Philadelphia is about to go completely dark at night. Here’s why

On a single night in October 2020, more than 1,000 birds crashed to their deaths against the windows of tall buildings in downtown Philadelphia. Blamed on a rare convergence of the semiannual migration period and bad weather, a major contributing factor was the abundance of lights left on inside tall buildings overnight. By the next morning, the streets were littered with dead birds.

“There were just hundreds of birds everywhere. It was like nothing we had ever experienced,” says Keith Russell, program manager for urban conservation at Audubon Mid-Atlantic, the regional office of the national bird-focused nonprofit. The group had been calling on building owners in the city to do something about bird collisions since 2006 and had been conducting regular counts of bird deaths in the city since 2008, but not much had changed.

Bird deaths resulting from collisions with buildings are nothing new. Seemingly clear flight paths seen through the windows of buildings, reflections of trees and other potential habitats, and the lure of bright and confusing lights during nighttime migration all contribute to a shocking number of bird-building crashes. Researchers estimate that collisions with buildings cause up to one billion bird deaths annually in the United States, making a very clear argument for why buildings and cities need to be designed with birds in mind.

But the scale of death on that October night was galvanizing. “There was a lot of learning and a lot of awareness that came out of that,” Russell says.

After 15 years of effort, Audubon Mid-Atlantic and several other local organizations have succeeded in convincing building owners to do more. Beginning April 1, and running for the duration of both the spring and autumn bird migration periods, buildings across Philadelphia will be voluntarily turning off their lights at night.

The initiative, Lights Out Philly, runs from April 1 to May 31 and again from August 15 to November 15, and it calls on building owners and managers to turn off, dim, or block any lights within buildings that are typically left on at night. It also calls for nonessential lights, such as those illuminating building signs or sponsor logos, to be turned off or switched to green or blue colors that are less likely to attract birds than red or white. For these twice-annual migration periods, turning off lights can help reduce the potentially deadly lure and distraction of buildings, keeping the tens of millions of birds that travel through Philadelphia along the Atlantic Flyway on their flight path.

The initiative has the backing of ?the City of Philadelphia’s Office of Sustainability and has received commitments from more than a dozen large building owners, the Building Owners and Managers Association of Philadelphia, and the Building Industry Association of Philadelphia. By turning off lights, building owners can save bird lives while also saving on energy costs. “This is good for the environment in more than one way,” says Russell.

Audubon Mid-Atlantic has already started monitoring the effectiveness of the program, with seven volunteers canvassing the downtown area beginning at 5:30 a.m. and running through the end of May.

Philadelphia joins 33 other cities in the United States that have their own Lights Out programs, including New York, Atlanta, and Chicago, which has had the program in place since 1999. Other efforts have been made to reduce the risk to birds in Philadelphia, including the installation of glass marked with tiny patterns that deter birds. But Russell says that during migration periods, turning off lights is crucial, especially in Philadelphia, which is one of only a few major cities on the Atlantic Flyway, and the site of the most significant mass collision event in recent memory.

“Even though glass is a huge problem, the lights are the main reason why we have mass collision events,” Russell says. “There have been a couple of those recorded in the city in the past, and there have also been mass collision deaths around the country in other cities. And they’re always associated with lights.”

Though the center of the city is where most bird deaths occur, its tall buildings and nighttime lights aren’t the only culprits. Russell says buildings throughout the city should consider pledging to join the Lights Out Philly effort, during the migration periods and beyond.

“This program also asks people that are living in low-rise buildings and single-family homes to participate,” he says. “That can really be very helpful to do this during migration, but ultimately if they extended this throughout the year it would be even better.”