I only worry because they cannot get to her to stay warm at night if I don't move them. Tonight, when I got home, one of the chicks was roosting under her wing. Cutest thing EVER! The other 2 were down on the ladder rungs with no heat source. They are almost 5 weeks old, so not quite feathered enough that I feel comfortable leaving them like that. It is currently about 35 degrees, dipping into the high 20's before dawn. As soon as I put them in the brooder, she wanted to come down and join them in there, so I patiently held the light while she worked her way down.
The other "issue" that I have seen is that they can still get through the 2" x 4" holes in the fence. The gates are open, but when the chicks work their way to the other side of the fence, mom gets upset and can't quite work out how to go around. Most days, my kids and I are home to help out in these situations, but Tuesdays, we are gone from 8 am to 7 pm. My husband will be home until noon tomorrow, so I think I will let them all out in the morning, then hope they do OK until I get home.
I totally agree with wanting to let the hen raise them naturally, but I also want to make sure they survive, KWIM?