By Pilita Clark, Environment Correspondent
Wind farms are killing about 200 bats a month in the UK, say scientists who
have called for turbines to be turned off at night to save the creatures.
Bat-friendly operators who agreed to take such a step should be paid more
for the electricity they generate, said Fiona Mathews, a biologist from
Exeter university who led a government-backed study of 29 onshore wind farms.
Some wind farms were already testing night-time switch-offs and researchers
were watching to see what effect this had, she revealed. “This approach
obviously affects electricity generation, though to a lesser extent than
one might imagine since the time that bats are at most risk is during low
wind-speeds in the summer” when turbines generate relatively little
electricity, Ms Mathews added.
The study showed 194 bats were killed per month, based on carcases found
underneath the turbines. The actual number could be higher because
scavengers may have removed some bodies.
The researchers said more work was needed to find out why bats ventured so
close to the farms. It is thought the animals might be attracted to insects
around the blades, or may switch off their sonar at the height of the
blades because they are not used to confronting objects of that size.
“Bats have been around for at least 30m years and during that time have
been able to fly happily without the risk of colliding with a spinning
object,” said Ms Mathews.
Erecting gigantic bat-proof nets around the turbines would be no solution
because it would interfere with wind flows, Ms Mathews said. US researchers
had also run into difficulties when experimenting with loud sounds to repel
the animals, partly because the electricity needed to power the speakers
was a significant drain, she added.
One wind farm operator said although he was unaware of any bat deaths near
his company’s projects, he was not sure that it would be politically
possible to pay generators to turn off turbines.
“If we are not generating power we should not get paid,” said Rod Wood,
managing director of the Community Windpower group, which has eight
Scottish farms operating or under construction.
The new study showed the main bat casualties were two common species, the
common pipistrelle and the soprano pipistrelle, tiny bats with
reddish-brown coats and blackish-brown ears. But researchers also found a
dead migratory Nathusius’s pipistrelle, which they said raised concerns
about whether onshore and offshore wind farms could pose a threat to
navigation routes.
“These animals will be encountering multiple on and offshore wind farm
sites as they make their way from eastern Europe along the north coast of
continental Europe and across to the UK,” said Ms Mathews.
Another author of the study, to be published in the Current Biology
journal, said that although wind farms killed bats it was important to
remember the wider benefits of renewable energy, which boosted biodiversity
by reducing the greenhouse gases that drive global warming.
“It is important that this is put into context alongside the many other
causes of bat mortality caused by humans, including collisions with
vehicles, kills by domestic cats, and range contraction due to climate
change,” said Paul Lintott.
The researchers said that although huge amounts of money were spent to
assess environmental risks before wind farms were built, this work was
“very poor” at identifying whether a site was likely to be risky for
wildlife once a wind farm was operating. “We therefore call for a switch in
emphasis from pre-construction to post-construction assessments,” said Dr
Mathews.
The research was funded by the government-backed Natural Environment
Research Council and drew on data collected in separate studies funded by
the environment and energy departments.
RenewableUK, the wind industry trade group, said it had been working with
the government and conservation groups for years to better understand bat
activity around wind farms and carried out “rigorous assessments” to make
sure projects were as safe as possible.
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