A site of bat conservation concern: Madzharovo, Eastern Rhodopes, Bulgaria

While Bulgaria has a rich bat fauna, with large colonies found in caves, mines and other underground roosts, only a small proportion of bat nursery colony roosts have been documented in buildings. During recent field research in the Madzharovo region, however, we discovered the world’s largest nursery colony of lesser horseshoe bats (Rhinolophus hipposideros) and Geoffroy’s bats (Myotis emarginatus). About 15 000 to 18 500 individuals of eight species use the complex of anthropogenic structures (an abandoned water reservoir and two buildings) as a summer roost, representing around half of all the bat species registered in the region. We strongly suggest that regular monitoring programmes and Species Action Plans are established in Bulgaria, which will ensure the conservation of nursery colonies, not only in Madzharovo, but also in the entire Eastern Rhodope mountains and help prevent future bat population declines.