The Royal Society
Light pollution is a rapidly growing global problem that can profoundly affect the behaviour of animals active at night [1]. Approximately 69% of mammals are nocturnal and one-third of these are bats. This taxon has a perilous conservation status—17% of species are listed as endangered or near threatened by the International Union for Conservation of Nature [2]. Given their importance as ecosystem service providers [3–5], and the potential for artificial lighting at night to exacerbate other conservation threats such as habitat fragmentation and climate change [1], serious consideration must be given to the potential positive and negative consequences of artificial lighting at night.
As the only mammals capable of true flight, bats are able to exploit widely dispersed ephemeral food supplies. Their nightly foraging movements exceed those of many other mammals, and lactating females will make multiple trips, returning at intervals to suckle their young. Long-distance movements are also undertaken, particularly when the animals switch between breeding, mating and hibernation sites.