BBC News reported on a new study that shows insects are attracted to white or grey colored wind turbines. If turbines are swarming with insects, they in turn attract bats (and birds), which are then killed by the revolving blades. Interestingly, the researchers found the color insects like least is purple so some researchers are now considering the question: should large wind farms be painted purple?
Chloe Long a PhD student at Loughborough University in the UK told BBC News that no one understood the connection between turbines and insects well. “It had been speculated that insects may be attracted to turbine structures for some reason and this then could attract insectivorous species, such as birds and bats, to forage in the vicinity.” So Long and her colleagues decided to conduct research to determine why insects were attracted to turbines and whether versions with lower environmental impact could be designed.
According to their research, in Europe one turbine kills some 20 to 40 bats each year, most often in summer evenings when insects are migrating. “Now scientists have ascertained that 90 percent of bat mortality occurs in northern Europe between late July and early October. A similar pattern occurs in North America.”
The researchers decided to measure how many insects were attracted to different colored turbines by using colored cards set in a “random sequence next to a 13m-high three-blade wind turbine situated in a meadow.” The colors tested included a range of colors: pure white, light and dark grey, blue, red, and purple. BBC News says the “insects attracted included small flies (body size less than 5mm); large flies (body size equal to or greater than 5mm); greenfly; moths and butterflies; thrips; beetles and crane flies.”
Research showed that turbine paint color has a significant impact both during the day and at night. Yellow, pure white or light grey turbines attracted the most number of insects, while purple attracted the least. However, they argue this doesn’t necessarily mean wind turbines should be painted purple. “The researchers found that the ultraviolet and infrared components of paint colour, which humans cannot see but insects can, also had a significant impact, with higher levels of both attracting more insects.” Paints can be combined with other ultraviolet or infrared glazes to alter the wavelengths that attract insects.
Also, paint color may not be the only factor — insects may also be attracted to the heat created by the blades. Long told BBC News: “If the solution were as simple as painting turbine structures in a different colour this could provide a cost-effective mitigation strategy.”
Still, more research should be undertaken to give bats a boost – their colonies are collapsing in many places. See an earlier post which discusses “White Nose Syndrome” and its effects on the U.S. bat population. While feared by many as carriers of disease, bats actually provide valuable ecosystem services.
Also, see more resources: The U.S. Fish and Wildlife Services recently issued a comprehensive set of recommendations to the U.S. Interior Secretary, which covers how to mitigate the impacts of turbines on wildlife. Also, the U.S. Geological Survey offers studies on bat fatalities and wind turbines.
Image credit: Bat Swarm, Australia. LJMcK / Flickr