We have mixed ages in our flock. We have three- 3 year old hens, ten- 12 week old hens, six-6 week olds and seven-4 week olds. We are located in MN and right now the temps are on the hot side with humidity. Makes it a bit miserable for the feathered beasts. We put fencing out a foot and a half along our run and coop, so if anything were to dog, it would hit that. We’ve been fortunate and haven’t lost any other than to old age/ sickness etc.. I can’t imagine what it would be like to have a fox or weasel wipe them out.