Lots of good info already posted. If you don't have extra pens to put whole flocks in while you slowly integrate, try pulling out the top two or three aggressors for a week while the new bird adjusts and once it is peaceful in the pen, add the new (old meanies) back in with the flock and they will be the newbies and not be looking to beat down any other hens, as they will be too busy finding their own place back in the flock. So sorry for your loss. That happened to me before with silkies. I should have known better but I lost two. It happens to the best of us. Sometimes because we like our chickens so much we think they like each other just as much... we forget they are chickens. At least that was what happened in my case.
