This is a guide to finding tree-roosts for ecologists and tree-care professionals. It is the result of the collaborative efforts of surveyors and amateur naturalists across Europe as part of the Bat Tree Habitat Key project. This is a guide to finding tree-roosts. It is the result of the collaborative efforts of professional surveyors and amateur naturalists across Europe as part of the Bat Tree Habitat Key project, and represents a combination of firsts: It is the first time legislation and planning policy have been reviewed and put to practical use to define an analysis framework with clearly identifiable thresholds for action. Yet, despite its efficacy in a professional context, it is also the first time a guide has been produced that is equally effective in achieving its objective for amateurs. It is the first time such a method has been evidence-supported throughout, with summary reviews of each aspect of the roosting ecology of the individual 14 tree-roosting species, with illustrative photographs and data to which the reader has open access. It is the first time a repeatable analysis framework has been defined against which the surveyor may compare their results at every stage, from the desk-study, through ground-truthing, survey and analysis, thereby ensuring nothing is overlooked and that every result can be objectively compared. The survey and analysis framework itself is ground-breaking in that it may readily be adapted for any taxa; from moths, through amphibians, reptiles, birds and all other mammals. Used diligently, these methods will reward disproportionately and imbue the reader with renewed confidence as they quickly progress from beginner to competency. Thus, this book is for everyone who has ever wanted to find a tree-roost, or to safeguard against inadvertently damaging one.