The first I heard of Fire Ants was in an article written by Bruce Brady of Brookhaven Mississippi in a free bi-monthly magazine distributed by the State of Mississippi which featured Outdoor articles of 'mainly' hunting and fishing. Bruce was a 'well know' Author at that time. He was either a regular, or free lance writer for
'Outdoor Life Magazine', which was in the top tear of the most popular Hunting and Fishing magazines in the United States of America at that time. You could find a copy at every barber shop in a time before the internet and youtube. A time when many country boys 'scraped' up 60 cents

in order to afford and get ahold of this prized printed, monthly magazine of outdoor reading and adventure.
Bruce warned of the invasive Fire Ant and what was to be expected in my State. He was right. Just a few years later I found my first, easily identified Fire Ant Hill on the
Mississippi/Alabama State line while hunting with my cousins. In fact I found many there. The large ant hills were just as Bruce Brady had described. Not long afterward 'and not before', they were in my area as well, which happened to be about the time these three species was 'recognized' in my location and about the time quail slowly began disappearing. (and not only these three species, their were others as well).

As
Si Robertson might say,
"That's a fact Jack" lol

Im not suggesting invasive species was the demise of quail in my area but I am stating when these three were recognized in my home location, the quail numbers began dropping as well.
Coincidental with spiders? I would say most defiantly, the others? I wonder but do not know. I think it may be some of that, as well as changes in farming, land management, and other reasons combined as others have written above.
Phillip