Solar lights can cause problems.
NATURE NOTESI HAVE received reports this year’s count of glow worm sightings has dropped considerably, which is cause for concern.
None at all have been recorded at Ashey or St John’s churchyards and numbers were well down at St Helens and Fishbourne, too.
One of the problems appears to be the presence of solar lights, which are becoming so commonplace, clearly making it hard for the males to find their glowing mates.
Caravan sites also seem to be popular locations for mass gatherings of solar lighting. This might seem to be a minor problem but if the existence of the solar lights continues to prevent successful mating, the inevitable consequence is the eradication of the species in those locations where such lights proliferate.
Light pollution is a big problem elsewhere for a variety of reasons, and there are several organisations which campaign to reduce the levels of lighting at night where it is appropriate to do so.
Unsurprisingly, one of the longest established is the appropriately named Campaign for Dark Skies (CfDS), set up by the British Astronomical Association.
Astronomical observation is an obvious activity which cannot be successfully carried out when light levels at night are high, but the campaign also represents non-astronomers who are worried for different reasons.
The Campaign to Protect Rural England (CPRE), which ran its own Dark Skies campaign, supports the CfDS and campaigns (among many other things) to achieve better planning decisions which prevent and reduce light pollution.
The problems of night lighting are not restricted to urban areas but also cause difficulties in rural areas. Bats can be disorientated by light and although attracted to lights, this may be more to do with the fact the insects on which they feed are also fatally attracted to light.
The insects which circle lights at night may die either from the heat of the bulbs, or because they fly until they are exhausted, at the expense of feeding and mating. Thus their survival is also put at risk by light pollution.
Birds can also be adversely affected by inappropriate levels of light at night. Some birds may sing or call longer into the night than normal, as a result, and consequently become less able to feed during the day due to the disruption to their rest pattern. Weaker birds are less likely to survive or to reproduce successfully.
Research in Canada has shown that high-rise buildings which are brightly lit at night cause the deaths of many migrating birds, which are disorientated by the light and crash into the buildings.
Inappropriate cycles of light and dark produce an effect on plants and trees, which may also be detrimental. Most plants will need a certain amount of darkness to trigger physiological processes; the pattern of darkness will include the daily cycle and also the seasonal cycle.
Disrupting these natural cycles will cause plants (and trees) to display similar disruption to their patterns of growth, leaf fall and resting periods, producing stress, which in turn will harm the health of the plant. Sometimes these 'tricks’ are used by horticulturalists to produce plants which will bloom at a prescribed time but one cannot continue to force plants in this way.
And we humans, as mammals ourselves, are not immune from these adverse effects. Some scientists think that night light disrupts the production of melatonin in our bodies, which, among other things, has a protective affect again cancer by suppressing the spread of rogue cells. For reasons that are apparently not fully understood, light pollution is particularly implicated in breast cancer and may also increase stress levels, causing a rise in heart disease.
Some official measures have been tried to reduce light pollution with varying degrees of success. New street lighting is now better designed so it throws light downwards, rather than up. Some countries have tried to legislate to encourage the dimming of lights on large buildings at night and to limit the brightness of outdoor security lighting.
Such measures not only help to keep energy use lower but may also be of significant benefit to wildlife. Perhaps we can encourage our own government to take the issue of light pollution seriously, since it is committed to conserving biodiversity.
A start could be made at local level by preventing the use of inappropriate lighting on new development and giving the night time back to wildlife.