They winter out there by the dunes, i'm sure quite a few of them decide to just stay in the area as long as the feed and water is plentiful. With all the agriculture in the area, it makes perfect sense!
We've started seeing more and more elk in area's like this, I think it's because they come down to get away from the wolves. When we went chukar hunting last Dec. We seen 33 bulls together where we've never seen them before.