A new study has presented convincing evidence that night lights cause serious altered behaviour among night-migrating birds.
Scientists from the University of Oxford, the Cornell Lab of Ornithology, and New York City Audubon examined migrating bird behaviour over seven years at a special location, the ‘Tribute in Light’ in New York City. The tribute is held to commemorate the 11 September 2001 terrorist attack on the World Trade Center.
During the tribute, two strong beams of light, each with 44 xenon bulbs of 7,000 watts, pierce the night sky, replicating a light-image of the ‘twin towers’ of the World Trade Center, where nearly 3,000 lives were lost.
"We found that migrating birds gather in large numbers because they're attracted to the light," says Benjamin Van Doren of Oxford University, a lead author of the study. "They slow down, start circling, and call more frequently. They end up burning energy without making any progress and risk colliding with nearby buildings or being caught by predators."
The New York City study has been a rare opportunity to witness the impact of powerful ground-based lights on nocturnally migrating birds, according to co-lead author Kyle Horton, now with the Cornell Lab but working at the University of Oklahoma during the study. "This analysis would not have been possible without the help of tribute organisers."