Bechstein's Bat
Myotis bechsteinii (Kuhl, 1817)
Order Chiroptera
Family Vespertilionidae
Conservation status: in Bulgaria: Vulnerable VU [B1 b(i, ii, iv)], BDA-II, III; International: IUCN-VU; BeC-II, BoC-II, HD-II, IV.
General distribution. Europe, in the north to Southern Sweden, in the east to the Caucasus Mountains, Azerbaijan and Northern Iran.
Distribution and abundance in Bulgaria. It was found for the first time in Bulgaria at the mouth of the river Kamchiya [1]. Until 1985, seven localities were known [2] and 34 localities until the end of 2006 [3], whereby 14 are situated at altitudes under 300 m, 8 are within altitudes of 301 – 1 000 m, and the rest are over 1 000 m. The highest locality is the Sharaliyska cave (1650 m) in Pirin. Highest is the density between 1 000 m and 1 400 m (an average of 8.2 individuals from 12 habitats), in regions with vast and compact forest massifs (the Central Balkan range, the Western Rhodopes, Strandzha). It is rare in the Danube Plain and absent in the open parts of Thrace.
Habitats. A typical inhabitant of old deciduous forests. Its numbers are highest in mesophilous forest massifs with permanent water basins, in the lowlands with a predomination of different species of oak and ash-tree, and in the mountains of beech. Singular individuals live in hollows in trees with a diameter of the trunk 13-20 cm at a height from the ground 0.7-5 m; colonies have been found only in older trees with a diameter of 40-55 cm at a height of 5-12 m [3]. Only two individuals have been found in caves during the winter. It has been found once in bat boxes (Ropotamo reserve).
Biology. The males most often live singularly and the females in small groups (of 5-10 individuals) or in colonies (of 10-30 individuals). The females have a strong attachment to the region of the tree hollow in which they were born [4]. The individual hunting area is small: 0,6 – 1 ha, often overlapping between the individuals of one colony. A stationary species that rarely makes longer migrations (a maximum of 60 km) [6]. In Bulgaria a vertical migration of 770 m has been registered between the shelter to the place of catching (2.7 km) [3]. In June it gives birth to 1 young suckled for about 3 weeks. From the end of August to the end of September, Bechstein's bats (about 90% male individuals, 10% female individuals) gather near the entrances of caves or of abandoned mine galleries with the aim of finding partners [3, 5].
Similar species. It differs from the other representatives of the genus Myotis, except the greater and lesser mouse-eared bat (Myotis myoti, M. blythii), by its longer ears, and from the latter two species by its smaller size – the length of the forearm is under 50 mm.
Negative factors. Selective felling of trees that are old and with hollows reduces the possibilities for finding appropriate shelters. Fragmentation of the compact forest habitats and discontinuation of the links between them.
Conservation measures taken. The species is protected according to the Biological Diversity Act, EUROBATS and all the other conventions (without CITES). Over 200 bat houses installed in 7 places in the country are included for monitoring in the National System for Biological Monitoring.
Conservation measures needed. Development of a management plan for the forest loving species of bats in Bulgaria. Carrying out focused monitoring in its more significant habitats. Declaration of the most important autumn swarming sites protected territories. Installation of bat boxes.
References. 1. Heinrich, 1936; 2. Benda et al., 2003; 3. Petrov, 2006; 4. Kerth et al., 2002; 5. Schunger et al., 2004; 6. Kerth & Petit, 2005.
Author: Boyan Petrov
