I seldom have birds just drop dead. Usually there will be subtle changes in behavior like a sudden reduction in rank, feathers held to conserve more heat, feather maintenance failing, loss of appetite usually with loss of weight, drifting away from flock, and change in roost location. Changes...
Older birds for me more likely to drop out from worm burden and sometimes even heat stress although free range birds seldom succumb to either. As the birds get older they do become more vulnerable to diurnal predators free-range.
American Dominiques I have are still doing well ranging 5 to 6 years. A measure of physical performance (flight) indicates they are slowing down. American Games are holding up much better where all intended for long-term keeping reach 6 years without trouble. We used to have games used as...