Wind Farms and Bats
_Environment correspondent Richard Black, BBC News website.
.........................................................................................................................................................................
Wind turbine rotating blades produce a pressure drop that can harm bats.
Bats are at risk from wind turbines, researchers have found, because the
rotating blades produce a change in air pressure that can kill the mammals.
Canadian scientists examined bats found dead at a wind farm, and
concluded that most had internal injuries consistent with sudden loss
of air pressure. Bats use echo-location to avoid hitting the blades but cannot
detect the sharp pressure changes around the turbine. The scientists say
wind farms are more of an issue for bats than for birds. "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,"
said Erin Baerwald, who led the research team at the University of Calgary.
.........................................................................................................................................................................
Wind turbine rotating blades produce a pressure drop that can harm bats.
Bats are at risk from wind turbines, researchers have found, because the
rotating blades produce a change in air pressure that can kill the mammals.
Canadian scientists examined bats found dead at a wind farm, and
concluded that most had internal injuries consistent with sudden loss
of air pressure. Bats use echo-location to avoid hitting the blades but cannot
detect the sharp pressure changes around the turbine. The scientists say
wind farms are more of an issue for bats than for birds. "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,"
said Erin Baerwald, who led the research team at the University of Calgary.
_Route cause:
> Bat deaths around wind farms have been widely documented across Europe and North America.
> Two years ago, EU nations formally agreed to make developers aware of the risks, and
find ways of monitoring bat migration routes.
> Earlier this year, a bid to build a wind farm near Bideford in north Devon was turned down
because of the potential impact on the mammals.
> Research is underway to find ways of scaring bats from wind farms, but among all this,
understanding of how turbines affect bats has been lacking.
The Calgary team collected carcasses of hoary and silver-haired bats killed at a wind farm in
south-western Alberta. Examinations showed that fewer than half had external injuries that
could have been caused by collision. But about 90% had internal haemorrhaging, most notably
in the chest cavity, a condition that puts pressure on the lung and can be fatal.
The idea is that the pressure around a rotating turbine blade is lower than in the surrounding air.
A bat flying into the low-pressure zone finds its lungs suddenly expanding, bursting capillaries
in the surrounding tissue which then becomes flooded with blood.
Birds, which have more rigid and robust lungs, do not undergo the same trauma from a sudden drop in pressure.
"Given that bats are far more susceptible to barotrauma than birds, and that bat fatalities at
wind turbines far outnumber bird fatalities at most sites, wildlife fatalities at wind turbines are now
a bat issue, not a bird issue," said Ms Baerwald.
Some research groups are investigating ways to keep bats away from wind farms, and a University
of Aberdeen group recently suggested radar emissions might act as a "bat-scarer".
[email protected]
.........................................................................................................................................................................................................................
> Two years ago, EU nations formally agreed to make developers aware of the risks, and
find ways of monitoring bat migration routes.
> Earlier this year, a bid to build a wind farm near Bideford in north Devon was turned down
because of the potential impact on the mammals.
> Research is underway to find ways of scaring bats from wind farms, but among all this,
understanding of how turbines affect bats has been lacking.
The Calgary team collected carcasses of hoary and silver-haired bats killed at a wind farm in
south-western Alberta. Examinations showed that fewer than half had external injuries that
could have been caused by collision. But about 90% had internal haemorrhaging, most notably
in the chest cavity, a condition that puts pressure on the lung and can be fatal.
The idea is that the pressure around a rotating turbine blade is lower than in the surrounding air.
A bat flying into the low-pressure zone finds its lungs suddenly expanding, bursting capillaries
in the surrounding tissue which then becomes flooded with blood.
Birds, which have more rigid and robust lungs, do not undergo the same trauma from a sudden drop in pressure.
"Given that bats are far more susceptible to barotrauma than birds, and that bat fatalities at
wind turbines far outnumber bird fatalities at most sites, wildlife fatalities at wind turbines are now
a bat issue, not a bird issue," said Ms Baerwald.
Some research groups are investigating ways to keep bats away from wind farms, and a University
of Aberdeen group recently suggested radar emissions might act as a "bat-scarer".
[email protected]
.........................................................................................................................................................................................................................
Find out more about Bats & Windfarms fromNatural England below
Natural_England_Bats_and_wind_farms.pdf | |
File Size: | 214 kb |
File Type: |