10 July 2008

When our young peregrine died last month, many people wondered how he could crash into a window without even seeing it.

In fact, windows are the number two human-induced cause of death in birds. According to Dr. Daniel Klem, Jr. of Muhlenberg College, 1 billion birds die every year in the U.S. by hitting windows. That’s 2.7 million birds per day.

Half of the birds who hit windows actually survive the initial impact but can easily be captured by predators while stunned. Those deaths don’t count as window kills, though they’re related.

Why do windows kill?

Take a look at the building pictured here. Even to us it looks like trees and sky. We’re too large to fit through the “fence” (the window frames that hold each pane) but birds think they can fly through it. Sometimes they see their own reflection and believe it’s a safe flyway because another bird is using it. Other times they can see into the room and try to fly inside. At night they’re attracted by lights.

People are fooled by glass too, but it doesn’t kill us. How many of us have bumped into a glass door because we didn’t see it? We survive because we move slowly – and not head first – into the glass.

How can we prevent window kills?

Sadly, a few decals won’t do the trick. The rest of the window is still dangerous.

Reflective glass must be treated on the outside to alter the entire look of the windows. The treatment must make the birds see a wall or a mesh too small to fly through. For buildings like the one pictured here, it means coating or etching the outside of the glass or installing mesh or outdoor blinds. It would even help – but only a little – if they didn’t wash the windows.

For transparent glass, closing the curtains or slanting the blinds is all you need to do. Window screens for keeping bugs out are excellent deterrents though they need to cover all the glass, not just half.

At night turn off the lights or close the drapes, especially in high-rise structures during spring and fall migration. Toronto, Ontario has begun a program to do just that, thanks to the Fatal Light Awareness Program (FLAP).

There are many resources on the web to help your home or business reduce window kills:

• There’s a handy fact sheet at FLAP.org with lots of resources and solutions that work.
• American Bird Conserancy has suggestions for your home.
• The Fatal Light Awareness Program has worked on this problem for 15 years. They have lots of suggestions including new research on UV coatings that birds can see but we cannot.
• Lots of resources are available at Birds and Buildings.

If you are an architect or designer or you are considering building a new office or home, think about the windows before you buy them! It’s an uphill battle to change a building after it’s built.

(photo from Wikimedia Commons.  Click on the photo to see the original.)