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Spacing: the Most Important Part
Again, birds take everything they see it literally. So, when a window reflects the sky or a tree, birds think that those things actually exist there! They don't ask themself is that tree really there? They ask, can I get to that tree? Can I fit? Hence, the essential part of any bird preventative is to divide up the window's surface so there’s no gaps large enough for a bird to fly "through."
Bird preventatives create visual noise. Visual noise, which is a collection of pictures and/or patterns covering something so that the object is busy or “noisy,” divides up a window’s surface into gaps that a bird cannot “fit” through. Since a bird realizes they cannot “fit,” they won’t collide with the window since they understand that flying “through” would be a bad idea.
Note: bird preventatives should be applied to the exterior side of a window. They can be applied to the interior, but they aren't always visible if there's a strong reflection on the exterior side, so they're not as effective.
Bird preventatives are most effective when they follow the American Bird Conservancy’s 2 by 2 rule; solutions should be applied every two inches horizontally and vertically for maximum effectiveness. A bird preventative without the correct spacing will not reduce collisions as effectively.
The 4 by 2 rule can also be used, as shown here. It is not as effective as the 2 by 2 rule for smaller birds, like hummingbirds.
Bird preventatives can also be applied only horizontally or vertically.
Bird-window collisions occur most frequently during migration, which is spring and fall. So, for those during temporary solutions, apply during spring and fall!
List of Bird Preventatives
Fortunately, there are many bird preventatives among a range of prices to protect birds. Some can even be homemade or applied by hand to keep cost minimal. Pricier, but more convenient, options are available too.
One of the most practical and easy solutions is to add screens to your windows. The small grid pattern deters birds, and the screens won't disrupt your outside views. Plus, there is the added bonus of being able to open a window without letting the bugs in!
Your screens should be on the exterior side of the window for maximum effectiveness (as with all bird preventatives). Aim for a dark-colored screen so birds can see it better—color contrast!
Paint can also work, although it is not as long-lasting as some of the other solutions on this page. ABC Birds recommends Tempera paint, which is non-toxic and can even withstand rain.
The most important thing is that the lines, pictures, or stencils used are spaced correctly (the 2 by 2 rule, of course!). If you only want to apply a bird preventative during migration, this would be a good, cheap option.
Photo courtesy of
Tape can deter birds when applied to the exterior surface of the window. Many tapes are only applied vertically or horizontally, but stick with the 2 by 2 rule if you can. While it stands to reason that many tapes could work for this, tape specifically designed to deter birds is recommended. “Birdtapes” can withstand a range of temperatures, and some are translucent on the interior side. These tapes usually come in white or black so they are more easily see.
ABC Birds has approved and recommends:
Feather FriendlyⓇ DIY tape, which can be found by clicking here. This DIY tape is clear with white dots placed appropriately.
CollidEscape’s bird tape (click here). Can be either white or clear with differing widths.
American Bird Conservation Birdtape (click here) is translucent and comes in either strips or squares.
Zen Wind Curtains
These “curtains” can be homemade or ordered from Acopian BirdSavers. Despite the name, they aren’t curtains. This product is made of vertical lines of paracord running down the exterior surface of a window. Above and below the window, the vertical pieces are tied to a horizontal piece of paracord. The horizontal piece is attached to the building through cable clamps. Vertical pieces should be 2 inches apart. Learn how to make them, or purchase some, by visiting Acopian BirdSavers (here).
All three images courtesy of Acopian BirdSavers.
Most birds, unlike us, can see UV light. This expensive glass comes coated with it, looking like a regular window to us, but not to birds. The surface is covered in vertical stripes or a 2 x 2 grid patten, and it’s long-lasting, although not completely permanent. A more expensive solution, but if you have an amazing view you don’t want to obscure, you can still help birds! Click here.
Dotted/Fritted Glass and Etched Glass
These methods are usually used commercially, but if you are a fan of modern design, these solutions could add to your home’s style.
Fritted Glass is glass covered in small white dots, spaced in a grid-like pattern appropriately. Etched Glass is decorative, made by making tiny cuts in the glass, and works for birds too!
These are more expensive solutions, but if you want the utmost convenience, this could work well for you. Look at some different glass designs, including dotted and etched, by clicking here.
ABC Birds Ratings
Each solution on this page has earned an approval rating from ABC Birds. Out of the solutions presented on this page, ABC Birds rates screens as the most effective. More solutions approved by ABC Birds can be found by clicking here.
Curious how the experts test some of the bird preventatives that are recommended? Learn about tunnel testing by clicking here.
Finding the Problem Windows
In a perfect world, all windows of a suburban house would have a bird preventative. However, if that is not feasible, target the most problematic windows to help the most birds:
To figure which windows are the most harmful, record any dead birds you find, outside and near a window, and the thud! of a collison. You should also step outside at different times of day to note which windows reflect the sky, the ground, or any surrounding vegetation. Also, be on the lookout for the “Dark Hole Effect.” This is when a window appears black and dark—this also attracts birds.
Then look at your observations. Did you find more dead birds under one specific window than others? Do you always hear a bird hitting a window on the north side of your house? What are your windows reflecting? Determine which windows are the most harmful based upon this data.
Even if none of your windows seem worse than others, still pick some windows to apply preventatives on! (A judgement call on which ones). You can always reach out to your local birding organization for advice if you want more guidance.
Notice how these windows reflect sky, surrounding plants, or appear dark. When you step outside to look at your windows, this is what you're looking for!
Why Should I Care?
Chances are, your house only has had a few bird-glass collisions. That might make you wonder; is it essential to bird-proof my home? The answer is yes. Bird-glass collisions are not a problem because hundreds fly into a few buildings. It’s because a few birds fly into each home! The impact of windows is cumulative. You can help lessen that impact.
Remember, almost 600 million birds* die each year from suburban homes. Glass collisions are the second leading cause of human-related bird fatalities.
*According to US Fish and Wildlife.