Wind Turbines Spread While Bats Take Beating
Enthusiasm for renewable energy means wind turbines are appearing everywhere. The big problem with wind turbines has been that they’re dangerous to birds. But researchers have found that they actually kill more bats, and the reason why has been a mystery–until now. As wind farms pursue a policy of replacing many smaller turbines with fewer larger ones two new reports indicates that bats are endangered by the swinging turbine blades.
While some experts have downplayed the danger to birds it seems that bats are taking a greater hit—often in a literal sense. Bats, being a rather unloved species com paired with birds, don't seem to carry as much weight with the eco-conscious. Two separate sets of researchers have reported two different ways that wind farms, with their rotating turbine blades, are dangerous, even deadly to bats. One report shows that bats, with their amazing flying and hunting abilities, are none the less being struck down by slashing turbine blades. A short film clip using infrared light shows such a collision taking place.
The danger is reported in an article by Jason Horner, et al, appearing in the Journal of Wildlife Management Video. Clips on this site are presented to support a study that deals with the recent finding that forest-dwelling bats are often found dead beneath operating wind turbines at wind energy facilities. Thermal infrared video cameras were used to record the flight behavior of bats at night near these turbines in an attempt to understand the cause of these fatalities. Quoting from the study report:
“We observed bats actively foraging near operating turbines, rather than simply passing through turbine sites. Our results indicate that bats: 1) approached both rotating and non-rotating blades, 2) followed or were trapped in blade-tip vortices, 3) investigated the various parts of the turbine with repeated fly-bys, and 4) were struck directly by rotating blades. Blade rotational speed was a significant negative predictor of collisions with turbine blades, suggesting that bats may be at higher risk of fatality on nights with low wind speeds.” (Journal of Wildlife Management 72(1):123–132; 2008)
This follows previous research that showed that bats can have their lungs ruptured from the sudden low pressure of passing turbine blades. As the accompanying video explains, a study published today finds the bats are actually drowning in mid-air. Biologist Erin Baerwald just couldn’t believe that these adept, radar equipped flying mammals were simply flying into the blades but surprising numbers of bats are being killed by wind turbine farms. Indeed, the Horner report showed that slow moving blades were more likely to cause a collision than faster moving blades.
“We always correct that way of thinking, saying, ‘No, no, the turbines are colliding with the bats,’” Baerwald says. “But this has really changed the way we think about it, in that the bats aren’t colliding with the turbines, the turbines aren’t colliding with the bats. It’s actually an undetectable hazard.” So bats don't even need to come in physical contact with the turbine blades, just a blade swooshing close by is enough to be fatal.
So what does this all mean? It means that wind power, like every other source of power, has its hazards and negative effects on nature. There is no free lunch, ecologically speaking. Every action by man—or any other species for that matter—affects the environment in some way. I'm all for wind power where it is appropriate and can operate economically. Now we know that appropriate means not along known bird migration routes, near nesting sites or areas with a lot of bat activity.