I can't tell exactly which bird is doing it, but it has to be one that is at least 1 1/2, 2 or 3 yrs. old. Unfortunately, I didn't start marking them until the new flock this year and I know my oldest birds have died. I feed everybody Southern States laying mash. Also, they're not sitting when this happens but sitting on their perch at night.
I'll get some oyster shells.
While I've got someone's attention! Any ideas how to lure my free range chickens back to the hen house at night. A raccoon got in there about a month ago and killed several an now about 2/3 of my flock won't come in at night.