Birds and wind farms
The impacts of wind turbines upon bird life are very site specific and are either by collision or migration interruption, rather than habitat or ecosystem impacts and disturbance.
There are 4 ways that a wind farm can affect birds.
Most birds are able to recognize 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 mean 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. This fact is a basic consideration in the environmental assessment and planning stage.
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. Some species of birds benefit from the change to the use of the land and numbers can increase. For example some commercial forestry may be removed for the wind farm and the now open portion of land can suit the hunting methods of some predatory birds.
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 identify that no disturbance takes place further than 800 metres from the turbines and that breeding birds have not been found to be affected at a distances exceeding 300 metres from the turbines.
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 at these largely undisturbed sites.
Ecological Consultant Dr Steve Percival provides an assessment methodology that can be used by prospective wind farm developers in Ireland in his report: Birds and Wind Farms in Ireland: A Review of Potential Issues and Impact Assessment (.pdf, 86kb)