I found these horses where they live year-round on the edge of the Wilton Mine slag piles, a ranch/farm that has turned the unusable ground in to pasture. The slag piles are all that remain of the underground lignite coal mines that once flourished on the east edge of town. Now the region is agriculture based, farming. Much of the ground where these horses feed is pasture ground. Not only are the hilly slag piles impossible to farm, the region is a bit dangerous. Sometimes a mine shaft will open up and swallow the tractor trying to work the region. Well, at least it used to be like that. No tractors have been swallowed that I know of for 20 years or so. Still, when a pit opens up while a farmer is trying to till the soil, it can cause his tractor or other equipment to fall in to the pit and break an axle.
So, eat on, horses. The slag piles are good food for you.