Pacific Island Ecosystems Research Center
Videographic techniques for monitoring and researching bat and nocturnal seabird activity at wind turbines.
Bats and birds are relatively small animals, whereas industrial wind turbines can attain heights of over 150 m (500 feet). Research into why bats and birds approach and how they behave near wind turbines is hindered by the difficulty of observing them in the dark at relatively long distances. Moreover, although the cumulative impact of fatalities over time can be substantial, the actual incidence of animal-turbine interactions may be fairly rare or infrequent on a nightly basis. It can take many hours of observation to detect such events, making direct real-time surveillance impractical. Videographic recording of the airspace around turbines typically results in hundreds or thousands of hours of material to review, and a major challenge of this approach is the efficient processing and interpretation of the large amounts of data acquired.
Fieldwork conducted in 2011 and 2012 by scientists from five USGS science centers (PIERC, FORT, FRESC, NOROCK, AND NPWRC), the University of Hawai‘i-Hilo, and Bat Conservation International assessed different methods of monitoring animal activity and fatality at turbines, including carcass searches, mobile radar, acoustic and video surveillance. Acoustic and video recordings of bats interacting with each other over sustained periods are providing new insights into the way bats behave around turbines. Radar tracking is also revealing differences in the way birds and bats approach turbines at the landscape scale. A better understanding of bird and bat activity around turbines may lead to solutions for reducing mortality while minimizing costs to the wind energy industry.
The endangered Hawaiian hoary bat (‘ōpe‘ape‘a; Lasiurus cinereus semotus), the only land mammal endemic to the Hawaiian Islands, is closely related to the bat species comprising about half of all fatalities on the mainland (Cryan 2011). Hawaiian hoary bats have recently been found dead beneath turbines on O‘ahu and Maui. Bird fatalities are also present but little is known about the pattern of bird movement or the relative risk posed by turbines to birds. Current research in Hawai‘i by PIERC in collaboration with other USGS science centers, the University of Hawai‘i-Hilo, Bat Conservation International, the USFWS and wind energy industry partners, aims to assess risk of energy development to endangered Hawaiian hoary bats and nocturnally active birds such as the federally and state-listed Newell‘s shearwater (‘a‘o; Puffinus auricularis newelli) and Hawaiian petrel (‘ua‘u; Pterodroma sandwichensis). The geographic setting is particularly appropriate because of the scope of active and planned wind energy development in response to the state‘s ambitious renewable energy mandate (70% renewable energy by 2030).
Arnett, E. B., K. Brown, W. P. Erickson, J. Fiedler, T. H. Henry, G. D. Johnson, J. Kerns, R. R. Koford, C. P. Nicholson, T. O‘Connell, M. Piorkowski, and R. Tankersley, Jr. 2008. Patterns of fatality of bats at wind energy facilities in North America. Journal of Wildlife Management 72: 61–78.
Cryan, P.M. 2011. Wind turbines as landscape impediments to the migratory connectivity of bats. Environmental Law 41:355-370.
Manville A.M. 2009. Towers, turbines, power lines, and buildings – steps being taken by the U.S. Fish and Wildlife Service to avoid or minimize take of migratory birds at these structures. In: Rich TD, Arizmendi C, Demarest DW, Thompson C, editors. Tundra to tropics: connecting birds, habitats and people; proceedings of the fourth international Partners in Flight conference, 13–16 February, 2008. McAllen, Texas: Partners in Flight. pp. 262–272.
Smallwood, K.S. 2013. Comparing bird and bat fatality-rate estimates among North American wind-energy projects. Wildlife Society Bulletin 37 19:33.
Alternative Energy and Wildlife
Wildlife and Wind Energy
Increased interest in renewable energy has led to the rapid expansion of the wind energy industry in the United States and many other parts of the world. Although wind energy provides a clean and much needed source of electricity, there are environmental concerns regarding bird and bat mortality. It is currently estimated that more than 888,000 bat and 573,000 bird fatalities occur each year at wind turbines in the U.S. and Canada (Smallwood 2011). The magnitude of this problem has the potential to result in rapid population declines and the endangerment of vulnerable species. However, the causes and species-specific risks of wind energy development to wildlife, particularly bats, remain poorly understood because of the difficulty of observing these events.
This clip shows a bat (not identified to species) flying near a turbine as imaged with a thermal camera. The recording shows the bat making numerous repeated passes behind the rotor swept area of a turbine. This activity is of particular interest to researchers because it provides a window into behavior that places bats at risk from turbine strikes. The clip was recorded in central Indiana in August 2012.
This clip shows a bat (not identified to species) flying near a turbine as imaged with a camera sensitive to near infrared light. The bat flies in rapidly from the top left, then turns and flies into the spinning rotor blades of the turbine. The bat appears to be deflected upwards by the blades and escapes a direct strike. The clip was recorded in central Indiana in August 2012. The recording was taken in complete darkness but objects are made visible with supplementary near infrared illumination that is not visible to bats.
This clip shows a Hawaiian hoary bat flying near a turbine as imaged with a thermal camera. The recording shows the bat investigating the area immediately around the turbine nacelle. This activity is of particular interest to researchers because it provides a window into behavior that places bats at risk from turbine strikes. The clip was recorded on Oahu Island, Hawaii, in June 2013.
This clip shows a pair of wedge-tailed shearwaters as imaged with a camera sensitive to near infrared light. The shearwaters appear out of the night sky at a distance of about 100 meters, and fly along the coast directly towards the camera. This clip demonstrates the application of high-resolution cameras to image nocturnal seabird activity. The recording was taken in near complete darkness but objects are made visible with supplementary near infrared illumination that is not visible to birds. The clip was recorded on Oahu Island, Hawaii, in September 2011.