Have access to a fishnet or similar or can make one ? Then make a simple frame and drape your net over it, shall keep them crows away. Ypu could also bend small cages from wire for individual pots. Try a scarecrow albeit I never saw one that worked, anything that moves, best would be if it moves in unpredictable pattern, also consider tying strips of cloth in the wind. Also there is reflextive / mirror spheres or glass balls intendet to do the job via reflexion of sunlight. Same thing here:
"Take an old glass pop bottle, and sliding a metal rod down the bottle’s mouth, tap the bottom out.
Tie some string (I used 10-pound test nylon fishing line) around the bottle’s neck, and tie it to a pole.
Drop the other end of the string down through the mouth of the bottle and tie a 20d (20-penny) nail to it so it’s hanging halfway past the bottom edges of the bottle, like a bell clapper. (See photo.)
Tie another string to the bottom of the nail, and to that, tie a shiny pie-pan (I used one of those CD computer programs that come in junk mail-a good use for it, I think.)" Not my receipt.
When the romans invaded areas east of the rhine, people would sacrifice them and tie them to trees later, just saying.
If everything fails: A portrait of yours on ypur rooftop, ultima ratio, might get in trouble with greenpeace for violating animals right tho