This book gives an overview of the biology of the dormouse. Leicestershire is at the northern limit for the dormouse and as a result their numbers are low; there are however, small pockets found in copses and other suitable locations i.e. hedgerows, especially those that join woodland to woodland in East Leicestershire and Rutland. The dormouse is of course notoriously difficult to locate and to study, especially throughout the summer months. Late autumn and early winter is the best time to ﬁnd evidence of their presence, old nests used during the summer are often well camouﬂaged and often covered by foliage, but in winter they stand out well against the bare background of the woods. The use of nesting places e. g. converted bird boxes or nesting tubes and camera traps help in locating dormice, their rivals and their predators. Such aids help enormously. A typical is quiet woodland or dense hedgerow, one that has the trees and shrubs that produces much of their food. Hazel, bramble, honeysuckle, beech, oak and birch. A dense understory is also essential for their survival and places to build summer nests. Every effort must be made to protect this most vulnerable small mammal; it would be a tragedy if we allow it to become extinct.