I have two ducklings that are a month old. Feathers are coming in nicely, but I think I've heard 8 weeks for fully feathered - is that right? I'd like to move them out to the duckhouse with the others, but don't know whether it's warm enough at night. We've had a few cool ones lately. They would be in a large cat carrier inside the duck house, so I'm not worried about group dynamics, just the temperature. Any idea how warm it needs to stay outside for the temp in a draft-free corner of a well-ventilated duck house to be okay?