Birds on 9/11The 9/11 light tribute with birds in dangerous spiral.Photos: Jennifer PredigerMuch was illuminated this past Saturday, September 11, as two beams of light glowed in New York to memorialize those lost nine years ago in the terrorist attack on the World Trade Center.

The “Tribute in Light” soars up through the space over Manhattan where the Twin Towers once were. Every year, the lights symbolize and resonate. They also highlight something majestic happening in the skies.

From across the East River on Governor’s Island, the lights appear to be filled with glitter. Golden specks twinkle in the rays. Get closer, and you can see that the glitter has wings.

The memorial lights coincide with the fall bird migration down the East Coast. The 88 spotlights that make the two beams can be a fatal attraction for the fliers. Since 2003, Audubon and the producers of the memorial have been working in partnership to protect the birds drawn into the light that can cause them to descend from the sky in a death spiral during these night migrations.

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“A number of shorebirds and songbirds use principally visual cues,” said John Rowden, citizen science manager of Audubon New York. “They use the star map and the moon. There was no moon [Saturday] night. So the star map is what they use to cue in on. The lights can be this disorienting and distracting thing for them. As we could see, they’d fly in and fly out and make these looping turns.”

If there are significant numbers of birds affected by the lights, they can be temporarily shut off to allow them to keep moving out of the city.

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This weekend, there were more birds than usual migrating. That meant many more birds in the lights than previous years. Thousands found themselves in a dangerous dance with brightness. Audubon staff, volunteers, and the Municipal Art Society, the sponsors of the light display, worked together to monitor the birds and shut off the lights for 20-minute intervals so that migrating birds and monarch butterflies heading to Mexico could pass through.

A dead Warbler.A fallen warbler.From about 8:30 to 11 p.m., the numbers of birds grew exponentially. They flew in circles up into the great heights where the lights reach. Then a pine warbler was found dead on the street below the memorial, so the team on the parking garage rooftop where the lights are positioned shut the lights down a little after 11 p.m.

“If you see any dead birds, it’s a cue there’s a problem,” Rowden said.

Bright city lights in general can have a detrimental impact on migrating birds’ finely tuned navigation systems. Lights Out New York, a NYC Audubon program, encourages office buildings to turn off their lights after midnight from September to November, the height of the annual avian pilgrimage.

“There were so many birds [this year] because of a combination of things. There had been a period where no birds were migrating,” noted Rowden. “Conditions were not favorable for them to migrate for a long period from southerly airflow. There would have been a headwind. There was a hurricane. Birds were piling up. So all those birds start pushing south.” 

LightsForty-four spotlights make one of the memorial tower beams.This September 11, the beams were turned off five times over the course of the night due to the high volume of air traffic in the flyway, a precaution that likely saved the lives of untold numbers.

The lights lit up the unexpected. Thousands of birds are flying overhead as we sleep. The unseen world goes unnoticed until you shine a light on it. The memorial lights will shine again next year.