So, my little flock is about 5 weeks old. I had them in a brooder in the house under a heat lamp and they seemed to be doing great. Growing at an incredible rate. My girlfriend and I came to the conclusion that they were outgrowing the brooder - we had 9 chicks in a rubber made tub that was roughly 2' x 3'. I read that at this age it was ok to start turning off the lamp a bit. So about a week ago, we started to turn off the lamp at night. They seemed just fine. Three days ago, we decided to move the brooder to my mud room, by the back door and remove the light altogether. It's still heated there, but a bit cooler. I'm nearing completion of the coop, but as sometimes the case, winter came early to Minnesota, and it got down to near zero last night. When we woke up today, the smallest of our Speckled Sussex was dead, and the smallest of our Black Australorp was lathargic and I assume will die. We moved them back to where they were, reintroduced the lamp, and separated my sick chick into here own box. So, obviously I've got some learning to do, but in the meantime, what do I do about a sad girlfriend?