Hi, this is my first post. Our family are first time chicken owners - we bought 50 chicks this spring. They are about 6 weeks old now. We bought a "special assorted bargain" straight run meaning we wouldn't know what breeds we were getting. Some are rare breeds. I've noticed in the past few days that 4 or 5 of them are losing the fluff on their backs but no feathers are coming in. I do not think they are being pecked for three reasons: 1 - we watch them a lot (they are new and fascinating you know!) and don't see pecking; 2 - there are two that look identical and both have the same lack of feathers on their backs; 3 - There are no bloody spots and no feathers lying around. It seems more like their feathers just aren't coming in. They seem healthy otherwise as far as I know. So... is this normal? Are they too hot? They do have plenty of space and room to get away from the heat. I'm just starting to wean them off their heat lamp because it has been cold here (northern wyoming). Are they sick? Any advice people can give would be much appreciated. I've been searching for information but haven't found anything similar to this. I can try to post pictures tomorrow if that is helpful. Thanks in advance!