I have a nice little flock of laying hens---a few hybrids (Cornish Rock), and various Rocks. Today I saw them devour the eggs in the nest box. I was working in the coop for half the day (installing insulation, wiring, & OSB board) and saw at least 3 hens tear into an egg at various times throughout the day. A few days ago I collected the eggs and noticed dried yolk all over them (meaning they had started egg eating earlier than today). This is a fairly new behavior. Any cures?