Use flashing lights to reduce mortality from artificial lights
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Flashing lights may prove less attractive to birds but remain equally visible to humans, making them suitable for warning lights, on communications towers or similar.
Supporting evidence from individual studies
A randomised, replicated and controlled trial on 24 control towers in Michigan, USA, during May and September 2005 (Gehring et al. 2009) found that there were significantly fewer bird carcasses found beneath towers lit with red or white flashing lights, compared with control towers using the Federal Aviation Administration standard of red flashing lights combined with non-flashing red lights (average mortality of 3.7 birds/tower for experimental towers vs. 13 birds/tower for controls). There were no differences between three different flashing-light treatments. Three tall (> 305 m) towers with non-flashing lights caused significantly more fatalities than any of the smaller towers. The majority of birds killed were night-migrating songbirds but also included gamebirds and woodpeckers.