From late Wednesday, 4 October, through early Thursday, 5 October, a peak estimate of 1.5 million birds were in the air over Cook county, home to the Chicago metropolitan area. Carcasses of Tennessee warblers, hermit thrush, American woodcocks and other varieties of songbirds were recovered.
Not every bird that hits the window is going to leave behind a body,” said Brendon Samuels, who researches bird window collisions at the University of Western Ontario.
He noted that the true extent of affected birds will unravel over a couple of days as people continue to pick up birds around downtown Chicago.
“In fact, we often see birds collide with glass and they continue flying some distance away, seriously injured in ways that ultimately they won’t survive past a few hours,” Samuels added.
Of all cities in the US, Chicago’s light pollution poses the greatest risk for migrating birds. Turning off building lights is one way to reduce fatalities. A 2021 study done in McCormick Place, the same site of Thursday’s bird deaths, found that shutting off half the lights in large buildings can reduce collisions by six to 11 times. McCormick Place is a participant of the Lights Out Chicago program, which has buildings voluntarily switch off or dim lights at night unless someone is inside.
“It is important to understand that there is an event going on at Lakeside Center [part of McCormick Place] this week, so, therefore, the lights have been on when occupied. Once the space is unoccupied, the lights have been turned off,” said a representative from McCormick Place.
“It’s a known hazard, and yet we still can’t see action being taken about it,” says Prince.
Having window glass with visual markers like dots or patterns can break up the appearance of reflection and let birds recognize whether there is a safe passage for them to fly through.
In 2020, Chicago approved a bird-friendly design ordinance but it is yet to take effect. In 2021, the Illinois governor, JB Pritzker, signed the Bird Safe Buildings Act, which “requires bird-friendly design to be incorporated into the construction and renovation of state-owned buildings” in the state, per Audobon.org.
“We have a lot of existing buildings that are killing birds, not just new construction,” said Samuels, adding that investments in retrofits, creating tax credits for such environmental initiatives and making windows more bird-friendly can be an economical way to solve this. “We already have solutions, we just need to put those into policy.”