Every year on September 11th, two brilliant light beams are projected high into the sky from Lower Manhattan as a powerful tribute to those lost during the tragic attacks of September 11th, 2001 (Fig. 1). The beams were initially set up as a temporary installation by the Municipal Art Society of New York, but have been so well received that they are now an annual installation of remembrance run by the National 9/11 Memorial & Museum.
Figure 1. The ‘Tribute in Light’ memorial light beam installation is projected from Lower Manhattan near Ground Zero every year on the anniversary of the September 11th attacks. (Source: Denise Gould via Wikimedia Commons.)
The memorial is titled, “Tribute in Light”, and is made from eighty-eight large spotlights organized into two squares, each comprised of forty-four 7,000-watt xenon light bulbs that are angled straight up into the night sky . These two light projection squares represent the twin towers destroyed by the attacks, and the light is so powerful that it travels up four miles high into the sky . I have viewed the memorial from across the harbor in Brooklyn, and it is incredibly moving to see the impressive light beams dominating the Manhattan skyline (Fig. 2).
Figure 2. The ‘Tribute in Light’ memorial light beams project high into the sky, rising four miles above the Manhattan skyline with great intensity. (Source: Bob Jagendorf via Wikimedia Commons.)
Unfortunately, these beautiful beams of commemorative symbolism unintentionally present a considerable challenge for migrating birds. It’s a situation of, ‘wrong place, wrong time’. New York City sits right along the Atlantic Flyway, a migration route used by about 500 bird species that travel along the eastern seaboard twice a year. In the early fall – right around 9/11 – birds fly south along the Atlantic Flyway to seek favorable environmental conditions for the winter (i.e. warmer temperatures and more food sources). Migration flights are primarily done at night, and birds have evolved to rely on light cues from the moon, the stars, and the setting sun to guide their navigation .
Artificial light is known to disrupt migratory navigation for many birds, and the intense strength of the ‘Tribute in Light’ beams does so to an extreme degree. Birds are attracted to the light and fly towards the bright beams, which are reportedly visible up to 60 miles away from Ground Zero in all directions . Once inside the beams, they get disoriented and aren’t able to navigate back out into the dark – they become essentially ‘trapped’ inside the light beams and fly around and around, circling and circling in the narrow beam to the point of exhaustion (Fig. 3). Dead and stunned birds have been found lying on the street directly below the beams (Fig. 4). The dead bird carcasses were especially alarming the first year of the installation, before there was any awareness of the bird migration complication.
Figure 3. The ‘Tribute in Light’ memorial light beams shown here are filled with migratory birds (white specks), temporarily ‘stuck’ in the beams due to disrupted navigation. (Source: Brian Tofte-Schumacher via Wikimedia Commons.)
Figure 4. A dead pine warbler found on the street below the ‘Tribute in Light’ memorial light beams. (Source: Jennifer Prediger via Grist Magazine.)
Thankfully, people have come together to find a way to keep the memorial lights on while minimizing harm to migrating birds. The New York City Audubon Society, in collaboration with first the Municipal Art Society of New York and then the National 9/11 Museum & Memorial, have joined forces to keep the installation safe for birds. As Debra Kriensky, a conservation biologist with the New York City Audubon Society said, “[9/11 survivors] have told me the last thing they want from this memorial, which is so meaningful and beautiful…is for there to be more death on this spot”. So what’s the solution?
Every year, volunteers are recruited to join the NYC Audubon Society and take two-hour shifts monitoring the light beams from the base of the installation, next to the huge spotlights. I had the opportunity to do this as a volunteer in 2012, and the experience has really stuck with me. We all lay down on the ground with binoculars, looking straight up into the beams and scanning for birds. There were three circumstances that could lead to a temporary shutdown of the beams: 1) 1000 or more birds counted circling in the beams at the same time, 2) a dead or stunned bird found fallen from the beams to the ground, or 3) birds circling very low down in the beams, indicating a struggle to stay in flight. If any of these three criteria were met, the beams would be turned off for a brief 20 minutes to allow the ‘trapped’ birds to disperse and continue southward.
With a little teamwork and a lot of communication across groups, a simple solution has saved the lives of countless birds over the years, while allowing this poignant art installation to continue honoring those lost in the 9/11 attacks.
 “Tribute in Light”. The Municipal Art Society of New York, 2017. Web. www.mas.org. Accessed 28 March 2017.
 “FLAP Canada”. Fatal Light Awareness Program Canada, 2017. Web. www.flap.org. Accessed 28 March 2017.
 “Making the 9/11 Memorial Lights Bird-Safe”. The National Audubon Society, 2015. Web. www.audubon.org. Access 28 March 2017.
More From Thats Life [Science]