This isn’t just a problem in Chicago. In 2014, research suggested anywhere between 365 million and 988 million birds die in window strikes every year across the US.
Almost 1,000 songbirds have died in a single night after smashing into the windows of a glass-fronted exhibition centre in Chicago.
Experts have described this as a “shocking outlier” – as typically, no more than 15 birds would perish at the McCormick Place, the largest convention centre in the US, on a typical evening.
David Willard, who has been checking the grounds for decades, described seeing a “carpet of dead birds” on Thursday morning.
“In 40 years of keeping track of what’s happening at McCormick, we’ve never seen anything remotely on that scale,” he said.
Avian experts say a lethal cocktail of rain, prime migration conditions and window-lined walls were to blame for the mass fatalities.
This is not just a problem in Chicago. In 2014, research suggested anywhere between 365 million and 988 million birds die in window strikes every year across the US.
Birds don’t understand that glass is a lethal barrier – and often head for windows when they see plants or bushes reflected in them.
And while species that migrate at night rely on stars for navigation, bright lights from buildings can both attract and confuse them.
Matt Igleski, executive director of the Chicago Audubon Society, said such incidents are “really common”.
He explained: “We see this in pretty much every major city during spring and fall migration. This was a very catastrophic single event, but when you add it all, it’s always like that.”
Songbirds feed during the day and migrate at night to avoid air turbulence and predators, but unusually warm southern winds throughout September left them in a holding pattern.