Some of Philadelphia’s skyline, including the Comcast towers, will go dark at midnight tonight, with more buildings shutting off their exterior lights this week and beyond as part of a voluntary program designed to prevent migrating birds from becoming lured by the lights and strike structures.

The owners of the towers, and owners of BNY Mellon Center, Liberty Place buildings, and other skyscrapers have all agreed to take part the new Lights Out Philly effort during bird migration seasons as they migrate north in the spring and south in the fall, with most flying at night. The lights throw birds off migration paths, leaving them exhausted and confused.

Participating owners have agreed to turn off all lights at the top of buildings, known as crowns, as well as facades, atriums, and lobbies from midnight to 6 a.m. Not all owners of city buildings are expected to participate right away, but organizers believe more will agree to go dark as the program expands.

Managers of the buildings are also asking tenants to voluntarily turn off interior lights, though some with overnight operations might chose to leave them on. Philadelphia also sees it as a chance to reduce energy use.

The program was announced in March and was the result of an Oct. 2 event when an estimated 1,000 to 1,500 birds flew into buildings in just a small 3½-block radius of Center City during overnight hours.

» READ MORE: Philly skyline will go mostly dark at night starting April 1 in an effort to save birds

At least a dozen other building operators or owners in Philadelphia also have pledged support for the effort including Brandywine Realty Trust, the city’s largest commercial landlord; Jefferson Center; One South Broad, and 1515 Market St.

The program is the result of a collaborative effort among the Academy of Natural Sciences of Drexel University, Delaware Valley Ornithological Club, Audubon Mid-Atlantic, and the Valley Forge and Wyncote chapters of the Audubon Society. The coalition created a Bird Safe Philly program that is endorsed by the city’s Office of Sustainability, the Building Owners and Managers Association Philadelphia, and the Building Industry Association of Philadelphia.

The group’s resulting Lights Out Philly program is modeled after the Audubon organization’s national program started in the U.S. in 1999. Audubon says that billions of birds fly between wintering and breeding grounds, with a majority migrating at night. They use the night sky to navigate so artificial lights and the glow around buildings can not only lure the birds to a collision, but throw them off, leaving them confused and exhausted in the morning leaving them more vulnerable to other dangers.

At least 40 cities are now participating in Lights Out.