Hello all, My wife and I got our first batch of baby chooks this past Monday. All was going well, with only one case of pasty butt. We had left for the afternoon. When we came home, my wife discovered one of the Black Australorp chicks had passed. He or she had a large pocket of air under the skin on the right side of the neck. Previous to this, we did not notice any lethargy. To my knowledge, there was no significant injury. Any idea about the cause. Is this simply a defect, or potentially a result of an infectious disease?