The game bird situation (other than turkeys) in my area of Indiana has been pretty dismal for almost thirty years now. This, IMO, is mostly due to the discontinuation of the "Soil Bank" program and the incentives which used to be offered to farmers to leave an 8-10 ft. strip along fence rows, etc. to provide for both cover and food plants for small game, especially birds. A part of the deal was providing brood stocks of game birds at no charge if the landowner would agree to permit some hunting there.
The horrible winter of 1977-78 resulted in massive losses of both bobwhite and pheasants throughout the entire northern 2/3rds of the state. Coupled with the steady losses of habitat where cover and food were available in sufficient quantity to enable a large enough percentage of the remaining populations to survive the subsequent winters to rebuild the numbers, it was a disaster of insurmountable proportions.
When the incentives dried up, fence row-to-fence row tilling became the rule for the farmers to recoup the lost income. "Marginal" agricultural land that was formerly left fallow under the "Soil Bank" program and was the major sanctuary for small game species went back into cultivation, or was lost to suburban sprawl.
While there are scattered pockets around the state where the wild populations of bobwhite and pheasant are large enough for hunters to enjoy some limited success, they're nowhere near as common or as large as they formerly were.
In my area, landowners who've set aside portions of their holdings to support good populations of game birds do so primarily to generate income from leasing the rights to hunt there. It's both reasonable and proper that they should; the state and federal governments no longer provide the incentives which supported and encouraged their permitting free access to hunters.
My grandfather told me of quail and rabbit hunting along the White River in the '20s the '30s.