Was pesting at a local dairy farm permission and a neighboring farmer was assisting my permission with his hay storage. He saw what I was doing and asked for some help for his hay bales. Don't know how the rest of the farmers do it but silos are out and they wrap the hay in big plastic round bales for storage. No barn work and they just grab a plastic bale and use it when needed during the year. His problem is the crows love to pick holes in the plastic covers and ruins major $$ worth of hay. The holes let moisture in and it ruins most of the bale. He says rats also like to bury into them and make nests. The slowly decomposing hay creates warmth and a nice cozy home for the rats. So...I had never thought of that before and he now has my information and will call me when the problem occurs. Maybe that's a type of permission to consider wherever you live.