Bison

Yes, all those black dots are bison.  Toward the end of our ride through the Badlands I realized that I had forgotten to get gas in Wall.  The light alerted me to my mistake.  Before too long, thank goodness, we saw a sign reading Interior 2 miles.  We asked the woman at the gate whether or not there was a gas station in Interior.  There was.  Saved by the "bell."  We returned to the park for the last section leading back to Interstate 90.  Before long we were on our way across the prairie to Sioux Falls.