At wind farms across the world, birds (particularly soaring species) are known to have a high risk of colliding with the turbines. These soaring species are further loosely divided into two groups for assesing ecological impact. (1) Migratory: Twice every year, many species of birds set out on their long journey across large swaths of land and sometimes seas, en masse. Turkey lies on the major migratory routes of such birds, with important bottlenecks in a few parts of the country (e.g. Bosphorus Strait). (2) Resident: Turkey is fairly mountainous, and higher elevations often house substantial populations of vultures and eagles. Additionaly Turkey’s many wetlands are home to large bird colonies.
For monitoring soaring species, we primarily rely on a technique called Vantage Point surveys where points within the project site that provide the best visual coverage are determined and at least 36 hours per season are spent observing birds. The findings are analysed using internationally recognized methods, such as Band and Biosis models, through which the risk of collision evaluated and the collision related mortality rate is estimated. Our estimations assist in customizing a plan to minimize collision risk such as lowering the cut-off speed for selected turbines or implementing an active turbine management system.
Potential impact of wind farms, at construction or operation phase, is not limited to only soaring species and instead encompasses all local avifauna. To account for this, breeding bird surveys include observations of breeding activity of resident species and identification of any species that are sensitive, rare and endangered that require additional mitigation.
Such species might include:
- Globally Threatened Species
- Threatened Species at National Level
- Locally rare species
Breeding bird surveys are also important for Critical Habitat assessment (IFC PS6 standards).
We identify such species and develop mitigation plans specifically tailored for them. A great example is the European Nightjar (Caprimulgus europaeus) at wind farm sites. European Nightjar may fly at rotor height during its peculiar courtship displays in the summer and collide with the blades. An ideal plan would target when and where the species would be most active (open areas on cloudless nights near full moon) in order to minimize both mortality and loss in energy production.