Photography as a low-impact method to survey bats

Bats are mammals of chief conservation concern and also represent potentially powerful bio-indicators. Surveying bats is thus an important task but the approaches adopted may either be too invasive (capture) or prone to identification errors (acoustic methods). We here report on the use of a photographic trap to survey bat species richness we tested at two drinking sites in central Italy. The species richness we estimated was similar to that obtained by a previous mist-netting effort at the same sites. We also photographed species often overlooked in acoustic surveys due to their faint echolocation calls. From the photographs we could frequently identify sex, reproductive status, age class and individual marks. Given the relative non-invasiveness of this approach, we strongly recommend it in lieu of capture at sensitive sites or to complement acoustic surveys in order to improve identification rates.