Avoid illumination of bat foraging, drinking and swarming sites
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Key bat habitats such as foraging, drinking and swarming sites should be left unlit to avoid disturbance to bats. Dark buffer zones may also be retained around them.
Supporting evidence from individual studies
A replicated, randomized, before-and-after study in 2015 of four cattle troughs within forest in central Italy (Russo et al. 2017) found that unlit troughs had higher drinking activity for five of six bat species/species groups than troughs illuminated with artificial light. More drinking buzzes were recorded for five bat species/species groups when troughs were unlit than when they were illuminated with artificial light: barbastelle bat Barbastella barbastellus (unlit: 584; lit: 306), brown long-eared bat Plecotus auritus (unlit: 78; lit: 0), Myotis spp. (unlit: 599; lit: 134), Kuhl’s pipistrelle Pipistrellus kuhlii (unlit: 116; lit: 64) and Savi’s pipistrelle Hypsugo savii (unlit: 39; lit: 10). For the common pipistrelle Pipistrellus pipistrellus, the difference was not significant when troughs were unlit (240 drinking buzzes) or illuminated (165 drinking buzzes). Each of four cattle troughs consisted of two troughs (6 x 1.5 m) joined together. Troughs were illuminated with a portable LED (light-emitting diode) white light (average 49 lux). Each of four sites was surveyed using bat detectors on two nights with five randomized lit and unlit 10 minute intervals/night in July–August 2015.Study and other actions tested