Foraging areas and relative density of bats (Chiroptera) in differently human transformed landscapes

This study on the foraging areas of bats was conducted on 64 transects (2 km long) in different habitats and urban zones in central Poland. Relative bat densities in the city (Warsaw) were only slightly lower than in comparable habitats outside the city. The maximum densities of foraging bats were noted in wooded and riparian habitats (in the city respectively 2.0 and 1.0 records/100 m per count; outside of the city - 1.8 and 1.5 records/100 m per count). Open areas were the least frequently visited by foraging bats. Built-up areas outside the city were characterized by higher densities than city built-up areas. The percent of Eptesicus serotinus records was highest in the central zone (about 66%) and decreased with the distance from the city centre. The main foraging areas of Nyctalus noctula were distributed in riparian habitats of all zones. Pipistrellus nathusii and Myotis spp. were more frequent in a landscape less transformed by human activity. Tree cover within a foraging site was the most important factor influencing bat density.