Okay, I know that this thread is over 2 years ago. I have an issue with my birds. since this winter started, I have lost 3 birds to hypothermia. And currently, I am nursing one back (first one I found was squatting and had rolled to his side and died and the other two died as a result rapid warming). There has been a concern for a primary cause. And that disease or illness maybe to cause. I have noticed that bird two and my current victim both had full crops. It was like their body's failed to process the contents of their crop. When I got to him, he was quite cold to the touch, but wrapped in a towel, off the shelf, his temperature came up rapidly. Now, I have given him vitamin B12, water laced with apple cider vinegar, and room in one of my old brooding boxes with a heat lamp running. The biggest thing I have noticed is his lack of weight. What can sap a birds weight to the point they weight nothing?