From: Ben Whitford, The Ecologist, More from this Affiliate
Published May 1, 2013 09:48 AM

Birds Strike: deaths caused by collisions with buildings severely dent populations

On a brisk May morning in 2001, countless dying birds fell like rain from the grey Toronto sky. In the east of the city, outside a hulking 18-storey office complex called Consilium Place, workers on cigarette breaks watched in horror as tiny feathered bodies thudded onto the pavement, fell into their laps, and crashed onto the picnic tables where they had laid out their coffee and morning snacks.


While the office workers sought shelter, a bird enthusiast named Michael Mesure called for backup. As founder of the Fatal Light Awareness Program, or FLAP, Mesure runs a team of volunteers who patrol Toronto in search of birds that have stunned themselves - or worse - by flying into one of the city's many mirrored-glass skyscrapers. Some mornings Mesure's team doesn't find many birds: perhaps just one, or two, or twenty.

In the space of six hours on that May morning, though, Mesure and a dozen or so volunteers found at least 500 birds. Ruby-throated hummingbirds, dark-eyed juncos, white-throated sparrows and Nashville warblers were carefully collected: the tiny corpses stored in plastic bags, the injured survivors placed gently in paper sacks for treatment and subsequent release. And still the birds kept falling. "It was literally hailing birds," Mesure says. "It was just a real sobering moment for us."

On a smaller scale, experts say, such scenes are repeated daily across North America as birds, unable to distinguish between blue sky and what Vladimir Nabokov poetically called "the false azure in the windowpane", careen into windows at speeds of up to 30 miles per hour. The resulting brain damage is thought to kill about 60% of birds on impact, with many of the remainder left nursing chipped beaks or internal injuries that subsequently prove fatal.

In all, it's estimated that the Toronto skyline accounts for about 1 million bird deaths a year — and even that is just a drop in the bucket. It's hard to put a precise number on collision-related mortalities, but researcher Scott Loss of the Smithsonian Institute is preparing to publish new research that, based on a sophisticated analysis of 23 previous studies, estimates that between 400 million and 1 billion birds die from window impacts each year in the U.S. alone.

That eye-popping number suggests that window impacts are putting a serious dent in the North American bird population. There are thought to be around 10 to 20 billion birds in the U.S., Loss says, so it's not unreasonable to assume that up to 10% of the entire U.S. bird population dies, year-in, year-out, due to building collisions.

Continue reading at The Ecologist.

Bird image via Shutterstock.

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