I live in northern Ontario. I went on vacation for a week and kept my chickens inside the coop instead of letting them out in the pen. When I was gone it was the mildest week ever. About 5 degrees Celsius. Normally it's -20 here or colder. I noticed that they are loosing a lot of feathers now...ones head has lost a ton of feathers. I have 5 chickens and they are about 10 months old. It's like a chicken exploded and feathers are everywhere. I have no heat in my coop or additional light. Is this normal and will I have to add heat if they loose too many feathers?