Well.. The rats eat both chickens and pigeons at my parents' farm. My dad had had around 40 pigeons last summer. Now he has none. His own fault, because he didn't deal with the problem when they started dying and disappearing, and they didn't kill any chickens this time (they are in an enclosure right beside the pigeons), but we've had chickens in the enclosure the pigeons were in before and also lost quite a few back then. There is a concrete floor, but the rats find its weak points so even though we've poisoned them and poured new concrete in their holes several times, it just takes a few years before they are back. So I do believe they would consider quail a lovely snack, given the chance. I have buttons living just 6 feet from the pigeon enclosure and the rats didn't make it in there - yet - but if they do, I have no doubt I'd quickly have an empty aviary. So I'd definitely do my best to make a rat proof enclosure.