Here's the scenario.... We have 12 chickens, 3 of which are silkies. They stay outside all day (temps are anywhere from 50-65) but I bring them in at night as the temperature has been fluctuating between 17-30 and I do not supply heat to the coop. The coldest they've been out in is around 35-40 before I bring them in. They are all 8 weeks old tomorrow. When I bring them in at night, I separate them into 2 rubbermaid bins for the night. They have food and water in their bins. I always keep the silkies together with a couple of the other bigger hens. 2 days ago, as I was sitting in the coop observing them in the morning after letting them out, I noticed one of the silkies kept pecking at one of the bigger girls backsides. Then I saw some blood. I picked her up and noticed that she was swollen, bloody and a good chunk of her tail feathers on one side was snapped clean off. I washed her wounds, have been applying neosporin, and keep her isolated in the house. She seems to be healing up. Then today I again let them out in the morning, hung out in the coop for a bit and noticed that another one has exactly the same thing going on!! So, I put her in isolation in another bin and treated her as well. I decided to check out all the chickens closely to see if I was missing anything else and found one of the chickens healing from the same type of wound only instead of being on her tail, it was both wings on exactly the same spot on either side. Her wings looked like they were already healing so I think it happened a few days ago. I went ahead and applied some neosporin to it to be on the safe side. Then, this morning as I was watching, I noticed a couple of the chickens pecking at one of the silkies feet. I looked closer and noticed she was bleeding too! Some of her feathers were snapped off. So, now I have 4 chickens in 4 separate bins in my house! So, I am wondering - is there any way to possible figure out if just one mean one is doing this? I am not sure if it's happening outside all day - they have plenty of room outdoors. Or, could it possibly be happening because they are in a bin overnight? I have 6 in one bin (a large rubbermaid) and 6 (including 3 silkies) in another slightly smaller rubbermaid. Should I just start leaving them out overnight or will that be too much temp shock for them? The house is around 50-55 at night and that's what they're used to. Again, outside temps at night are upper teens to 30 at the highest. Since they are 8 weeks, maybe they will be fine? Can the silkies handle those temps? I am open to suggestions as I just want to find out what circumstances might be causing this. I am just surprised that someone is doing all this damage. I can't end up with 12 bins for a bunch of injured babies!!