Posted this before but didn't get any answers...sigh. What does 'fully fledged' mean and what does it look like? Mine are losing feathers, have lost all of their fuzz but still have bald spots under their arm pits. I want to put them into the coop but not sure when it will be safe for them because it's getting down into the low 30's at night. I have a heat lamp I can use. Coop won't be finished for a couple weekends more. Thanks.