Two-thirds of bird migration takes place during hours of darkness, mainly to avoid predation. It has long been known that artificial light sources can cause migratory birds to lose their ability to orientate and navigate. This can take them away from safe stop-over habitats and pull them towards artificial light sources, causing collisions into buildings or other tall structures, or to fly round the lighting until they become exhausted. 

Research published by the University of California (2017) indicates that hundreds of millions of birds die annually across America from nocturnal collisions with buildings.(1) Specifically the Ground Zero ‘Tribute of Light’ Memorial light up on 11 September each year was shown to attract an additional 1.1 million birds in just 7 days (over 7 years). More recent research in China, reported in the American Ornithological Journal March 2020(2), recommended the following to reduce bird losses during their migrations: 

• Reducing the number of artificial light source in important migration areas; 
• Strengthening bird monitoring in key areas under particular weather conditions and
• temporarily turning off light sources when birds gather to reduce bird collisions; and  
• Using light sources that are visually insensitive to birds (lower Blue-white light content). 

Cases involving young petrel and Manx shearwater chicks (both rare breeds of seabirds) emerging from their burrow nests flying towards artificial bright light sources have been reported in New Zealand(3) and in the Western Isles of Scotland.(4) Resident groups and conservation bodies responded to lend a hand in rescuing the young birds and the harmful lights were switched off during the night to try to help protect them in taking their maiden flights. Due to their anatomy these grounded birds find it difficult to take off from built‐up areas and many fall victim to predation, cars, dehydration or starvation. The shearwaters migrate thousands of miles from Rum to South America each autumn, but some disorientated juveniles don’t make it any further than the mainland, crash landing at the port of Mallaig.

We are not aware of any evidence of problems in Cumbria on bird migration and light pollution, but would be interested to hear from anyone with any local knowledge of effects.

(1). https://www.pnas.org/content/early/2017/09/26/1708574114

(2). https://academic.oup.com/condor/article-abstract/122/2/duaa002/5780833?redirectedFrom=fulltext

(3). https://www.nzherald.co.nz/nz/crashing-petrels-moving-south-as-lights-dimmed-in-punakaiki/2RCXYOBBZWSFWA4GAQ42WFEYO4/

(4). https://www.pressandjournal.co.uk/fp/news/highlands/424721/helping-hand-for-crashed-birds-in-west-highlands/ and https://onlinelibrary.wiley.com/doi/10.1111/ibi.12594

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