There are a lot of typical behaviors for broodies. Flattening in the nest and zoning out is one. They will often be very defensive of the nest and swell up and threaten you if you get close. They normally leave the nest once a day to eat, drink, and poop. That poop is often really large and stinky because they’ve been holding it. They normally walk around puffed up and making a regular pocking sound. All these are typical behaviors but not all broodies do all of them. I’ve also had hens not really serious enough about going broody exhibit a lot of these behaviors.
Something else broodies do. They stay on the nest 24/7 except when they leave for their daily constitutional. In warm weather, these constitutionals may last over an hour and they may take more than one a day. In cold weather they don’t last long and they don’t take many of them. But they always spend the night on the nest instead of roosting. My test is that the broody has to spend two consecutive nights on the nest before I trust her with eggs. You are dealing with living animals so nothing is guaranteed, but if they spend two consecutive nights on the nest before I give them eggs, they have always hatched chicks for me.
If she truly is broody, you need to collect all the eggs you want her to hatch and start them at the same time. If you don’t start them at the same time, you get what is called a staggered hatch. You can deal with that in an incubator, though it can be challenging. With a broody that generally means the late eggs don’t hatch.
Something else you need to do is mark the eggs you want her to hatch and check under her daily to remove any eggs that are not marked. As long as you collect these extra eggs every day, you can still use them. Other hens might lay with the broody or the broody may even carry eggs from other nests back to hers. That’s fairly rare but yes, they can really do that. Gathering the extras daily will stop that staggered hatch problem, but also if a hen gets so many eggs she can’t cover them all, you usually get very poor hatch rates. If the hen is really defensive of her nest, you might want to wear long sleeves and gloves when you check her nest. I check late in the day after all the other hens have finished laying and just toss her off the nest. Sometimes they’ll take a mini-constitutional and sometimes they hop right back on the nest.
As long as you start the eggs at the same time and check for new ones, you don’t have to do anything else. Hens have been doing this for thousands of years with no human intervention.
Good luck!
