Hello, I have a mottled Java that hatched 7 mixed breed chicks 4 weeks ago. They live in a separate part of the coop and free range at their choice all day, and have done so since birth. My question is the mother hen wants to go back to the flock and even laid an egg today. Should I give the chicks a heat lamp? They feathered out fast, but I’m in Massachusetts and it has been cold at night like 40 degrees. Or should I allow them all into the flock, the chicks technically can wonder into the run and there hasn’t been any attacks? Thanks.