Step-by-step explanation:
in most cases, crows are very intelligent and very observent. While it doesn't work EVERYTIME, it does work in the beginning to scare off the crows to keep them from stealing crops farmed by farmers/plant growers. But they do in the later days of process will just realize the human like form isn't real and not harmful. It does work at times for crows...but it won't last for long.