The increase of artificial night lighting is only one of the consequences of intense urbanisation. There is no doubt that chemical and noise pollution can have a strong impact on ecosystems. To date, however, the more subtle consequences of light pollution on wild populations of animals have not received enough attention.
Artificial light at night has fatal consequences for many nocturnal animals. Millions of insects, for example, die each year through the attraction to street lamps.
Migratory birds get distracted by artificial night light, and consequently, go astray and even crash into illuminated high-rise buildings. Although artificial light has not always such fatal impact, it nevertheless can have a substantial influence on an animal's life. This problem was investigated by Bart Kempenaers and colleagues from the Max Planck Institute for Ornithology in Seewiesen in five species of songbirds.
They studied the effect of street lighting at the outskirts of forest habitat on the song behaviour of male birds. Indeed, males from four out of five species started to sing earlier in the morning than males that lived in locations without artificial night light. This effect was most pronounced for those species known to engage in early dawn singing.
For example, male robins living near street lights started singing on average 80 minutes earlier than their counterparts sleeping in the dark.