Bat Rock Habitat Key is the sister project to Bat Tree Habitat Key and is another altruistic collaborative project, set up by Henry Andrews, that has been running since 2018. The project objective is to provide evidence-supported accounts of how each bat species resident in the British Isles exploit rock environments as roost sites. This is achieved by data review, collection and analysis within a standardised framework, as well as the collection of photographic accounts which may be contributed to by anyone and are made publicly available for everyone. The project website, data review, analysis and publication are funded by the sale of this book.