Friday, 23 January 2004

Light pollution and wildlife

A few years ago I was involved in organising a conference on the impact of roads on wildlife, held at the Linnean Society of London. One of the issues discussed was light pollution, and ever since then I have been very aware of the enormous amount of light pollution worldwide. When flying across the Amazon at night, en route to Patagonia, everywhere I looked I could see lights. When I arrived back in Norwich at 3 am in the middle of winter there were four species of songbirds in full song – because of the brilliant street lighting. Everywhere there is the glow of orange-yellow sodium and other street lighting. This must have devastating effects on a wide range of wildlife, from migrating birds to insects. I was therefore very encouraged to read a letter in this Spring’s Birds Magazine, published by the RSPB. Councillor Clive Finch, from Lincolnshire describes how in his capacity as a local authority committee member he has been able to utilise legally enforceable conditions on planning applications to reduce light pollution. As he points out it is something everyone can lobby their local authorities in the UK to do. And probably in other parts of the world too.

My personal belief is that light pollution is having a far greater impact on wildlife than is generally recognised; it is very difficult to monitor. So we should all try and do something about it – just turning of patio lights at night would be a start. But trying to get local authorities to have all unnecessary lights extinguished after 11pm would be a good target.


  1. Light pollution is extremely damaging to the environment, as I pointed out in my letter to the BAA journal in 1994. Lights left on all night attract insects, and I saw plenty of evidence for this when I lived in Africa in the 1980's and early 1990's. They would spiral around the lights and if not killed outright by the high temperatures would fall to the ground too tired either to breed or to procreate. Consequently over long periods of time the lights will sweep up insects over wide areas. This is going to have concomitant effects on higher order consumers such as spiders, birds, small mammals, reptiles and amphibians.

    Some lighting is worse than others. Halogen, mercury and high pressure sodium (SON) are very damaging, while low pressure sodium (SOX)is less so. However all types are culpable.

    Insects are also very important as pollinators, so if their numbers decline, so does the number of successful pollinations. Consequently plant diversity is also affected, further enhancing insect decline in an ever increasing positive feedback cycle. Plant flowering cycles can also be affected as the plants are tricked into behaving as if it were summer, with extended daylight. Abscission can also be affected.

    Wildlife groups have commented extensively on the decline of many common species of animals and plants over the past forty or fifty years. What is not generally realised is that this mirrors the expansion of street, security, commercial, sports, and decorative lighting over the same period.

    Unfortunately people are now addicted to light, and this is encouraged by the lighting industry in order to maximise profits. What is now needed is a culture change in our attitudes towards nocturnal lighting. We have already seen this with a view to littering, dog-fouling, drink-driving, seat-belts and smoking in public places. Lighting should only be used when and where necessary, and switched off when not in use. Consequently it should be applied sparingly, when needed, where needed, and in the correct amounts. Better lighting design will help, along with an 11.00p.m. curfew on minor roads in suburban areas in which the lighting is not switched on again until the following night. This will help the environment to recover from the worst effects. Lighting in rural areas is not appropriate, and should not be applied unless absolutely necessary. Those involved in road safety should seek alternative methods that are available without naive recourse to street lighting.

  2. It's a long time since I wrote the original blog, and everything I have seen since confirms what Colin Henshaw is pointing out. I.e. the situation is much worse than I described. When I fly intercontinentally, it is reall depressing to realise that it is almost impossible to not see electric lights at some point between the night-time horizons.

    Like Cilin I recall the huge numbers of insects attracted to lights in Africa, and also when I first visited Greece in 1963, I remember vividly watching Green Toads (Bufo viridis) sitting beneath (th then rare and occasional) stree light, gobbling up insects.

  3. I have found this "missive".
    It makes interesting reading -