Some years back my sweet friend Ms. M made a discovery
On a migration route
We lived together on a bird migration route. All kinds of birds. Dozens of species. Thousands of birds. And we had trouble with birds smacking into the windows. We tried everything. Silouettes of predators. Etc. And one day Ms. M discovered, “stabilimentum”.
Fancy latin for spider web decorations. Spiders don’t like to have birds destroy their webs. So they put decorations in the middle to warn the birds. Clever spiders. And a handy trick for bird enthusiasts. Especially us all with feeders.
How to do it
Take one small tube of silicone. I use white. You could try clear. Make a small to medium size (the size of your hand) zig zag pattern in the middle of your window. You’ll not even notice it, but the birds will.
On really large windows you may need to do the corners of the window also.
Your bird friends say “thank you.”