How to Keep Birds From Flying Into Windows

Preventing window collisions is easy to do.


Placing reflective decals on a window.

(JDzacovsky /

Birds are one of nature’s wonders. Thousands of species grace the skies, trees, and undergrowth, forming a vital part of every ecosystem. 

Unfortunately  human architecture has erected a roadblock in the way of a healthy bird population in the form of windows. Birds cannot see glass and often fly into glass windows and doors, leading to injury or death. Thankfully, there are easy  ways to prevent this.

More than a billion every year
According to Chatelaine, more than a billion birds are killed per year in window collisions in North America alone. This is a staggering number of deaths.

The reason for this is that birds can’t actually see glass. Either they think the reflection of the sky seen in a window is the sky, or that what is seen through the window is just a nice place to perch and hang out. In truth, humans can’t see glass either. We are just trained from birth to understand that the material between those solid rectangles is also solid. Birds do not have that training.

In addition, according to the Cornell lab’s organization All About Birds, some birds can also attack their own reflections in the window, thinking that it is another bird encroaching on their territory. This too, can be fatal. 

“Birds are incapable of learning the concept,” Dr. Christine Sheppard of the American Bird Conservancy told Chatelaine , “And they have no idea about these cues. They have no way to understand the difference between a reflection and a piece of habitat.”

Luckily, there are ways to keep birds from colliding with windows.

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Stripes and dots
This first thing to do, according to the Cornell lab, is to figure out which windows are the worst for birds. Go outside, and look at windows from the perspective of a bird. Are they opaque in sunlight? Which are reflective and which are transparent? Once the most offending windows are identified they can be retrofitted to prevent bird collisions in a number of ways.

The main concept is to create markings in close proximity on the outside of windows to break up the reflective surface and allow the birds to perceive the glass as a solid material. 

Some ways to do this are to draw on the windows in tempera paint which is weatherproof, but also easily removable. Another option is to place decals or other sticky objects in close proximity to each other on the outside of the window.

In a similar vein, specialized patterned tape with dots and stripes can be placed on the window. “Zen curtains” or closely spaced ropes that hang vertically down the window are also a good option. And finally, using a window screen will make it possible for birds to see a window.

It is amazing to think that small changes can make a huge difference in the lives of so many feathery avians.

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