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Source: http://www.canada.com/calgaryherald/news/city/story.html?id=18e8615e-2919-49fe-a4c5-f919b2a2e98a
Wind turbines linked to death of migratory bats
Michelle Butterfield, Calgary Herald
Published: Tuesday, August 26, 2008
University of Calgary researchers have found out what's killing large numbers of bats every year near the town of Pincher Creek.
A study conducted over the past two years indicates sudden air pressure changes around wind turbines are likely behind the migratory bat deaths.
The study found 90 per cent of the bats found dead below turbines near Pincher Creek suffered severe injuries to their respiratory systems consistent with the sudden drop in air pressure that occurs near the turbine blades. Few of the bats showed signs of coming into contact with the blades.
"When we find the bats at the turbines, we find very little external injuries," said researcher Brandon Klug, who performed autopsies on the animals.
"It led us to think something else is at play," he said.
Unlike birds, bats do not have a strong respiratory system and are less able to withstand sudden pressure changes in the air. When outside pressure drops, a bat's air sac overexpands, bursting the capillaries around it, filling the lungs with fluid and blood -- similar to drowning, said Klug.
The study began after TransAlta wind farmers noticed dead bats at the base of the turbines near Pincher Creek.
"We were very concerned with finding an answer as to why the bats were dying," said Jason Edworthy, director of stakeholder relations for TransAlta, who approached the U of C.
TransAlta donated to the research project -- both with funding and by turning off the turbines during periods of migration to see if it reduced the mortality rate.
Although the utility lost money by shutting down the turbines, Edworthy said it was worth it.
"The most important thing to us, over and above money, is finding the problem," he said.
It is not known why the bats are getting so close to the turbines, but project leader Erin Baerwald said they're looking at several suggestions.
"There have been theories they may be drawn to the turbines, or insects are drawn to them and the bats are eating the insects," she said.
The flying mammals also might be drawn to them because of their tall, tree-like structure.
And while this problem is occurring worldwide, Baerwald said it's difficult to determine the effect on Alberta bat populations.
"It's really hard to say what kind of impact this is having because we don't know how many of these bats are out there," she said.
Bat deterrents have been tested, including noise, lights and nets, but none has been effective.
Baerwald said they will continue researching operational methods, such as turning off turbines during the night when bats migrate, which has proved effective so far.
mbutterfield@theherald.canwest.com
Wind turbines linked to death of migratory bats
Michelle Butterfield, Calgary Herald
Published: Tuesday, August 26, 2008
University of Calgary researchers have found out what's killing large numbers of bats every year near the town of Pincher Creek.
A study conducted over the past two years indicates sudden air pressure changes around wind turbines are likely behind the migratory bat deaths.
The study found 90 per cent of the bats found dead below turbines near Pincher Creek suffered severe injuries to their respiratory systems consistent with the sudden drop in air pressure that occurs near the turbine blades. Few of the bats showed signs of coming into contact with the blades.
"When we find the bats at the turbines, we find very little external injuries," said researcher Brandon Klug, who performed autopsies on the animals.
"It led us to think something else is at play," he said.
Unlike birds, bats do not have a strong respiratory system and are less able to withstand sudden pressure changes in the air. When outside pressure drops, a bat's air sac overexpands, bursting the capillaries around it, filling the lungs with fluid and blood -- similar to drowning, said Klug.
The study began after TransAlta wind farmers noticed dead bats at the base of the turbines near Pincher Creek.
"We were very concerned with finding an answer as to why the bats were dying," said Jason Edworthy, director of stakeholder relations for TransAlta, who approached the U of C.
TransAlta donated to the research project -- both with funding and by turning off the turbines during periods of migration to see if it reduced the mortality rate.
Although the utility lost money by shutting down the turbines, Edworthy said it was worth it.
"The most important thing to us, over and above money, is finding the problem," he said.
It is not known why the bats are getting so close to the turbines, but project leader Erin Baerwald said they're looking at several suggestions.
"There have been theories they may be drawn to the turbines, or insects are drawn to them and the bats are eating the insects," she said.
The flying mammals also might be drawn to them because of their tall, tree-like structure.
And while this problem is occurring worldwide, Baerwald said it's difficult to determine the effect on Alberta bat populations.
"It's really hard to say what kind of impact this is having because we don't know how many of these bats are out there," she said.
Bat deterrents have been tested, including noise, lights and nets, but none has been effective.
Baerwald said they will continue researching operational methods, such as turning off turbines during the night when bats migrate, which has proved effective so far.
mbutterfield@theherald.canwest.com