Is polarized light why birds run into windows?

Birds sometimes run into windows, especially big plate glass windows. Is polarized light or the blocking of same part of the reason?

I went into a store and forgot to switch to my regular glasses my prescription sunglasses, which are polarized. I can’t see without my glasses so I left them on in the store.

I was looking at some flashlights in a display case. I reached out to grab one and my hand hit the plexiglass in front of the flashlights. I hadn’t noticed that the case was enclosed.

When I lowered my sunglasses I could clearly see the plexiglass because of light reflecting off its surface. The polarized sunglasses blocked those reflections.

On the drive home I thought about how we see glass. Assuming the glass transmits light efficiently, doesn’t have anything on its surface, and doesn’t color the light, we see glass because of reflections.

Is that why birds run into windows – because the polarized light is being blocked? Maybe the birds are wearing polarized glasses or their natural equivalent, or maybe the glass is acting as a polarizing filter.

RelatedWhy every photographer needs a polarizing filter

2 Responses to Is polarized light why birds run into windows?

  1. Lurker says:

    It’s also how fishing birds hunt. They can see right though the water’s surface.

  2. Les Jones says:

    I was thinking about that. Birds that eat fish obviously have to see below the surface, so they’re using polarization. It wouldn’t surprise me that any predatory bird has polarizing filters to cut through haze caused by dust or reflections off of rock, ice, or other reflective surfaces.