Despite low overall numbers of fatal interactions with wind turbines, raptors are an avian guild of concern with respect to wind energy development worldwide. There are several interacting causes for this concern: raptor populations tend to be relatively small, therefore low overall numbers do not necessarily translate to low population impact; raptor species are larger, more conspicuous, and more charismatic than most other avian taxa; and the flight dynamics of many species bring them into direct conflict with wind energy facilities. Due to this combination of perception and ecology, avoidance and minimization of impacts on raptors is an active area of research and development within the wind energy industry. In this paper, we review the knowledge base regarding interactions between raptors and wind turbines and highlight some promising approaches to impact minimization.
Fatality records indicate that some species groups are more vulnerable than others to collision fatalities. In Europe and North America, buteos, eagles, kestrels, and old world vultures are the most common raptor fatalities, whereas falcons and harriers are relatively uncommon fatalities. These differences in fatalities suggest that obligate soaring birds and those with foraging behaviors that place them in proximity to turbines while also reducing vigilance are most vulnerable to collisions. Avoiding raptor fatalities begins with siting, and early screening of potential wind farm locations can identify land covers, topography, and raptor communities that generate high risk. Recent work based on flight dynamics has provided tools for predicting risk based on the distribution of orographic updrafts, and these tools show promise for planning turbine locations to reduce collision risk for soaring birds. Avoidance of impacts to birds that use hovering or kiting flights, such as the American kestrel and red-tailed hawk in North America, likely requires additional evaluation of foraging patterns. Once turbines are operational, avoidance of fatalities entails monitoring and operational modifications to reduce fatality risk. Newly developed technologies, such as machine vision, are transforming how raptors are monitored, and may increase the economic viability of post-construction fatality avoidance.