Cities turn out lights to save migrating birds
Dozens of U.S. cities are being transformed this spring, enveloped in darkness as the lights that usually brighten up their skylines are turned off at night to prevent birds from fatal impacts during their annual migrations.
Each year, an estimated 365 million to 1 billion birds die by smacking into reflective or transparent windows in deadly cases of mistaken identity, believing the glass to be unimpeded sky.
“These birds are dying right in front of their eyes,” said Connie Sanchez, the bird-friendly buildings program manager for the National Audubon Society, which for two decades has asked cities to dim their lights from about mid-March through May and again in the fall, under its Lights Out initiative.
Since late last year, at least six cities have joined forces with the 35 other places where the society, local organizations, ornithology experts and some of the nation’s largest companies have been helping birds navigate in urban centers. The efforts are gaining ground in cities including Chicago, Houston and New York City, which are among the top 10 in the United States for light pollution.
Buildings in Philadelphia have also joined the nationwide effort, a step that experts hope will help to avoid a repeat of the deaths of more than 1,000 birds in October, an event reported by the Philadelphia Inquirer as one of the largest such avian fatalities in decades.
Bird populations are already imperiled by climate change, habitat loss and cats. Turning lights out at night can mitigate one more risk to their lives, experts say.
But before a city knows if a lights-out campaign will work, it first has to know how many birds it might help. The Cornell Lab of Ornithology has used radar data to identify abnormal bird densities. In some cities, the approach is old-fashioned shoe leather.
Three days a week, at about 7 a.m., volunteers hit the streets of Jacksonville, Fla., peering into shrubs or searching the bases of the city’s tallest buildings. In the week of March 14, they found two warblers and a dove. The tiny bodies were put into bags and handed over to the zoo for analysis.
Then the business of forensics begins. As in any cause of death investigation, clues must be extracted from their surroundings. In the case of birds, the only certainties are flight, gravity and thin air.
Moments after a fatal impact, birds plummet to sidewalks, drop onto high-rise ledges inaccessible to the public or sink into bushes on private land until discovered there inexplicably dead, throwing the possible answers to the who, what, when and where of their deaths into disarray.
Sometimes, stunned by the impact, they keep flying before they fall, making the place of their original blow difficult to trace. Often, cleaning crews sweep up carcasses before the volunteers can document them.
Bird strikes against buildings have been recorded for decades in Philadelphia. The first recorded window kills date to the 1890s, when City Hall was lit up, said Nate Rice, the ornithology collection manager at Drexel’s Academy of Natural Sciences. Rice said the academy’s database now has 823 specimens that have been identified as window strikes in Philadelphia.
“If we can generalize, say, ‘Let’s keep lights out or at a minimum during peak migration time,’ this can have an impact on wild bird populations,” he said.
Modern architecture has accelerated the problem as sky-piercing, reflective structures are illuminated at night.