Low-E Windows Mean More Bird Crashes

Jim Mallery

Now that you have done the responsible thing--replaced all those old, energy-sucking windows in your old house with the efficient low-E (low emissivity) glass--you very possibly have noticed your next environmental concern: You have more bird crashes against your windows, sometimes with fatal results.

Why Do Low-E Windows Cause Bird Crashes?

Low-E windows have a thin metallic film that blocks infrared light and some ultraviolet light. They can be designed to keep heat inside a house, or to keep it out, depending on your climatic situation. Any new home will have them, and all old houses, unless you are fortunate to live in a climate that requires neither significant heating nor cooling, should get them. As far as glass is concerned, they are the best insulating factor out there. But they also are more reflective than the old glass, and as such, lead to more bird crashes.

Birds are more likely to hit your windows in the morning or late afternoon when the sun is lower and the reflections brighter. They usually thud into windows because they see the reflection of trees or clear sky in the glass and think they are flying in safe environs. While some glass people will say the addition of low-E windows does not make much difference, many a homeowner who has upgraded to low-E will tell you otherwise.

So what to do? No current solution has been proven totally effective, or acceptable, for most homeowners, but here are some suggestions:

  • You can drop screens over the windows, but while there are some screens advertised as nearly clear, they still reduce your vision.
  • Decorative window decals warn birds that a solid surface is in front of them and reduce the problem, but they are far from 100% effective, and you now have decals on your glass.
  • If you are a birdlover, you may have birdfeeders in your yard. Put the feeders near your windows. The birds don't have time to gain enough speed to hurt themselves before they strike the glass. Unfortunately, this brings the mess of spilled birdseed and droppings right next to your home. Also, some birds may be reluctant to come that close to your window.
  • It is believed that most birds see ultraviolet light, so some bird enthusiasts have tried marking their windows with hi-lite pens, which reflect some ultraviolet light. The marks are nearly invisible on the window, but the birds see reflected UV light off them and shy away from the window. But again, you can see the marks, and the method is not completely successful in stopping bird crashes.

When Bird Crashes into Low-E Window--and Bird Loses

What if a bird hits your window and drops stunned, but not dead, to the ground? Experts recommend placing the bird in a paper bag while it recovers, thus keeping it away from predators. As soon as you hear it fluttering, open the bag and hope it flies away.

Unfortunately, unless you don't mind visual obstructions in front of your windows, there isn't much you can do to prevent bird crashes. The energy-saving benefits of installing the low-e glass in your old house are many--just be prepared for a few more bird casualties.

About the Author

Jim Mallery, a semi-retired journalist and onetime registered contractor, has extensive experience remodeling, repairing, and rebuilding homes.



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