Wind turbines put bats under (low) pressure
Scientists probe barotrauma fatalities
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A research team from the University of Calgary has found that a large percentage of bat fatalities at wind turbine sites are caused by a sudden drop in air pressure around the turbine blades, the BBC reports.
Reports of bat deaths at wind farms had previously been documented in Europe and the US, but quite why these generally exceeded the numbers of dead birds succumbing to the fatal blades had not been explained.
The Calgary team now says that while bats can use their echolocation to pinpoint the blades, they "cannot detect the sharp pressure changes around the turbine".
If a bat enters this zone, it can suffer "barotrauma" - internal haemorrhaging provoked by sudden expansion of the lungs* which puts pressure on surrounding tissue and bursts capillaries. Birds, which have more "rigid and robust" lungs, are less susceptible to the condition.
Lead scientist Erin Baerwald said: "An atmospheric pressure drop at wind turbine blades is an undetectable - and potentially unforseeable - hazard for bats, thus partially explaining the large number of bat fatalities at these specific structures."
To prove their case, Baerwald and colleagues examined carcasses of hoary and silver-haired bats dispatched by a wind farm in south-western Alberta. They found that while "fewer than half had external injuries that could have been caused by collision", 90 per cent demonstrated internal haemorrhaging, "most notably in the chest cavity".
The findings indicated that "wildlife fatalities at wind turbines are now a bat issue, not a bird issue", Baerwald concluded.
The EU acted on the bat slaughter two years ago, before the exact cause was known, and "formally agreed to make developers aware of the risks, and find ways of monitoring bat migration routes". Accordingly, a proposal earlier this to build a wind farm near Bideford in north Devon was rejected "because of the potential impact on the mammals".
The Calagary team's findings are reported in the journal Current Biology. ®
Bootnote
*Just to clarify, the sudden drop in pressure expands the air already in the lungs. As our diving expert Lewis Page put it: "If the bat remembers to exhale when passing a wind turbine it should be ok."
COMMENTS
@DAvid Halko
How much water IS there on earth? A shitload. A huge shitload. Such a massive shitload that 2.5% of that is still a shitload.
Oh, and put a pan of warm water in the frigde (at -8) and put some ice in it. The ice melts.
And what temperature is the ocean at the edges of the polar ice caps? Currently +4 C.
The ice melts.
It may continue to melt more than it freezes until September is almost gone.
@AC - "Polar Ice"
Anonymous Coward suggests - "ice sheets on Greenland and Antarctica hold simply *vast* quantities of water (60% low end estimates of total fresh water on the planet) which *isn't* currently floating on the oceans."
Only 2.5% of the water on the earth is Fresh Water, we are not talking about "Vast Quantities"
http://wiki.answers.com/Q/What_is_the_ratio_of_fresh_water_to_salt_water_in_the_world
Antarctica is below freezing all year round - which means it is not melting the way the "chicken littles" are screaming, to create fear in people.
The "fear mongerers" who are screaming the loudest are the ones who will profit the most from people.
Wouldn't a blade strike also cause hemorraging?
What sort of, ahem, batty scientist, concludes that a sudden drop in pressure will cause bat lungs to burst?
Wouldn't the bat have to be really close to the blades for this to happen?
I don't buy it...blade strike I say
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