Conserving energy and stargazing are two of many reasons people opt to turn their lights out at night, but over the next three days, experts are urging residents to also flip their switches between 11 p.m. and 6 a.m. to help save the lives of millions of migrating birds.
Over the next two nights, millions of birds are expected to migrate across Chicagoland in one of the biggest migration movements of the season so far, according to the Chicago Bird Collision Monitors, a volunteer conservation project that works to protect migratory birds through rescue, advocacy and outreach efforts.
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But with migration comes lethal dangers, including starvation, predators and high-speed crashes into building windows.
“We think that the Midwest is going to be the epicenter of migrations for the next few nights in the U.S.,” said Benjamin Van Doren, a postdoctoral associate at the Cornell Lab of Ornithology.
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Studies published in 2019 confirmed what conservationists have long suspected: Chicago’s skyline — a landscape dominated by glass superstructures situated on one of the continent’s busiest flyways — is the most dangerous metropolitan area in the contiguous U.S. for migratory birds.
Van Doren said there are several factors that cause bird collisions.
“Collisions that occur during the daytime happen because birds see a reflective sky or reflected vegetation or trees in a window and they think its a place they can fly to and thus crash into a window,” Van Doren said. “For collisions that occur at night, which happen in urban areas, we recommend turning out lights because migratory birds are attracted to lights.”
This week’s migration is part of the estimated 3.5 billion birds returning north to the United States each spring, according to a 2018 study published in Nature Ecology & Evolution.
Of the 3.5 billion, roughly 25% of migratory birds die between the time they leave the United States in the fall and return in the spring. A significant number of bird mortalities occur during migration, according to the study.
Van Doren said that the middle of May is the peak of spring migration due to warmer temperatures and favorable wind conditions that come from the south and provide a tailwind on their way north.
Van Doren was part of a team that launched a new migration dashboard in April that allows residents to see how many birds are migrating in the area in real time.
The dashboard, which is part of a larger tool called BirdCast, predicts and monitors bird migrations on a daily basis and shows the most frequently encountered bird species on the move.
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“Using that dashboard, we estimated about seven million birds flew over Cook County [Sunday] night,” Van Doren said. “I expect similar sized movements over the next couple of days.
