This guidance is intended for all types of onshore wind farms for which surveys are required, from single turbines to multi-turbine farms, regardless of size. It is based on, and adapted from the second edition of The Bat Conservation Trust Bat Surveys - Good Practice Guidelines, Surveying For Onshore Wind Farms (Hundt, L. 2011; editor). Although the guidance covers single large wind turbines and wind farm facilities (multiple large wind turbines), it is important that any assessment considers the scale of the likely impacts and takes a proportionate approach. The impact of a single large wind turbine will differ from that of a wind farm, not only regarding the likely direct impact on bats, but also because of the area of habitat affected and the infrastructure required. The relatively lower risk of a single or small number of turbines needs to be balanced against the suitability of the site for bats. In large scale schemes, because of the area involved there may be more options for micro-siting (short-distance location adjustments to turbine positions) and also for on- or off-site habitat enhancement schemes.