DYNAMICS OF THE NUMBER OF BATS HIBERNATING IN THE MORAVIAN KARST IN 1983 TO 1992

Visual censuses of hibernating bats were organised annually in 37 unde rground spaces, largely natural caves, in the Moravian karst between-1 983 to 1992. The total number of hibernating bats increased significan tly during the 10 - year period. The most striking increase in numbers was observed in the greater mouse-eared bat. Myotis myotis, with a le ss pronounced increase recorded in the lesser horseshoe bat, Rhinoloph us hipposideros. In other bat species (Burbastella barbastellus, Pleco tus spp., small Myotis spp.) no apparent trends were observed. Possibl e explanations for the observed changes in the abundance of wintering bats are discussed.