Actually now that you say it I do think I remember something about an experimental stocking of them out there. Kind of strange how such minor habitat differences can make or break birds. Too bad they never took hold. Or maybe not. We will never know.
That actually was a home range for sharpies! They were well established till about the 1930's as the agriculture change the range. I have seen lots of prairie chickens across Nebraska, the sharpies tend to be more alturistic range wide, they are happy with rose hips and grasshoppers, will sometimes use harvested crops, but I think they actually are using freeze dried hoppers. I have seen them in a stark winter, with about 12" of snow on the ground, roosting in cottonwoods, crops full of rose hips and leaves. In areas with the pair, it's the chicken you find low on the slope, instead up in the wind on the ridges, all most always in denser grass. Sharpies where in the open. Roost down into burrows in the snow, both have nostril flairs that make heavy ice and snow possible, a bain of the pheasant, these guys don't ice beak over. As suggested they are regionally migratory, if the area is slammed by snow, they are capable of 60+ mile flights. Sometimes you see them flying like ducks, with obviously no theory of a local landind spot. I have seen them do that on a wild flush, going at least 3-5 miles. We don't walk them up! It's kind of amazing. On snow they play around in the swirly stuff like kids. Both are my favorite birds. Easily can be the most frustrating, bird, one day you'll shoot your limit in 5 minutes, next day you walk 10 miles to find a flock, or one that lets you get close, then it's all over in a couple of minutes. Now find the silver dot on the horizon, it's your car, about 5 miles across giant sand hills to find your way out! it's either 10 degrees, or 80 degrees. Up north sharpies us serviceberry, plum brush, sitting in the shade. Up in Nebraska, I have seen them in serviceberry, twice in 20 years, they are always on the top of ridges, on one side or another a few feet from the crest. I you are in wild rose hips, up there, you are in the right place. I do not doubt that sharpies are agressive, they certainly bully pheasants, like a pheasant does to a domestic chicken, my relatives shot pheasants to let the chickens eat with a .22 short. They let the sharpies have at it. I guess because they were rare in those days.