"Just because a hen is sitting on a nest doesn't necessarily mean she's setting. She may still be thinking about the egg she just laid or she may be hiding from some bully that's higher in the peck order. To test a hen for broodiness, gently reach beneath her and remove any eggs you find there. If she runs off in a hysterical snit, she's not broody. If she pecks your hand, puffs out her feathers, or growls, things are looking good."
I tested this out today.
After much thought, I decided on a plan of action for the brooding hen. I fixed up a nest in the old rabbit cage that we had and put it in the stall where Tom had built a platform for the goats this past spring. Then I had to figure out how to get the hen to move. She would not be coaxed off of her eggs with food. So I carefully stuck my hand in her nest up under her trying to get her to move and expecting to be pecked. She did not peck, but much to my surprise, she did growl. I carefully lifted her out, first checking under her wings where Storey had warned that hens sometimes hold eggs and she did have one under each wing. When I got her out, she discovered that she was hungry and went after the scratch that I had put in the trough. While she was eating, I put the eggs in the tub of warm water I had taken with me and washed all the gunk off of them. Then I quickly took them out to the prepared nest and ran back to get the hen.
The big question was would she sit on them in the new place and would she stay?
I checked on her seven hours later and she was still there. I think if she doesn't try to leave for the night, my plan will have been successful.
Many dangers lie ahead, though. More from Storey's:
"If she does manage to hatch out a brood, other chickens may kill the fuzzy intruders, much as they would kill a mouse or a frog that wanders into their yard." and "Occasionally a hen will be so horrified by the appearance of interlopers beneath her that she'll attack the little fuzzballs. Be ready to rescue the chicks and brood them yourself."