Perhaps she is your head hen...my head hen doesn't allow any other hens even in the coop while she is laying. I have 4 nest boxes at the moment, she could be hunkered down in one of them and if another hen comes in while she is doing her business she will get out of her nest and chase them out, then go about her business.Perhaps my earlier description was unclear, but the one that had been sitting in nesting boxes for many hours per day is the one that got up our of her bedding box and chased another hen out of a nesting box that wasn't even the one she was laying in!
The ridiculous part of all this egg maneuvering is that two different chickens have been caught moving Hei Hei's eggs back and forth today. I'm afraid they're going to end up cracking it.
The other night I found one egg on the ground, so I'm wondering whether these nesting box guarding antics are going to cause some of my girls to lay them outside which would not be ideal.