That and you need to be persistent. Scare them once and they'll come back when things seem to have calmed down again, you need to make them associate this place with danger. Make them see it as a place not worth coming back to.

[Which was what the scarecrows had been for before they decided to go on strike. A permanent reminder for the crows that this was a place to be avoided.]

Maybe. If my brother was here he might have been able to just bargain with them instead.