Mitigating wildlife collisions with wind turbines: A review of techniques, evidence, knowledge gaps and avenues for future research

Abstract

As global wind energy production rapidly expands, so too have concerns about collision impacts for bird and bat species conservation, driving development of a diversity of anticollision technology. This review compares seven metrics across bat and bird anticollision strategies: (1) detection range, (2) detection probability, (3) species specificity, (4) changes to avoidance behaviour, (5) collision fatalities, (6) setup and maintenance costs, and (7) energy production losses. Of 52 operational and deterrent strategies or tools reviewed, less than half have independent testing data available and many knowledge gaps persist, especially for newer or under-development methods. For large birds, radar systems have greatest detection range (6.13 ± 3.99 km), but limited species specificity, and have no available data for anticollision success. Cameras have shorter range (0.69 ± 0.44 km) but good identification accuracy for large birds (83 ± 20%), with 66 ± 23% collision reduction. Blade painting has had mixed results (two successful and two unsuccessful studies to date; average 7 ± 61% reduction in bird mortalities). For bats, acoustic detection reveals the most proximal collision risk, and acoustic-activated curtailment shows the greatest success in reducing fatalitites (66 ± 34% anticollision success), while ultrasonic bat deterrents have had limited success (23 ± 40% reduction in fatalities). Technology investment ranges from relatively low (e.g., blade feathering below cut-in, blanket curtailment, deterrents such as vegetation removal through mowing, or blade painting prior to construction), through to very high (e.g., radar, camera, and acoustic detection systems for smart curtailment), with varying degrees of maintenance also required. There is a general lack of data on the lost revenue due to energy production losses. Additional data on energy production losses are required to balance the economic costs of curtailment with conservation benefits (i.e. fatalities per MWh) to help inform decisions in selecting mitigation approaches for the wind industry. This review provides researchers, project proponents, and policy makers with a scientific and comprehensive reference for the effectivness of anticollision technology, improving biodiversity outcomes for this important renewable energy resource.