Best Ways to Keep Birds from Hitting Windows

We've all seen birds smack into windows, and now there are several products on the market that are supposed to help birds avoid window collisions. But do they work?

Dan Klem, an ornithologist at Muhlenberg College in Allentown, Pennsylvania conducted experiments to find the best ways to stop birds from hitting windows.

The results?
Window Alert Decals: Ineffective when used alone, but effective if almost completely covering the windows.

FeatherGuard: Ineffective unless enough are used to almost completely cover the window

CollidEscape: Mostly effective, though one bird did hit it during trials.

Other useful treatments included glass with a ceramic frit pattern and glass with alternating strips of UV reflecting and absorbing film.

The published study results are online here:

Preventing Bird–Window Collisions. The Wilson Journal of Ornithology 121(2):314-321. Daniel Klem Jr.