Just hog nature...not really odd. Sounders will pass through my acreage and root up and eat the nuts off the nutgrass. 3-4 weeks later in summers and early fall when we have excess rain the grass grows back fast and you can depend on them to come back to that same spot and eat the young tender stuff.
Also, HW and EH as much ground as you have covered in the river bottoms over the years, I know you have noticed where they root in a drift pile of leaves and wood only to return there right after the next rain. but the drift has to be at the right elevation where it stays moist and not up on a little hog back (no pun intended) ridge where the drift is all dry.