New evidence indicates that millions of bats are being slaughtered every year by wind turbines. This astonishing figure of wildlife massacre arises from a reasonable extrapolation of casualty numbers collected by a group of German zoologists. Their data cover a number of years, and more specifically a recent two-month detailed survey at a wind farm near Berlin. Germany has nearly 30,000 onshore wind turbines, and the researchers suggested their findings translated to 200,000 bat fatalities every year in that country alone. Land-based wind turbines are common across many parts of the world, and a total figure running into millions is possible.
The researchers note that the annual German losses of bats will “cause a decline of populations of high collision-risk species”. They warn that this population decline “could manifest rapidly”, since mostly females and juvenile bats get killed by turbines. Bats have low reproductive rates and may not be able to compensate quickly for the casualties, they note.
The paper is of considerable interest and the full methodology of the field work, along with considerations about turbine age and operational curtailments, are shown here. The researchers took data going back 20 years from the national carcass repository in Germany and from a detailed 2021 two-month search of the ground near three turbines west of Berlin. It was estimated that nearly 300 bats died during the 2021 field survey, and this equated to 55 casualties per megawatt generated.
These are shocking figures. Bat ‘migrations’ were occurring at the time of the field survey, but such movement is common in bat populations. The UK has 14 GW of installed onshore wind capacity, or 14,000 MW. A multiplication of 55 casualties per MW produces 770,000 bat deaths. Of course all this installed capacity is unlikely to be in continual use, and periods of low bat movement and hibernation will lower the death toll considerably. But promoters of green energy need to be specific about the annual bat carnage they are prepared to accept – 50,000 deaths, 100,000, 200,000? The U.K. Government’s own in-house green activist unit, the Committee for Climate Change, is recommending that Britain should more than double its onshore wind capacity to 29 GW by the end of the decade.