It's a bigger problem than you might imagine.
Most of us have experienced the sadness of seeing a bird die from colliding with a window. Those who enjoy a rural home often find themselves in the unfortunate position of attracting birds to their deaths. A Large picture window is delightful for communing with mother nature but deadly to birds.
Daniel Klem, an ornithologist and professor at Mulhenberg college in Allentown, Pa, has spoken extensively on behalf of birds and birders to promote awareness of just how many birds are killed each year in collisions with windows.
Between 100 million and 1 billion birds die in glass collisions every year in North America alone, according to Klem in an interview with Audubon Magazine (March 2004). "Nobody sets out to intentionally kill birds," he says. "They just like a nice view."
Some buildings are, as Klem called it "bird slaughterhouses." The majority of these collisions happen with large office buildings with shiny or mirrored windows.
WHY DO BIRDS DO THIS?
First of all, it helps to understand things from the birds point of view. A bird's vision is much better, in many ways, than a human's. Much of their brain is dedicated to sight. In fact, birds are able to see ultraviolet light (UV), something for which humans would need a black light. But their *interpretation* of a view is the problem.
Birds who see the sky beautifully reflected in a big picture window will often fly right into it. If a bird can see completely through your house (front and rear windows) it may think it is a sort of tunnel it can fly through.
Birds fleeing from predators may try to take cover in plants that you may have immediately inside your window, not seeing the glass.
Some birds, especially Northern Cardinals and American Robins, are very birds, and will try to attack what they "see" (their own reflection) as an interloper repeatedly, often causing their own death.
WHAT CAN I DO TO STOP IT?
If a bird flies into a window, it may only be stunned. Cover it with a colander or other object with holes so the bird can breathe, to protect it from predators. Birds are very delicate creatures, however, and it is more than likely it will have managed to kill itself.
According to the Audubon article, the very best solution (although not practical for most readers) is to use what is called "fritted" glass, which has rows of small circles etched into it. The dots don't obscure vision that much as long as you are not standing directly in front of the window. I have listed a number of companies which manufacture fritted glass at the end of this article. If your concern is the replacement of windows in a large office building, or how to design windows for your new home, this is an excellent solution.
Most of my readers, however, cannot go that route. Happily, there are also a number of much more inexpensive ways to address the problem
* Simply draw curtains or blinds over the offending window: white curtains or blinds are the safest.
* Hang decorative objects or a bird feeder in front of the window keep in mind that birds will still try to fly through spaces that are even 2 inches wide.
* Decorative anti-collision window films. These are barely noticeable to humans but as they are UV reflective, they are seen as an obstacle by birds, alerting them that there is a barrier there. You may need to use more than one per window. I have listed a number of sources for these decals at the end of this article. It is inexpensive and can actually be attractive.
*Make sure to move plants away from windows as birds fleeing could mistake it for protective cover and try to escape into it.
*Smear a filmy (soap or other) solution on your windows so that the birds cannot see their reflections, especially in nesting season. Obviously this defeats the purpose of a picture window so it might not be for everyone. However, it can serve as a temporary fix until you find another solution. Another temporary fix is to tape a piece of paper or cardboard to the window.
* Attach netting or hardware cloth over your windows. It will act as a "shock absorber" and birds will bounce off of it, rather than crash and harm themselves.
* Attach special plastic sheets to your window which decrease the reflectivity of the window but still allow you enjoy your view (such as CollidEscape, and again I have provided some links below).
*An interesting and inexpensive solution is the "Warning Web" - a cunning spider web design available at Droll Yankees. This work by showing the birds there is "something there" that will not allow them through. It even has a replica of the white pattern that spiders weave into their web which alerts birds to its presence, and keeps them from flying through the web (called a zig-zag stabilimentum)
*Another old trick is to hang pine cones on slender thread or fishing line at various heights in front of windows. Again keep in mind, birds will see an opening of 2 inches or larger as an okay opening to fly though.
* Holographic "Scare Tape." It creates a reflection in motion, which frightens birds away, not only from your garden but also from your windows. This is very inexpensive, and seems to be available from a large variety of garden shops.
*Hang a bird feeder on your window. It will decrease collisions, but make sure it is right up close (within two feet) to the window. A bird feeder any farther from a window will actually increase the problem. A bird can get up to "suicide speed" if it is much farther away than that. Other feeders should be placed more than 15 away from any windows.
SOME SOURCES:
HOLOGRAPHIC SCARE TAPE:
http://www.provenrepellents.com/products.php?pi d=2122
http://www.biconet.com/birds/scareTape.html
htt p://www.missionhillsnursery.com/Merchant2/merchant.m vc?Screen=PROD&Product_Code=T-042&Category_Code=T
SPI DER WEB DECAL and UV/SEMI-TRANSPARENT DECALS
Spider Web by Droll Yankees: http://www.duncraft.com/Droll-Yankees-Window-Warning -Web-P2213C0.aspx)
Birdalert: http://www.old-fashioned-values.com/get_item_birdale rt_stop-birds-flying-into-windows.htm
Whispering Windows: http://www.wpines.com/
Nixalite: http://www.nixalite.com/windowalertdecal.aspx
Fiddlec reek Farms: http://www.fiddlecreekfarms.com/store/scripts/prodLi st.asp?idCategory=396
Songbird Garden: http://www.songbirdgarden.com/store/scripts/prodView .asp?idproduct=2615
Old Fashioned Values: http://www.old-fashioned-values.com/get_item_birdale rt_stop-birds-flying-into-windows.htm (decals visible in the UV light spectrum)
COLLIDESCAPE FILM
http://www.lfdcollidescape.com/mainindex.php?pag e=home&country=united_states)
FRITTED GLASS SOURCES:
http://www.beclawat.com/glass.htm#fritted
htt p://www.nationalglass.com.au/products/09/09.html
Bird safe building can be found here: http://www.birdsandbuildings.org/docs/3BirdSafeDesig nsPart1.pdf
A number of companies that manufacture fritted glass can be found on Thomas Net
http://www.thomasnet.com/products/fritted-glass-3 4840702-1.html