Nearly 7 million birds flew across Washington state on the night of Sept. 17, with even more expected over the weekend, according to the Cornell Lab of Ornithology.
Scientists are asking people to turn their outdoor lights off to help birds find their way south.
It's no secret that many birds fly south for the winter. It's less commonly known that they often migrate invisibly — at night.
The cover of night provides safety from predators and less-turbulent air to fly in. Many birds are attracted to artificial light. City lights can disorient them and prevent them from reaching their destinations or even make them crash into a building.
"At a time of year when all their energy needs to go to flying sometimes thousands of miles, these hazards can mean the difference between life or death," according to the U.S. Fish and Wildlife Service.
Fall migration through Washington state reaches its peak in late September and early October, according to the Cornell Lab.
Bird experts say extinguishing or dimming lights, especially after 11 p.m., can help migrating birds stay on track.
"There are millions of birds that go over Clallam County in the fall and spring, and all the artificial night at night screws up the birds," said Olympic Peninsula Audubon Society volunteer Patti Giffin of Sequim. The group has spearheaded a "lights out" campaign in Washington along with the Olympic Peninsula chapter of the nonprofit DarkSky International.
"Anytime in September, October, early November is important for the lights out effort," she said.
Giffin looked up the Cornell Lab's tally of birds that had flown across Clallam County on the Olympic Peninsula the previous night: 938,400 birds.
"Do you believe that? It's so amazing. It's because we're on the Pacific Flyway," a major north–south route for migratory birds extending from Alaska to Patagonia, Giffin said.
Every day, at least 1 million birds in the United States collide into buildings, according to a 2014 study by the Smithsonian Conservation Biology Institute. Many of those deadly collisions happen at night.
Dark Sky International has designated eight locations in Oregon, including the cities of Antelope and Sisters, as Dark Sky Places, that have taken steps to reduce their light pollution. No locations in Washington state have the designation.
"Oregon's way ahead of us," Giffin said.
Giffin said she's made changes at home as well as trying to get cities and homeowners' associations to mandate bird-friendly lighting.
"I turn out the lights at night in my house that are by windows. I shut the drapes," Giffin said. "I don't use the porch light, especially during migration time, unless I'm expecting company."
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This story comes to you from the Northwest News Network, a collaboration between public media organizations in Oregon and Washington.
