The winter owl banked just in time to pass
And save herself from breaking window glass.
And her wings straining suddenly aspread
Caught color from the last of evening red
In a display of underdown and quill
To glassed-in children at the windowsill.
— Robert Frost
The winter owl of Frost’s poem was saved an ignoble death, it seems, by the sight of children’s faces pressed against the window, which she must have seen at the last moment in order for her to bank with “wings straining suddenly aspread.” Birds colliding with windows is a huge problem. Birds, of course, have little history with glass, and to them it must appear as shockingly hardened air.
According to a 2014 study, up to 1 billion birds die per year from window strikes in the United States alone. The vast bulk of these deaths occur at night, and it is a particular problem on the East Coast. Nocturnal migrating songbirds will often die by the thousands when they are pushed down to low altitudes by a low cloud ceiling or fog; for unknown reasons, they are attracted to building lights and will divert from their path to fly to them. The same thing happens at lighthouses.
Daytime strikes are more of a problem in our area. Just last week someone posted images to an online news magazine of three dead cedar waxwings that had flown into the poster’s window. Twice recently, collared doves have flown into windows at my house, leaving a few feathers and a rather attractive impression of the wings upon the glass. These strikes seem to happen most often when birds are startled, sometimes by a hawk (Cooper’s hawks seem to delight in using feeders as their own personal larders), or in my case, I believe, by uninvited cats that wander through the yard.
Neither of the doves that struck my windows were immediately killed, but even when birds shake themselves off and fly away, they often die later from internal bleeding and bruising.
So what to do? There are solutions. First, you need to identify the windows that are most likely to be a danger to birds. If you stand outside and, when looking at the window, see sky or vegetation, that is what the birds will see and be tempted to fearlessly fly into as an escape route. To protect small birds, it is advised that you place vertical marks no more than 4 inches apart and horizontal marks 2 inches apart to make spaces so small a bird would not want to attempt to fly through. These marks can be applied with soap or tempera paint.
Many people put decals on their windows, but these are only going to be effective if they are placed close enough together so the bird doesn’t think it can fly through the gaps. The oft-used hawk silhouettes don’t appear to be an effective deterrent. More successful are netting, screens or ropes that hang on the outside of the window. Highly effective are Acopian BirdSavers, also known as Zen Wind Curtains, closely spaced ropes that hang in front of the window. An advantage to these is that they can be aesthetically pleasing. Mosquito netting and screens can also work.
A final problem with birds and glass can occur in the spring when you might hear a tap-tap-tapping at the window. Leprechauns are not the culprits. Some bird species — frequently towhees in our area — will see their reflections and attempt to get the other birds out of their territory. Any of the above solutions for window strikes will work as a deterrent. Fortunately, such territorial displays are not detrimental to the bird’s well-being, although you might imagine the poor bird’s mental health will be affected.