Of Birds and Blades
Joelle Gehring, Ph.D., is senior conservation scientist at the University of Michigan, collaborating with scientists, industry representatives, regulators and others on reducing bird deaths caused by collision with communication and wind towers. She published a summary of recent research quantifying such deaths and recommending solutions — subjects of great interest in Wyoming. Some of her conclusions, based upon many site studies, are presented below.
• Taller towers (over 1,000 feet) kill about four times more migrating birds than shorter ones (380-480 feet). Most wind turbines in Wyoming are about 300 feet at the tip of the blade.
• Towers anchored with guy wires kill about sixteen times more birds than self-standing towers of comparable height.
• Replacement of steady-burning red lights, used to warn aircraft, with flashing lights such as white strobe lights reduced fatalities by more than 50 percent.
Estimates of the number of migratory songbirds killed by communication towers range from 4 million to 50 million birds per year. Meanwhile, cell phone towers and public safety communication towers are springing up like weeds.
Gehring estimates that as of early 2010, there were about 31,000 utility-scale wind turbines operating in the United States. New turbines range from 350-420 feet tall. Warblers, vireos, kinglets and larks are frequent victims, with quail, hawks, shorebirds and waterfowl also among the dead. Night migration, common among many avian species, contributes substantially to the deaths.
However, Gehring concludes that deaths due to wind turbines are much lower per tower than at communication towers.
(Editor’s note: Paul Kerlinger, a co-author with Gehring of “Understanding Bird Collisions at Communications Towers and Wind Turbines: Status of Impacts and Research,” has worked as a paid consultant for the wind industry. Their research was partially funded by the wind industry. Click here for additional details.)
Since many communication towers are erected by public agencies, often for public safety purposes, the public should push such agencies to implement strategies to build self-standing towers instead of guyed structures, and to install flashing lights that do not attract birds. Private companies should be encouraged to do the same.
Gehring recommends that the height of the top of the rotating blades of wind turbines be limited to no more than 500 feet and areas with populations of rare and endangered species be avoided.
Adapted with permission from “Understanding Bird Collisions at Communications Towers and Wind Turbines: Status of Impacts and Research,” Paul Kerlinger, Joelle Gehring and Richard Curry, Birding magazine, January, 2011. Any errors in interpretation are laid at the feet of The Sage Grouse.
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