I made a little pen like thing with no roof or bottom just sides I always take out my quail chicks out in it they dust bathe run around and eat the grass,since they were 2 weeks old, every once in awhile one would fly out it was no big deal I'd catch them and put em back with the reast well there almost 5 weeks old I thought they can still handle it. But the one that usually flys out. flew out I laugh because he didn't go far and when I went to catch him he flew in my face and then flew off and I haven't seen him since... he was the prettiest one too I hope he comes back... but I doubt it Now I only have five left.
Perhaps it is time to think of a more permanent structure (keeping in mind that there are predators about that will eat your birds in no time flat) ?