SPA. Habitat heterogeneity, variety of karstic landforms and availability of numerous underground roosts are considered as key reasons for this high diversity. Cave-dwelling species such as R. ferrumequinum, R. hipposideros, M. myotis and M. blythii are the most commonly found in the mountain. Maternity colonies were found only for R. hipposideros. Breeding of other species was not confirmed in any of the studied roosts in 2011 and 2012. Hibernating individuals of nine species were found in 28 caves. The highest diversity of bats was found during the autumn swarming in Dinevata Peshtera Cave (17 species), Dushnika Cave (14 species), Svinskata Dupka Cave (12 species), Golyamata Balabanova Dupka Cave (11 species) and Travninata Cave (10 species). The richest region is Iskrets–Dobravitsa with 18 species occurring in it.