**4. Conclusion**

Turkish Thrace, located in the north-west of Turkey, served as a bridge between the Balkans, Anatolia, and Mediterranean. Thrace is one of the major biogeographic zones in Turkey and, due to its karst formation, there are many caves with different characteristics in the region. Due to these features, Thrace region, which has been an important glacial refuge for bats in the past, still provides a pretty opportunity to be hosted particularly for obligatory cavedwelling bats. Turkish Thrace hosts large populations of many bat species [32–38].

Roost selection is essential for bats that spend more than half of their lives in roost [13]. Caves may serve as one of the most adequate roosting sites for bats because of the relatively stable microclimatic characteristics. Dupnisa Cave System and Koyunbaba Cave are the most important underground habitats for bat populations in southeastern Europe [34–38]. The hosting of large populations (56,600 hibernating bats and 11,000 breeding/nursing bats) of many bat species (18 species) is an indicator that Dupnisa Cave System is the most important shelter in the region. In addition to this, Koyunbaba Cave, which is used by a large breeding/nursing population (29,500) consisting of 11 bat species, is the most important summer roost in the region. Some bat species are listed as Near Threatened in the IUCN Red List, because of their declining populations in most of the European countries [43]. However, the populations of these species in Balkans and Turkey are stable [43], because Turkish Thrace provides many appropriate shelters to use by bats such as Dupnisa Cave System and Koyunbaba Cave.

Many species have very specific microclimatic requirements for roosts [18]. Microclimatic requirements of bats show seasonal variations according to their annual life cycle. Microclimatic conditions of roost and microclimatic requirements of species may contribute to patterns of association of bats [18, 23, 44]. Therefore, cave availability for bats is increased by providing alternative microclimatic conditions according to seasons. Most of the caves in Turkish Thrace are appropriate shelters for winter colonies of bats and also for their nurseries. When there are alternative roosts, bats prefer the most appropriate ones to others. Therefore, Dupnisa Cave System is mainly used as a winter roost by bats, whereas Koyunbaba Cave is mainly used as a summer roost. Dupnisa Cave System and Koyunbaba Cave have different roost characteristics and microclimates and are used by different bat species for different purposes at different levels according to seasons. Therefore, they are alternative roosts to each other for bat population throughout the year. These caves, which complement each other in terms of seasonal use, are a chance for bats that have limited roosts. This makes these caves more important for the future of the bats in the region.

Growing urbanization across the world is resulting in negative impacts on bats and their key roosting habitats. Disturbance and destruction at caves is a widespread and major threat for cave-dwelling bats. Populations of some bat species are threatened globally due to human disturbance and roost lost caused by the increase in human population and land use. The protection of caves should be the most effective of bat conservation programs because a single cave can shelter thousands of bats from various species. Our findings related to these caves give some important clues for the population status and roost ecology of the bat species in Turkish Thrace. Also, it is very important for the implementation of any plans contributing to the protection of the roosts. The conservation of the caves, primarily Dupnisa Cave System and Koyunbaba Cave, whose importance for bats and other cave inhabitants was scientifically proven, is very important for the future of endangered species. Such preservation actions are made obligatory by international agreements including Turkey.
