Windows: Indiscriminate Killers

You’re sitting at the dining room table, reading the paper and glancing occasionally at your bird feeders, when SMACK!, something slams into the window. It’s happened a few times in the past, so you know what you’ll find, you just don’t yet know whether the victim will be a cardinal, mourning dove, Cooper’s hawk, or perhaps a migrating ovenbird.

These fatal collisions don’t happen often at any one house, so most of us don’t address the problem. Even at the nature center, our efforts to reduce the number of birds killed when flying into Visitor Center windows have gone no further than putting up a few hawk silhouettes to break up the reflection of the glass. The number of birds killed has been reduced, but at least a dozen still die each year, especially during migration.

So a dozen die here, and a few die at your house – it doesn’t sound like a serious problem, does it? The numbers add up, though, house by house, skyscraper by skyscraper, until each year, over one BILLION birds die in window collisions. And that’s a conservative estimate, according to Dr. Daniel Klem, who has studied this conservation issue for nearly three decades. Klem is a research ornithologist from Muhlenberg College in Allentown, Pennsylvania. He studies not just the scope of the problem, but viable solutions as well.

The basic problem for birds is that they see trees and sky reflected in windows. They don’t recognize the window as part of a building, and continue ahead at full steam. Even at times when there is no reflection, windows placed across from each other create the illusion that birds can fly through to what they see on the other side.

Window kills occur on all sizes of windows, all sizes of buildings, and in all four seasons. So what can you do to lessen the impact (literally!) of your windows? Klem has studied many possible solutions, including placing bird feeders closer to windows, and architectural and glass style options such as angling windows outwards, using glass with imbedded dots (resulting in a frosted appearance), and designing buildings with deeply recessed windows.

He found silhouettes and other window decals have little effect, as they are too small to impact more than a very small area of the window. Moving feeders to within a few feet of windows is helpful. The greatest potential for solving the problem, however, appears to lie in architectural design and window manufacturing arenas. To learn more about how to protect birds from striking windows at your house, check out thise website www.birdsandbuildings.org.

Once it's completed, our renovated Visitor Center will include porch overhangs and other methods of reducing window kills at CNC. Stay tuned for future updates on this important issue!

- Janea Little, CNC Senior Naturalist