Wind and storms affect how deadly wind-energy turbines are for bats. Several studies in North America report that most bats die during nights of light wind, blowing at less than 13 miles per hour (21 kilometres per hour). Bat mortality at wind turbines also spikes just before and after a storm front passes by.
Different wind energy installations within a region have documented similar timing in fatalities, suggesting that a weather pattern can have widespread influence.
Most bats that get killed at wind turbine sites are on their fall migration. Observations at the Mountaineer Wind Energy Center in West Virginia reveal that bats don’t just pass through wind turbine installations.
Bats actually investigate the turbines by repeatedly flying by and approaching the blades. The animals will follow a moving blade and some even become trapped in the air vortices near a blade’s tip. Rotating blades end up smacking the more unfortunate bats. Hundreds of dead and injured bats have been found beneath the wind turbines at the West Virginia installation.
Bats that roost in trees, such as hoary bats, are the most frequent victims of this and 19 wind-energy facilities studied in United States and Canada. Some turbines are also death traps for female bats in spring. Pregnant Brazilian bats died at a wind energy site in Oklahoma and female silver-haired bats were killed by turbines in Tennessee and Alberta.
Edward B. Arnett, W. Kent Brown, Wallace P. Erickson, Jenny K. Fiedler, Brenda L. Hamilton, Travis H. Henry, Aaftab Jain, Gregory D. Johnson, Jessica Kerns, Rolf R. Koford, Charles P. Nicholson, Timothy J. O’Connell, Martin D. Piorkowski and Roger D. Tankersley Jr. 2008. Patterns of Bat Fatalities at Wind Energy Facilities in North America. Journal of Wildlife Management. 72(1): 61-78.
Jason W. Horn, Edward B. Arnett and Thomas H. Kunz. 2008. Behavioral Responses of Bats to Operating Wind Turbines. Journal of Wildlife Management. 72(1): 123-132.
By Liz Osborne
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