Birds can’t be very smart, if they continue to be fooled by scarecrows.
People can’t be very smart, if they continue to believe scarecrows are effective against birds.
Maybe if they drew a really mean face on the scarecrow, that might work better.
note: My mother used to shoot a few crows and hang them from our cherry trees.
Crows don’t like that for some reason.
Maybe they didn’t like the string my mother used to tie them up.