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 Septem ber the m ajority of individuals remained in lethargy. The m axim um num bers were reached in the end of October (in 1984 - 70 individuals, in 1985 - 52 individuals). Studied forts are only autum n shelters for the majority of individuals, not proper hibernacula. It was found th at the process o f bat ringing resulted faster leaving undergrounds. Disturbance with the frequency once per two weeks changed natu ral dynam ics in lower degree than m ore frequent controls.