Turn Off the Lights This Spring and Fall; Save Millions of Lives

The artificial light of New York City (here, Manhattan) draws night-migrating birds off of their ancient migration routes. Once drawn into the urban landscape, birds may become disoriented and are more likely to strike windows, both at night and in the morning. " Photo: Daniel Mennerich/CC BY-NC-ND 2.0


This article appears in the Spring 2023 issue of The Urban Audubon.

By Carol Peace Robins

Seventy percent of North American bird species are migratory—and among those, more than three-quarters migrate at night. In short, this means that roughly half of all North American birds are nocturnal migrants. We know that artificial light at night does great harm to these nighttime travelers. But exactly how and why this happens takes some explaining.

The Problem

To start, artificial lighting, both external and internal, attracts migrating birds. But this phenomenon must be considered at several different scales: locally, lights cause collisions; at a larger scale, lights attract birds toward cities; and at a regional scale, birds are pulled off of their historic migratory routes. As many as one billion birds die in window collisions each year in the U.S., and many of these collisions can be attributed to light pollution.

Lured away from their ancient routes, migratory birds end up in a web of glare. Their innate abilities to use the Earth’s magnetic field and celestial clues to determine location and direction, which have evolved to function in the natural light of the night sky, are thrown off course. Disoriented by the light, they may flutter around aimlessly, becoming exhausted. They may strike buildings at night, often repeatedly. And they may be stranded in inhospitable areas after sunrise—and then collide with windows that offer illusions of safety in reflected sky and trees, causing injury that leaves them susceptible to predators, and often death.

The collision victims pictured here (roughly from right to left, one Yellow-rumped Warbler, three Golden-crowned Kinglets, one Swamp Sparrow, three Brown Creepers, one White-throated Sparrow, and one Ovenbird) were found by Project Safe Flight volunteer Melissa Breyer on her collision monitoring route in the World Trade Center area this past October 15. These preventable deaths are the result of a combination of artificial light at night and reflective glass. Photo courtesy of Melissa Breyer

How often birds collide at night and how often in daylight is not entirely clear (and that question is a subject of future NYC Bird Alliance research). But altogether, NYC Bird Alliance’s Project Safe Flight data indicate that up to a quarter million birds die each year in window collisions in New York City alone.


Turning off the lights is one obvious remedy to this problem—but making that happen isn’t easy. Lately New York has made great progress at both City and State levels. In December 2021, supported by the advocacy of NYC Bird Alliance and other environmental, academic, and animal welfare organizations, the New York City Council passed two laws that are good steps forward:

  • Int. 274 requires all City-owned or occupied buildings to turn off outdoor lights from 11pm to 6am during peak periods of spring and fall migration. 
  • Int. 271 requires City buildings to install occupancy sensors, ensuring that indoor lighting shuts off automatically when no one is present.

A third proposed City Council law, Re-Int. 265, would hold all commercial and mercantile buildings in the City to the same requirements as City-owned buildings. This bill did not advance to a vote in 2021 but now has a sponsor in City Council Member Francisco Moya of Queens. NYC Bird Alliance is working with a coalition of partner organizations to ensure the bill comes up for a vote this year, and to build grassroots support to aid its passage.

As for New York State, in January 2022, State Senator Brad Hoylman-Sigal (representing lower and midtown Manhattan) and Assembly Member Patricia Fahy (representing Albany and surrounding areas) introduced the Dark Skies Act, which would require that most nonessential outdoor lighting be extinguished after 11pm. This bill, which has strong support from our partners at Audubon New York, will likely come to a vote soon.


And do such measures work? The two previously passed New York City Council Lights Out laws mentioned above are still being phased in, so it’s too early to assess results. But elsewhere, there are plenty of indications that Lights Out saves birds. 

  • NYC Bird Alliance Advisory Council Member Andrew Farnsworth of Cornell Lab of Ornithology, a co-author of a Chicago-based study, reports that when half the illuminated windows of Chicago’s McCormick Place, a large conference hall on a lake front, were turned off during spring migration, collisions were reduced by 60 percent. 
  • In Germany, a study of a 41-story building during six autumn migrations concluded that “the numbers of casualties found . . . illustrate the significant negative effect on birds that such buildings have” due to artificial light at night.

Evidence of the importance of reducing artificial lighting is also beginning to mount closer to home. In 2022, building managers at downtown Manhattan’s Brookfield Place turned out lights along one façade during spring and fall migration, in consultation with NYC Bird Alliance. To test this Lights Out measure, Project Safe Flight volunteers monitored collisions before and after the policy was in place. The volunteers found zero collision victims in spring, and in the fall saw collisions reduced by 77 percent compared to the previous year.

Two important caveats to these exciting results are that the Lights Out efforts at Brookfield Place took place at just one façade among many at the building complex—birds may have still collided elsewhere—and that there is high variation in the number of collisions between years. We need more than one year of data to confirm if this Lights Out effort was effective. There is still a significant amount of work to do to make Brookfield Place bird-safe, but these early efforts are evidence that Lights Out may be a viable solution.

Lights Out legislation—and implementation—is essential. As is bird-friendly design. Current Lights Out advocacy efforts follow on the heels of the 2019 passage of New York City’s landmark Local Law 15, which requires all new construction and significantly altered buildings to use bird-safe materials. Imagine how many millions of birds will be saved if both bird-friendly design and reductions in lighting become part of our everyday lives—here and all over the world.

Learn more about upcoming Lights Out legislation, and how you can help, on our Lights Out legislation page