I have 2 month old chickens they are rhode islands and I put them in the big coop because they were out growing there brooder. But I've lost 2 since they appear lethargic and cant keep balance then they die. It gets about 50 degrees at night and they are in a enclosed area. could they be to cold or could it be something else? I was told they would be ok at this age without a heat lamp as I have no power to my coop at this time. Are there any other ways to keep them warm at night?