I’m guessing that they are molting? The Pekins are showing yellow pin feathers the one Rouen is all ruffled looking. It has been hot, the duck house is well ventilated and they only go in at dark. The have several water sources and they also have a kiddie pool and lots of shade. The bedding is hay which gets refreshed daily and changed weekly. The reason I mention all this is the Rouen that lives inside at night because she has a broken leg looks pretty good. It only occurred to me today maybe the hay is the problem. Or maybe they are just molting. They are about 10-11 weeks old.