I consulted a breeder friend who has raised lots of both chickens and quail and he was adamant that they stay separated. Part of the reasoning is, why take that chance and wipe out a flock? Same with the wild waterfowl joining a flock. For me the stakes are too high to go against the advice of those with experience on that. However, I did go against that advice to separate turkeys at first. Now, they do get raised separate if for no other reason than that they have different feed requirements.