At this point, something clicked in my brain and I realized my gal was "broody" and wanted to hatch a clutch of eggs. Even though we collect the eggs every day and most of the time she was sitting on an empty nest, she was determined to sit there, hoping some chicks would appear. She had no way of knowing that her attempt to become a mother was all for naught as we don't have a rooster to help in this regard. Here she is sitting on the nest.
I've done some reading and talked to a couple of other folks about broody chickens. Apparently, one way to break this cycle is to separate her from the other hens and keep her in a pen or cage away from the nest boxes until she "forgets" about hatching eggs. So, here's what we've done.
The pen is a simple, portable affair that Tom built several years ago for something or other. It may have even housed a compost pile at one point. At any rate, it is just 4 panels, each made of board frames covered with chicken wire. Each of the 4 panels is connected to one of the others with hinges at the top and bottom, like this.
This creates 2 sections that can be folded up for easy storage and transport. The open side of each section has a hook and eye, so it can be secured to the other section.
I have been putting Big Bertha in this pen during the day. I'm not sure this is going to work because she still joins the other chickens at night in the coop and that is where the nest boxes are. So, she usually gets in a nest box before Tom gets over there each morning to open the coop and let them out for the day, thus reinforcing her desire to hatch eggs. He gets up early, but not always as early as the chickens!
We'll see if this works. I have covered the pen with shade cloth to keep her cool and have put a water bowl and food bowl in the pen. The first day I put her in the pen, the other hens were very curious about this new turn of events.
She was not at all happy about being in the pen, much less having the other girls peering in at her. She puffed up her feathers and spread her wings out in a menacing manner.
Although she was not wet, this gives new meaning to the phrase "mad as a wet hen"!