Investigation into Bechstein's Bats and their underground habitats in the broader area of the Krka NP in 2024

Investigation into Bechstein's Bats and their underground habitats in the broader area of the Krka NP in 2024
During 2024, the company Geonatura d.o.o. conducted an investigation of bats in the area of ​​the ecological network HR2000918 or the wider area of ​​the Krka NP

The aim of the research was to determine the population status of the Bechstein's bat Myotis bechsteinii, or rather its presence, and to investigate underground structures as potential bat shelters. All the field research, data processing, and organization of information were conducted using standard methods. By combining methods, using underground habitat surveys with above-ground habitat surveys, network sampling, and vocalization recording, the presence of 18 out of the at least 22 expected bat species was confirmed.

The Bechstein's bat species most often uses holes and cracks in trees for shelter, and its key hunting habitat is considered to be old stands of deciduous and richly structured forests with clearings. The investigated conducted within this project is the first targeted research aimed at determining the status of this species in the broader area of ​​the Krka National Park. In June and July of 2024, the presence of one male was recorded in the unused building of the Torak Water Pumping Station, which was also identified as an occasional shelter for single individuals of the species M. emarginatus, R. hipposideros, and R. ferrumequinum. Important habitats for the species include older stands of downy oak and Oriental hornbeam forests and mixed floodplain woods. In 2024, the presence of the species was confirmed by sampling with nets at three locations within or near the aforementioned habitat types. Further research is needed to determine the availability of these habitats and to identify other sites where the species is present. According to the known ecology of the species, the males live solitary lives during the summer, while birthing colonies usually consist of 10 to 50 females who frequently change shelters. According to the results of research to the present, it is possible that individual males are more frequently present in the research area, while further research is needed to determine whether pregnant females and females with young also utilize the broader area of ​​the Krka National Park.

Potential underground bat habitats were also investigated. Six shelters of single individuals of the species R. ferrumequinum and R. hipposideros were recorded, as well as four new important bat roosts (Stara jametina, Golubnjača na Liveru, Mišja pećina, and Špilja Buhara), all caves in which the presence of seven out of nine conservation target species was confirmed. The area south of the Monastery of St. Archangel to the Skradinski buk Waterfall remains insufficiently explored due to difficulties with accessibility, and it is very likely that other significant bat habitats exist in the broader area of ​​the Krka National Park.