Few sounds are as disheartening to a homeowner as that of a bird colliding with a window. And with good reason, since studies show not only that such collisions are frequently fatal — one in two results in the death of the bird — but that they are also all too common.
In the United States, no fewer than 264 different bird species are known to strike windows. That’s almost 27 percent of the 990 species that American birdwatchers have reported to eBird, Cornell Lab’s real-time online database of bird sightings. Sadly, species as tiny as the ruby-throated hummingbird and as imposing as the golden eagle made the list.
The number of individual birds involved in fatal window collisions is even more shocking. According to an estimate published in 2014 by scientists with the U.S. Fish and Wildlife Service and the Smithsonian’s Conservation Biology Institute, the toll in the United States alone could be as high as 988 million— every year.
Windows pose a deadly threat to birds because birds don’t perceive sheet glass as a barrier. When they look through clear glass, they see an apparent passageway that they can move through to reach whatever is visible on the other side. When they see trees, shrubs or other attractive greenery reflected in a window, they frequently decide to fly toward the reflection.
As you might expect, glass-covered skyscrapers are the site of many collisions, but high-rises account for less than 1 percent of the mortality rate. The overwhelming majority occurs at structures under 12 stories tall, and 44 percent occurs close to home — at buildings one to three stories high, including residences.
This means that homeowners who take steps to decrease the number of window strikes around their home, even by a little, can have a big impact, and doing so is pretty easy. There are two main strategies you can employ, and both are highly effective.
The first is making your otherwise invisible glass visible to birds. Accomplishing this can be as simple as dangling feathers, Mylar strips, old CD-ROMs, or other objects in front of a problem window or dabbing tempera paint on its exterior — any type of pattern will do.
Feathers on Windows: Dangling feathers or other products in front of a window can significantly lower the number of bird strikes to your home.
You can also give one of the following readily available products a try:
- WindowAlert and other window decals: Made of translucent vinyl and available in a variety of shapes, including leaves, snowflakes, hummingbirds and dragonflies, the decals adhere to a window’s exterior and reflect bright ultraviolet light, visible to many birds, while breaking up any reflections that birds might see in the glass.
- ABC BirdTape: Simple, practical and developed by experts at the American Bird Conservancy, a leading nonprofit bird-conservation organization, translucent ABC BirdTape comes in 50-foot rolls and in two widths, three-quarters of an inch and three inches, so you can cover the exterior of a problem window with orderly stripes or squares, making the glass visible from the outside while still permitting you to see out from the inside.
- Acopian BirdSavers: Acopian Bird-Savers consist of a curtain of dark-colored nylon parachute cords that can be affixed near the top of a window and, spaced about 4 inches apart, dangle in front of its outer surface. They work because birds see the cords and try to avoid them. Homeowners who install them love the way they look. You can order them pre-assembled or make your own. Instructions are on the website.
- CollidEscape film: If you’ve ever ridden a city bus covered from bumper to bumper in advertisements, you’ve already seen self-adhesive window film in action. CollidEscape works the same way. Applied to the exterior of a problem window, it will keep birds from seeing deceiving reflections and make the glass plainly visible, while tiny perforations in the film will allow you, indoors, to take in the sights outdoors.
The second strategy to employ to prevent bird-window collisions is placing a barrier between the bird and the window. Two products do this well: the Bird Crash Preventer and the Bird Screen.
- The Bird Crash Preventer is a pre-assembled curtain of monofilament lines that cover the exterior of a problem window. Brackets that you attach above and below hold the lines taut 3 inches apart and a safe 5 inches from the surface of the glass. The lines won’t obstruct your view at all, but birds have no trouble seeing them and steer clear.
- The Bird Screen, a soft, flexible, dark fiberglass screen, hangs several inches in front of a window. Anchored above and below using hooks screwed into the window frame or brackets attached to the pane with suction cups, it provides a gentle cushion for birds that fly into it, preventing injury, while still allowing you to look out. Both the Bird Crash Preventer and the Bird Screen are available in a variety of sizes, allowing you to cover sunroom windows and sliding glass doors as well as most windows, so don’t assume your problem window is too wide or too tall.
And don’t fall into the trap of thinking that you need to treat every window in your home. Because you don’t. If you’ve noticed that birds seem to hit only one or two windows, concentrate your efforts on those one or two first. Treating them may be all it takes to solve your collision problem.
One final tip: If you worry about window collisions but like to feed birds in your yard, consider switching to a window-mounted feeder. You’ll find many styles and sizes online or at your local nature center. Most yard birds will like them just as much as other feeder styles, and you’ll have a front-row seat from inside the house. Plus, placing the feeder close to the window will keep your guests from building the momentum needed to cause injury in a window collision.