Why should any hunter, in or out of prairie dog country, care whether any or all subspecies go extinct?
Simply because, as animals, we are all dependent upon the larger ecosystem for our lives. Stealing from Haldane, "Ecosystems are not only more complex than we know, they are more complex than we _can_ know." Therefore, we must follow Leopold's dictum of the intelligent tinkerer and keep all the cogs and wheels, even when we know not what they do.