Impacts of Street Lighting on Biodiversity
This was a collaborative project with University of Exeter that ran from 2012 to 2015. It focused on the responses of bats and their invertebrate prey to artificial night-time lighting and was part of a wider DEFRA funded project to assess the impacts of street lighting on biodiversity.
The project focused on bats as bioindicators with the aim being to assess, through landscape-scale approaches, the impact of alternative road lighting schemes on biodiversity, and to develop evidence-based guidance for policy makers. Much of the project focused on the response of a range of bat species to artificial light and will study how this affects factors such as their foraging behaviour and colony size.
Over two and a half years a huge number of sound files were collected from the areas surrounding maternity and hibernation sites of lesser and greater horseshoe bats. We deployed static detectors in large numbers within the foraging area for both species to record presence/absence at light and dark locations to find out if horseshoe bats avoid artificial lighting and to what extent.
In addition to acoustic monitoring, habitat databases and street light mapping were worked on using ArcGIS. This form of analysis was a very powerful tool to compliment the sound analysis, and gave a larger scale view of the habitat and light preferences that horseshoe bats have. We also worked with Devon County Council who agreed for us to monitor bat activity during a change-over period from a full night street lighting scheme to part night lighting scheme in various small towns and villages. These changes are becoming a common practice across the UK to reduce energy costs. Activity surveys during the lighting scheme change were very useful in obtaining a direct measure of how bat activity is affected by street lighting.
The results of the study were published in a paper in the Animal Conservation journal. We hope to continue to produce further papers from the project during 2015 and to complete some small-scale experiments over the coming field season monitoring Daubenton’s bats over lit and unlit waterways.
Photograph: Lesser horseshoe bat © Frank Greenaway