I have brooders built under my poop boards and have also made make shift brooders out of dog crates and normally move my broodys to a secure area still within the coop.
My main reasons for doing this is especially for lower ranking hens that get constantly kicked off the nest when others want to lay. And this also helps ensure broody and her chicks are safe and she can focus on them.
My hatches are all specific so I mark all eggs by date and who's eggs I've set and also draw a circle all the way around each egg so I know at a glance if there's more eggs layed as any more eggs layed after a couple days after setting and I run the chance of a staggered hatch and potentially the chance she'll abandon them eggs anyways after a couple days to get her chicks off the nest.
I usually wait til roughly a week before hatch to ensure she's fully committed, and then pick a time when she comes off the nest to do her dailys and then quickly move her nest box to that secured area. I make sure there is no eggs in any other nest boxes for her to mistaken for hers and put her in the brooder and she finds the eggs herself and settled in. I've never had a issue doing it this way with 10 separate broodys this year.
Here's some of my brooders if you need ideas. I have plexiglass I put up to have 2 separate brooders under the poop boards or I can remove to make just one L shape area. In some of the pics note the nest boxes are close to the doors. This is just while she's sitting and hatching, I can maintain her nest if needed. When she comes off the nest to take them out I pull any left over eggs, refresh the nest and then push it back to give her the max space with the babies.
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This is 6 littles I currently have I incubated so the other side was empty for a few days after moving them from the house but I've since removed the plexiglass to give them the whole space under both poop boards to run.
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