Each year, more than one billion birds in the U.S. die from colliding with windows. To put this in perspective: in 2023, more than 1,000 birds were killed in a single night at McCormick Place Lakeside Center in Chicago during migration. The following summer, the building installed bird-safe window film and began turning off its lights at night. The result? During the very next fall migration when bird strikes are generally high, bird collisions were reduced by 95%.
Glass collisions are a problem for large urban buildings and private residences alike. In fact, 44% of bird deaths due to glass strikes are from private residences, and the vast majority of bird deaths from glass are from buildings under 11 stories. The good news is these deaths are easily preventable.
The problem is: Birds do not see glass. To them, glass either reflects the surrounding landscape—trees, sky, or buildings—or appears as a clear passageway, such as on walkways or between windows. In both cases, the bird sees what looks like safe habitat or open air and flies straight into it, often at full speed.
The solution is just as straightforward: make the presence of glass visible. The key is that the reflection or view through the glass must be visually interrupted—birds need a clear signal that glass isn’t open air. Patterns are crucial, and the spaces between markings should be no larger than 2 inches wide (about the size of your fist). Otherwise, birds may think they can fold their wings and slip through.
Here are several proven ways to retrofit windows (all must be applied on the exterior of the glass to work properly—and most can be DIY):
- Patterned films or dot strips – Products like Solyx Window Film and Feather Friendly Bird Collision Tape create visible patterns that break up reflections while still letting in plenty of light.
- Bird Crash Preventer – A system of closely spaced monofilament lines that preserves your view from inside while making the window visible and safe for birds.
- Acopian BirdSavers (“Zen curtains”) – Strips of cord or string suspended in front of the glass. These can be purchased ready-made or built as a DIY project.
- Oil-based paint markers – A creative, low-cost option. Draw patterns or artwork directly on the exterior glass. As long as no “open” space is larger than a fist, your design can be as simple or artistic as you like—and it doubles as bird-safe art!
For more ideas on making the glass in your home or commercial building safe, check out American Bird Conservancy’s info which has tested and provides ratings for the most effective materials.