Abstract
Renewable energy sources are expanding but may negatively affect wildlife in complex ways. Raptors are susceptible to wind turbines; collisions with turbines are well-studied, but the potential for spatial displacement has received less attention. We studied the effects of wind turbines on the distribution and abundance of raptors at a renowned wintering and migration stopover site on Amherst Island, Ontario, Canada. We used standardized surveys involving 3,284 observations of raptors to record their presence and precise locations during winter and spring migration for three years before and three years after the windfarm was built, incorporating both spatial and temporal controls. We found no evidence that wind turbines impacted how 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) used Amherst Island during winter and spring migration. Similarly, we found no evidence for declines in abundance of these species, or of Short-eared Owl (Asio flammeus) and Northern Shrike (Lanius borealis), following turbine construction. Our results illustrate how spatial controls, in the absence of temporal controls, can lead to inaccurate assessments of turbine impacts for species that use habitats differentially.