Collision Risk Modelling

Collision Risk Modelling is important, as wind farm installations are known to present a risk of collision to a variety of bird species. Globally, evidence of the severity of this risk is limited, but studies have shown that inappropriately sited turbines can kill or injure hundreds of birds per year. The species affected are often larger and less manoeuverable in the air, such as eagles, larger hawks, swans and divers.

Wind turbines present a collision risk to birds and bats

Wind turbines present a collision risk to birds and bats

In the UK, the primary method of assessing this risk is the Collision Risk Model (CRM), as developed by Band et al (2007) and detailed in guidance from Scottish Natural Heritage (SNH). The model processes raw data collected from Vantage Point surveys, normally carried out over the course of a full year, and includes details such as a bird’s flight height, direction and time spent in the airspace to be affected by proposed turbine installations. An ‘avoidance rate’ figure is added to the model, using the best currently available data on a species’ ability to detect and avoid colliding with the blades. The final output is a figure which illustrates the estimated number of fatal collisions per year for each species.

Having worked with the CRM for several years, our senior ecologist Rich Hall has assessed its accuracy against his own knowledge of each proposed installation site and how it effects the movement of birds. The assessment of an experienced ornithologist such as Rich is vital to support and interpret the results of the CRM, as specific habitat types can have a significant effect on the model’s output.

Data on actual collision risk is extremely limited and studies of birds and their interaction with existing wind farms is sorely needed. Recent papers have suggested that some birds, such as certain goose species, may be far better at detecting and avoiding offshore installations than previously thought. The CRM is the best method currently available for assessing this risk but, as with all model-based assessment, continuous analysis and improvement is vital to ensure the accuracy of information which is intended to minimise ecological impacts and maximise the chances of survival for important bird species.

Read our blogs on the percentage of seabirds that steer to avoid collision with offshore wind farms and the 2015 Conference on Wind Energy and Wildlife Impacts for more on the impact of wind farms on birds.

Contact Baker Consultants for more details about Collision Risk Modelling

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