There was a particularly invisible glass wall in a parking lot near me. I guess enough people walked into it that they did the low-tech human version of this by

There was a particularly invisible glass wall in a parking lot near me. I guess enough people walked into it that they did the low-tech human version of this by sellotaping a piece of paper onto it that simply said “window”... I can’t imagine birds understanding that, but it was hilarious to see.