Green Cross Code for birds

It doesn't look great, and my neighbours might think it's more evidence that I'm potty, but there's a reason for the paper crosses on my windows.

It's good to see the birds at the feeders just outside my windows, but their babies aren't good at recognising glass. Several have flown into the windows. I'm hoping the crosses will show them there's an obstacle there. I know you can buy bird or butterfly stickers (I have some on other windows), but this was the best I could do today.