Translation of Issue 55 pages 10-13 Ymgyrch Gweld Sêr

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Seeing Stars Campaign

Most of us are familiar with the term “pollution”. However, we probably tend to associate it mainly with air pollution from the impacts of unwanted gases in the atmosphere, or with water pollution caused by chemicals or oil spillages. In this article, GETHIN DAVIES discusses a less familiar type of pollution which is on the increase throughout the world – light pollution.

Light pollution is defined as a disruptive glaze from the sky caused by excessive, misdirected or obtrusive artificial light. It causes problems for a number of reasons. Firstly, several impacts on human health have been attributed to artificial light and light pollution, including sleep deprivation (which in turn can lead to stress), and an increased risk of cancer due to lower levels of melatonin being produced(1). It can also have a significant adverse effect on the landscape at night and on our ability to see the stars, which is not a good thing for astronomers! Excessive light can also be unsustainable and expensive to maintain – very timely concerns given the current economic and climatic uncertainty. However, despite the importance of each of the reasons noted above, this article focuses on the possible adverse effects of artificial light on nature, and how the Snowdonia National Park Authority hopes to improve the situation for our nocturnal wildlife.

There has been a continuous natural cycle of day and night on Earth for millions of years as the planet orbits the Sun(2). The vast majority of species have therefore evolved in order to survive under these conditions. This is why, amongst the majority of organisms, a clear division is evident between the lifestyles of diurnal organisms (active during the day) and nocturnal organisms (active at night). As we ourselves are primarily a diurnal species, humans could be accused of forgetting about some of our nocturnal relatives, or at the very least of paying less attention to them. However, you may be surprised to know that a very large number of species are considered to be nocturnal, and that they account for approximately 60% of all vertebrates (animals with backbones) and 30% of invertebrates (animals without backbones) (3). These nocturnal creatures include bats, twelve species of which are currently thought to reside within and around the Snowdonia area.

The impact of artificial light on nocturnal wildlife has been studied for several decades. Some of the earliest known references date back to 1950, when the Robinson brothers studied the impact of high light levels on nocturnal flying insects(4). Subsequent studies have shed further light (forgive the pun!) on the scale of the influence of artificial light on the behaviour of nocturnal species. This is interesting work, because quite simply, species on planet Earth have not been programmed to deal with artificial light. For example:

•    It can disrupt the commuting behaviour of native species of bats such as the lesser horseshoe bat Rhinolophus hipposideros. Under street lighting, the average number of times that the bats fly along commuting corridors has been found to be significantly fewer(5);

•    The migratory behaviour of the wild Atlantic salmon (Salmo salar) can change under street lighting conditions, which can in turn affect the fitness of these fish(6);

•    Many nocturnal mammals avoid lit up areas; this limits the range of their eating habits and also limits the length of time they spend searching for food each night(1);

•    The long term impact on the reproductive physiology of the European Blackbird (Turdus merula)(7);

•    It is estimated that as many as one third of all flying insects that are attracted to street lights/artificial lights die as a result of collisions with hot lamps, confusion or fatigue, which can often lead to a greater risk from predators(8).

However, many things remain a mystery. For example, we know very little about the possible impacts of excessive light on populations of species, and we have no knowledge of the extent to which light pollution has contributed to the decrease in the moth population recorded in the UK over the last few decades. Furthermore, most research only focuses on a small number of groups of species, meaning that the real extent of the harmful effects associated with excessive light in a wider environmental context remain very unclear(9). As a result, we can only assume that further research would help to significantly increase our awareness and understanding.

Although we are fortunate enough to be comparatively free of excessive artificial light here in Snowdonia, we cannot be complacent, and we are therefore eager to safeguard our dark sky for future generations. As a consequence, the Snowdonia National Park Authority is now following in the footsteps of many other areas of the United Kingdom, including the Brecon Beacons National Park, by applying for International Dark Sky Reserve status. If successful, the application would mean that approximately 1,342 square miles of Wales would become an officially designated International Dark Sky Reserve, representing 16.72% of the country’s land area. This would make Wales the country with the highest percentage of land area officially designated as an International Dark Sky Reserve anywhere in the world!

In order to promote and celebrate our Seeing Stars campaign, a conference was held at Plas Tan y Bwlch in February this year, where a number of guest speakers made presentations on the different reasons why we are seeking to ensure this prestigious designation. The event was well attended by around 80 individuals representing stakeholder groups, including local authority lighting engineers, ecologists, astronomers and those involved in the tourism sectors. For me personally, one of the highlights of the conference was the contribution made by Bob Mizon from the Campaign for Dark Skies, who said:

“It’s now too late for most of England, which is now blighted with light pollution in the majority of areas. But you’re still lucky enough here in Wales to have large areas which are still relatively free of light pollution, and thus have exceptional night time sky quality. These must be preserved for all to enjoy in future generations.”

His words reinforced our belief that what we are seeking to achieve is both valid and valuable.

The only way we can achieve our aim of protecting the dark sky here in Snowdonia is by working alongside relevant stakeholders to improve the situation. We do not expect people to turn off their lights completely, as we recognise that the safety of individuals is of paramount importance, and that gaining the support of local communities is vital in order to achieve our aim. However, we seek to promote the use of well designed and appropriate lighting, wherever and whenever necessary.

Discussions on street lighting have already taken place with the relevant authorities. We therefore hope, over time, that a work programme can be developed which introduces lighting of a more suitable design and spectrum in the National Park, especially in the ecologically sensitive areas such as valleys, bat commuting corridors and feeding areas. By working alongside residents and business owners, we also intend to reduce light emissions from residential properties, holiday accommodation, outdoor activities centres and commercial properties. Not only would such changes improve the situation for nocturnal wildlife, they would also have many other advantages, such as improving the sustainability of our communities (modern LED lights are up to 70% more efficient than traditional sodium burning lamps) and providing new opportunities in the tourism sector by attracting astronomers from nearby urban areas, especially in the winter when things tend to be a little quieter.

Given the global increase in light pollution, and no sign that the situation is about to change, the impact on nocturnal wildlife is inevitable. We are also living in an age where society is becoming increasingly urban and losing touch with the environment. It is hoped that a project of this nature will highlight the problem of excessive light, whilst protecting a part of Wales that is comparatively free from obtrusive light, for everyone’s benefit. It is a project which offers many advantages, both from an environmental and socio-economic perspective, and is in keeping with the holistic approach to conservation work currently being encouraged. If nothing else, it is hoped that the project will encourage more people to venture out at night to enjoy the open air. You never know, we may see some of you stargazing in Snowdonia in years to come!

Gethin Davies works for the Department of Conservation, Trees and Agriculture at Snowdonia National Park Authority, namely the department which leads on the Snowdonia Seeing Stars campaign. For more information about the Snowdonia Dark Sky Initiative, contact Gethin on 01766 772 255 or

1. The Royal Commission on Environmental Pollution. (2009). Artificial Light in the Environment. The StationEry Office, Norwich.
2. Schopf, E. L. (2006). Fossil Evidence of Archaen life. Philosophical Transactions, The Royal Society.
3. Hölker, F., Wolter, C., Perkin, E.K., & Tockner, K. (2010). Light pollution as a biodiversity threat. Trends in Ecology and Evolution 25, 681-682. PubMed
4. Bateman, J. A. (2003). Animal Traps & Trapping. Coch-y-Bonddu Books, Machynlleth.
5. Stone, E. L., Jones, G., & Harris, S. (2009). Street lighting disturbs commuting bats. Current Biology 19: 1123-1127.
6. Riley, W. D., Bendall, B., Ives, M. J., Edmonds, N. J., and Maxwell, D. (2012). Street lighting disrupts the diel migratory pattern of wild Atlantic salmon, Salmo salar L., smolts leaving their natal stream. Aquaculture, Vol 330-333; p74-81.
7. Dominoni, D.M., Quetting, M., and Partecke, J. (2013). Long-Term Effects of Chronic Light Pollution on Seasonal Functions of European Blackbirds (Turdus merula). PLoS ONE 8(12): e85069
8. Bruce-White, C., and Shardlow, M. (2011). A Review of the Impact of Artificial Light on Invertebrates. Buglife, Peterborough.
9. Gaston, K. J., Gaston, S., Bennie, J., and Hopkins, J. (2014). Reducing the impacts of artificial light. British Wildlife, Vol 25. No. 5, p 333-339, British Wildlife Publishing, Oxford.