As bright beams illuminate the New York City skies above the National 9/11 Museum & Memorial’s Tribute in Light, thousands of migratory birds circle and call, disoriented by the lights. As the swirl intensifies, Cornell Lab of Ornithology scientist Andrew Farnsworth gives the signal, the lights turn off, and the birds disperse into the night.
Each year, nearly 600 million birds are estimated to die in collisions with buildings in the United States alone. By observing birds at the Tribute and using radar to detect birds aloft beyond the beams, Andrew and collaborators showed that densities of birds over lower Manhattan could reach 150 times normal levels when drawn in by the lights. The Cornell Lab’s BirdCast project now tracks and forecasts bird migration with radar across the country, enabling groups like Houston Audubon to ask their cities to save birds by turning off lights during peak migration.