I just went out to my coup and found one of my polish hens dead. I had been out there a just couple hours ago to bring them some food, so whatever it was, it happened very suddenly. She was flat on the ground, and feathers had been plucked from her thigh. My silkie rooster was mounting the body, which was confusing, I'm not sure if that is normal behavior. She was young, just about ready to start laying. I just don't know what could have caused an otherwise healthy chicken to die so suddenly, in a flock that is well-adjusted. I've had this flock for a while now, without any problems, between 6 and 8 chickens. The only thing that has been different is that I noticed my moran started to brood. She is the biggest hen, and is very dominant. I want to make sure my other hens stay safe. I was keeping an eye on them through the french doors, but they all just went in the coop for the night. I'm not sure if there is too much to figure out... but I've only been keeping chickens for less than 6 months, and there are probably more knowledgeable people here! I've only experienced one other death, and it was a serama with a kidney problem. Her death was explainable, and even expected, but this has me puzzled. Any insights?