It's only my opinion. But my experience has been any pheasant, hen or rooster, which survives the first two weeks, is virtually the equal of a wild bird. The rub comes in that if you have a wild population now, the birds have naturally expanded to occupy the existing habitat already, your release birds if thery survive, occupying the same habitat structure,will compete with the wild birds, for whats available, with one or the other the looser. Have you ever noticed how pheasants in particular will refill superior habitat? During the hunting season some patches always hold birds, because as birds are removed, birds in surrounding inferior habitat, move in and fill the better habitat as the mortality removes the birds who previously occupied it. Same with the introduced birds. Exception being if there has been a lack of success with spring hatches, or survival, which has been the case in Southwest Iowa, NE Kansas, SW Nebraska, NW Missouri, where we have basically no birds of the year, with a remnant population of two year old+ birds. In this case there is unoccuppied suitable habitat, waiting to be occuppied by a super compensation hatch, hopefully this year! But a fall release of birds this year, might have provided hunting opportunities which were not available, plus allowed for some additional hardened hens to provide recovery stock. Percentages of survival as qouted by the professionals are dismal, but I have always suspected that those numbers are skewed by things like release the day before hunting season, rearing techniques, etc. After all if the percentages are that bad, how did we ever get them in the first place! since every jack one of them came out of a cage orginally, and I seriously doubt the release techniques practiced in the 1880's followed any great impact study or scientific research. More like a couple guys with a wagon full of pen raised pheasant/chickens rolled out of town till they found a likely spot and set them free. Survival, and success, as with all things relies upon the lowest common denominator, is it lack of winter cover, lack of nesting cover, lack of nesting success due to weather, lack of escape cover where they aren't bothered, it's almost never food, except during times of deep snows and thick ice. Good Luck, band them so you know what happens to them. I release mine in an area devoid of pheasants naturally, I have seen mine survive for three years,and reproduce on their own, but mine is an isolated habitat in a desert of fescue, and subdivisons, so I will never establish a self sustaining population. But it's fun to try and it gives me some dog work opportunities.