This is the first monograph in English broadly addressing all vertebrate and many key invertebrate groups of Bulgaria, their faunistics, origin, geographical and ecological distribution, and conservation issues are addressed by the experts on each group.The book includes 22 chapters by 28 authors, united by a single theme: biogeography and ecology. From the single-celled organisms in the Black Sea sand to the endemic cave crustaceans, from the mountain glacial relict insects to the most diverse bird fauna in Europe, the unique fauna of Bulgaria has been a subject of study of mostly Bulgarian zoologists for more than a century.