Is purple the new grey?

By John Hassell

Location, location… colour. While the proper siting of wind turbines is understood to be critically important to reducing their impact on wildlife, it now appears that the colour of a turbine might also be a significant factor. Armed with the knowledge that bats, like birds, suffer high mortality rates around wind farms, researchers based in Leicestershire, England, postulated that changing the colour of turbines would make the structures less attractive to the insects bats eat and, in turn, reduce the number of bat fatalities.

To test their hypothesis, professors James Flint and Paul Lepper, working with PhD candidate Chloe Long from Loughborough University in England, placed coloured cards, each roughly 20 by 30 centimetres, in a randomly spaced grid pattern at the base of 13-metre high wind turbines. The researchers found that colour significantly influenced the number of insects buzzing about. Yellow cards attracted the largest number of insects – probably due to the prevalence of yellow in flowers – and purple cards attracted the fewest insects. Cards mimicking the conventional colour of wind turbines, white or light grey, attracted the second largest number of insects.

Aesthetics aside, the low cost of painting white or grey turbines a different colour makes it a financially appealing option. Nevertheless, the scientists caution that other factors are at play and more research is needed. For example, in 2009 scientists at the University of Calgary found that slowing wind turbines to a near standstill during low-wind periods can reduce bat mortality by up to 60 percent without a significant reduction in energy yields.

“Developing mitigation techniques is critical if we hope to avoid harm to wildlife,” says Anne Bell, Ontario Nature’s senior director of conservation and education. “Clearly, society needs to invest in this sort of research. Let’s not forget, however, that the most important factor in reducing negative impacts is to properly site wind-power projects. We must keep them out of important wildlife habitat and migratory corridors.”

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