November 10, 2007
U.S., Wildlife

Assessing Impacts of Wind-Energy Development on Nocturnally Active Birds and Bats: A Guidance Document

Kunz, Thomas; Arnett, Edward; Cooper, Brian; Erickson, Wallace; Larkin, Ronald; Mabee, Todd; Morrison, Michael; Strickland, M. Dale; and Szewczak, Joseph

THOMAS H. KUNZ, Department of Biology, Boston University, Boston, MA
EDWARD B. ARNETT, Bat Conservation International, Austin, TX
BRIAN M. COOPER, Alaska Biological Research, Inc., Forest Grove, OR
WALLACE P. ERICKSON, Western EcoSystems Technology, Inc., Cheyenne, WY
RONALD P. LARKIN, Illinois Natural History Survey, Champaign, IL
TODD MABEE, Alaska Biological Research, Inc., Forest Grove, OR
MICHAEL L. MORRISON, Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX
M. DALE STRICKLAND, Western EcoSystems Technology, Inc., Cheyenne, WY
JOSEPH M. SZEWCZAK, Department of Biological Sciences, Humboldt State University, Arcata, CA

ABSTRACT: Our purpose is to provide researchers, consultants, decision-makers, and other stakeholders with guidance to methods and metrics for investigating nocturnally active birds and bats in relation to utility-scale wind-energy development. The primary objectives of such studies are to 1) assess potential impacts on resident and migratory species, 2) quantify fatality rates on resident and migratory populations, 3) determine the causes of bird and bat fatalities, and 4) develop, assess, and implement methods for reducing risks to bird and bat populations and their habitats. We describe methods and tools and their uses, discuss limitations, assumptions, and data interpretation, present case studies and examples, and offer suggestions for improving studies on nocturnally active birds and bats in relation to wind-energy development. We suggest best practices for research and monitoring studies using selected methods and metrics, but this is not intended as cookbook. We caution that each proposed and executed study will be different, and that decisions about which methods and metrics to use will depend upon several considerations, including study objectives, expected and realized risks to bird and bat populations, as well as budgetary and logistical considerations. Developed to complement and extend the existing National Wind Coordinating Committee document ‘‘Methods and Metrics for Assessing Impacts of Wind Energy Facilities on Wildlife’’ (Anderson et al. 1999), we provide information that stakeholders can use to aid in evaluating potential and actual impacts of wind power development on nocturnally active birds and bats. We hope that decision-makers will find these guidelines helpful as they assemble information needed to support the permitting process, and that the public will use this guidance document as they participate in the permitting processes. We further hope that the wind industry will find valuable guidance from this document when 1) complying with data requirements as a part of the permitting process, 2) evaluating sites for potential development, 3) assessing impacts of operational wind-energy facilities, and 4) mitigating local and cumulative impacts on nocturnally active birds and bats.



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
– Radiotracking

The Journal of Wildlife Management is the official publication of The Wildlife Society (TWS), which, founded in 1937, is an international non-profit scientific and educational association dedicated to excellence in wildlife stewardship through science and education. To learn more about the society please visit: [1].

Download original document: “Wind-Energy Development on Birds and Bats [2]

URL to article:

URLs in this post:


[2] Wind-Energy Development on Birds and Bats: