I too am a proponent of leaving them with the flock. My broody always has taken them outside in the run by the time they are two days old, and takes them back to the coop at dark. She always has left the nest she hatched in and created a new nest on the floor. And I let her do it just like she wants. A day or too before she hatches, I make sure there is clean bedding.
If she has been with the flock all along, they have gotten used to giving her a bit of space, and generally she will be off to the edge of the flock, between the flock and the chicks. Within a little time, the older birds don't pay much attention to the chicks and they are eating between the rooster;'s legs. Occasionally an older bird will give a mind your manners peck, but it is the easiest way to integrate.
If you separate them, you lose most of the advantage of the broody with the flock. Because what happens is about 5 weeks, is people want to put the whole group back with the flock, however, now the broody hen is the stranger too. She is losing the hormones that keeps her protective of the chicks, and desperately fighting for her own pecking order. Often times the flock will kill the chicks unless separated.
However, a lot depends on the opening to the coop. my opening to the coop is nearly on the ground, my chicks have no problem getting in or out. Others have a steep ramp up to the coop, and have reported chicks having problems getting back into the coop.
At about 3.5 weeks, I put a wide board up at roost level. Every one of my broodys have gotten those chicks up there roosting with the flock at about 4-5 weeks. I think this keeps the broody interested longer in her chicks, as the urge to roosts becomes so strong, she will leave the chicks to do it. This way they learn to roost, although at first, they are still snuggled up under mamma.
Currently I am praying for a broody hen!
Mrs K
