Bird Window Strikes

White Crowned Sparrow Zonotrichia leucophrys Courtesy US FWS Gary Kramer, Photographer
White Crowned Sparrow
Zonotrichia leucophrys
Courtesy US FWS
Gary Kramer, Photographer
THUNK! We have all been startled by the loud thunk of a bird hitting a window. In the United States window collisions kill an estimated 1 billion birds a year with 44% of bird window collisions occur at homes throughout the year. So, changes made around your home can help maintain our bird populations.

What happens to birds that crash into windows? About half of them die immediately from head injuries, broken necks and internal bleeding. The other half may recover. If you see a stunned bird, move it to a safe space away from cats or other predators, or place it in or under a box. Try not to handle the bird and don’t give the bird food or water. In 10-30 minutes the bird will likely be recovered enough to fly away.

Why do birds fly into windows? Birds don’t see glass as a solid object. Birds see the window as an opening that they can fly through or the see reflections of sky and trees in the window

The USU Bird Strike Project has been doing research on bird window collisions on the USU campus for the past several years. We have found that the vegetation planted outside the window has a greater influence on window strikes than window area. You can prevent window strikes by not planting fruit bearing trees and shrubs or setting up bird feeders 15-45 ‘in front of windows. Small birds can reach speeds of 30 mph within 15’. So, put those bird feeders right next to the window or more than 45’ away.Bird Window Strikes

If you have a window that experiences frequent collisions, treat the window to convince birds that they cannot fly through that space. Raptor stickers are popular but ineffective. Birds don’t see the stickers as predators. Small birds do not want to fly through spaces that are smaller than 2” high and 4” across. The width is the most important measurement. You need to convince the birds that the open spaces are no larger than 4” across.

There are a variety of effective ways to prevent bird window collisions; some of these are available commercially and others are do-it-yourself. I applied Feather Friendly Design vinyl to my windows and it has been very successful. The home installation materials come as strips of vinyl with small squares about ¼” in size every 4”. The strips are applied to the window with a credit card, then you peel away the strip, leaving the small squares. A DIY version is to dip your pinkie finger in paint and apply it every four inches on your window. Bird Tape is available in strips that can be applied every four inches to your window. Another option is to hang paracord at 4” intervals in front of the window. Window screens will prevent birds from hitting windows and shades can limit the amount of reflection that birds see. The American Bird Conservancy website has even more options for homeowners.
Bird populations are under a number of threats from urbanization, climate change and introduced predators. Some threats, like climate change, are difficult to tackle. But preventing bird collisions is a relatively easy step we can all take to preserve our bird populations.

I’m Kim Sullivan of the USU College of Science and I’m Wild about Utah.


Photos: Courtesy US FWS, Gary Kramer, Photographer,
Audio: Courtesy and Copyright Kevin Colver
Text: Kim Sullivan, Bridgerland Audubon Society
Additional Reading: Lyle Bingham & Hilary Shughart, Bridgerland Audubon Society

Additional Reading

Protecting Birds Against Window Strikes, Bridgerland Audubon,

Grow Native For Birds, Bridgerland Audubon,

Strand, Holly, Bird vs. Window, Wild About Utah, November 10, 2010,

Strand, Holly, Bird vs. Window, Wild About Utah, December 9, 2008,

Rachel Sagers, Brinnlie Harward, Landon Keller and Haley Schmid with Dr. Kim Sullivan, Patterns of Bird Window Strikes on USU Campus and Physical Features that Increase Risk for Collision, Department of Biology, (Honors Program,) Utah State University,

How to Keep Birds From Hitting Windows, American Bird Conservancy,

Messmer, Terry, Cowell, Samuel, Dietrich, Dietrich, and Sullivan, Kimberly, Ask an Expert: Seven Tips to Keep Birds from Hitting Your Windows, Utah State University Extension, March 28, 2017,

Cowell, Samuel, Dietrich, Dietrich, Sullivan, Kimberly and Messmer, Terry, Reducing the Risk of Birds Colliding into Windows:
A Practical Guide for Homes and Businesses [NR/Wildlife/2017-01pr], Utah State University Extension, March 2017,