Flaco’s Death Calls Attention to Bird Strikes and How to Prevent Them

Memorials sprang up in New York City over the weekend in honor of Flaco, a Eurasian eagle-owl who died on Friday after apparently striking a building on the Upper West Side.

His ability to thrive for a year in Manhattan after escaping from the Central Park Zoo last February captivated much of the city, offering an enchanting object lesson about the power of instinct and the beauty of urban wildlife.

His death may prove equally instructive.

Flaco is among the estimated one billion birds that will die this year in the United States after striking buildings.

Building strikes are one of the main causes of death for birds — and one of the easiest threats to solve, according to Christine Sheppard, director of the glass collisions program at the American Bird Conservancy.

“This is one conservation issue where we know exactly how to fix it,” Ms. Sheppard said. “We just need to get people to do it.”

Here’s what to know about why birds strike glass windows and some of the ways humans can help:

Why do birds crash into windows?

Most species of migrating birds travel at night. Cities’ artificial light draws them in, disorienting the birds and making them more prone to collisions with windows that, in the daytime, reflect vegetation and open sky.