(Chiroptera: Vespertilionidae)

Abstract. The first record of Myotis bechsteinii in Bulgaria dates from 1935. Since then, a total of 55 fe-males, 141 males and two individuals of unknown sex have been recorded. Up to now only three breeding colonies have been found in Bulgaria. At present, the Bechstein’s bat is known from 34 localities (33 UTM squares) situated from sea level up to 1650 m. Since its first discovery, only two males have been found hibernating in caves. Besides that no data are available on wintering sites of the species in Bulgaria. Al-though most localities were at altitudes below 300 m, the highest number of individuals during summer was found in mountain beech and mixed coniferous woodlands at an elevation between 800 m and 1450 m a. s. l. During the swarming period, some individuals were found to make vertical migrations of ca. 770 m between their roosts and the site of the capture. Myotis bechsteinii was found in Pleistocene and Early Holocene deposits of only two caves in Bulgaria. However, it was one of the most abundant and common species during that time. At present, conservation of mature forests (i.e. sustainable forest management), maintenance of their connectivity and further planting of new forest clearings are considered the most important factors that could promote the occurrence of the species