What would cause a seemingly healthy 5 month old chicken to die? We have a mixed flock of 3 year olds and five month olds. They were successfully integrated about a month ago. My husband and I went out of town for 2 nights, leaving the girls enough food and water during our absence. When we got home we found our 5 month old buff orpington dead in the enclosed run. And she had been dead for at least a day. All of the others seem fine and we didn't notice anything wrong with this one before hand. I just need to know if there is anything I should be looking for in the other chickens.