Some pen-raised birds make it. Maybe encounters with wild birds helps. However, I worry about the long-term impacts of the mixture of pen-raised DNA with wild. "Wild" mallards on the east coast are virtually all hybrids of wild and surviving pen-raised. The genes of these surviving pen-raised mallards are producing observable changes in wild populations that might be impacting survival. I don't think this has been studied much in pheasants, but there are sure a lot of them released.