^{Volunteers monitor the Tribute in Light every 20 minutes to make sure a critical mass of birds is not circling the lights. Photo: NYC Audubon}

Katherine Chen and Dustin Partridge, PhD | September 18, 2022

From 8pm on September 11, 2022 to 6am on September 12, 2022, NYC Audubon scientists, board members, Young Conservationist members, and other dedicated volunteers were stationed on the roof of the Battery Parking Garage in lower Manhattan. Equipped with binoculars, clipboards, raincoats, and lots of caffeine, these individuals were tasked throughout the night with regularly looking up at and monitoring the Tribute in Light, the stirring annual light installation honoring the lives lost during the 9/11 terrorist attacks. The Battery Parking Garage serves as the base for the Tribute, which is powered by 88 high-intensity light beams and is visible from many miles away from dusk to dawn each year.

For over 25 years, NYC Audubon's Project Safe Flight has studied the factors that lead migratory birds to collide with buildings in New York City, and through our research, we've learned that artificial light is one of the primary causes.

We've gained tremendous insight into artificial light's effects on birds largely through our annual monitoring of the Tribute in Light, which takes place during the middle of fall migration and can sometimes attract huge numbers of night-migrating birds traveling from up to five kilometers away. The attracted birds can then get “caught” in light beams, circling endlessly and depleting the precious energy needed to continue on their migrations. 

Luckily for our birds, the Tribute organizer National 9/11 Memorial & Museum has allowed us to monitor the installation for over 21 years to ensure a critical mass of birds does not get trapped in the light beams for long periods and permitted us to conduct artificial light research at the site with Cornell Lab of Ornithology. Through this partnership, we've been able to further our understanding of artificial light’s effects on birds, demonstrating that the twin beams can attract bird densities up to 150 times higher than when the lights are not on.

To prevent unnecessary harm to birds, we monitor for a high buildup of birds at the Tribute each year, methodically counting the number of birds in the light beams every 20 minutes throughout the night. Whenever this count surpasses a threshold of 1,000 birds between both beams, or if birds are seen circling and calling low in the beams, we ask the production team to turn off the lights for 15-20 minutes to allow the birds to regain their bearings and fly away safely. The Tribute in Light organizers are always respectful of our requests and we are continually thankful for their willingness to help us ensure that the Tribute is safe for nocturnally migrating birds. 

It misted, drizzled, and poured throughout the night, yet New York City Audubon stayed outside, beneath the beams, monitoring for birds straight through the night. While the conditions for monitors were poor, we actually felt incredibly lucky to be out at the Tribute during this downpour: rainy weather nights deter birds from traveling on their migrations, which hopefully would mean very low migration activity across the city and, most importantly for us, few birds being attracted to the lights. 

 

Indeed, the rain resulted in few birds flying through the city, and the fog seemed to dissipate the effects of the light beams, making them possibly less of an attractant to birds. Over the course of the entire night, there were never more than 10 individual birds stuck in the beams, and none were trapped for long. 

While there was little activity in the beams, we did identify some species passing through our area: Common nighthawks were observed throughout the night, while American Redstart night-flight calls were heard and several other warblers were observed. In the early hours of the morning, we were delighted to see a Peregrine Falcon actively hunting rock pigeons along the beams. And we found a katydid hanging around the Tribute as well!

This year, we were joined by members of the BirdCast team such as researchers from the Cornell Lab of Ornithology, Dr. Kyle Horton's AeroEco Lab from Colorado State University, and Dr. Jeff Kelly’s lab from the University of Oklahoma. While research activities were planned for the evening, including thermal imaging of birds and night flight call recording, there were never enough birds or dry enough weather to use the equipment. 

We thank our volunteers, board members, and visiting researchers for staying up all night to keep the Tribute in Lights safe for migrating birds, despite the wet weather. We also thank Michael Ahern Productions and the National September 11 Memorial & Museum for continuing their partnership with us over the years. We will be back on-site in 2023 and once again will be ready to turn the lights off, if needed.

Learn more about our research on artificial light and what you can do to help limit artificial light pollution’s impact on our City’s birds on our Artificial Light page!