Often you'll find when you have one very aggressive coturnix hen, that she has a wound somewhere about her. Usually it will be on the feet, back, or head. When a rooster tries to breed that hen she'll get mad and peck everyone. Other times you'll find the thin thread their little minds hangs from has snapped and nothing can be done. Segregate her but try to keep her in full sight of the pen, leave her out for a week or two. Then during the night add her back into the cage. You can also keep her in the cage under a milk crate for the last couple days if your cage is large enough. Hopefully the separation will give her time to get over whatever her issue is. If not, send her to freezer camp.
