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Like in all densely populated areas, nocturnal illumination is gradually increasing in the Netherlands – at the moment, only in a few areas the stars are still visible at night.

To date there’s however very little information on the impact of artificial, nocturnal light on our flora and fauna. For example, we know bats make use of moths that are attracted to streetlights. But, as a result of this, do other species of bat have less food? And how about animals that keep track of the length of day in order to accurately time yearly activities, such as great tits which need to breed exactly at the right time? If artificial light prevents them keeping track of day length, these birds will start breeding too late or too early to utilize the peak in caterpillars in spring.

In order to gain more knowledge about the impact of artificial light in the Netherlands, the project ‘Impact of artificial light on flora and fauna in The Netherlands’ has been started. At several locations in the Netherlands, natural habitat is experimentally illuminated, and the presence of many species and species groups is carefully monitored. In separate in-depth studies the impact of light on birds and moths is studied in detail.

The project is funded by the Technology Foundation STW, and is scientifically led by the Netherlands Institute of Ecology (NIOO-KNAW) and the Wageningen University (WUR). The industry is represented by Philips and the Dutch Oil Company (Nederlandse Aardolie Maatschappij, NAM). The monitoring of animal and plant species at the research sites is done by NGO’s: the butterfly foundation (Vlinderstichting), birding society (SOVON), mammal society (Zoogdiervereniging), plant society (FLORON), amphibian, fish, and reptile society (RAVON) and the Dutch Centre for Avian Migration and Demography (Vogeltrekstation). Research sites are located on property of the Ministery of Defense, Natuurmonumenten, the National Forestry (Staatsbosbeheer), Het Drentse Landschap, and the Ede municipality.

The knowledge collected in this project will contribute to effective application of nature friendly lighting, and the avoidance of nocturnal lighting in case sensitive species are present.

White light at one of the research sites. At  the start of the project, we had an extensive assessment of all present species. After the installation of the lights, we monitor which species disappear and show up.

White light at one of the research sites. At the start of the project, we had an extensive assessment of all present species. After the installation of the lights, we monitor which species disappear and show up (photograph: NIOO-KNAW/Kamiel Spoelstra).

Green light at one of the research sites. The light appears red because of a reduced amount of red light.

Green light at one of the research sites. The light appears green because of a reduced amount of red light (photograph: NIOO-KNAW/Kamiel Spoelstra).

Red light at one of the research sites. The light is red because the blue part of the spectrum is reduced.

Red light at one of the research sites. The light is red because the blue part of the spectrum is reduced (photograph: NIOO-KNAW/Kamiel Spoelstra.

We monitor species at non-illuminated sites with fake light posts. Even without light, just the presence of poles may influence the ecosystem (photograph: NIOO-KNAW/Kamiel Spoelstra).

We monitor species at non-illuminated sites with fake light posts. Even without light, just the presence of poles may influence the ecosystem (photograph: NIOO-KNAW/Kamiel Spoelstra).