Wind energy is one of the fastest growing sectors of the energy industry, but not without environmental consequences. Nocturnally active birds and bats have become prey to turbines, yet little guidance could be found for assessing impacts of wind energy on this group until now. A new article published in the latest issue of The Journal of Wildlife Management gives guidance about the methods and metrics of this subject.

Songbirds are by far the most abundant flying vertebrates in most terrestrial ecosystems and until recently have been the most frequently reported fatalities at utility-scale wind facilities in the United States. A previous study showed that 78 percent of carcasses found at wind-energy facilities outside of California were songbirds protected by the Migratory Bird Treaty Act. Among these, approximately half were nocturnal.

Recent monitoring studies indicate that utility-scale wind-energy facilities have killed considerably more bats than were expected based on earlier studies. Large numbers of bats have been killed at wind-energy facilities constructed along forested ridge tops in the eastern United States.

Requirements and implementation of preconstruction monitoring are far less consistent than postconstruction fatality-monitoring protocols. Some states have no requirements for preconstruction surveys, whereas others have minimum requirements for surveys on threatened or endangered species or species of concern.

Making meaningful visual observations of nocturnal activity requires not only selecting the appropriate methods and equipment, but also including the temporal and spatial scales required to answer relevant questions, said the study researchers. The following are their recommended methods for the study of impacts of wind-energy facilities on nocturnally active birds and bats:

-Moon watching
-Ceilometer (spotlight)
-Night vision (image intensifier)
-Thermal infrared imaging cameras
-NEXRAD, Doppler weather surveillance radar
-Marine (X-band) radar
-Tracking radar
-Audio microphones for birds
-Ultrasound microphones for bats

Article PDF here.