If birds occasionally hit your picture windows are you willing to try a simple experiment to stop it?

Brids occasionally crash into my north and south facing windows – especially after I clean them. Sometimes the birds are stunned and recover but often they do not – and become food for the neighborhood fox.

I read that many birds can see in the UV region and that encouraged me to try an experiment that might help.
I made a few squiggly lines and a couple of asterisk patterns on the outside of my windows with yellow and green highlighters. The marks are barely visible from inside the house but you can see them if you know they are there.
The good news is that the bird collisions have almost stopped!

I used 4 different markers, 2 yellow and 2 green: Sanford Major Accent and Promarx Glowline Yellow, and Sharpie Highlighter and Avery Fluorescent Green. I don’t know if one is better than the other. I used them all and it seems to be working.

Is this an isolated case or have I discovered something?

Are you willing to try marking your window with highlighter to see if it makes a difference? The marks come off easily so nothing is lost.
Want to try it?