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ENVIRONMENT: BIRD MORTALITY
source: www.irish-energy.ie/content/content.asp?
section_id=1222&language_id=1
www.nationalwind.org/pubs/avian_
collisions.pdf
www.ewea.org/documents/Facts_
Summary.pdf
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There are 4 ways that a wind farm can affect birds:
Collision – most birds are able to recognise that they are approaching wind turbines and alter their flight paths accordingly. Some species are less versatile in flight or have poorer sight, but the developments in wind turbine technology means that turbines are larger, move more slowly and are further distances apart, offering flight corridors. Even so, wind farms should not be sited along known important migration paths for these species.
- It is estimated that 33,000 birds are killed annually by wind turbines operating in the US, an average of 2.2 fatalities for each of the 15,000 turbines. In Spain, a study showed 0.13 dead birds per year per turbine.
- A US study published in 2001* puts wind turbine collisions into perspective with bird collisions with other structures: between 100 million and 1,000 million birds are estimated to die each year from colliding with vehicles, buildings, power lines and other structures, with wind power responsible for 1 out of every 5,000 - 10,000 avian fatalities.
Direct habitat loss – the land used to build roads and foundations is typically between 2 and
4% of the entire site, so the majority of the site habitat remains intact. Nevertheless, wind farm developers should ensure that there is minimal disturbance to site-specific species during the construction and operational phases.
Indirect habitat loss – disturbance of birds may occur in the vicinity of a wind farm development, notably during the increased activity of the construction phase. Several studies however indicate that no disturbance takes place further than 800 metres from the turbines and, further, that breeding birds have not been found to be affected at distances exceeding 300 metres from the turbines.
Positive effects – along with the contribution to reducing the effects of global warming, wind farms discourage further development in the immediate vicinity of the project and often provide a level of protection for these largely undisturbed sites.
* “Avian collisions with wind turbines: A summary of existing studies and comparisons to other sources of avian collision mortality in the United States”. A study carried out by Western Ecosystems Technology for the National Wind Coordinating Committee.
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