This guide provides descriptions of when the bat species resident in Britain and Ireland use natural and human-made rock habitats, how they use them, and the environments each species occupies therein. For the first time it brings together findings from historical scientific investigations, useful photographic accounts and open-access biological records, along with a rich seam of new data – all in a practical and user-friendly structure. The book encompasses: Descriptions of the features that a climber, caver or professional ecologist might encounter on and in rock habitats where bats roost; Recording criteria for both the physical and environmental attributes of different features and situations; Identification of suitability thresholds against which the recorded information can be compared to assess the likelihood that a specific feature might be exploited by a particular bat species; and Suggestions for how to avoid mistakes and difficulties when performing a survey. The intention is that using this book will help generate standardised biological records which can feed into the fully accessible online database at www.batrockhabitatkey.co.uk. These data will be analysed to search for patterns that can increase the confidence in the suitability thresholds and help build roost features that deliver the environment each species really needs. As well as offering many new insights, this book allows the reader to participate in cutting-edge research.