On the morning of Friday, Oct. 2, Philadelphia residents, workers, shoppers, and downtown tourists were horrified and heartbroken to see the ground littered with hundreds of beautiful dead and injured birds. Feathered corpses and dazed but vulnerable survivors, in a rainbow of colors, littered the streets and sidewalks of Center City. Thousands of warblers, thrushes, wrens, vireos, and other songbirds were making their annual fall migration south from their northern breeding grounds.
Unfortunately, Philadelphia’s brightly lit buildings attracted many of them to their deaths. A combination of rain, fog, low clouds, and exceptionally bright lights caused them to strike the windows of office and apartment buildings.
About 70% of North America’s land birds (350-400 species) are migratory. Of these, more than 80% migrate at night. Illuminated buildings and other bright lights can confuse and disorient these nocturnal migrants, often with fatal consequences. Most native songbirds live in rural or forested habitats that are light-free at night. During migration, intense lights can cause birds to collide with windows or walls, or cause them to circle in confusion, leaving them weak and exhausted when they land. Reducing and turning off unnecessary lights would save millions of these beautiful and highly beneficial birds from painful injuries and death.
Nighttime collisions are not just a problem in Philadelphia. Scientists estimate that up to one billion birds collide with buildings in the U.S. every year. Sadly, most of these birds die from their injuries. In large cities like Philadelphia, these collisions peak during the spring and fall migration periods. Many of the deaths that occur at night go unnoticed, cleaned up by vigilant maintenance crews before the morning commute begins. Fortunately, this is a problem that we can do something about.
In 2005, New York City inaugurated a Lights Out program to protect migrating birds. This successful effort now involves iconic buildings like the Chrysler Building, the Rockefeller Center, and the Time Warner Center. In 2015, New York’s Gov. Andrew Cuomo launched a statewide Lights Out Initiative. State-owned and state-managed buildings turn off nonessential outdoor lighting during peak periods of bird migration.
In Chicago, approximately 100 buildings are now involved in a similar program. Virtually all the buildings downtown with over 40 stories are participating. A study by the Field Museum in Chicago found that turning off the lights at one downtown waterfront building reduced migratory bird deaths by 80%. Over a 20-year period, over 30,000 birds had been killed in window-strikes at this building alone.
Of course, dousing lights has the added benefit of reducing energy use and saving money for the building owners and taxpayers alike.
In Philadelphia, we could save tens of thousands of birds annually if building owners would turn off, or at least reduce, their nonessential building lights. Here are a few of the ways the National Audubon Society suggests that we can accomplish this, particularly during migratory periods:
Turn off exterior decorative lighting and interior lighting, especially on higher stories.
Reduce atrium lighting wherever possible.
Use targeted task and area lighting for workers staying late, or pull window coverings.
Downshield exterior lighting to eliminate horizontal glare and all light directed upward.
Install timers and/or automatic motion sensors and controls wherever possible.
When converting to new lighting, assess the quality and quantity of light needed, avoiding overlighting with more recent, brighter technology.
Some cities that have already adopted “Lights Out” initiatives for birds include Atlanta, Chicago, Toronto, and Wilmington. What could be a better time than now to start our own “Lights Out” initiative in Philadelphia? Let’s help make Philadelphia a bird-safe city. Please think about what you can do to help.
Robert M. Peck is a senior fellow at the Academy of Natural Sciences of Drexel University. Keith Russell is the program manager of Urban Conservation at Audubon Pennsylvania. Stephen Maciejewsk and Linda Widdop of the Delaware Valley Ornithological Club and Leigh Altadonna of the Wyncote Audubon Society contributed research to this piece.