Archive
DON’T LIGHT THE DARKNESS
19/09/2024
Those of you familiar with our reports know that we have been concerned about nocturnal artificial light on nature for many years. Not only does artificial lighting outside (and leaking from inside our buildings) impede our enjoyment of the night sky and adversely impact astronomy, but it also disrupts the natural rhythms of both nocturnal and diurnal wildlife and even ourselves. Lights shining on nests, roosts, and hunting territories are obviously problematic, but it goes beyond that.
We know that artificial light at night affects insects (think clouds of moths and other species swarming around an isolated street light or your porch light), but it seems even spiders are affected. A study of the orb-weaving spider Hortophora biapicata (L. Koch, 1871) by Willmott et alii in Australia[1] found that artificial light at night impairs the structural development of their brain. Indeed, the authors note that artificial nocturnal lighting “alters natural cycles of light and is linked to the disruption of a multitude of light-dependent biological rhythms and physiological functions”.
In our standard survey report instructions, we emphasise the problem of nocturnal light pollution in the text, writing that developers: “avoid unnecessary negative impacts of new lighting at night, e.g. on bats, invertebrates, plants, night sky.” They should minimise the hours when lighting is used, avoid light spillage by using directional down-lighting, reduce brightness of necessary illumination, avoid floodlights and glare, and keep light from shining on bat roost entries, mammal holes, etc., especially avoiding lights with ultra-violet output.
Betts Ecology, and increasingly planning authorities, insist on lighting policies which minimise light pollution on our sites. These include cowls, downlighters, low wattage bulbs and glare prevention, but they are difficult to monitor and implement without co-operation from residents and owner/occupiers. We ask everyone please to be aware of the harm done by light pollution and avoid all unnecessary use of exterior lighting – un-cowled floodlights with automatic sensors are particularly troublesome.
Although rather thin on ecological impacts in my view, the government have a web page on this topic which is worth a read at https://www.gov.uk/guidance/light-pollution.
[1] https://doi.org/10.1098/rsbl.2024.0202 Royal Society Biology Letters.
