Behavior of bats at wind turbines

Proceedings of the National Academy of Sciences
By: , and 

Links

Abstract

Wind turbines are causing unprecedented numbers of bat fatalities. Many fatalities involve tree-roosting bats, but reasons for this higher susceptibility remain unknown. To better understand behaviors associated with risk, we monitored bats at three experimentally manipulated wind turbines in Indiana, United States, from July 29 to October 1, 2012, using thermal cameras and other methods. We observed bats on 993 occasions and saw many behaviors, including close approaches, flight loops and dives, hovering, and chases. Most bats altered course toward turbines during observation. Based on these new observations, we tested the hypotheses that wind speed and blade rotation speed influenced the way that bats interacted with turbines. We found that bats were detected more frequently at lower wind speeds and typically approached turbines on the leeward (downwind) side. The proportion of leeward approaches increased with wind speed when blades were prevented from turning, yet decreased when blades could turn. Bats were observed more frequently at turbines on moonlit nights. Taken together, these observations suggest that bats may orient toward turbines by sensing air currents and using vision, and that air turbulence caused by fast-moving blades creates conditions that are less attractive to bats passing in close proximity. Tree bats may respond to streams of air flowing downwind from trees at night while searching for roosts, conspecifics, and nocturnal insect prey that could accumulate in such flows. Fatalities of tree bats at turbines may be the consequence of behaviors that evolved to provide selective advantages when elicited by tall trees, but are now maladaptive when elicited by wind turbines.

Study Area

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Behavior of bats at wind turbines
Series title Proceedings of the National Academy of Sciences
DOI 10.1073/pnas.1406672111
Volume 111
Issue 42
Year Published 2014
Language English
Publisher U.S. National Academy of Sciences
Contributing office(s) Forest and Rangeland Ecosystem Science Center, Fort Collins Science Center, Pacific Island Ecosystems Research Center
Description 6 p.
First page 15126
Last page 15131
Country United States
State Indiana
Online Only (Y/N) N
Additional Online Files (Y/N) N