In the process of growing from baby to adult a chicken may suffocate in a solid block adjacent to it. I created 15 cells each 1x1 and 2 blocks high from dirt. I threw eggs into each cell until one chicken spawned. They remained in their cells and grew to adults. At this time 2 of the 15 died by suffocation as soon as they grew. It seemed that the larger size of the adult caused them to be far enough into the adjacent dirt block to suffocate. This may be related to other suffocation problems, but I had not seen others in recent versions and this was specific enough to warrant reporting.