9/11 tribute lights dramatically alter bird migration: Study

The two light beams formed by 88 7,000-watt bulbs, shone annually in New York as a tribute to 9/11 victims, "dramatically alter nocturnal bird migration", a US-based study has found. Researchers estimate the installation influenced about 1.1 million birds during seven such days. Birds were observed to aggregate and follow circular paths, slow down and call more frequently than normal.