The annual Tribute in Light, in which beams of light are shown into the sky to commemorate the victims of the September 11th terror attacks, has been an essential part of the city's 9/11 memorial since 2002. But starting around 2006, the NYC Audubon has been monitoring the tribute because of its potentially hazardous affect on birds, which has led to the light being turned off for portions of the evening.
"It's probably the most stressful night for me every year, I'm up on the roof all night long, just watching the birds hoping we don't get too many, hoping we don't have to make the call," Kaitlyn Parkins, Associate Director of Conservation & Science with NYC Audubon, told Gothamist. "We want the lights to be on, we understand what an important memorial it is. When the birds are trapped and they're coming in low and exhausting their energy trapped in the beams, it's incredibly upsetting."
Installing the lights usually takes a crew of about 30 technicians, electricians, and stagehands over a week before the switch is even turned on. The light installation involves "eighty-eight 7,000-watt xenon light bulbs positioned into two 48-foot squares, echoing the shape and orientation of the Twin Towers," according to the National September 11 Memorial & Museum, which manages the installation. On a clear night, the lights can be seen 60 miles away and extend four miles into the sky.
The artificial light attracts a variety of birds, including fledgling seabirds and migrating songbirds, which can lead to them becoming disoriented, flying in circles, or even crashing into buildings. Parkins clarified that bird collisions are not an exclusive result of the Tribute In Light: "What the Tribute does is pull birds in and they can get trapped in the light and exhausted, but there's this narrative that they're then crashing into buildings all night long, and that's not the case," Parkins said.
Bird collisions are already a problem throughout the city, starting in September as birds start migrating: "We've had quite a few collisions [this year], my understanding is that some of our volunteers found around 50 birds that collided with buildings this morning," Parkins said.
One study in 2017 found that the memorial's light beams cause birds to aggregate in high densities, decrease flight speeds, follow circular flight paths, and vocalize frequently. Between 2009 and 2016, around 1.1 million birds were influenced by the installation, with many of them becoming disoriented and collapsing in the street.
"The Tribute In Light really brings attention to the fact that, even though you can't see them, there are hundreds of millions of birds flying over New York City, and there are things that humans do to impede that," Dr. Susan Elbin, director of conservation and science at NYC Audubon and an author of the study, previously told Gothamist.
Over the years, NYC Audubon has gathered enough evidence to prove that turning off the lights for periods of time will help birds continue their migration. So every year, they have teams of experienced counters take two-hour shifts underneath, scanning the beams, taking a photo of the sky every 20 minutes, and counting the number of birds.
"When that number gets over 1,000, the lights are turned off for about 20 minutes, which allows the birds to disperse, and then the lights are turned back on," Parkins said. "And we do that all night, from 8 p.m. to 6 a.m."
As for how much it is turned off, that's variable depending on weather and migration density: "Last year we didn't have to turn the lights off at all, but in previous years we've had to turn the lights off ten or more times."
Besides their work monitoring the Tribute In Light, NYC Audubon has engaged in a few other initiatives to try to help birds during this crucial period. That includes Lights Out New York—which has gotten major structures including the Chrysler building to go dark from midnight until dawn during the two-month peak migration period that begins each September—and Project Safe Flight, which encourages bird-friendly building designs (like retrofitting buildings with less reflective glass), and enlists volunteers to help keep track of bird deaths.
