The Influence of Artificial Night Lighting on Bats

Abstract

This thesis summarizes studies on the influence of artificial night lighting on bats. It reviews normal bat biology, the influences of light on behaviour and possible mitigation strategies. Artificial light can have both positive and negative effects, depending on the species. Some species use lights to forage, since many types of lamps attract insects. On the other hand, many bat species avoid lights when commuting, foraging or when selecting a roost site, possibly resulting in a lower fitness when forced to take alternative routes or roosts. Several measures have been developed to reduce disturbance of bats by lights. The type of light, light colour, light intensity and the timing of artificial lighting can all be adjusted so that bats are less affected. Planting screening vegetation can also reduce light spillage in the surrounding environment of the lights. To promote and sustain a diverse bat population a diverse environment is needed. Therefore, urban areas populated by bats should also contain darker places, such as unlit parks, to support bats that are disadvantaged in light circumstances.