As we reported earlier, birds typically collide with a window during the daytime for one of two reasons:
Either the window is reflecting the surrounding habitat, and birds can’t tell the difference, or the window is transparent, and birds see through it to appealing objects on the other side.
Fortunately, a number of products are now on the market that will make the windows of your house less dangerous to birds without substantially reducing your ability to see through the glass from the inside. These include UV-reflecting glass, tapes, decals, and liquids and antireflective vinyl or polyester films and decals.
Below are links to manufacturers of bird-protecting strings, nettings, and screens that you can apply to the exterior of the windows of your home. Netting and screens put a barrier between the window and the birds, preventing those that fly into it from striking the glass. Strings create a curtain-like visual deterrent that birds see and try to avoid.
Ingenious and attractive, BirdSavers consist of one-eighth-inch-diameter nylon cords that dangle about four inches apart in front of a window’s exterior, where they are visible to birds, which avoid them. Velcro secures the hanging cords to the top of the window. Recommended by Contributing Editor David Sibley and Daniel Klem Jr., professor of ornithology and conservation biology at Muhlenberg College in Pennsylvania, who has been studying bird-window collisions for more than 20 years. Instructions on the website describe how you can build your own. Proceeds support conservation programs at the Acopian Center for the Environment.
A preassembled curtain of taut monofilament lines strung three inches apart and five inches from the exterior of a window or sliding-door side panel. Birds see the lines and avoid them, while the space between the lines and glass gives birds that touch them a chance to spread their wings and brace themselves. Available in dark brown and white.
Bird-exclusion netting made from durable, lightweight polypropylene. Useful for keeping birds out of eaves or open spaces. Secure with net clips, hooks, or a staple gun. Hang the netting tightly at least two inches from the glass to provide a firm barrier that will keep birds from hitting the window.
An attractive transparent black fiberglass screen that hangs loosely in front of a pane of glass, providing a gentle cushion for birds that strike it. Screw hooks and suction-cup brackets, included with purchase, secure the screen to a window or sliding door. Custom sizes available.
Five bird deterrents that don’t work
1. Hawk silhouettes: One window decal in the shape of a hawk will not frighten birds. Shape is not important.
2. Single window decals: Affixing a single decal to a window will not deter birds. To lessen the area of exposed glass and help make a window visible to birds, use multiple decals (even multiple decals in the shape of a hawk).
3. Plastic owls: Birds learn quickly that a motionless plastic owl is not a threat.
4. Noise deterrents: Common noise deterrents — high-frequency ultrasound, noise cannons, and recorded distress calls — are ineffective at preventing birds from colliding with windows.
5. Magnetic fields: Some deterrents emit a magnetic field said to disrupt birds’ geomagnetic orientation and encourage them to avoid the area. Magnetic fields are not effective at protecting birds from window collisions.
Source: Bird-Window Collision Reduction: Tips and Techniques for Residents, Fatal Light Awareness Program
This post was excerpted from the article “Surefire Ways to Make Windows Friendly to Birds,” which appeared in the April 2013 issue of BirdWatching magazine. Read the full article and download a PDF.