The more time goes by the more I suspect the spots could be a result of excess calcium because he does eat layer feed. They do look and feel like calcium.
I haven’t tried digging any out yet. If I do, I will certainly get detailed pictures and post them here.
Since posting this I‘ve been putting out a selection of all flock and layer feed. I don’t know if the roosters are choosing to eat the all flock feed or what. They are all free range so what one eats, all the other have access to so...
Will continue to update as it goes. xo