My chickens (6 Ply Barred Rock & 6 Golden Red) are about 11 months old. In the past 2 days I've noticed that several of them have silver dollar sized bald spots on their rumps - below the anus but not quite between their legs. On inspection the bald spots are clean and do not appear red, inflamed, irritated, or scarred. I don't see any indication of fighting and have not observed any of them picking at these bald spots. In the past two weeks my egg yield has dropped - some days only 6-8 eggs, but some days still getting 10-11 as has been normal. Is this the beginning of moult? Any advice appreciated!