Changes in numbers of Myotis daubentoni (Kuhl, 1819) in autumn shelters and the effect of disturbance

Undergrounds of 2 forts in Central Poland were inhabited by Myotis daubentoni at the beginning of August. From the half of September the majority of individuals remained in lethargy. The maximum numbers were reached in the end of October (in 1984 - 70 individuals, in 1985 - 52 individuals). Studied forts are only autumn shelters for the majority of individuals, non proper hibernacula. It was found that the process of bat ringing resulted faster leaving undergrounds. Disturbance with the frequency once per two weeks changed natural dynamics in lower degree than more frequent controls.