The Impact of Wind Turbines on the Distribution of Wintering and Migrating Raptors

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Mitchell, Kate E.
Wind turbines , Windmills , Raptors , Birds , Bald Eagles , Snowy Owls , Ontario , Renewable Energy , Green Energy , Species distributions , Abundance , BACI
Renewable energy sources, including wind power, are rapidly expanding as governments aim to fight climate change. However, wind turbines may negatively affect surrounding wildlife. Raptors are birds of prey and are potentially susceptible to being negatively affected by wind turbines. Raptor collisions with wind turbines are well-studied, but the potential for their spatial displacement due to wind turbines has received less attention. Understanding both collisions and displacement is necessary to comprehend the overall effects of wind turbines on raptors. Amherst Island, Ontario, Canada is renowned for its number and diversity of wintering raptors. Wind turbines were built on the island in 2018. In this study, we used standardized surveys to record the presence, number, and precise location of raptors on Amherst Island during winter and spring migration for three years before (2015, 2016, 2017) and three years after (2019, 2022, 2023) the windfarm was built. We recorded 3,277 observations of raptors which we used to test whether the turbines affected raptor distributions, incorporating both spatial and temporal controls. We found no evidence that any of our six focal raptor species – Northern Harrier (Circus hudsonicus), Bald Eagle (Haliaeetus leucocephalus), Red-tailed Hawk (Buteo jamaicensis), Rough-legged Hawk (Buteo lagopus), Snowy Owl (Bubo scandiacus), or American Kestrel (Falco sparverius) – changed their distributions in response to wind turbines. Similarly, we found no evidence of changes in the distributions of different age classes of Bald Eagle in response to wind turbines. Changes in overall population sizes on Amherst Island for our six focal species, as well as for Short-eared Owl (Asio flammeus) and Northern Shrike (Lanius borealis), mirrored regional trends in abundance, suggesting no impacts of wind turbines on raptor abundance. Overall, despite some collisions between raptors and wind turbines recorded in monitoring studies, we found no evidence of negative impacts of wind turbines on how our focal species use Amherst Island during winter and spring migration. As the need for renewable energy grows, using strong methods to study potential effects of wind turbines on surrounding wildlife will help ensure appropriate sites are chosen for future windfarms.
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