We’ve had birds crash into our window over and over. It often happens in the spring. What makes a bird attack a window?

Birds don’t see the world as mammals do. What we recognize as just a reflection in a window might look like another bird to a bird.

Most birds that are active during the day have eyes on either side of their heads. This gives them a wide field of view – an advantage for detecting predators. But this advantage comes at the expense of depth perception, which depends on overlapping fields of view formed by both eyes. The lack of depth perception might contribute to birds’ mistaken belief that the reflection he sees is another bird.

Image via Mike's Birding Blog

Also, birds perceive colors differently from mammals. It’s likely that birds can see colors and intensities beyond what people can see. To a bird’s eyes, the reflection in the window may be bright enough to look like a real bird.

You say the crashes occur in spring. That’s partly because early spring is the first half of the breeding season, when male birds are defining and defending territories. Your windows might be within a bird’s selected territory. The bird sees his own reflection as an intruder, so he attacks.

Here’s another reason that the crashes might occur more in spring. That’s also the beginning of migration season. During March, April, and May, many migratory species are moving northward to set up breeding territories. Thus, there is a lot of bird movement that would increase the likelihood of window strikes.

How can you prevent birds from attacking your windows? It’s not easy.

Fake owls or rubber snakes don’t work, experts say.

Closing the drapes doesn’t work, either. The bird still sees its reflection on the outer window glass.

You can try cutting out the shapes of birds and placing them on your windows. Image via dailydanny.com

To save some aggressive birds a few headaches, we’ve tried placing cut-out shapes of birds on windows. In particular, you might try silhouettes of falcons or other predators. That seems to have some success, for a time at least.

You could cover the windows – from the outside – to prevent birds from seeing their own reflections. This would be particularly appealing if, say, the bird were attacking your bedroom window at dawn, waking you up. If you do choose to cover your windows, try a medium-weight, plastic painter’s drop cloth, which lets some light in the room while eliminating reflections. Let the plastic covering hang freely over the window, where it can be blown by the wind to help frighten the bird away.

Just be aware that covering one window might cause a bird to start attacking a different window.

That’s why, experts suggest, the best strategy for keeping birds from attacking your windows might to do nothing – and wait.