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Thursday, June 13, 2024 | Back issues
Courthouse News Service Courthouse News Service

Embracing Philadelphia’s Dark Side: Birders Push for a Change in Lighting

When bird-migration patterns turn the skies into a highway, brightly lit buildings give way to airborne roadkill. A group of nature enthusiasts hope local businesses will opt to change that.

PHILADELPHIA (CN) — Evidence of birds that didn’t make it all the way south for winter are not uncommon. Audubon volunteers typically find a dozen by the day within a 3½-block radius in Center City Philadelphia — all the victims of window collisions.

Last fall, however, bird deaths plunged into the thousands.

“We just hadn't had anything like this, that we're aware of, for quite a long time,” Keith Russell, urban conservation program manager with Audubon Mid-Atlantic, said in a call Friday.

The event prompted Philadelphia’s induction into a group of 33 other U.S. cities that call on members of their commercial districts every fall and spring to consider turning off as many lights as they can, both indoors and out.

Lights Out runs between April and May, then again August through November. The strictly voluntary program has also been embraced in New York, Boston and Chicago. In Philadelphia, it’s made possible by Bird Safe Philly, a partnership of the Academy of Natural Sciences of Drexel University, the Delaware Valley Ornithological Club, Audubon Mid-Atlantic and several regional Audubon chapters.

“We felt this was an opportunity to try to bring awareness to the issue of bird window collisions in Philadelphia, which has been going on for over 100 years,” Russell explained. “The first collision in Philadelphia was recorded in 1896 at City Hall,” the same year lights were first installed on Philadelphia’s City Hall tower.

Because birds use cues from the stars to navigate during migration, experts say, lights can be particularly confusing on cloudy nights.

This large group of dead birds was discovered after an exceptionally bad day for Philadelphia window strikes: Oct. 2, 2020. (Photo by Stephen Maciejewski, courtesy of Academy of Natural Sciences, via Courthouse News)

On the night of Oct. 2, 2020, when up to 1,500 met their demise in center city Philadelphia, the skies were both cloudy and rainy. This may have caused birds to fly lower than usual. It must have been a peak day of the journey. Around that time, temperatures in the northern reaches of Canada, Maine and upstate New York had dropped suddenly — potentially then triggering the birds to take flight en masse toward Central and South America.

“We have huge, huge numbers of birds that pass through. Philadelphia is a migration superhighway,” he said. “We're responsible for millions of birds living and traveling all over the continent, so it's important to protect these birds from undue harm that's caused by us.”

In addition to the issue of city lighting, transparent and reflective glass can trick birds into thinking they have found a place to land, Russell noted.

Scientists have estimated that anywhere from 365 million to 1 billion birds die in collisions with man-made structures every year in the United States.

The species that fly into Philly buildings most often are common yellowthroats, white-throated  sparrows, gray catbirds and ovenbirds. Russell said some birds appear to be more susceptible than others to window collisions. 

“But why they're more susceptible is probably a complicated issue that we don't fully understand,” he continued. “There are some birds that migrate to Philadelphia in really large numbers like the yellow-rumped warbler, and we almost never find them. There are other birds that are much less numerous like the yellow-breasted chat, and they appear often.”

Rows of bird specimens in the Ornithology Collection of the Academy of Natural Sciences of Drexel University. (Photo courtesy of ANS via Courthouse News)

Jason Weckstein, associate curator of ornithology at Drexel University's Academy of Natural Sciences, catalogues specimens found by Audubon volunteers. He adds them to the museum’s collection of more than 220,000 birds. 

He said in a call Friday that, in addition to monitoring which species have run into windows, the samples create a historical record that shows how birds evolve.

For one thing, the comparisons show how large some birds are getting.

“It’s very likely somehow related to climate change,” Weckstein said.

To see if its Lights Out campaign has an impact, the Bird Safe Philly coalition will be broadening its monitoring throughout the city.

Among nearly 20 “early adopters” of the initiative are several iconic members of the Philadelphia skyline: One and Two Liberty Place, the Comcast Technology Center and Comcast Center, the Mellon Bank Building, all of Brandywine Realty Trust's Center City, and University City buildings.

The buildings are a few of the 475 members of the Building Owners and Managers Association of Philadelphia who own or manage commercial properties.

Weckstein noted that Bird Safe Philly is asking citizens to monitor bird collisions, too, via iNaturalist, which allows users to submit photos of bird collisions. The academy will also be putting a dropoff area outside for anyone who wants to donate birds they find dead near windows.

Like charity, though, bird safety can begin at home. 

“If you have a window on your house that you're regularly finding birds hitting you can put a treatment on the glass,” he said. “Having the lights down can help as well.”

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