My Eastern hens fight quite a bit. Usually it doesn't last long, but sometimes it does. They most always start by one hen talking chit to another. A low purr followed by some sarcastic whines and louder purrs, building to loud fighting purrs, clucks, putts and lots of whining.
Doesn't matter the season when a hen will fight.
Hens can kill each other in some cases. Toms more often. One mouth clamped on to another's mouth is deadly.