by Bridger Donaldson

Birds and Glass: Preventing Avian Window Collisions

Many of us have at some point come across a deceased bird underneath a window or investigated after hearing the startling noise of a bird hitting a glass pane.

One of the largest anthropogenic causes of avian death in the US, along with habitat destruction and cats, is collisions with glass. It’s estimated that up to one billion birds are killed annually after colliding with windows.

This, along with many other factors, is driving massive bird decline across the continent. Denny Olson, in character as Prof. Avian Guano, addresses this fantastically in the video “BIRD TROUBLE”. It is the second video in an entertaining three-part series that teaches why birds matter, why they are threatened, and ways we can help.

Birds fly into windows because they can’t distinguish the difference between the reflection and nearby sky and habitat. Luckily, there are ways you can help reduce or eliminate these collisions. Two of the best, simplest methods of prevention are shown below.

String Across Window

This window has small nails placed along the bottom and top, spaced about an inch or two apart, and string has been strung between the nails to break up the reflection. You can do this with anything that hangs or crosses over the window, although string is the simplest method. It also looks more “human” and less like an inviting spot of shrubbery.

Stickers/Tape Dots

This method has the same effect as the string to break up the reflection, though might be easier to do or looks better depending on the window and your preference. This can be done with anything that will stick to the window and can be readily seen from the outside. In general, lighter colors work better than darker ones. Ideally, the dots/lines should be spaced less than two inches apart in a grid. This will help dissuade our smallest birds, like hummingbirds, from flying into the glass. If you want an effective solution that takes less time, you can buy strips (Feather Friendly®, as an example) that are easily applied to the window and look great. A major upside of these is they don’t need to be removed when cleaning the glass.

You don’t necessarily need to apply these solutions to every window in your house. Start by addressing the windows that have had a bird collision before, reflect nearby habitat that birds interact with, or are near feeders and other spaces active with bird life.

Also, in my experience, it doesn’t take long to adjust to the slight obstruction to the view. I have fairly big pieces of atrocious bright blue painter’s tape on some of my windows, and I don’t really notice them anymore. Your eyes will train themselves to look past them, hopefully to spot a new bird out in your yard.

Noteworthy is that Flathead Audubon is doing a study on bird strikes. Operation Bird Collision is ongoing and it’s easy to be part of the survey. All members are encouraged to join. Tell us when you start to observe the areas around your windows for dead birds. After a year, we would like to know how many days you recorded information on window mortality (that includes days with no mortality). Contact Dave Manuwal ( to enroll. Tell Dave when you find a bird. If you are not sure of its identity, photograph it and send Dave the photo.

I hope the information in this article helps you in your efforts to make your home safer for birds, thank you for any action you take!