My chickens have started eating their eggs. The hens had gotten up on a shelf and eggs rolled off giving the chickens the taste of raw eggs. I fixed it so they cannot get up on the shelf, but they are now breaking eggs in the lay boxes a few times a week. I am not sure which ones are doing it. They get a mix of layer feed and all flock feed, and have access to oyster shell at all times. Is there anything else I can do to get them to stop the behavior?