Monitoring of bat hibernation colonies in ten caves in Serbia in February 2019

Abstract

European bat species feed exclusively on insects, and due to lack of prey during the cold months of the year, many species spend the winter hibernating within the underground roosts. During the regular monitoring scheme, from February 15th to February 17th, 2019, ten speleological objects in Eastern and Western Serbia were checked for the presence of bats, resulting in records of over 29 000 individuals. There were 11 recorded species: Rhinolophus ferrumequinum, R. euryale, R. blasii, R. hipposideros, Miniopterus schreibersii, Myotis myotis/blythii, M. capaccinii, Eptesicus serotinus, Nyctalus noctula, Plecotus auritus and Pipistrellus sp. The monitoring activities included entering the objects and performing a detailed search of all areas, identifying species without capturing or disturbing them, counting the bats on-site or from photographs (spotcounting method) or estimate of the number of individuals by using block method in case of extremely large groups when it was impossible to directly count bats. Among the surveyed caves in Eastern Serbia (Ravanička Pećina, Toplik, Vernjikica, Lazareva Pećina, Canetova Pećina, Dudićeva Pećina and Gradašnička Pećina), the most outstandingcave was Vernjikica in the vicinity of village Zlot near the city Bor. It stands out both by its size and by the number of hibernating bats (around 25 000 individuals), while the dominant species was Schreiber's Bent-winged Bat Miniopterus schreibersii. Monitoring was also performed in three caves in Western Serbia (Ćebića Pećina, Tmuša and Petnička Pećina), where Ćebića Pećina was the most impotant to mention, both because the number of recorded species and number of recoveries of previously marked individuals. Regular monitoring activities in caves during the hibernation season is important for keeping track of bat population size and structure, as well as for identifying key roosts that need to be protected.