Shedding Light on FAA Lighting at Wind Farms
Researchers and conservationists have known for a long time that certain kinds of lights present a threat to migrating birds, and possibly bats as well. For example, concentrations of these lights, as occur in large cities, can confuse and disorient migrating birds as they make their long journeys.
The night skies aren’t dark outside of cities either, because to protect aircraft, the Federal Aviation Administration (FAA) requires lighting on structures more than 199 feet tall. Examples of structures that feature aircraft warning lights include tall buildings, bridges, communication towers, and wind turbines.
As wind farms started to become more commonplace across the U.S., researchers and conservationists began to wonder if aviation lighting at wind farms could affect wildlife. Studies have found that the synchronized, flashing red lights recommended by the FAA for commercial wind turbines do not increase collision risk for migrating songbirds. As for bats – well, it’s complicated. But wind-wildlife stakeholders have proactively undertaken research to expand what is known about this topic, and to understand and quantify any risks.
A Big Discovery with Far-Reaching Implications
In 2003, biologist and wind turbine lighting expert Dr. Paul Kerlinger was part of a team that conducted a study of the relative collision risks posed to migrating songbirds by different nighttime lighting systems for communication towers in Michigan. At the time, standard FAA lighting called for a combination of steady and flashing red lights, although the study looked at flashing white lights as well. One of the findings was that communication towers lit with only flashing red or white lights had 50-70% fewer avian fatalities than towers with lighting systems that included steady lights. This was a major discovery, and its implications extended beyond communication towers to other tall structures, including wind turbines.
“I like to call this the biggest event in wind turbine lighting that almost no one has heard of,” chuckled Dr. Kerlinger. The Michigan study – which didn’t even look at wind turbines – is nevertheless very significant for the wind industry, because it resulted in changes to standard FAA lighting requirements. “Were it not for that study, wind turbines taller than 500 feet would all be required to include steady red lights in their lighting systems. This would not only significantly increase costs, but we now know that it would also result in much higher fatality rates among migrating song birds,” he explained.
Dr. Kerlinger speaks highly of his experiences with the wind industry. “I’ve worked with other industries on lighting issues, but wind companies stand out for their willingness to talk openly about potential issues and work collaboratively to find solutions,” he remarked.
The National Audubon Society is strongly in favor of the updated FAA lighting requirements, which apply to a wide range of potential hazards to birds in flight. “The research indicates that flashing lights on vertical structures like communication towers or wind turbines won’t attract or disorient birds, which is good news for anyone who cares about protecting birds,” said Jack Clarke, Director of Public Policy for Mass Audubon.
Bats: No “One-Size-Fits-All” Solution
While there seems to be broad consensus among researchers that FAA lighting doesn’t attract birds, less is known about bats, primarily because fewer studies have been done. The one constant seems to be that different species of bats behave differently at different times of the year.
“When it comes to bats and wind turbines, it’s not a one-size-fits-all situation,” explained Dr. Amanda Hale, Associate Professor of Biology at Texas Christian University. “We know that some bats are at risk of collision with wind turbines at certain times of the year, but it has been difficult to figure out exactly what factors, or combination of factors, may be at play for all impacted species.”
“Our study found either no relationship (4 bat species) or a negative relationship (1 bat species) between FAA lighting and fatality rates at a wind energy facility in the southern Great Plains,” Dr. Hale elaborated. “To be able to confirm if FAA lights have any effect on certain species of bats, we need to compile species-specific bat fatality data from lighted and non-lighted turbines across North America. By taking a comprehensive look at this large data set, we will be able to identify patterns and test hypotheses of collision-risk factors that will lead to greater understanding.”
Collaborating to Find Science-Based Answers
Members of the conservation community echo the call for further research into interactions between wildlife and structures built by humans. “While FAA lighting on wind farms isn’t an issue for birds, they face other threats like the lights and reflective windows on tall buildings in urban settings,” noted Mass Audubon’s Jack Clarke. “AWWI’s collaborative approach to working with industry can serve as a great model for other campaigns focused on bird safety, like Audubon’s Lights Out program.”
“We have made great strides in understanding how FAA lighting can affect wildlife,” observed Christi Calabrese, Director of Permitting and Environmental Affairs for EDP Renewables. “There will always be more to learn, but we are committed to continuing to work closely with AWWI and other partners to identify areas that need more research, exploring them using sound science, and figuring out how to minimize or eliminate any risks.”