9/11 Tribute in Light Illuminates Thousands of Migrating Songbirds

By Hugh Powell
September 13, 2012
9/11 tribute in light Photo by Greg Chow via Creative Commons.

On the eleventh anniversary of 9/11, twin spotlights once again shot into the night sky above Manhattan to offer a tribute to the men and women we lost during the 2001 attacks.

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It was a clear and cool night, almost calm and with a hint of a southerly breeze. In another long-repeated annual event, thousands of birds passed over New York City on their way to winter homes in the southern U.S. and Central and South America. Cornell Lab scientist Andrew Farnsworth was on hand to count them.

Farnsworth spent the early evening until about 10:00 p.m. atop the Empire State Building and then watched from the Tribute in Light itself until 12:30 a.m. (accompanied by other birders and a Wall Street Journal reporter). In all he saw at least 2,000 birds and heard the faint chip notes of many more. He identified 28 species passing overhead and at times flying through the beams of light, where the rush of bodies looked like flurries of snow, he said.

Watching carefully with binoculars, he was able to identify a bewildering diversity of the tiny, 5-inch songbirds as they passed through the beams, recording Magnolia, Chestnut-sided, Black-and-white, and Blackpoll warblers, as well as Common Yellowthroats, Ovenbirds, Northern Waterthrushes, and 43 American Redstarts. Five male Black-throated Blue Warblers were still in such bright plumage that they “stand out like a sore thumb in the lights,” he wrote in his eBird checklist for the night. He also recorded Wood Thrushes, Swainson’s Thrushes, Veeries, Rose-breasted Grosbeaks, Gray Catbirds, and Baltimore Orioles.

The lights illuminated a few larger birds as well, including a young Laughing Gull that was trying to catch insects, three Green Herons, an unidentified rail (likely a Sora)—as well as a Peregrine Falcon that made repeated hunting dives at the smaller birds. Farnsworth said he saw at least five successful attacks on warblers.

The Tribute in Light happens during a time of peak migration in the Northeast. The birds often become briefly disoriented in the lights, and most years the lights are briefly shut off throughout the night to allow circling birds to reorient themselves. This year, on a night with only moderate migrant traffic, Farnsworth saw no evidence of casualties (aside from the peregrine’s catches).

The Tribute serves as a double reminder: that city lights, when left on en masse, nationwide, for an entire migration season, take a major toll on migrating birds (see the Fatal Light Awareness Program for more); but also, of the great spectacle of bird migration that accompanies us through fall. An invisible river of animals, rivaling any scene from the Serengeti but consisting of half-ounce birds that pass quietly overhead, in the dark.

Farnsworth is a lead scientist in our BirdCast project. Its ambitious goal is to produce accurate, real-time forecasts of local migration by combining data from radar, weather conditions, and acoustic recordings of the birds’ own brief call notes, which can be identified to species. While it will be a boon to anxious birders wondering what might turn up near them (you can check predictions at the BirdCast website), BirdCast also aims to provide advance knowledge of hazardous conditions at wind turbines so they can reduce their impact on birds.

The project is still in its first year, although researchers have been applying technology to the study of migration for decades. Weather radar is good at detecting flying birds, even allowing Farnsworth to estimate the numbers of birds aloft on Tuesday night, for instance. Judging by the radar readings, he said, one cubic kilometer of New York City sky probably contained 100–200 birds at any one time on September 11. That’s not bad, according to Farnsworth, but the two previous nights had been even better, when some 600–1,000 birds filled the same volume of sky. They were audible even over city noises—cars in the Brooklyn Battery Tunnel, sirens, construction work—the birds’ short, sibilant call notes raining down at the rate of 3 to 5 per second at times.

Which brings up a third reminder from the Tribute in Light: if dozens of species, and thousands of birds, routinely pass over a metropolis in pitch darkness, night after night, then doesn’t that make autumn one of the most exciting times to be a bird watcher?

BirdCast is funded by the National Science Foundation and the Leon Levy Foundation, and involves partners at the Cornell Lab, Microsoft, the National Oceanic and Atmospheric Administration, and the University of Massachusetts at Amherst.


  • Ellen Kessler

    How many birds died during the tribute because the beams threw them off course, causing them to crash into skyscrapers?

  • Jeanette Downing

    Really enjoyed article and information gathered,tribute to 911 as well as being informed of nightime flight activity and migration of birds. Thank you for expanding our knowledge.

    Warm regards, Jeanette

  • Renee Ward

    The beams are just light, why would it harm the bird? I think they are used to encountering lights.

  • Brian

    Ellen: That was answered in the article. “…Farnsworth saw no evidence of casualties…”

  • Kathy

    Ellen, in the article it is stated, “This year, on a night with only moderate migrant traffic, Farnsworth saw no evidence of casualties (aside from the peregrine’s catches).

  • ellen kessler

    I asked because, if I remember correctly, there were numerous avian deaths during the 10th year anniversary light show.

  • Amy

    I think spotting dead warblers laying on the ground from the top of a skyscraper, in the middle of the night, would be difficult, don’t you think?

    To look for casualties, a better way would be prowling the streets in the early morning hours. Farnsworth quit counting at 12:30 AM.

    So, just because this observer did not notice any casualties does not mean there was none. It is likely there were many.

  • Hugh

    Hi Amy – Your reasoning is right-on, and in fact there were people out looking on the streets for dead birds the next morning—we don’t have reports on what they found yet. The larger point to be taken from this event is not so much that the Tribute in Light is a hazard to birds, but that the skyscrapers and other city lights that stay on all night, all year, over much of the continent, create a much larger and more persistent problem for birds. The Fatal Light Awareness Program has more on this if you’re interested. Thanks for commenting – Hugh

  • Ellen

    While what you say about 24-hour-a-day lights is valid, Hugh, you’re diluting the discussion about the bird deaths during the 9/11 tribute. Knowing fully well that this was peak migration time for many species, the tribute lighting should have been more subdued. The lights don’t have to be seen from outer space in order to make a point. To me, the tribute is quickly losing its meaning.

  • casey

    Loved this article. I’m a new birder and the comment on looking for dead birds the following morning made me wonder… do you add a bird species to your list if you only saw it dead? Unfortunately the most magnificent Cedar Waxwing fatally crashed into my garage door window panels and that is the only one I’ve seen. It was March in Alabama. Thankfully, that was the only bird that I’m aware of that has crashed into them.

  • Lucy

    Add the waxwing to your list, Casey, and hopefully you’ll see one soon in happier conditions.

9/11 Tribute in Light Illuminates Thousands of Migrating Songbirds