We have lost most of our quail to fireants, As you can guess, fire ant control and quail raising, has become HUGE $$ makers for some. From what I have seen in the upper panhandle and what I have heard, there wasn't much history of flocks of turkey or huge numbers of quail anyway. They where there, but not as "thick" as after better farming practices came into effect. Pheasant where brought over as Dave said to dd that to the hunting opportunity. I know the droughts we have experienced over the last few years have nearly decimated all three species, Pheasants more than the natives.
Dust bowl didnt help, but did encourage better land management and I have been told that is why they started the CRP program, but not sure if that is fact.