Ecological assessments of wind farms fail to adequately predict collision threats to bats, according to academics at the University of Exeter.
Sniffer dogs used to locate dead bats at 29 windfarms found 194 carcasses a month, with the number ranging from one to 64. The main casualties were the common pipistrelle and soprano pipistrelle, the research found.
Dr Fiona Mathews, a mammalian biologist at the university, said money was being spent on pre-construction assessments but almost nothing was done once the turbines were in operation to assess whether these had been useful or whether any mitigation actually delivered benefits for conservation.
She said: ‘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. 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.’
She suggested that either the ecological assessments carried out pre-construction were not sufficiently thorough or that bats may have changed their behaviour when the turbines were built. For example, since they were not used to encountering objects at the height of a turbine, they might switch their sonars off, she said. Alternatively, they might fly towards the turbines in search of insects.
Shutting down turbines at night in the summer when bats are most active would reduce deaths, Mathews said: ‘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, and turbines are generating relatively little electricity anyway at these times.’ sh
Mathews, who is also chair of the Mammal Society, is working with turbine operators to pilot this approach.
The research, supported by NERC, drew on data collected as part of the separate National Bats and Wind Turbines project, which was funded by Defra, Natural England, Natural Resources Wales, Scottish Natural Heritage, the Department of Energy and Climate Change, and Renewable UK.
Josh Fothergill, IEMA policy and engagement lead, said that both pre- and post-construction surveys were needed: ‘Monitoring and acting post construction would be useful but should we also look to improve pre-construction assessment rather than shift the emphasis to post-construction. We want to avoid impacts rather than find them afterwards.’
Jason Reeves, policy and communications manager at the Chartered Institute of Ecology and Environmental Management: 'Post-development monitoring is a concern for all development in the UK and CIEEM would like to see much greater emphasis put on this. However, the extent to which monitoring is implemented is determined by the relevant competent authority.'