Press release NIOO-KNAW

Red light has no effect on bat activity

1 June 2017

Artificial light at night can have a disruptive effect on bats, but not if the light is red. Switching to red light may therefore limit or prevent habitat loss for rare, light-shy bat species. The latest issue of Proceedings of the Royal Society B publishes results from five years of pioneering research led by the Netherlands Institute of Ecology (NIOO-KNAW).

Image courtesy Kamiel Spoelstra/NIOO

It's the first time researchers have succeeded in measuring the effects of light with different spectra on the activity of slow-flying, light-shy bats in their foraging habitat. 'We've found these bats to be equally active in red light and darkness', says principal researcher Kamiel Spoelstra. 'White and green light, on the other hand, substantially reduce the bats' level of activity.'

The effect of red light on more common bat species such as the pipistrelle is reduced as well. Unlike a strong increase in activity of this species in white and green light, the activity in red light is comparable to darkness. This is caused by the strong attraction of insects to white and green (and not red) light. Pipistrelles opportunistically feed on these accumulated insects.

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