By Molly Daly

By Molly Daly

PHILADELPHIA (CBS) – The deaths of two of the Franklin Institute hawk fledglings after flying into windows points to a worldwide problem.

For five years, the growth of the Franklin Institute nestlings has been followed by fans around the world — through the nest cam, the Franklin Hawkaholics Facebook page, and the Hawkwatch at the Franklin Institute blog . Although the original adult male hawk, dubbed Dad by fans, was killed last year, the fledglings from the first four broods are believed to have survived to migrate in the fall.

Blogger Della Micah says the deaths of two of this year’s fledglings serve as a wakeup call.

“The 80-90 percent mortality rate for red-tailed hawks in their first year is absolutely proving.” Micah says the manner in which the fledglings died opened her eyes to a widespread problem. “I certainly think the birds hitting windows that they can’t see definitely raise awareness for me.”

Muhlenberg Biology professor Daniel Klem has devoted his career to the study of bird-glass collisions. He says it’s impossible to know exactly how or what birds see — so researchers study their behavior for insight.

“Birds just really behave as if clear and reflective windows are invisible to them.” Klem says that every year, window strikes claim the lives of about a billion birds in the United States alone.

But he says it’s preventable. “It’s very important that you destroy the reflection, so you don’t get the animals being deceived by the facing habitat and sky that’s mirrored in the pane.”

That can be done on a residential scale with decals or screening. On a larger scale, Klem has been pushing for the production of glass with a pattern in the ultraviolet range that birds can see, but we can’t.

With more glass-clad green buildings going up, says Klem, the need grows more pressing.

“It doesn’t matter what they label their ‘green’ buildings,” Klem said. “A building’s never green if it’s killing birds.”

Della Micah says the way in which the two young hawks died may help spur change.

“I hope if there’s good which can come from this, is that people really take a look at any large sheets of glass for which they’re responsible, that a bird potentially, could fly into, and try to take some of the appropriate measures, to make it more bird-friendly.”

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