A few of my hens hang out in nest boxes a lot. One is an older hen, she is fine, but just wants some peace, especially from her Roo, he leaves any hen in a box alone. In a different section there is a young hen that is low in pecking order, so she hangs out in box alot because the other hens leave her alone when she's in there. Both hens do often come out, eat & drink & go out to dust bathe, etc. but there are times they need a quiet break. One of my sweet Roos even likes time in a nest box, he goes in and makes sweet clucky sounds for 20 minutes, then his hens all try to get in with him, which is impossible, so then they start whining & all I see are the butt ends of several hens sticking outside the box, it's hilarious. I have cushy wood chips in the boxes, it's a nice, comfortable place for a chicken to lay an egg or just take a break. I did notice a hen in a box a lot & when I checked her over she had some bumblefoot, so maybe just check your hen over, make sure no mites, no bumblefoot, etc., look in her mouth & smell breath too, just make sure she's feeling well. Sometimes after being ill they may need some probiotics to get feeling chipper again.
