Released pheasants have a very low survival rate in the wild, even when they're released onto game farms and preserves which are expressly designed to provide ideal year-round habitat for birds. In SD there are a lot of commercial pheasant hunting preserves, licensed by the state and allowed a longer hunting season & higher bag limits with the stipulation that the preserve has to release a certain number of pen-raised birds onto the property each year and also must identify whether all birds killed are pen-raised or wild, and keep a tally on how many of each are killed. (Pen-raised birds are supposed to have enlarged nostrils from wearing blinders or they'll have one of their toes clipped off when they're tiny chicks, one or the other is a required means of identification if you're releasing native gamebird species in this state.)
And even on these preserves, where upwards of six or seven THOUSAND pen-raised birds every year are set free on huge acreages with abundant food plots of corn and milo, fruit-tree rich shelterbelts, open grasslands and thick cozy sloughs, where serious predator-control measures are in place all year round, where no crops are harvested or hayfields mowed, where nobody even lets their bird dog go for a fun run in a field during nesting season for fear of disturbing hens or hatchlings...basically a place designed to give even the dumbest, fattest, slowest pen-raised prairie parrot in the world, the absolute best chance at survival that he could possibly ask for...
....the overall statistics still suggest about a 3% survival rate for pen-raised birds on managed habitat, not taking into account the ones killed by the hunters.
So, it would stand to reason that the survival rate would be dramatically lower- if not nonexistent- for birds released into areas not being managed for gamebird habitat. And it is- even wild bird numbers will suffer in areas where farm/harvest practices leave zero cover or food source for birds in winter.
It's a nice idea- and would be great if releasing birds would help boost wild populations but unfortunately, doesn't seem to be the case. Even if you're getting the hens for free, feed costs would still be significant (phez need a 28% protein gamebird formulated feed for something like the first 8 weeks of growth? Not cheap feed and not available just anywhere). I believe 18 weeks is when pheasant producers consider them "mature" so that's 18 weeks of feed. Not to mention other assorted challenges with pheasants- they require far more space per bird than most other gamebird species or they'll beat the crap out of each other, their brooder temp and lighting has to be just right especially when young, even hens can have issues with picking/cannibalism as they mature and may need to be peepered- a huge job if you have a lot of birds- I know a guy who has to devote a whole Saturday and his whole family's help for a 2000 bird flock when "peeper day" arrives. And yes, they can pick up diseases from chickens- most concern is from direct contact or airborne but things can linger in the environment- so any housing that previously held chickens should be thoroughly cleaned and sanitized before bringing the phez in. I've had two or three offers to try my hand at raising a crop of pheasants (I was commercially raising quail/chukar with no problem)- the profit margin for roosters IS quite high, something like $8 per bird profit a few yrs ago when I ran the numbers, but like HECK was I going to put up with four and a half months of the hassle required to get there, lol.
