How to Protect Birds From the Scourge of Windows

Welcome to Wildlife Week, an exploration of what happens when nature and home meet.

We are all lucky to be living in a world of birds. Peregrine falcons nest in New York City skyscrapers; feral parrots squawk in San Francisco; roadrunners sprint the desert Southwest; loons make their plaintive call from the lakes of Minnesota; and thousands more species do their weird and amazing bird things in all places in between. In exchange for being able to look at birds, the least we can do is to mitigate the dangers we have created for them, which means bird proofing our windows.

Windows are a dual threat to birds. Depending on the angle in which light hits glass, it can appear either transparent or reflective. If it appears transparent, a bird cannot always perceive that a barrier exists, and may attempt to fly through it. If glass is reflective, a bird may believe that whatever is being reflected lies on the other side, like a tree or field, and attempt to fly through it.

Both outcomes are disastrous. A 2014 study from the Smithsonian estimated between 365 and 998 million birds are killed by collisions with buildings, mainly due to windows, each year. It’s estimated that the true figure is significantly higher— well over a billion—owing to more and larger windows in new construction and the possibility of underreporting by that study; the study counted carcasses, and many bird deaths come at a later point, from an injured bird dying away from the collision site. 

The stories of bird deaths by collision are gruesome. And according to the U.S. Fish and Wildlife Service, collisions are the second-leading unnatural cause of bird deaths in the country, behind only predation by cats. (Please keep your cats indoors!) Luckily, there are plenty of very easy and cost-effective ways to protect birds from the horrors of windows without having to give up your interior natural light.

What does bird-proofing need to accomplish?

The key to bird-proofing windows is to make it clear that your windows are barriers, rather than portals or whatever they reflect. Closing your curtains or blinds can help, but remember that there are two possible reasons birds fly into windows: either they think they can get through them to what’s on the other side, or they think that whatever’s being reflected lies on the other side of the window. If your windows are reflective, closing blinds won’t always help; dark curtains or blinds can make them more reflective, and thus more dangerous.

Generally, you’ll want to create some kind of pattern on your windows, which serves to show the birds that this is an impassable wall. You’ll want a fairly in-depth pattern, one that leaves no unmarked space larger than about four square inches, according to Audubon; anything smaller, and small birds may think they can daredevil their way through the "gap." If you have lots of small birds, like hummingbirds, nearby, you’ll want that gap to be even smaller.

How to keep birds safe

One attractive method to bird-proof your windows is the Acopian BirdSaver, which is a series of vertically hanging lines of thin paracord. Paracord is inexpensive and inconspicuous, and Acopian is thoughtful enough to offer either ready-made solutions or DIY instructions to make your own. This particular method is surprisingly attractive; it almost looks like Alyson Shotz’s famed Mirror Fence art piece.

You can also opt for cheery patterns applied in the form of tape applied to windows; dots are common and effective. Polka-dotted windows maintain plenty of light flowing into your house while also conveying to birds that this is a no-fly zone.

If you have kids, or an artistic bent, you can paint your windows. The best option there is tempera paint, which is available in marker form for easy drawing. These markers are inexpensive and, as the name suggests, very temporary; some soapy water and a rag will wash it right off if it’s relatively thin. (Thicker coats can still be fairly easily removed with a razor blade.) 

What options don’t work so well?

Stickers and decals might be appealing, but they typically don’t cover enough of the window to allow a bird to understand that the window is not something they should fly into.

Similarly, while a big sticker or picture of a predator, like a hawk, might seem like it would have a kind of scarecrow effect, there’s little evidence that birds will be any more scared of a hawk sticker than any other shape. And those stickers have similar issues as any other sticker: to really have an effect, you’d have to blanket your window like a dive-bar bathroom. (Most would probably not like that effect, but if that’s what you want to do, by all means!)

There’s some conflicting information on bird feeders. Some suggest that feeders attached directly to windows via suction cups can effectively inform birds that they should not approach a window at high velocity, or that they can prevent a scared bird from fleeing a feeder into a window. Others suggest keeping feeders far from windows to simply keep birds away from the danger zone altogether. One potential issue is that, on a large window, a single small feeder may not convey that the entire sheet of glass is there, and a bird might attempt to fly behind the feeder. 

When should you bird-proof?

Unfortunately, birds can and will collide with windows at any time of the year, and even any time of day. But it’s most important to have some kind of window-proofing during the peak migration times, which occur in spring and fall.  

Photo:  Bulgac via Getty Images