New Industry Standard Guidance Document ‘Bats and Onshore Wind Turbines: Survey, Assessment and Mitigation’

A new guidance document has been published by the Statutory Nature Conservation Organisations (SNCOs) for England, Wales and Scotland (Natural England, Natural Resources Wales and Scottish Natural Heritage) which was prepared with the Bat Conservation Trust (BCT), University of Exeter, Scottish Power Renewables, Ecotricity Ltd and RenewableUK. It is now the industry standard guidance document on survey, assessment and mitigation for bats when considering onshore wind turbines, and replaces previous guidance, notably Chapter 10 of the BCT Bat Surveys: Good Practice Guidelines (2nd Edition) and Natural England’s TIN051 Bats and onshore wind turbines (Interim guidance). The document makes reference to BCT’s Bat Surveys for Professional Ecologists: Good Practice Guidelines 3rd edition).

Bats are protected by both domestic and international legislation. Wind turbines can have direct negative impacts on bats by collision but also by barotrauma, caused by rapid changes in air pressure close to turbine blades. The guidance focuses on these direct impacts, but also considers indirect impacts such as displacement from suitable foraging habitat, loss of roosts and the potential for wind farms to form barriers to commuting or foraging habitat.

The new guidance emphasises the importance of a desk study to inform field survey, and highlights the value of static acoustic detectors as part of the survey work. While transect surveys can comprise a valid part of the survey effort, this emphasis on static detectors recognises the value longer temporal duration of data obtained through static detectors as opposed to that from transects: transect or vantage point data can supplement static detector data, but not replace it.

The guidance highlights the need to identify and then survey features that could support maternity roosts and hibernation or swarming sites. The aim is to identify presence or absence of roosts, and if bats are present, the species, approximate number of animals, roost function and flightlines away from the roost.

The guidance provides information on quantifying activity and species vulnerability, and a standardised format for presenting bat activity data, before demonstrating how to calculate potential risk and applying mitigation. It then gives an overview of post-construction monitoring methodology for sites where this is required.

An initial read of the new guidance suggests that it is based on higher quality evidence-based research than previous guidance, and allows the ecological consultant to assess what survey methods will produce the data needed to provide accurate advice. The emphasis on static detectors is based on good ecological principles, and will likely reduce costs for the client while enabling the consultant to accurately assess ecological impacts.

Bats and Onshore Wind Turbines: Survey, Assessment and Mitigation’ can be downloaded from

John McTaguebats, guidance