I'm all for repopulating/releasing native quail, but you might need to consider whether the habitat and food sources are there. For instance, quail chicks require lots of protein to grow, more so than adult birds. I may be wrong, but I find it unlikely that an urban park may have the necessary amount of insects (I'm talking about insects that chicks are capable of catching like pill bugs and not referring to flying/fast insects). On another point, what about the quail themselves? If left alone with no disturbance, are they capable of bringing up broods? If so, when the chicks hatch, do they stick close to their mother or do they wander off often and making themselves vulnerable to predation? Although I've never kept bobwhite quail, I've read that some domesticated birds are not effective brooders. I do not know everything and there are so many variables involved for a successful reintroduction. I do not know if there are any, but I recommend choosing a stock of bobwhite that retains most of their behavioral instincts and staying away from bobwhite breeds like the jumbos. It does not beat releasing trapped wild bobwhites for reintroduction, but it is a good idea to release those that have a slight advantage at surviving. As an fyi, I'm not saying that you shouldn't release birds, but just suggesting a few things for you to consider.