Abstract
Wind energy development is a key component in the transition to sustainable clean energy. Collision probability depends on turbine dimensions and species-specific behaviour, and understanding these relationships is essential for effective Environmental Impact Assessment (EIA). We applied a simulation approach based on flight-height distributions of a medium-sized diurnal raptor, the Common Buzzard (Buteo buteo). Long-term Global Positioning System (GPS) tracking data from an area with over 200 operating wind turbines in Northeastern Bulgaria were combined with Monte Carlo simulations of the Band collision risk model, and the predictions were validated against 18 years of systematic carcass searches under 114 turbines. Importantly, collision probability of the Common Buzzard was season-dependent, being greater during breeding and wintering, when flights occurred at lower altitudes, and lower during migration, when birds flew higher. Both the simulations and the field data supported an overall relatively low collision probability, indicating a high avoidance rate in this species. These findings suggest that wind energy planning should account for seasonal variation in flight behaviour and community composition, while long-term monitoring remains essential to ensure that cumulative impacts are adequately assessed.
Simple Summary
Wind farms are growing fast, but their real impact on birds is still debated. We tracked eight Common Buzzards with high-precision Global Positioning System over several years in Northeast Bulgaria, where more than 200 wind turbines have operated for over 15 years. Using these flight-height data, we ran Monte-Carlo simulations based on the Band collision risk model to estimate how often Common Buzzards might collide with turbines of different sizes. We then checked our predictions against 18 years of systematic carcass searches under 114 turbines. Both the simulations and the field data point to a relatively low collision probability for Common Buzzards, and this probability varies with season: it is lowest during migration, when birds fly higher, and highest in winter and breeding, when they stay low. Our findings show that realistic flight-height distributions and seasonal behaviour must be included in Environmental Impact Assessments. Our results also suggest that Common Buzzards may quickly habituate to wind farms, although continued monitoring is essential.