Hi, My americana's have recently started laying. I opened some of their eggs sat for breakfast and the yolks were really dark yellow and had that bullseye I read about. I have a roo but he is by himself because he is a white polish and when he was little the hens picked his head feathers. Is there a problem with these eggs? Also, they are only laying light tan eggs. No blue or green. What determines shell color? Food? The color of the bird? I am new at this so forgive all the ?s..