I feel so bad. I had a new small flock of hens with a rooster that I am trying to integrate into my old flock. They were staying in chicken tractor covered with a tarp (with roosts off the ground). I was following the advice on this site, integrating them by keeping them separate with a fence between for several weeks, then doing a few "get togethers" with some supervision (for the roosters to get on). They weren't ready to put together when the rainy cold weather hit....The flock was out yesterday despite the rain and went away wet for the night. They were covered, but this am the whole flock was dead....It rained all night and the lowest temperature was 32 degrees F. I am devastated. Can someone tell me, is it because they went in wet? I would have thought their body heat on the roost would have warmed the tractor up enough. There was hay in the boxes.