Birds are not only beautiful creatures, they are also a vital part of the ecosystem, helping humans by controlling the pest population, protecting drinking water, and carrying seeds across the miles to propagate all types of plants. As they take flight, birds also face dangers that people have literally built in their paths.
Construction is booming in the United States, both commercial and residential. Almost all of these structures have a common feature that is a bird’s nemesis: glass. Tania Homayoun, a biologist at the Wildlife Diversity Program at Texas Parks and Wildlife, says that birds around the world have trouble with glass. Collisions killing almost 600 million birds a year in the United States alone. About 253 million of those die by flying into residential buildings. (Buildings are the second-leading cause of death for birds after cats.)
“Birds do not perceive glass in the same way humans do,” explains Homayoun. “Even if we cannot clearly see a pane of glass in a window or door, as humans, we have context and knowledge that suggest to us that there is a barrier there. For birds, issues with glass typically come down to their properties of reflectivity and/or transparency.”
So, what can you do? Whether you are planning a new home now, doing renovations, or living in a home that you didn’t build originally, you can take a few easy steps to reduce the chances of birds being injured or killed.
Use Less Glass
It might seem obvious, but a lower percentage of glass surfaces on a home’s exterior will reduce the chances that a bird will smack into it. Modern technologies have made it much easier to put a large picture window or even floor-to-ceiling windows in homes, and the look is definitely dramatic. Such windows let in abundant natural light and brighten up a room, even making smaller spaces look larger. But the trade-off is a greater risk of injury for birds. Another consideration that might discourage the use of a lot of glass in construction: windows are the primary place where buildings gain and lose heat, accounting for 25 to 30 percent of your total heating and energy use. And the more energy you use, the bigger the utility bill will be.
Add a Barrier
If your home’s windows don’t already have screens, adding them can help reduce bird accidents. Screens are one of the most cost-effective ways to keep birds away from windows, according to the American Bird Conservancy. The best types of screens would actually go on the outside of the window, adhered with suction cups to hold the screen away from the actual glass. That helps protect birds if they still manage to fly into them.
Filter the Light
Translucent glass is the biggest danger for birds. “Some of the newer glass products used in renovations or new home construction may have energy-efficient treatments that can make them more reflective,” says Homayoun. “Sometimes older buildings that never experienced bird collisions may start to have problems when these new windows are installed.”
Adding etching or using frosted glass in your design signals to birds that there is a barrier they need to avoid. These types of glasses can be installed when the home is built, of course, but windows also can be retrofitted on site to enhance safety.
Block it Out
You have probably seen block glass used in bathrooms. This design allows light to filter in while keeping prying eyes from seeing inside the room. Block glass doesn’t reflect vegetation like translucent windows do, and the pattern in block glass again alerts birds that something is in their way and they need to change course.
Just Add Stickers
Protecting birds can sometimes be as easy as sticking something on the window itself. “There are films you can buy. You can put soap on windows,” says Nicole Netherton, executive director of Travis Audubon in Austin, Texas. “It’s really about birds being able to see the glass.” Netherton says whatever you choose to stick onto your windows should be two inches apart so that they are in birds’ field of vision.
Turn Off the Lights
Daytime collisions are most common, because that is when trees and other vegetation reflect the most sunlight and make birds think they are heading into the open sky. However, the proliferation of artificial light at night is a real problem as well.
“Many of our native songbird species migrate at night and artificial light sources can impair their ability to safely navigate through brightly-lit areas, like cities and suburbs,” says Homayoun. “Large-scale artificial light at night can attract migrating birds into dangerous spaces where the risk of collision increases. Collectively, all the light we use in and around our homes can contribute to sky glow, glare, and light pollution.” Turning off exterior lights at night helps birds find safe passage over your home. Also, avoid adding landscaping lights that shine upward.
Even the type of lighting you use in the house can affect the chances of a bird flying into the windows. Using slightly "warm" light bulbs reduces exposure to blue light, which is harmful to birds, says Homayoun.
“For LED bulbs, look for a color temperature of 3,000 Kelvins or less,” Homayoun says. This can reduce sky glow and light trespass.
Threats to Birds. U.S. Fish & Wildlife Services.
Loss, Scott R. et al. Bird–Building Collisions In The United States: Estimates Of Annual Mortality And Species Vulnerability. The Condor, vol 116, no. 1, 2014, pp. 8-23. Oxford University Press (OUP). doi:10.1650/condor-13-090.1.
Update or Replace Windows. U.S. Department of Energy Office of Energy Saver.
How to Keep Birds From Hitting Windows. American Bird Conservancy.