Abstract. As the result of our studies in 1993-1999 and literature analysis for the south-western part of Belarus there have been registered 16 species of Chiroptera. Barbastella barbastellus is considered to be a rare species on the whole territory of Belarus and is included into National Red Book of protected species. In the Brest region Barbastella barbastellus is distributed not evenly. All the records for this species fall in the narrow belt 10 – 20 km wide that stretches along the border between Belarus and Poland from north to south. This is also a frontier area of climatic isotherm of +4oC on the level of the ground.
Barbastella barbastellus is a typical sinantrop species. It is most numerous on the outskirts of settlements that adjoin natural forests, bushy areas, rivers and streams. During summer period B. barbastellus makes relatively small colonies of up to 10 female. Summer roosts are located maximum 16 km away from winter roosts.
In winter, colonies of 20 – 3000 individuals in one roost are common. Cases of wintering of 1-3 individuals are rare (n=6). Among all the wintering species of Chiroptera only B. barbastellus can make close contact groups of up to 66 individuals (18/12/97 in an obsolete underground fortification made of bricks). Wooden cellars serve as wintering places only for 0,01% of the individuals. In close contact groups there also were registered single specimen of other species: Myotis daubentonii, M. nattereri, P. auritus, E. serotinus.
In the last decade Barbastella barbastellus shows an increase in numbers due to relatively warm winters and an increasing number of abandoned cellars.