Increasing evidence of cryptic diversity in European bats raises fundamental questions for key mechanisms enabling sympatric occurrence of ecologically and morphologically similar species that could be resolved only with complex knowledge of their biology. The goals of the proposed project are to (1) gather and analyze data on spatial activity, roosting preferences, seasonal dynamics, spatio-temporal and genetic structure of the population and feeding ecology of Nymph's bat (Myotis alcathoe), one of the least known European cryptic bat species, in several model study areas in Czech Republic and to (2) elucidate key factors underlying sympatric coexistence of this species with its two cryptic congeners, the whiskered bat (Myotis mystacinus) and the Brandt's bat (Myotis brandtii). To address this goal, a wide spectrum of standard research and analytic techniques including radiotracking, analysis of faecal pellets, molecular genetics and multidimensional statistic methods will be used.