I have 9 chicks that are about 2.5 weeks old. They are all beginning to get feathers. There is a group of three that are physically small than the other 2 groups of three. When I was feeding and changing their water tonight and checking for "crusty butts," I noticed that one of the smaller birds behind has an area about the size of a dime with no feathers at all. There is skin without injury and no pecking wounds. What might this little chick be experiencing. How can I help it or is it just part of the process. All nine occupy an area about 2.5 feet wide by 4 feet long brooder box.