At one airport in the US, I learned about how this is accomplished with what sounds like a shotgun. Apparently this is a propane cannon[1] and there are a wide

At one airport in the US, I learned about how this is accomplished with what sounds like a shotgun. Apparently this is a propane cannon[1] and there are a wide variety of such "scarecrow" devices. I would guess crows prefer hunter-gatherers over horticulture/agriculture societies of humans! A weird twist. 1: https://en.wikipedia.org/wiki/Bird_scarer#Propane_cannons https://en.wikipedia.org/wiki/Bird_scarer#Propane_cannons