Reflective Home Windows—Photo: Dee Renee Ericks
Bird Collisions With Glass
SOLUTIONS for HOME
Birds do not perceive glass like humans do. Collisions happen when birds fly towards natural reflections in window glass, where they see clouds, sky, or vegetation.
Western Tanager Photo by Jim Gift
Researchers estimate that up to 1 billion birds die every year in the United States alone from colliding with a window—this makes window collisions one of the top three threats to wild bird populations, third only to habitat destruction and cats.
Collisions can occur at any window, any time of day and year. Problems peak during spring and fall migration. Research shows that 54-76 percent of window collisions are fatal.
Feathers left on glass by window strike. Photo by Dee Renee Ericks
During the daytime, birds collide with windows because they see reflections of the landscape in the glass (e.g., clouds, sky, vegetation, or the ground); or they see through glass to perceived habitat (including potted plants) or to the sky on the other side.
Reflection of nearby habitat confuses birds. Photo by Dee Renee Ericks
Birds do not recognize glass as a solid object. Glass is a problem because it is confusing for birds as an invisible obstacle and as a reflective surface. It is an indiscriminate killer, culling the healthiest members of a population as well as the weakest. To make matters worse, many of the victims are songbirds whose populations are already in decline.
Orange-crowned Warbler struck reflective window. Photo by Dee Renee Ericks
Bird-building collisions can happen at any time of the day and year, but tend to increase during migration and when young birds start flying. Therefore, the most crucial times for these measures are during spring and fall migration and in the breeding season.
Stunned Yellow-rump Warbler Photo: Bob Phreaner
Many birds that seem fine following a window collision may later die from related injuries. Birds that fly away often suffer concussions and internal injuries. A collision which kills a parent bird may lead to the deaths of babies.
What You Can Do To Help
For a bird-friendly home, start by identifying problem windows. Not all windows pose equal danger. The amount of reflectivity can vary with the seasons and changes to sun angle.
To get started, fix:
Windows that have already caused collisions.
Large windows and glass doors, especially those that reflect habitat (including sky).
Windows across from bird feeders, bird baths, and fruit-bearing plants.
Red-breasted Nuthatch Photo: Glenn Kory/Audubon Photography Awards
Place Visible Patterns on Outside of Glass:
The key to making glass bird-friendly is to create a visible pattern that breaks up transparent or reflective areas of glass. Birds will avoid glass if the markings are tightly grouped, realizing they cannot fit through the transparent or reflective areas of glass.
Vertical stripes or decal placement should be minimum ¼ inch wide with a maximum spacing of 4 inches.
Horizontal stripes or decal placement should be at least ¼ inch wide, maximum spacing of 2 inches.
Tests have shown these dimensions to be the most effective at preventing bird strikes.
Birds need strong clues on or around glass to warn them that it’s there.
Decals and Window Film:
An easy way to apply the correct spacing of markings across your window: Feather Friendly® small-format or medium-format products
FEATHER FRIENDLY® dot pattern bird tape. The markers are easy to apply, readily apparent on the outside, but are obscure gray markers looking from the inside, out.
Photo: featherfriendly.com
WINDOW DECALS work if they are placed on the OUTSIDE of a window, and spaced 2 to 4” apart. For the best protection, pair with UV Liquid between the decals.
Cords, Shades, and Screens etc:
CORDS:
Hanging cords, strings or ribbons in front of your windows can be effective and unobtrusive.
Acopian BirdSavers™known as “zen curtains,” are closely spaced cords that hang down over windows. They do the work of tape or decals but are easier to install and can be aesthetically pleasing. Make them yourself (DIY), or order custom-made based on the size of your window(s).
Photo: Cornell Lab
CLOSE BLINDS
Blinds, or curtains can help break up exterior reflections.
Photo courtesy Ruan Richard Rodrigues, Unsplash
INSTALL EXTERNAL SCREENS
External insect window screens reduce bird collisions by minimizing window reflections and alerting birds that windows are barriers.
Photo courtesy Darrin Henein, Unsplash
DRAW PATTERNS ON GLASS
Create patterns on exterior surface of reflective windows. Multiple markings 2” to 4” apart is optimal. A bar of soap, oil-based Sharpie drawings, and tempera paint are excellent markers on glass.
Non-toxic tempera paint patterns or artwork applied to exterior glass can reduce bird collisions for many years. Tempera paint is easily removed using vinegar and water. You can use either a grid pattern of 2 inches by 2 inches, or get creative and paint patterns or artwork on your window.
Photo: Dee Renee Ericks
Other BirdSafe actions:
MOVE BIRD FEEDERS AND BATHS far away from (>30 feet) or close to (<3 feet) windows
Photo: Linda Butler/Audubon Photography Awards
MOVE PLANTS AWAY FROM WINDOWS
Birds see house plants through the glass and try to fly to or through them.
Photo: Courtesy Nathan Fertig, Unsplash
CollideEscape™ bird tape and ABC Bird Tape are options, and are only effective when spaced very closely (2”to 4” apart). Make your own patterns and design.
Note: Hawk silhouettes do NOTHING to deter birds.
See also:
Lights Out
At night, nocturnal migrants, which includes most songbirds, crash because they fly into lighted windows. Researchers aren’t sure why, but artificial lights at night also divert and disorient migrating birds, drawing them into urban areas, which leaves them vulnerable to threats such as building collisions. About 80 percent of migratory birds in North America migrate at night.
VISIT:
North Olympic Wildlife Habitat Project, Backyard Habitat Certification Program for more information on landscaping for birds.
Photo by Evan Barrientos/Audubon
A local source for some of the products mentioned above is Wild Birds Unlimited® located in Gardiner, Washington. They currently carry the UV paint pens called WindowAlert® UV Liquid, WindowAlert® ultraviolet decals, and Feather Friendly® tape. Contact them at (360) 797-7100 to check for availability.
(Note: No window product can guarantee elimination of window collisions. Results will vary depending on local bird populations, landscape conditions, product used, and building design. We are providing these product suggestions as a convenience, and there are many more that may work in a similar way to suit your needs.)