My buff orphingtons are all great but the SLW's all are missing alot of feathers around butt area down to inbetween their legs. Its down to 20' at night now so I'm worried they just started laying eggs a few weeks ago. I don't know if they are molting or if they are pulling each others feathers out.
Molts ordinarily start at the head and neck. I'd bet that is feather pulling. You might want to check the feather pulling threads on the FAQ page. If you can identify one chicken that is doing most of it or is the ringleader, a week of jail should do the trick.
Have you checked them for mites? Could be that, or the girls might just be pecking eachother's behinds. A spray of Poultry Protector or any other mite spray p0robably wouldn't hurt. If they're pecking eachother, once the skin gets red, they won't stop pecking and can draw blood. As far as them being warm, if you have a nice deep litter of shavings and a dry coop, I think they'll be fine. Good luck!!
Bare butts generally means feather picking. I'm sorry. That's an unfortunate habit. Don't worry about them getting cold, though. Wyandottes are extremely cold hardy, so they will be OK. I had several bare hens last winter because of a nasty roo and a bunch of feather pickers. I made fleece saddles for 2 girls (tiny, petite EEs) who had more bare patches than feathered patches, but the rest I left them be. They seemed absolutely oblivious to the fact that their butts were bare. I would try to locate the feather picker(s) before you end of with a bald flock like I did. It kind of takes the joy out of raising chickens when they all look terrible and half-pecked. It's also a habit that spreads through the flock like wildfire. You start with one feather picker and before you know it they are all doing it. Good luck.
Like i said 6 buffs 3 SLW's and only 2 SLW's have bare butts. They are not friendly either my buffs are like cats...the SLW's are just mean and pains in the back side.