Why Bats Need a 'Happy Hour' and Swedes Try to Comply

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Bat killed by collision with a turbine.

Bats love bugs, and previous Swedish studies have shows that when bats know an area is bug-infested, they'll migrate through it in search of tasty prey, even when the risk from collisions with wind turbines is high.

Bats in Swedish, American, and German studies in fact didn't avoid turbines at all, instead congregating to them. Researchers theorize that bugs swarm around the turbines in warm weather. The bats also used the turbine towers and blades as a resting spot during hunting. Unfortunately, moving turbines can cause death to bats, which are already threatened in many regions by a deadly infectious 'white nose' fungus.

That's why the Swedish Municipality of Halland, in granting permits to seven wind parks in southern Sweden, has asked developer Eolus to set up a happy hour for bats - an hour just before sunset and one hour before the sun rises when turbines might be 'turned off' to let bats find their bugs in peace.

Bats generally forage, a 2007 Swedish report found, in calm weather or low winds, making it easier for wind turbine operators to lose less income if they shut their turbines down an hour or two a day when bats were thought to be foraging.

While Eolus might be the first to get this request from Swedish authorities, it likely won't be the last. A Swedish report last year estimated that if the Swedes build out windpower as much as they plan to, it will be a death sentence for as many as 50,000 bats and an equal number of birds each year. The Swedish estimate is that each individual turbine kills approximately three bats and three birds annually, due to collisions.

Damp coastal areas seem to be the most dangerous places for wind turbines, as far as birds and bats are concerned. In addition, long, warm, late summer evenings with little wind seem to be prime hunting time for bats.

Tags: Animals | Bats | Conservation