As seen in a recent Haute Blog post: Architects are Shocked that their Glass Buildings Kill Millions of Birds every Year  yet the public is unaware of the problem. The post is based on an article in Audubon Magazine called: Clear & Present Danger .
There’s a lot of interesting information in the article.
“Ornithologist Daniel Klem of Muhlenberg College, in Allentown, Pennsylvania. Between 100 million and 1 billion birds die in glass collisions every year in North America alone, Klem estimates. At the very least, that’s an average of one bird a year slamming into each of the roughly 100 million homes, apartment buildings, office towers, schools, and storefronts that dot the American landscape. “Glass is one of the world’s great bird killers,” rivaled only by habitat destruction and perhaps cats, says the blunt-spoken, 57-year-old ornithologist.
Glass gets less attention than other threats, however, because “most kills are pretty small, just a bird here or there,” says Frank Gill, Audubon’s director of science. “Few people see the big picture.””
Says one ornithologist:
Nobody sets out to intentionally kill birds, they just like a nice view.
Here’s another well done presentation:
Windows: A Clear Danger to Birds [NPR] 
There are a lot of advice sites on prevention [Google] 
With the growing trend toward glass facades in new developments, this problem doesn’t appear to have a happy ending.