The project was conducted by BEKE (Bükk Mammalogical Society, Hungary) between February and December 2009, funded by The Wildlife and Species Conservation Devision of the Department for Environment, Food and Rural Affairs (DEFRA, United Kingdom).

The life of forest-dwelling bat species is poorly known. Information on their roost preferences and habitat use are crucial to protect them. The major threat to these species is the intensive sylviculture, which destructs their roosts and foraging places as well. In order to get essential data on the forest-dwelling bat fauna, a complex research project was planned on these species in Hungary.

One of the project's aims was to collect data on the differences of bat activity in clearcuts and forests, as clearcutting is an actual and significant problem in North-East Hungary. Acoustic samplings were conducted in these degraded and semi-natural habitats. To evaluate the data of the recorded bats, calls (identified on species or genus level) were sorted into two species group, based on the bats’ feeding strategy and habitat use which links them to habitats with „closed” or „opened” character. In one of the two sample series we found significant differences between the bat activity of the two types of habitats, more calls of the “closed habitat species group” (including the most valuable forest-dwelling bat species except for Nyctalus lasiopterus) were recorded in forests.

The main target species of the project was Nyctalus lasiopterus. An intensive detector survey was conducted in order to find new populations throughout the country. One new locality of the N. lasiopterus was found in the Zemplén Mountains where the species was not observed since 2000. At the most significant known location of the Hungarian population, four specimens were tagged with radio transmitters. Four new roosts were located, high numbers of social and emerging calls of the species were recorded for analysis. All of the roosts were in beech trees. 52 emerging specimens were counted at one roost, which is the biggest sized roosting group in Hungary till now. Data on the temperature of the tagged bats were also collected, resulted valuable data on the changing of the body temperature of the bats in the case of significant shifts in the outer temperature.

Data collected during the implementation of the project are suitable for conservational applications besides their scientific value. These data on the occurrence and habitat use of the researched species will be used in the conservational maintenance plans regarding the sampled areas.