Bird-Friendly Communities

Why Collisions Happen

Two confusing effects cause birds to hit windows in our homes.

It has nothing to do with intelligence. People also need visual cues to avoid walking through clear glass. The difference is that birds simply don’t see glass the way we do. Two confusing effects cause birds to hit windows in our homes: reflections and “see-through” effects.


Birds see the things they know and need – habitat and open sky – reflected on our windows. Almost any kind of glass can create a perfect mirror in certain light. Birds fly to the reflected habitat or sky and hit the glass in their path.

See-through effects

When birds see habitat or sky through one or more panes of glass, they may attempt to fly through, not realizing there is a solid barrier in their path. A sun porch, gazebo, linkway or two windows on a corner of your home can create this dangerous effect.

What about lighting?

Most homes don’t have a lot of bright lighting pointing up into the sky. That’s the primary lighting we work with building managers to reduce in larger corporate buildings through our Lights Out program. Still, any light reduction you make around your home makes sense as light pollution affects many animals, including humans. If you notice certain lighted windows that attract collision victims, take steps to block the escape of light and to add visual cues or markings to the window’s surface.

How you can help, right now