mounting bells to repel birds

because my grain has risen, today I put a bell made of tin to keep the birds away. there are various ways farmers repel birds. some were repelling using propellers, some were repelling using wooden frames made to look like humans, and some were using bells made of tin.

The little birds that like to eat the liquid rice grains are a pest to farmers. because it will cause reduced rice capacity. in the can I put pebbles in it. and tie it with rope. when the bird comes, the rope is pulled. and the chimes will sound.

for those of you who are farmers, how do you repel birds. is there any other way. please let me know so i can learn from you.