OveraMare - I see that you live in the southern states. I have long wondered if the more temperate climate aids in the length of bird's life. I also do get winters with cold snaps of -35 degrees. Our day length in December is very short, less than 9.5 hours, with chickens roosting before 4:00 pm and not coming off the roost till nearly 8:00 am. I know I have good husbandry - good feed, clean water, adequate protection.
I have never come close to any bird living 8 years old. I like Folly love to let them out, and have had numerous encounters with the smartest coons at night and coyotes in the day. I too, have addressed that. But even with that the oldest bird I ever had was 4.5 years old.
And the thing is, she was OLD. Stiff, arthritic, crabby and not a good layer. She was a good mother, and had hatched out numerous clutches for me, and she was staying her natural life...but when she died, I was kind of glad, cause really it was not such a good life. I would not want a flock of very old birds.
And it always surprises me, when this comes up. Sometimes I think posts indicating that birds naturally live until they are 8 years old, just make people feel guilty when theirs do not.
Mrs K