There was a good reason the Tribute in Light beams were shut off several times on Friday night.

The blue beams of light that shine into the sky from the site of the World Trade Center towers on Sept. 11 attract thousands of migrating birds, which become trapped and injured in the lights. The New York Audubon Society has 200 volunteers on hand to monitor the lights all night.

The 88 7,000-watt xenon bulbs beams, which the 9/11 Memorial describes as "the most powerful shafts of light ever projected from Earth," were on until sunrise Saturday. They were turned off at least 4 times, according to spokesman David J. Ringer, as 1,000 birds began to circle and some drop to the ground.

Ringer said the weather pattern created the heaviest migration since 2010. The birds included "lots of warblers: redstart, yellow, b&w, ovenbird, parula," according to a tweet from Ringer. "Very hard to ID individuals. Orioles, tanagers too."


"[Survivors] have told me the last thing they want from this memorial, which is so meaningful and beautiful ... s for there to be more death on this spot,” Debra Kriensky, a conservation biologist at New York City Audubon who helps organize the monitoring, said in an explanation from the group.