There were plenty of quail here in southern Indiana when I was a kid.
The blizzard of 78 hit them hard but they rebounded pretty well in my area in the 80’s.
They started disappearing in the 90’s and for years I never saw any even when rabbit hunting. No fire ants or hogs here.
As of the last five years I’ve seen coveys where I haven’t seen any in 15 years or better.
I now know where five coveys are so things are looking better.
If the winter gets bad me and the boys will put cracked corn out where a couple of the coveys hang out.
There’s a lot of factors contributing to their decline. Destruction of cover is a big one and predators also but man is their biggest enemy around here.