My dad tried a few years ago with no luck.Setup was similar to bill's with a large pen near the house that had plenty of cover inside it (ivy under pines).We had hoped to at least hear one or 2 the next year from the 150 or so we released but we never did.The dumb things just wouldn't go for cover,even with my vizsla on point and just about poking at them,they just stood there.I never saw the dog so confused,here he was expecting a chase and all they did was sit there.
Now we doubt many if any at all survived,but while walking my dog 2 years later he did flush a few quail in the area we released them,but since then nothing.I doubt they where from the released birds but none the less we are going to give it a go again as it is fun.