Bird populations have declined over the past 30 years. According to study in 2019, North America has 3 billion fewer birds than it did in 1970, a 29% decrease.
Scientists, including Oklahoma State University wildlife ecology professor Scott Loss, estimate that up to 1 billion birds die every yearin the United States after colliding with a building — a side effect of light pollution from cities. Now, researchers are using weather radar technology to track migrations with the hope to predict and prevent collisions.
"Birds have a tremendous value to ecosystems and their functions, their pollinators, they're seed dispersers," Loss says. "They control certain undesirable insects and other pests."
Loss says coming up with solutions to bird window collisions could go a long way toward helping birds, particularly those that fly at night.
Radar technology may be part of the solution. When large flocks are seen migrating across the country, cities could be given a heads-up to dim lights. Loss says the radar works similarly to a weather forecast.
"Just like precipitation, the color scale represents intensity of the radar return with heavy precipitation, you get the darker greens, the yellows, the reds,” Loss says. With heavy bird migration, you get the same."
Scientists have been able to pick up birds on radar since the 1940s. Now, recent research from Oklahoma State University shows that the number of collisions could be predicted by how many birds migrate at night.
"When we saw a lot of birds coming through the airspace, and they were migrating at lower heights, we would expect, you know, a higher number of collisions to occur," said Jared Elmore, a research associate at Mississippi State University and lead author of the study.
Conservation efforts are already playing out in Texas with a pilot project called Lights Out Texas.
Loss is working with the Cornell Lab of Ornithology to partner with politicians and local conservation groups to encourage residents and businesses to dim nonessential lights in major cities like Dallas, Houston and Austin through June 14.
Some politicians have jumped on board. Dallas mayor Eric Johnson recently encouraged businesses and homeowners to dim lights from April 19 to May 7, when a large number of birds were expected to fly over the area.
Light pollution
Migratory birds travel every night in the spring and fall, and use the stars and the earth’s magnetic field to guide them from place to place, according to Andrew Farnsworth, a senior research associate at the Cornell Lab of Ornithology.
Light pollution from cities can throw those senses off.
"As soon as you add light pollution into the mix, which light is an incredibly strong stimulus in terms of attracting and disorienting birds, it really adversely impacts their capabilities to use those orientation and navigation tools that they have," Farnsworth said.
Sirena Lao, an environmental outreach and education specialist at the San Francisco Bird Observatory that studied light pollution and bird collisions as a graduate student at OSU, said light pollution leads birds to danger.
"Birds are kind of driven off course by light pollution, they're often attracted to bright city lights," Lao said. "… So birds will kind of veer off course and fly towards these cities, which, you know, leads them to even more hazards."
Hope for change
The Lights Out Texas project ends June 14 for spring migration, and Loss said the project will continue in the fall. After that, Loss and Farnsworth will analyze collisions data in comparison with lighting data to see how effective the program was.
Elmore said he hopes his research could inform public policy.
"It (the radar) can hopefully be more effective than just, you know, making a broad suggestion of, 'hey, turn off your lights all the time,' because people don't like to do that," Elmore said. "But if you can nail down a few times out of the year, when it would be greatly beneficial to turn off those lights, then people may be more likely to, you know, follow those suggestions."
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