Effects of Artificial Lighting on Insectivorous Bat Communities in Urban Ecosystems

Abstract

One of the greatest defining forces of nature is the light-dark cycle, which is now highly disrupted by anthropogenic light pollution. Artificial light is most prevalent in cities, and negatively affects many nocturnal taxa in urban ecosystems. Urban insectivorous bats are likely to be among the taxa most affected by light pollution. My research uses a range of surveying techniques to address the issues of public lighting in terms of location and spectra, and in different ecologically important habitats; urban forests, waterways and wetlands. My results showed that a change in street lighting spectra from the common mercury vapour to new light emitting diode technology causes a decrease in the activity of fast and slow flying bats and that bat diversity was highest in dark forest remnants. I also concluded that lights at the edges of urban forests significantly reduces the activity of specialist slow flying bats at those habitat edges, but not faster flying bats. The specialist bat, Myotis macropus, a vulnerable trawling bat species, had a consistent negative response after the introduction of artificial light to a waterway. I lastly examined the effects of different colours of light on bats at wetlands and concluded that white lights cause a significantly negative community-level response where in comparison red lights did not, however these responses to artificial light may be species-specific and context-dependent. My research shows that disrupting the light-dark cycle in urban areas is discouraging specialist bats with whilst encouraging generalist, faster flying species. We should avoid using street lights near ecologically sensitive areas such as small urban remnants and forests, narrow corridors and waterways, and use narrower spectrum streetlights in these areas if public lighting is necessary.