Why Birds Attack Windows and Mirrors—and How You Can Stop Them

It’s a pleasant spring morning, you’re lazing in bed, and then—clackety thunk-thunk clack!

A bird is thrashing away at your window and raising quite a racket. It’s annoying and it’s interrupting your sleep, but how about the bird? Is it sick? Frightened? What’s going on? 

Not to worry. This is a fairly common behavior during breeding season with a simple explanation: The bird sees its reflection in the window and is trying to drive away the potential rival. Northern Cardinals and American Robins are known for sparring with their own likenesses, but they’re not the only species to do so, and it’s common for both males and females. And the behavior isn’t limited to building windows—birds often attack vehicle windows and exterior mirrors, too. 

The bad news is that some individuals seemingly become obsessed with these phantom foes and might return to do battle day after day. “They have not adapted to the man-made invention of glass, so they see their reflection and they fight it,” says Eli Haislip, manager at The Wood Thrush Shop, a bird-feeding store in Nashville. “They’re not going to learn that it’s not real. It’s just going to become an ingrained behavior.”

The good news? This behavior typically isn’t harmful to the bird, and there are simple ways to stop it. (To be clear, this is not the same as a bird crashing into your window at speed, which is often fatal—here’s how to prevent that.) 

To deter a bird from attacking its reflection, you’ll need to get rid of the reflection. The simplest way to do so is by placing something on the outside of the window—inside won’t cut it. Hanging a sheet, blanket, or piece of cardboard over the window will do the trick, Haislip says. (This might not be the most aesthetically pleasing solution, but it’s easy, and you should be able to take down the object after a few days.) 

Other experts recommend installing an exterior screen over the window, or marking up the glass with a bar of soap. Window decals designed to stop bird collisions can also prevent this behavior. 

If the window’s placement makes it difficult or unsafe to access, Haislip recommends anchoring Mylar balloons to a heavy object such that they’ll float and flutter just outside the window. 

And if the bird is focused on a vehicle’s mirrors, the simplest fix may be to fold them in. Another quick and easy option is to cover them with paper bags when the car is parked. Opt for paper, Haislip says—plastic bags can mar your car’s clear coat. 

With these simple fixes, you can help a confused bird save its energy to overcome the real threats it faces. And you can get some well-deserved rest.