@Flbt - yes have heard all of them and there is logic in some. I might agree with “Fire ants” in some areas But not many fire ants in areas on NJ I hunted, also pesticides - even though Pheasant “thrived on DDT”…maybe the Glyphsate is Not as good. But coon, possum, hawks all about the same past 75 years and trapping helped but stopping trapping wasn’t what made ground nesting birds go from being plentiful to extinct. While I do Not mean to poke holes in your reasoning - and your thoughts are good ones and shared by many —. I believe those problems could be “solved” at least in small areas —- 1000 to 5000 acre tracts of land where they still can NOT get a sustaining breeding population of quail & pheasant to RE establish. I don’t have the answer or even a theory - Not a Biologist but thinking it was something more subtle or more complex - otherwise there would be large pockets where restoration efforts would’ve already succeeded. When you think of how little effort went into the successful introduction of Pheasants from China - over 100 years ago and NO Science or biologists, no habitat or environmental Impact Study was done AND the Pheasant population exploded into the tens of millions in 30 years….and NOW “Nobody” can solve the problem?