Can birds see glass? Birds see reflections of habitat and sky or corridors to fly through. Learn about installing bird deterrents for windows to keep feathered friends safe.
I’ve been there: It began with a horrible thud on our large sunroom window. The death of a male robin during breeding season 2009 was my wake-up call. I became determined to learn how to protect birds from window collisions. So, I turned to bird conservationists and makers of bird-safe products to figure out what could be done.
Can Birds See Glass?
Nearly one billion birds die annually in the United States because of window collisions, according to the U.S. Fish and Wildlife Service. Birds fly into windows because they simply don’t see the glass. They see reflections of habitat and sky, or corridors to fly through. Homeowners may not see dead birds near windows because the birds often fly away and die or are scavenged. After window strikes, our feathered friends can suffer concussions, eye injuries, and broken beaks and bills that render them unable to eat.
Daniel Klem Jr., professor of ornithology and conservation biology at Muhlenberg College in Allentown, Pennsylvania, has dedicated his career to protecting birds from windows. His book Solid Air: Invisible Killer offers plenty of solutions. “Our residential windows are knocking off the strongest and most common bird species in astronomical numbers,” Klem says. “Unlike other mortality factors, like weather and predators, where studies show rebounding populations, windows take the strongest as well as the weak.”
Researchers say the highest number of window collisions occur on the lowest three stories of buildings, mainly residences where vegetation is reflected most. So, native plantings, which can boost bird populations, can also put those increased populations at risk when they’re planted close to homes. Jim Cubie, a retired U.S. senator and policy and outreach consultant with the Ornithology Center at Muhlenberg College, is equal parts native plant advocate and avian conservationist. He says, “Practicing sustainable stewardship means protecting birds simultaneously to planting natives, or we’ve actually conserved little.”
So, if birds are going to continue to play essential roles in our sustainable habitats, homeowners must retrofit window exteriors to turn the tide.
First, what doesn’t work: single decals or common garden netting. Hawk silhouettes and single decals won’t deter birds unless they entirely cover window exteriors, spaced no more than 2 inches apart. And birds can get caught in the netting, while the flimsy material rips or frequently needs to be pulled taut.
Thankfully, a slew of inexpensive, bird-safe retrofit products have come to market.
Bird Deterrent for Windows
Feather Friendly offers collision deterrents that homeowners can buy and then apply themselves. Feather Friendly’s regular deterrents for homeowners are 1/4-inch-wide dotted film markers. They come precut in narrow strips. Squares of white or light blue are also available. These films allow creative types to design their own patterns, and the films can be removed without damaging windows. Before ordering, customers can send images of their windows so the products can be tailored.
CollidEscape also offers tapes, including “budget tapes” in white, spiderweb clear, and translucent blue, as well as exterior sheet films that mimic the screen effect.
I installed white CollidEscape sheet film on my huge picture window 14 years ago, and I witnessed no strikes in the 12 years it was up. It comes perforated with tiny holes, so it’s barely noticeable, like looking out through a screen. The company’s specialty program manager, Jeff Rank, explains, “It’s engineered so that your eye naturally focuses past the black to see the view outdoors clearly.” CollidEscape also comes in charcoal exterior.
Bryan Lenz, Glass Collisions Program Manager and Bird City Network Director with ABC, says, “For added sustainability, get solar screens for the outside. They’re denser, to shade the sun, and you can still see out.”
If you’re building anew or replacing windows, Cubie says the choices for bird-safe glass on a residential scale aren’t good yet. He says homeowners should install whatever windows are best, and then immediately retrofit glass exteriors with deterrents.
After 12 years of our sunroom window being covered with white CollidEscape sheet film, we needed to replace the glass and then used U.S.-made Acopian BirdSavers. BirdSavers are made of 1/8-inch-diameter, dark-green “paracord.” Also called “zen window curtains,” because their gentle swaying in the wind has a calming effect, these material cords are effective. “They’ve even been used on a multistory building in Chicago,” says Klem. So, BirdSavers cords don’t get tangled, even in the Windy City! And Acopian BirdSavers owner Jeff Acopian just wants to save birds, so he offers detailed instructions for how to make your own on the company website.
The cheapest deterrents are DIY: Fasten regular twine above and below exterior window glass in vertical strings spaced 2 inches apart. For film, homeowners can use any clear film that can be printed, as long as it’s a full, unobstructed graphic covering exterior surfaces.
Paul Groleau, vice president of Feather Friendly, offers another cheap choice: “The lowest-tech, most eco-conscious option may be plant-based soap,” he says. “Anything that will cause disruption of the reflection. The biggest thing is spacing. Or, for emergencies, cover window exteriors with tempera paint.”
So, the solution to the existential threat we pose to already plummeting bird populations is within reach; unlike bird-safe windows, it’s as transparent as can be.