We have recently purchased 9 hens and 1 Rooster (all Plymouth Rocks). We got 3 Buff's, 3 Barred, and 3 Partridge. In the last 2 months, 2 of our Buff's have died. We have no idea from what, as they seemed healthy with no signs of illness or injury. About 3 weeks ago one of them started isolating herself and didn't eat or drink much. She slowly got worse and worse and after about 5-7 days she died. She was skinny when she passed, even though I saw her eating and drinking from time to time, just not at the same level as before. Then another Buff started showing the same symptoms about a week ago and died yesterday. We bought our birds from a guy who 'shows' them, as they were beautiful birds and well taken care of. Has anyone heard of any sort of weakness in this colour of heritage bird? So far none of our other Plymouth's have displayed any signs so it just appears to be the two Buffs. We're wondering if it's a genetic issue from overbreeding?