Coop is 18 sq ft, pen is 36. I had four girls, and thought this was enough. I was wrong. My dominant hen(a Gold Comet) got bored during the winter and began plucking my sweet little RIR bald. She then went so far as to begin begin pecking at the bare spots till she bled. Then the other wretched birds joined. Not wanting my favorite hen to be eaten alive, we sent her off to live at a friend's property(she runs an egg co-op with a few dozen free range hens). I hoped that removing the smallest hen, as well as having fewer birds in my small run would be enough to fix the problem. Nope. That evil canibalistic GC just moved down the pecking order and began plucking the feathers of my Australorp. I was certain the Wyandotte would be next. Rather than ship off the Austrorp(and eventually the Wyandotte), we took the GC to the co-op, and brought back the poor picked on little RIR, who had been recovering nicely. My hope now is that the GC will not be the dominant hen and won't be allowed to pick on the other hens in the co-op, and as they are free-range they have room to run away. Withing seconds of bringing back my RIR, they Australorp went straight for the wound and began pecking. Dang. (that was supposed to be a different word, but it was deleted) Well, it seemed the only thing I could do was to open up the pen and let them out into my garden. My hope this time was that they would be distracted by foraging and would be less inclined to peck her out of boredom. And she would have more room to run away. Within hours they had destroyed my lovely little garden, so I changed tact again, and removed a small section of the fencing on the pen to allow them out into the lawn instead. Now, this goes against city regulation, which states I must keep them cooped or penned, at a distance of not less than 40' from a residence, school, or church. Oh well. The pecking has stopped, and they seem to love wandering about my yard, tearing up my lawn and digging up all my bulbs(which are gearing up for spring). It's also pretty fun to watch them run about the yard, tails up in the air as they root about looking for something to eat. Between having something fun to do, and room to get away from each other, and possibly increased raw protein from bugs, I think this will fix or at least reduce the problem. But I have dogs too, and can't always let the hens out. So I have realized I need a bigger pen. My coop sits up against the fence, right in the middle of the garden, with about eight feet to either side(one side is filled with the three-bin compost and the other with the pen). I have decided to tear down the smaller pen, and build a larger one that fills the entirety of the back of the garden, coming out three feet in front of the coop, as well as either side. This will increase the pen by about fourfold. I will, however, now have to enter the pen to get to the coop. Less convenient for me, but more room for the birds. And because of my garden layout, I will not actually lose any growing room, just some pathway. The compost bins will now be in the pen, and I'm sure the hens won't complain about that at all. I still plan on letting those wretched birds out each evening to forage for a few hours before dark. This also means I think I can expand my flock from three birds(started with four) to six. I'm rather excited about this. All three hens lay light brown eggs, and I would love a more colorful basket. I am thinking of adding a Marans, an EE and maybe a Leghorn. So that's my story of the Evil Wretched Canibal Chicken, and how forced me to build a larger pen and break local chicken ordinance.