Well, they do seem to like it in the ditch where there's lots of water. See behind them, there's an oak tree between the Xanthos and the house. Also once it stops raining in the fall, there's probably not nearly enough water for them to travel far. The beauty of our sandy soil, it really does dry out fast.
I don't think that's a 'runner' type, either. They seem to make pups right next to the big ones, but I haven't seen them even appearing 'downstream' which would be on the other side of the road, so it would seem they're not seeding or sending pups out too far.