cross marine areas seasonally, particularly in late summer and autumn.

Although direct collision data at sea remain scarce, bats are known to be vulnerable to turbine strikes on land and may exhibit avoidance behaviour near offshore turbines.

Climate dynamics are also shifting migration timing. Recent research from the Max Planck Institute shows that species such as the noctule are adjusting their routes and departure times in response to temperature and air patterns.

Together, these findings make one thing clear: bats are a consistent, if under-documented, part of offshore ecosystems. Integrating their monitoring into wind energy planning is no longer optional; it is an essential part of understanding how renewable infrastructure interacts with biodiversity.

The monitoring challenge: complexity and opportunity

How to monitor bats offshore: technical and ecological challenges explained

Unlike birds, bats are small, nocturnal, and often fly at low altitudes. Monitoring them offshore brings unique challenges:

• Detection limits: Acoustic detectors capture echolocation calls but have short range and are affected by background noise.
• Temporal bias: Most detections occur in late summer and autumn; seasonal gaps persist in spring and early summer.
• Collision evidence: Standard carcass searches are impossible at sea, leaving no direct evidence of fatalities.
• Habitat effects: Understanding displacement or attraction requires long-term, multi-sensor observation.

No single method provides a complete picture. Integrating acoustic, radar, thermal, and high-resolution optical monitoring is the most effective approach to understanding offshore bat behaviour.

Closing the gap with integrated monitoring

How integrated monitoring improves offshore biodiversity data

Fixed-position monitoring platforms, installed directly on turbines or offshore substations, are emerging as a practical way to improve offshore biodiversity insight. When combined with acoustic detectors or thermal cameras, site-based vision systems can:

• Provide continuous presence data across nights, seasons, and years
• Capture flight height and trajectories relative to turbines
• Integrate with automated control systems, such as shutdown-on-demand (SDOD)
• Deliver species-level verification through expert ecological review

Anchoring monitoring directly at project sites allows developers to move from assumptions to evidence-based management. This approach supports permitting confidence, improves mitigation design, and builds the dataset regulators increasingly require for offshore projects.

Policy and regulation: signals of what’s coming

Emerging offshore wind regulations on bat monitoring and biodiversity

United Kingdom – Natural England (2025)

A comprehensive review by Natural England identifies bats as a receptor of concern for offshore wind and highlights persistent evidence gaps on migration and turbine interactions (Natural England, 2025).

Global and EU guidance

While EUROBATS has historically focused on land-based impacts, recent implementation reports and national guidance, such as Norway’s 2022 submission to the EUROBATS Secretariat, call for bats to be included in environmental assessments for offshore wind. This mirrors broader policy shifts in the EU toward inclusive biodiversity governance.

Global NGOs – Bat Conservation International

Bat Conservation International has urged a coordinated global response to wind-related bat fatalities, calling for open data, systematic monitoring, and harmonised mitigation standards (Bat Conservation International, 2023).

Taken together, these signals suggest that bats will soon feature more prominently in offshore permitting and biodiversity safeguards.

From blind spot to biodiversity priority

Data gaps in monitoring bats in offshore wind development

The offshore wind industry has invested heavily in bird monitoring, but bats remain its biodiversity blind spot. Addressing this requires:

• Standardised monitoring protocols across Europe
• Multi-technology integration combining optical, radar, acoustic, and thermal methods
• Inclusion in Environmental Impact Assessments (EIAs) and adaptive management frameworks
• Transparency in data reporting and uncertainty

For developers, this is not only about compliance. Filling the knowledge gap helps de-risk projects, anticipate regulatory change, and build stakeholder confidence.

Continuous, high-resolution monitoring technologies, including camera-based systems used alongside acoustic and thermal detectors, are helping build the evidence base decision-makers need.

📍 To find out more about innovation in offshore biodiversity monitoring, get in touch!

Further reading

• Ellerbrok, J. S., Farwig, N., Peter, F., Rehling, F., & Voigt, C. C. (2023). Forest gaps around wind turbines attract bat species with high collision risk. Biological Conservation, 288, 110347.
• U.S. Offshore Wind Synthesis of Environmental Effects Research (SEER). (2022). Bat and Bird Interactions with Offshore Wind Energy Development.
• Natural England (2025). Assessing Migration of Bat Species and Interactions with Offshore Wind Farms.
• Bat Conservation International (2024). Urgent Call for Global Response to Bat Fatalities from Wind Energy.