By Molly Daly

PHILADELPHIA (CBS) — One of the young red-tailed hawks that recently left the nest at the Franklin Institute (see related story) has died.

Hawk Watch at the Franklin Institute blogger Della Micah says it happened Wednesday afternoon.

“Sadly, the female twin [photo] flew into a window at Moore College of Art,” she tells KYW Newsradio.

Micah says all three of the fledglings had been making hunting runs that morning, in hot pursuit of other birds.

“They’re like teenagers — they’ve got a great engine, but they don’t always know how to control it,” she says.  “You hope that they will see a window or a building coming up.  I think she was just intent on catching the bird.”

Or, perhaps seeing vegetation and sky reflected in the window, she kept going because she didn’t know it was a solid object.

It’s estimated that glass claims the lives of one billion birds every year.  (There are ways to make glass less reflective and more visible to birds, by using decals or so-called “fritted” glass.)

Meanwhile, the avian family’s fans, who have watched the birds’ development on the nest cam and through the blog and Franklin Hawkaholics Facebook page, are shocked and saddened.

“You really develop an attachment to them, and you feel the pride of any aunts and uncles when you see the youngsters heading off into the world,” notes Micah, the blogger.  “These young hawks are at such an exciting time of learning to hunt and fly.  This young female was such a beautiful, beautiful hawk, and to be taken out so quickly… it is sad.”

The young hawk’s body was taken to the Academy of Natural Sciences, to be added to its vast collection.

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