The main focus of the project is to determine the impact of light pollution from street-lighting on bat commuting and foraging behaviour along linear features. We work at 11 lesser horseshoe bat maternity roosts in Wales and south west England. We use an experimental approach conducting lighting experiments along hedgerow flight paths within the vicinity of maternity roosts. Flight paths are identified using AnaBat II and SD1 ultrasonic detectors (Titley Electronics, Ballina, New South Wales, Australia) which record relative bat activity and species diversity. Hedges are illuminated using two portable streetlights to test for changes in species diversity and activity before and after illumination. Our streetlights have been obtained under guidance from the Institution for Lighting Engineers (ILE) to ensure that they closely match those used on the streets. You can find our results so far in publications and on the results 2008 and 2009 pages.

We are working in collaboration with Cornwall County Council to test the effect of new lighting technologies on bats in areas with established streetlights. Cornwall County Council have commenced a pioneering "Invest to Save Project" which aims to replace all Cornwall streetlights with new white spectrum reduced wattage "Cosmopolis" lamps. Bats & Lighting Project Research Assistant Andy Wakefield has secured a PTES Internship grant and is comparing bat activity before and after the new lamps are installed to test their effect on bats in Cornwall. You can find out more about the Cornwal County Switch Over here.

Lesser horseshoe bats use hedgerows and other linear landscape features as commuting routes to travel through the landscape to reach foraging areas. Connectivity of such features within the landscape is therefore important for this species. We use AnaBat detectors at hedgerows around maternity roosts to record bat activity. We then measure hedgerow characteristics and weather variables in order to determine how bats choose flight paths, and which features are most important in path selection.

We also investigate the effect of lighting on emergence behaviour. Emergence counts are conducted at the roost every evening during the lighting experiments. Observers stand and count bats as they emerge recording time and light levels. This allows us to determine whether disruption of flight paths around the roost has any effect on emergence time and duration.