The study found that street lights under the scheme were still on when the majority of bat activity occurs. Image courtesy

Part-night lighting is ineffective in capturing natural peaks in bat activity

Part-night lighting, a proposed mitigation option to reduce the negative impacts of light pollution, is unlikely to benefit bats, a study published this week confirms.

The research shows that natural peaks in bat activity for the greater horseshoe bat, a light sensitive species, occur one hour after sunset with a smaller second peak before sunrise. Proposed part-night lighting schemes switch streetlights off when human activity is low, usually after midnight, which means that street lights are still on when the majority of bat activity occurs.

Julie Day of Biosciences the University of Exeter said: “We’re just starting to understand the negative impacts of light pollution on wildlife. Part-night lighting, which has been widely implemented across Europe, may be really useful in reducing energy expenditure and carbon emissions but if we’re worrying about bats, we need to think of other solutions.”

Dr Henry Schofield, Conservation Programmes Manager at The Vincent Wildlife Trust commented: “Greater horseshoe bat populations are slowly recovering from a major decline during the 20th century but they continue to face emerging threats that could halt this welcome recovery. One of these is the dramatic increase we have witnessed in recent decades in the amount of artificial lighting in our environment. This species avoids lit areas and the presence of artificial lighting can act as a barrier in the landscape preventing it from accessing its foraging areas and disrupting its natural nocturnal activity.”

‘Part-night lighting: implications for bat conservation’ by Julie Day, James Baker, Henry Schofield, Fiona Mathews and Kevin J. Gaston is published in the journal Animal Conservation.

Date: 20 March 2015

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