Bat Tree Habitat Key is an entirely altruistic collaborative project that has been running since 2010. The project objective is to provide an identical detailed account of how each bat species exploits trees as roost sites. This is achieved by data review, collection and analysis within a standardised format, as well as the collection of photographic accounts, which may be contributed by anyone, and are made publicly available for everyone (see www.battreehabitatkey.co.uk and an associated Facebook page). Regardless of political upheaval, the egalitarian nature of Bat Tree Habitat Key combined with the active encouragement of criticism, continues to foster a sense of camaraderie between naturalists of all levels and walks of life across Europe, and the wider world.