I was given 4 birds to start off, 2 hens, 2 roos. I noticed one hen limping, she was dead the next morning. These birds were all hatched together in July. A few weeks later the other hen died. I then bought 4 mature hens, they were 2yrs old and had stopped laying for the winter. Last week one if them died? A few days later another one was dead? This morning a hen and one if the roos is dead and the remaining hen looks like it won't last the day! I have one healthy roo out if all my chickens?! I'm new to chicken keeping, but have a new hen house that can hold 12 birds, Ive a huge run for them, fox proofed. They are feed every day with corn and crumb and I keep the water feeder topped up. None of the dead birds look like they have been attacked? Is my last roo a serial killer?! I am bewildered and confused, can anyone offer an explanation or advice on this matter?