It's definitely anecdotal, but the explosion of corn feeders (and raccoons) has coincided with the decline in turkeys where I hunt in south MS.
It pisses off the others in my lease, but when they fill a feeder up, I set coon traps a week later. I've killed a PILE down here. Can't really say it's helped a lot, but it just isn't natural to have a coon population as high as we have down here
I run traps each time I come back to TN (I'm only trapping nuisance raccoons, so I'm legal), but we just didn't hatch out any poults this year for whatever reason. Sill makes me feel better.