tire tracks, boot tracks, and dog tracks in the road are about your only indicators. Hunting WIHA its always a gamble on how hard its been hunted. On opening weekend, after the first field you hunt after daylight you're mostly trading fields with others anyway.
I'll admit to my poor navigation abilities on the opener. left a WIHA, idea was to go check out some others, didn't like them, kept driving, checked some others, kept driving, flipping between map and phone, kept driving.
Oh, this one looks good, wheat and milo. Lets hunt it. Dog gets birdy on first pass, my buddy shoots a rooster. Hey, this is a good field. Only 100 yards further before we realize that it was the same field we'd just hunted, shot birds out of, and left to go look for a different field, only to enter it from the other end of the field.
Point being, after a field has been hunted, it can still hold birds.