The Tribute in Light is an iconic scene in New York City on Sept. 11. The art installation honors those killed in the 2001 attacks and the resolve of the city in the following days, months and years.
The lights beam from dusk to dawn every year. However, birds can briefly interrupt the tribute.
Volunteers with the group New York City Audubon monitor the beams from 8 p.m. on Sept. 11 to 6 a.m. on Sept. 12.
Armed with binoculars, volunteers gather on the roof of a parking garage in lower Manhattan, monitoring whether the beams of light are disrupting migration patterns.
In addition to disrupting migration patterns, the organization says that its research has found that artificial lighting can disorient nocturnally migrating birds and even cause them to fly directly into glass windows.
SEE MORE: Do you remember where you were during 9/11?
"When they see habitat or sky either reflected in glass, or through it, such as in a courtyard, the birds collide at full speed," NYC Audobon states. "Many die on impact."
The volunteers count the birds caught up in the beams. When they reach a threshold of 1,000, the organization puts in a request to have the lights shut off for 15 to 20 minutes.
New York City Audubon says the organizers of the tribute are always respectful of its request, which allows the birds to reorient themselves and continue on their journey.
In 2022, New York City Audubon did not request for the lights to be turned off at any point. It was a rainy night, which the organization said led to low migration activity.
Rain is also in the forecast for Monday night in New York City, which could again lead to fewer birds migrating in the area.
SEE MORE: Remembering the 4-legged heroes of 9/11
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