Both through ongoing and previous studies of the conflict between birds and wind turbines carried out in the Smøla wind power plant, the white-tailed eagle, Haliaeetus albicilla, has been identified as the most vulnerable species. The Smøla wind power plant has an impact on the white-tailed eagle both through increased disturbance as well as increased mortality from collisions with turbines.
The assessments are based on a set of different data sources and different analyses: (i) monitoring data on reproductive success and nest locations for the white-tailed eagle, (ii) data on eagle night roosts, (iii) analysis of flight activity levels and collision risk modelling, (iv) sensitivity analysis for birds in general based on data from the Merlin avian radar, and (v) analysis of turbine-related collision risk sensitivity from bird fatality data. Together these data sources form a solid basis for assessing the potential impacts of a repowered Smøla wind power plant.
In general, we expect the layout with 30 5MW turbines to have lowest conflict level for the white-tailed eagle. The modeled collision risk of a repowered wind power plant with 30 turbines are expected to have approximately 32% of the collision risk compared to the existing wind power station, i.e. significantly less than in the existing power plant. A renewed wind power plant with 50 3MW turbines is expected to have a collision risk that is approximately 71% of that of the existing wind power plant. The reduced risk of a power plant with 30 turbines compared to the existing power plant and the 50-turbine layout is due to both the reduction of the number of turbines, and better individual turbine siting.
A summed vulnerability map for white-tailed eagles was developed, based on data on reproductive success, nest location, flight activity levels and night roost locations. According to this summed vulnerability map, the eagles have the highest vulnerability is present in the outer edges of the proposed layouts, as well as in an area in the south west between the two westernmost turbine strings. Other parts of the power plant will have less vulnerability compared to the existing power plant. Overall, the 30-turbine layout is expected to have least impact to the summarized white-tailed eagle vulnerability.
We recommend that an adaptive management plan is established as a follow-up program that regularly assesses the conflict level with the white-tailed eagle and whether mitigation measures should be initiated. This requires monitoring of the conflict level in the post construction period. The ongoing project INTACT working on identifying potential mitigation measures. Results from the INTACT project will be ready well in advance of the construction phase of a repowered Smøla wind power plant, and should be taken into account in the follow-up program. In addition to mitigation measures, compensation measures could be used to compensate for e.g. bird mortality in the repowered wind power plant.