Recently, one of my chickens started pecking a hole in her egg after she laid. Today, I lost THREE eggs to holes. There is always a hole about 1/2 inch at it's widest, and the egg is still inside the shell. Some information about my hens. My chickens free range. They have unlimited access to oyster shell. They get layer scratch with 16% protein. This has happened once before, when I only had three hens, and it eventually stopped. I don't pull eggs as they are laid, because I want to encourage the rest of the hens to use the same nests. (this seems to work to keep the rest from trying to lay out in the yard until this new pecking thing.) I still have a few pullets laying witches eggs. I don't know if this has any relevance, but I'm including it. All of my hens are one year or younger. My questions: 1. How do I stop this? 2. If I can't stop it, how do I figure out who's doing it, and cull them? Edited to say I had some good ideas to start trouble shooting with! Thanks everyone!