I set a broody buff orphington on 10 eggs. One day another hen laid in her nest. On the 13th day I checked the eggs and all was fine. I did not check on the 14th day but on the evening of the 15th day I check on her eggs while she was off the nest. She only had 8 eggs. The eggs were not rolled out on the ground and were not in the nest. Again today I checked the nest and she has 7 eggs. I am thinking rather than get off the nest and eat , that she is eating an egg a day. There are no shells in the nest so she is eating the entire egg. What causes this and what can I do about it.