By "birds", if you mean pheasants, there is almost nothing in the Hills themselves. There's a few in the creek bottoms surrounding the hills, but it's mostly private ranches. If you want the native sharp-tails and prairie chickens check out the Ft. Pierre National Grasslands, about two hours to the east near the capital Pierre (SoDaks pronounce it "peer"). You will also run into a few more pheasants there along the Missouri River. There can be lots of birds in places and the country is simply beautiful.
