I had a lunch meeting with one of the NBCI staff last week. He used to frequent QDMA. Essentially 25% of an area suitable for quail must be optimum quail habitat....so about 1000 ac suitable land area minimum for NBCI (25% of that optimum quail habitat...250 ac). We talked quite a bit about quail and habitat, obviously. One question he had was do you think you have quail returning because of your management or current weather patterns? Quite honestly, consistently good weather patterns for the last several years in a row are diving this quail return on a regional basis...extended drought is particularly hard on quail but they return faster in the semi-arid than humid grasslands...Why is that?...density of forage at ground level IMO...more suitable humidity in normal rainfall years...and more plant structural changes after drought in the east than west! Quail will find the most suitable local habitat for nesting as they return...this is where management comes into play...a local effect which is constrained by efforts of your neighbors.
Generally, I hear most of the bobs right now on my place in tame pastures with a woody/brush component on thin rocky soils where sod grasses struggle....so there is a nice complement of forbs, legumes and intermediate native bunch grass....sparse enough where quail chicks can bug for insects....yet close enough to sufficiently thick grass for nesting/security cover. I call these areas 'the breaks'! I can't tell what goes on in the native units right now because I'm running a saw or ATV back in there and not paying much attention...but the fall/winter covey goes to the native unit!
Ungrazed (or non impacted) humid range land as you mention quickly becomes too thick at the 1-4" height where chicks travel.....bunch grasses are favored over sod grasses in that same regard. So the difference you see between the ungrazed 50 and the properly grazed range land (not overstocked) is to be expected. Quail are no different that deer or any other wildlife....the ecosystem must have diversity and complexity as a whole with a complimentary patchwork of small areas which differ in plant density to support wildlife diversity. So...that is why when our herd moves through a rotation you will see a mix of high impact, moderate impact and light impact. The extremes of pasture where all plants are overgrazed (overstocking) and the idle pasture where all plants are too thick from no impact are equally detrimental to quail!
NBCI
https://bringbackbobwhites.org/
Just graze and observe,
Doug