@lizswope
Hi
Bantam cochins and crosses of them are wonderful broodies. I have 3 of them broody right now, but my flock size is at capacity, so I'm trying to resist setting eggs! I would set your broody up with a separate nest box, within the coop but away from the communal boxes. You could just make a free standing one with a roof and place it in a corner facing a wall with a gap between it and the wall so that she can climb in and out, but it is still quite dark and secluded. The advantage of this is that if the other hens start laying in it, you can easily move it closer to the wall so that they can't get in and she can't get out, then slide it back and let her out once a day for food and water and poop and move it back up to the wall to block her in once she returns. I find this system works very well for me. The broody sits in a trance in the dark undisturbed until you move it back and let the light in. Usually that is enough to trigger her to get up and have a broody break, but sometimes you have to lift her off and encourage her to eat by scattering some scratch or meal worms. I do chores whilst she is having a break which is 15-30 mins and then fasten her back in, knowing that she is secure with her eggs for the rest of the day. The problem with communal boxes is that broodies sometimes get pushed out of their nest or go for a break and another hen gets in there to lay and then she can't get back in. If they are in the nest box a while, she may go to an adjacent nest box to wait and then go into a broody trance and forget she hasn't got back into the correct nest. If her nest is in a slightly different location to the communal nest boxes and looks different, it helps to home into it better, but it may take several days for her to reprogram to a new nest site, so best to move her and get her settled for a few days before you set the fertile eggs.
Do make sure to dust the nest with whatever you use to treat mites and ensure that she has access to a dust bathing area when she takes her broody break.
For info, a strong cardboard box with a hole cut in the side and inverted over the nest and a piece of plywood placed on top to weight it down and stop hens dropping through when they climb on it, can be sufficient to act as a nest box. Then it can be easily lifted off when you want the broody to get up and take a break and put back over the nest once she has got out. Of course you can also construct a small nest box with timber and ply but make sure it is covered and just has a small entry hole or curtains. Obviously the nest box needs to be in a secure place to keep her safe from predators. I don't know how secure your pen in the photos is, but if it is secure I would put the nest box in the far left hand corner behind the dust bath? with the entrance facing towards the wall and leaving a 5-6 inch gap between it and the wooden wall. You might need to keep it snug up to the wall when you first put her in it until she settles, but if you give her some eggs to keep her happy, she should settle pretty quickly.
I hope that gives you some simple ideas as to how to manage the situation. I'm a firm believer in keeping the broody with the flock as much as possible, but she also needs privacy, so setting her up with her own nest away from the communal nest boxes but still within the communal area is a good compromise.
I have an old cupboard that I use. I drilled a few holes in the door to let in a little light and provide ventilation. I keep the cupboard in the hen house and I have a smaller drawer (from a bedside cabinet that was being scrapped) that I dust with DE, add nesting material, usually damp shaving in the bottom and hay on top, another dusting of DE into the hay, then place the eggs in. Place the drawer in the location that the broody is currently sitting and transfer her to it, then move the drawer with nest, eggs and broody altogether into the cupboard at night when it is dark and there is no chance of her moving. Once a day, I open the door and then feed chickens and muck out etc. Broody comes out and eats with the flock and then when she is ready to return to her nest I keep an eye on her and if she goes back to the old location, I wait for her to settle and then move her to the nest in the cupboard and fasten her in. After 2-3 days, she gets the hang of it and goes back to the cupboard nest herself....(it helps to remove eggs from all the other nests) You can put a little container of food and water in there for her or I just put a little pot of fermented feed in there, so there is no risk of water getting spilt and she will not get thirsty because the food is moist. She probably doesn't need that food, but it makes me feel better locking her up if I know she has something there if she wants it. In reality, she doesn't mind being locked up.... or more likely, is unaware that she is locked up. Occasionally I will find her keen to get out on a morning, but it is usually when she hears the other hens getting excited about being let out and that stirs her from her trance.
Good luck with your girl and I hope it all goes well for you.
Regards
Barbara