| Summary: | Artificial light is a contributing factor to habitat fragmentation and habitat loss for nocturnal animals such as bats. While fast flying species of bats sometimes can benefit from street lights, slower flying species are the ones most affected by lights due to their increased vulnerability to predation. Old churches are suitable roosting places for bats but are increasingly lit up for aesthetic reasons. This may lead to bat species loss and reduced diversity. In order to test whether species richness of occurring bat species correlates to the number of up lit sides of churches, 9 different sites in Vänersborgs municipality were observed. The area around churches and graveyards at each site were searched for bats using automatically recording autoboxes, manual heterodyne and time expansion bat detectors. For all sites combined, 10 species were found in total which means there is a high abundance of bat species in Vänersborg’s municipality. My results show that bat species richness is reduced with the number of lit sides of church buildings. Each up lit side reduces bat species richness on an average with 2 species. Especially slower flying species of bats are negatively affected by artificial light. I conclude that lighting is threatening the general survival of bats and I recommend that (1) artificial lights for only esthetic reasons on old buildings were bats occur should be removed. (2) if lights are necessary, that lighting should be restricted to one of the least sensitive areas, depending on occurring species. This way resident bats species will have dark corridors to move through between their roots and feeding grounds.
|
|---|