Well it is NOT overcrowding. Their coop is 9 1/2 x 12 with a 7 1/2 foot ceiling. The nest box is external, the feeder is hung from the ceiling and the water is a 3/4" pipe with nipples attached to the wall. Plenty of floor space. They have 19 feet of roost at 4' and 8 feet at 2'. Plus they get out of the coop almost every day for many, many hours. Even if they decide not to go outside to hunt bugs or eat grass, they have a 6' x 50' alley outside the coop to wander around. And they get kitchen scraps and BOSS and scratch. And the attack yesterday was whiIe they were all out eating their pre bedtime scratch. I wasn't paying enough attention to which Fav attacked the other but now I see that Clemence doesn't have her beard picked out so the smoking gun is in her foot. For supposedly being a "bottom of the order" breed, these two are pretty feisty. But it could be stress other than their physical environment. I don't know how chickens think or what goes on when I'm not watching.
In any case, I'll take the suggestions to heart and see if she stops.
Bruce

But seriously, I can't for the life of me understand what's going on there.....keep us posted...