We recently placed styrofoam vent covers over our house vents for the winter. When the chickens are out free ranging they insist on pecking at the styrofoam covers. They are destroying them and probably eatting a bit of the styrofoam in the process. I chase them away, but within minutes they are back at it. Has anyone had any luck with deterent sprays that might repel the girls from this new sourse of entertainment?