Very interesting topic!
I wonder if the latitude over there is the same as our best producing habitat.[/QUOTE
Wild pheasants and the wild mallard ducks have been in Asia for tens of thousands of years. So pheasants in China or Asia are thick at every latitude.
Pheasants are found in the natural wild state across Asia east to Korea, Manchuria, Sichuan southern China, between latitude 20 and 48 north.
If you would move those latitudes to north America, the 48 north latitude would put the wild pheasant range as far north as Minot N. Dakota.
The 20 north latitude would put the wild pheasants as far south as Tampico, Mexico, (the bobwhite quail range goes deep into Mexico).
There is still room far the slow expansion of the wild pheasant range. Wild pheasants have slowly expanded their wild range south of Lubbock Texas.
Read the article below it shows that all wild true pheasants (Ring-necked type) are close kin using mitochondrial DNA. The early ornithologists in the last century may have gotten a little carried away with all named subspecies of ring-necked pheasant. This was done years and years before anybody knew about DNA.
http://www.ncbi.nlm.nih.gov/pubmed/19328240
William Beebe who did extensive research on wild pheasants in China reported shooting a Strauchi or Sichuan pheasant (rooster with no ring) right outside of Shanghai.
That is the same area where in 1881 judge Owen Denny caught or trapped the wild pheasants that were first successfully released in Oregon. That shows that natural wild range the subspecies naturally merged or overlapped.
Shanghai is near the 31 north latitude putting it in a U.S. latitude close to Albany, Georgia or Austin, Texas.