The Effects of Artificial Light on Bats

Walking down a street at night, it’s hard not to notice all of the insects flying around the streetlights. This is because the bulbs used emit a large spectrum of wavelengths, with many going into the ultraviolet range, which attract bugs. Unfortunately, predators, like bats, have noticed their presence. Not all bats can endure the light, but those that can have found feasts in well-lit areas. Now, however, streetlamps are being equipped with LEDs, which do not emit UV wavelengths. As a result, insects no longer hang around the lights like they used to. A team of researchers recently set out to explore how switching over to LED lights could affect bats.

Bat recorders, which log a bat’s echolocation noises, were put on streetlights in six German cities. The findings showed that some species not affected by the lights, such as the Common pipistrelle, came around the lights about 50% less of the time. Others, like the Nathusius pipistrelle, were active around the streetlamps just as often as before. Meanwhile, bats that are sensitive to light flew by more than four times as often.

Christian Voigt, one of the head scientists of the experiment, was quoted in Science Daily as saying, “We therefore conclude that bats which are sensitive to light might benefit from the increasing use of LED, but opportunistic species will suffer from it.” He went on to say that this means there will be more insects in cities, and while the number of mosquitos will grow, so too will the number of moths and other pollinators.

It is still too early to say whether these new LED lights are better or worse overall for the ecosystem compared to the old ones. Scientists will convene in Berlin this November to discuss their observations on how bats are affected. This, hopefully, will result in a set of instructions on how to be eco-friendlier with outdoor lighting.

How can cities ensure their streetlights are producing the right kind of light? How can scientists perform similar experiments with the same illumination levels? Konica Minolta Sensing has a number of light measurement products. The CL-500A Illuminance Spectrophotometer and CL-70F Illuminance Meter, for instance, are both portable, meaning you can quickly and easily check streetlamps. Ensure your lights are environmentally friendly with Konica Minolta Sensing.