Current wisdom suggests they are not very effective. Birds get used to a scarecrow after a few days and return to their business as if it weren't there. Use a long-sleeve shirt and pants. Don't stuff the sleeves or pants legs. Let them flap around in the wind.
Every few days change the location of the scarecrow.
Use an old soccer or kick ball for the head and paint giant eyes on it. I do know for sure that our dogs were fooled. When I first carried it out to the field, they were scared of it. Harvested, cleaned, and bagged, an ample supply of veggies fills the crisper drawer in our refrigerator. All rights reserved.