Wind farms are killing thousands of bats, study says

Wind turbines against dark blue night sky (capacity mechanism)
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Hundreds of bats are being killed each month at wind farms in the UK, according to a study.

The study, by academics at the University of Exeter, found 194 bats were killed every month at 29 on-shore wind farms.

At the 29 wind farms studied by the researchers in work published in the journal Current Biology, casualty rates varied from 1 to 64 per month across the sites.

The research team derived these estimates from searching for bat carcasses with sniffer dogs beneath the turbines and then accounting for both observer efficiency and a carcass removal rate by predators.

The researchers said these deaths, which could amount to up to 80,000 per years if all of Britain’s wind farms were taken into account, could be prevented by better risk assessments and simple changes to operation of turbines.

Dr Fiona Mathews of the University of Exeter, who led the research, said that simple mitigation measures such as turning off turbines at night at peak times for bats could save many bat lives.

Dr Mathews, a mammalian biologist at the University of Exeter, said more research was needed into the behaviour of bats after turbines were built, including whether they may ‘switch off’ their sonar at the height of turbines, because they are not used to encountering objects at that altitude.

“There are effective ways of preventing bat deaths. Unfortunately we have found that assessments conducted when wind farms are being planned are very poor at identifying whether a site is likely to be risky. This means that appropriate action is not taken to protect bats,” Dr Mathews said.

“We therefore call for a switch in emphasis from pre-construction to post-construction assessments, so that any problem can be nipped in the bud early on.”

First author on the Current Biology paper, Dr Paul Lintott, said that although wind farms do kill bats it is important to remember the wider benefits of renewable energy in reducing greenhouse gas emissions and the positive impact that this will have on global biodiversity.

“Although bats are killed by wind turbines 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,” Dr Lintott said.

“Our findings demonstrate that costly pre-construction surveys are relatively poor at predicting if bat casualties will occur.

“However, by focusing resources on stopping turbines during high risk periods we should be able to minimise the collision risk to local bat populations whilst also benefiting globally from the transition to a greener economy.”

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