Significant bird mortality has been recorded at other wind turbine sites. Migrating birds such as swallows, martins and swifts would be at risk as well as resident birds such as buzzards, owls and sky larks.
Research on the effect on bird populations of upland wind farms in Scotland and Northern England has shown that birds tend to stop nesting within half a mile of any turbine, across a range of species. “Our results highlight significant avoidance of otherwise suitable habitat close to turbines in at least seven of the 12 species studied, with equivocal evidence for avoidance in a further two species.” [James Pearce-Higgins, an ecologist with the RSPB in Scotland whose research was conducted with scientists from Scottish National Heritage and the Scottish Government’s Environment Research Directorate.
- Unexpectedly high bat mortality has been recorded at other wind turbine sites, out of proportion to the respective bird and bat populations, and to an extent which has alarmed researchers [c.f. e.g. Washington Post 1.1.2005].
- The South Hams have significant bat populations including endangered species e.g. greater horseshoe bats.
- There are bat migration routes between the South Hams and Buckfastleigh caves. Any environmental impact study needs to cover both the spring and late autumn migration periods. TRESOC’s website says that “bat activity surveys will begin from April onwards” but in the South Hams, bats begin to emerge from hibernation in March, so their survey may miss much of the spring migration.
- There is scientific evidence that bats are attracted to wind vanes and suffer disorientation due to ultrasound reflections. “Echoes returning from moving blades had features which could render them attractive to bats or which might make it difficult for the bat to accurately detect and locate blades in sufficient time to avoid a collision.” [Long, Flint & Lepper, Loughborough University, reported by the Acoustical Society of America, Oct 2010]
- Air pressure fluctuations caused by rotating blades can kill bats without the blades even touching the bats. (“Wind turbines make bat lungs explode” New Scientist 25.8.2008). In one study, 90% of the dead bats had signs of internal haemorrhaging, while only half showed signs of direct contact with the blades.
The effect upon bat populations of accidental deaths can be serious and even threaten the existence of colonies as bat females typically produce only one baby per year, if that, so that the rate of replacement is very slow.
Reductions in bat and bird populations could affect the rest of the local ecosystems, particularly increasing populations of insects, including agricultural pests. Dr Gary McCracken’s research into the effect of bat deaths caused by wind turbines, published in the journal Science, estimates that bats could be worth billions to agriculture around the world. “Without bats, crop yields are affected. Pesticide applications go up. …Not acting is not an option because the life histories of these flying nocturnal mammals – characterised by long generation times and low reproductive rates – mean that population recovery is unlikely for decades or even centuries, if at all.” [Daily Telegraph 2.4.2011 ]