Tuesday, April 16, 2019

Top Cities Where Lights Endanger Migratory Birds

An American Redstart killed in a building collision

An estimated 600 million birds die from building collisions every year in the United States. Scientists at the Cornell Lab of Ornithology have published new research highlighting artificial light at night as a contributing factor.

The research was published in the journal Frontiers in Ecology and the Environment. It combines satellite data showing light pollution levels with weather radar measuring bird migration density.

Researchers ranked metropolitan areas where, due to a combination of light pollution and geography, birds are at the greatest risk of becoming attracted to and disoriented by lights and crashing into buildings.

most dangerous cities for birdsBecause many birds alter their migration routes between spring and fall, rankings of the most-dangerous cities change slightly with the season. During spring migration, billions of birds pass through the central United States between the Rockies and the Appalachians, so cities primarily in the middle of the country comprise the most-dangerous list for that season. Heavy spring migration along the West Coast also puts Los Angeles on the spring most-dangerous list. Fall bird migration tends to be intense along the heavily light-polluted Atlantic seaboard, which is why four eastern cities make the list in autumn.

In a statement to the press, lead author Kyle Horton, a Rose Postdoctoral Fellow at the Cornell Lab said: “Chicago, Houston, and Dallas are uniquely positioned in the heart of North America’s most trafficked aerial corridors. This, in combination with being some of the largest cities in the US, make them a serious threat to the passage of migrants, regardless of season.”

Although bird migration in spring and fall lasts for months, the heaviest migratory activity occurs during the span of just a few days. For example, a top-ranked light-polluting city can expect half of its bird-migration traffic to pass through over seven nights spaced out during the season; these nights are unique for each city and depend upon wind conditions, temperature, and timing.

Horton also notes that, given an estimated quarter-million birds die from collisions with houses and residences every year, even homeowners in these most dangerous metro areas for migrating birds can play an important role.

“If you don’t need lights on, turn them off,” states Horton. “It’s a large-scale issue, but acting even at the very local level to reduce lighting can make a difference. While we’re hopeful that major reductions in light pollution at the city level are on the horizon, we’re excited that even small-scale actions can make a big difference.”

Support for this study came from the Edward W. Rose Postdoctoral Fellowship, Marshall Aid Commemoration Commission, the Leon Levy Foundation, and the National Science Foundation.

Images, from above: An American Redstart killed in a building collision by Ben Norman, and Most Dangerous Cities For Birds Chart.

Related Stories

Stories under the Almanack's Editorial Staff byline come from press releases and other notices.

Send news updates and story ideas to Alamanck Editor Melissa Hart at editor@adirondackalmanack.com.

4 Responses

  1. Charlie S says:

    600 million! Geez. We’re worse than I thought! Poor birds! Where I live the mayor is like other mayors…he likes lights. It wasn’t long ago that new LED lights were installed around the library. I woke up one morning early like I do every morning, when the stars are out and the noisy populace is sleeping. Upon stepping out my door I immediately noticed the neighborhood was much more lit up than it had been. They installed very bright LED’s on top of steel posts so that now it is always daylight in my neighborhood. It is quite evident that the birds are thrown for a loop by all of this brightness as they start singing early, and lately I’ve been seeing them dancing around under the trees and even tagging after each other from limb to limb. They touch down on the ground then fly off again and alight on bare limbs….hours before sunup. Let there be light! Our leaders are all about cosmetics and it’s a shame there are so few who have illumined souls. Most of what we have are leaders who accommodate brick and mortar. Build build build! Every time I see another structure go up, which is quite frequently down here in the Capital region, I cannot but help think about how there is one less haven for the unseen critters, which we don’t see even when our vision is 20/20. 600 million bird deaths a year! Geez! I see no hope for the human race.

    • Boreas says:


      Geez indeed! And that is just in the US! You can also add to this number many more millions of bird strikes at radio, TV, and microwave (cell) towers – either from the tower itself or its guy wires. And we are still learning about wind energy kills to birds. That’s progress!!

      It would seem the least we could do is continue to create or conserve habitat when possible to bolster their breeding success. Keeping cats indoors and neutering or euthanizing feral domestic cats can also play a part. But cat predation is much different, even though it seems to get more press. Cats are predators, and birds have at least co-evolved with them and have some instinctive defenses to predation. But birds have no defenses against virtually invisible (to birds), unnatural barriers in the night sky. Unfortunately, there is virtually no political willpower to address the issue.

  2. Charlie S says:

    Cats are another thing yes Boreas, and wires and wind mills. It is all so very sad that we do not think about the birds, or all wildlife, when we go about our business.

    • Boreas says:


      An interesting notion is what will humans do if they decide to terraform Mars or other celestial bodies. They will certainly bring plants, but will they bring animals? And if so, which ones? Just the warm, cuddly ones? Just the ones we can domesticate and eat? Will they bring biting insects and vermin and predators? If what we are doing to this planet unnerves us, think about the junkyard we are already creating in space.

Wait! Before you go:

Catch up on all your Adirondack
news, delivered weekly to your inbox