Structure and dynamics of a winter colony of bats

Abstract

Studies were made during two consecutive winter seasons, 1975-1977, of the structure and dynamics of a bat colony in the old fortifications in the Lubuskie Lake District (western Poland). Over 10000 bats belonging to 11 species were found to hibernate. Numbers, dominance, constancy of occurrence, species diversity, capacity and density of individuals in the colony were determined. Maximum density in the population of hibernating bats was 152.6 individuals per 100m of corridor. Slight differences were found in the value of the species diversity index (H) between different months, and also between successive study seasons. Capacity index (K) reached its maximum value at the turning point between December and January. It was found that different species appear and disappear within a given time, and that exchange of individuals takes place during hibernation. In autumn M.daubentoni dominated in the colony, in winter B.barbastellus, in spring M.myotis. There was a decrease in the numbers of bats in the colony during the course of the studies, this applying to different species to a different degree.