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12. Birds and bats
Early in the development of wind power it was reported from various parts of the world that birds were likely to be killed by rotor blades
This is hardly surprising. Wind turbines are so gigantic that, though the rotor appears to be travelling quite slowly, the blade tip velocity of a big machine often exceeds 150 mph – two or three times the motorway speed limit. Anyone who has struck a bird with a car will know that even a 20 mph collision is lethal.
A bird which just avoids a blade tip has only 1.2 to 1.3 seconds to dodge the next blade, approaching from about 80 yards to 90 yards away on a strongly curved path and probably outside the range at which many birds would be aware of a moving hazard, even in good visibility. For example a V80 machine gives about 77 yards sightline and 1.2 seconds until the next blade arrives - this might exercise a fighter pilot's skill! (See section 7. Technical aspects of wind turbines).
It did not take the developers long to realise that this was a potential publicity disaster.
What 'they' say
"Quite simply, birds are in far more danger from colliding with overhead power lines, or being eaten by domestic cats, or hit by vehicles than they are from wind turbines..." (BWEA website)
"The Royal Society for the Protection of Birds (RSPB) supports the sustainable development of renewable energy such as wind power because it helps mitigate climate change, which they believe "poses the most significant long-term threat to the environment..." (Yes2wind)
"Environmental assessments are required as part of the planning process, to ensure wind farms are properly sited and configured in relation to bird movements. These assessments have improved the understanding of bird ecology, helping conservation." (DTI Myths).
However, despite the RSPB's support for the deployment of windpower, the organisation has more recently acknowledged that a problem may arise. An objection has been lodged to Amec/British Energy's 600 MW scheme for the Isle of Lewis: - "'We believe this wind farm proposal is not just bad for birds but bad for the development of renewables as well,' said Anne McCall, RSPB Planning and Development Manager. The area is "protected under European law for a variety of important birds, including golden eagles, merlins, black-throated divers, red-throated divers, dunlins and greenshanks." ( http://www.rspb.org.uk/policy/windfarms/objection.asp )
Not all RSPB objections are effective and at Edinbane on Skye planning consent was granted despite RSPB's contention that the site was too close to sea eagles and several breeding pairs of golden eagles, as well as merlin and hen harriers. An RSPB officer commented anonymously: 'The fact is we don't really know what will happen. Developers do environmental assessments but they own the research. And consultants are under pressure from the energy companies for the right answers."
(Observer, October 5 2003).
These reports highlight the main fear that the very large, slow flying raptors are most at risk and in the UK these are all rare and potentially threatened species. Many hunt for food on the ground below by 'telescoping' from above and may have no self-protective instinct at all against attack from the air (no survival of the fittest pressure until wind turbines came along). The fact that kite and vulture have proved the most likely raptors to die in European wind farms supports this interpretation - they are, par excellence, 'circling telescopers'. They may not even take great notice of the hurtling blades (note the crows and buzzards which are quite at home amongst [the slower!] traffic on a motorway).
By January 2006, 69 red kite and 56 buzzard had been killed in Germany (Brandenburg State Environment Office 2006). Nearer home, two red kite deaths have already been confirmed in mid-Wales, with only a relatively small number of turbines as yet.
The Brandenburg figures relied on scoring corpses found by the public. Many will be missed, and scavengers such as fox and badger may remove many more. Direct studies intended to detect bird death reveal frightening numbers in habitats similar to many in the UK. At three wind farms in Flanders (Belgium) the collision numbers varied from 0 to 125 birds per wind turbine per year. The mean number in 2002 was 24, 35 and 18 birds per wind turbine per year at the three 'farms' (Natuur.Oriolus 69 (3) 2003)."
In the US, "Research by raptor experts for the California Energy Commission (CEC) indicates that each year, Altamont Pass wind turbines kill an estimated 881 to 1,300 birds of prey, including more than 75 golden eagles, several hundred red-tailed hawks, several hundred burrowing owls, and hundreds of additional raptors including American kestrels, great horned owls, ferruginous hawks, and barn owls. These kills of over 40 different bird species are in violation of federal and state wildlife protection laws." (http://www.biologicaldiversity.org/swcbd/programs/bdes/altamont/altamont.html )
Smallwood and Thelander (2004) reported to the CEC: - "The assertion that the APWRA is anomalous in its bird mortality is largely untrue... Whereas the available data suggest that the APWRA kills more raptors than do other wind energy generating facilities, the risk index demonstrates that the APWRA kills no more raptors relative to the number seen per hour than do most other wind energy facilities. Adjusting for local relative abundance, the existing data indicate that most wind energy generating facilities have an equal impact on the local raptors.”
In September 2005, the San Francisco. Chronicle reported that half of the 5,000 windmills in the Altamont Pass will be closed for three months this winter to protect migratory birds following years' of protests from environmentalists.
Despite such evidence, the wind power developers and RSPB in the UK have attempted to dismiss the huge toll of raptors at the Altamont Pass Wind Resource Area (APWRA) in California, saying it on a migration route and irrelevant to the UK. However if Smallwood and Thelander are correct about correction for abundance, once some of the big wind stations are built we are likely to see unacceptable losses.
BWEA’s pathetic attempt to deflect criticism by suggesting that "more birds are eaten by domestic cats or hit by vehicles" does the organisation more harm than good. As I have written elsewhere: "when did you last see a domestic pussy-cat wrestle a red kite to the ground for the coup de grace?" And how many sea eagles are struck by cars compared with the 4 sea eagles killed in 5 months by 68 turbines and power lines at the Smola windfarm off the Norwegian coast (Alv Ottar Folkestad, Norwegian Ornithological Society 2005)?
Scottish National Heritage (SNH) has recently written to the Scottish Executive admitting that collision risk to sea eagles and golden eagles at the proposed Muaitheabhal Windfarm had been underestimated by a factor of about 54 times (Letter dated 5 December 2005). This alters a predicted kill of one golden eagle every 3 to 6 years to an outrageous, one per 3 to 6 weeks. SNH repeated in this letter that it was willing to continue to discuss, with the developer, any means of achieving an “acceptable collision risk.”
Bats
It was not until early 2004 that news really spread about the vulnerability of bats to wind turbines. Wendy Williams, a journalist for Windpower Monthly published 'When Blade Meets Bat' in Scientific American (Feb. 2004) and recorded the death of at least 400 migrating bats at Mountaineer Wind Energy Center, Backbone Mountain, West Virginia. Other publications suggest that allowing for carcasses missed, or carried off by scavengers, over 2000 bats were killed and possibly many more at this site.
Bats navigate by echo location but cannot cope with the speed of wind turbine blades and are most vulnerable when the wind speed is low, which is when their prey is flying. One study has shown fewest bats killed on nights when wind speeds were above 13 mph. It is also apparent that some bats die of 'shock' and are found dead but uninjured beneath the machines, probably from being buffeted by wake vortices.
Bat deaths are also recorded throughout Europe with many hundreds of deaths despite the problem of finding and recording such tiny corpses in competition with scavengers. These numbers are the tip of an iceberg and will surely prove much greater. It is only within the last couple of years that bats began to be studied in EIAs.
It is of interest that UK law makes it an offence knowingly to "Set and use articles capable of catching, injuring or killing a bat...” or to "Possess articles capable of being used to commit an offence, or to attempt to commit an offence." (Bat Conservation Trust information leaflet).
Relevant articles, news items, papers, reports
Windfarm Wasteland - Birds and Bat strikes
A compilation of articles covering the impact of wind turbines on bird and bat species.
Contents:
- Evidence of bird and bat strikes by wind turbines
- Legal aspects
- Research
Avian Hearing and the Avoidance of Wind Turbines. The full PDF report of one of the reseach items in the compliation above
R. Dooling, Ph.D.
University of Maryland College Park, Maryland
National Renewable Energy Laboratory
RENEWABLE ENERGY INDUSTRY ENVIRONMENTAL IMPACTS
By Andrew Chapman - 15/11/03
Andrew is a Consulting Engineer with a private practice who has held senior positions in leading Australian engineering and environmental consultancies. He has provided engineering and environmental services to major corporations in Japan, South East Asia and throughout Australia. He served on the Victorian Government’s Conservation Advisory Committee and over 11 years Chaired or was member of panels appointed to conduct hearings under the Victorian Government’s Planning and Environment and Environment Effects Acts
(This is a stand-alone version of one of the articles in the compliation)
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The Case against Windfarms