Window collisions are the second biggest killer of birds with just under half of those collisions being with homes and smaller buildings. In a study last year, about 3.5 billion birds died from Bird-Window Collisions. The two biggest factors for why birds fly into windows are transparency and reflectiveness. The birds either see something on the other side of the glass that they want to get to — we call this the pass through effect. Reflectiveness is when they see a reflection of something they want to get to.
But how do we prevent bird-window collisions? There are many ways you can help! Treating problematic windows can decrease the risk of a bird-window collision.
Bird collision window treatments
Dots: Putting these small dots on a window can decrease the transparency and reflectiveness. These bird dots also stay on for long periods of time, even in Wisconsin weather. They can stay on a window for up to 10 years. Bird dots are one of the easiest and effective ways to prevent bird-window collisions.
Photo by Ellie Meng
Photo by Joelle Ghring
Tempera Paint: Whether it’s plain white or full of colors, putting tempera paint on a window reduces the chance of a bird window collision. Tempera paint is washable and may come off over time so it’s best for people who like to change things up every once in a while.
Photo by Ellie Meng
Paracord: Paracord curtains (a.k.a. Zen curtains) hang in front of a window. They can move in the wind which helps the birds realize that they can’t fly through the window. These curtains are also very relaxing to watch but they do not obstruct the outside view.
Photo by Ann Morrow
*Remember, when picking a window treatment, you should always choose something you like. If you want a treatment to be most effective, make sure that gaps are no more than 2 inches apart. If there is a gap bigger than 2 inches, birds may be inclined to fly through it, making the treatment ineffective.
Written by Ellie Meng
Ellie is a Senior Girl Scout in troop 7889. She is working on her Girl Scout Gold Award. She helped put up these dots as well as observing these windows during the migration period to identify which windows were problematic. Specifically with the Humane Society, Ellie worked with volunteers over the summer of 2025 to use bird dots to treat the training room windows. She partnered with the Southern Wisconsin Bird Alliance and Dane County Humane Society in order to prevent bird-window collisions.
