One more passed today. This one looked to have ben picked open a bit just below the vent. At first I thought it was poo stuck to his down. I cleaned him up a bit and noticed that the mass hanging out went through the skin. I kept an eye on him and since no one was picking at it, I left him in. I checked back often and his energy level went way down. He eventually laid down and didn't get up again.
Last night it got down to 18F, and the little chicks just piled up right outside the focus of the heat lamps and huddled together. I was nervous about their temps, but they kept quiet, so I figure they were happy.