Killdeer "displaying" in order to divert attention from its nest, probably. This is what it states in my bird book. Sometimes they pretend they have a broken wing, or hurt foot, to try to lure predators away from their nests or youngsters.

You can see the catchlight in its eye here, despite it facing away from me.

Really a pretty bird, and we were so happy to have seen this, just near the little trail near a beach area, as we drove past. I had seen one from a distance as we entered the area, but DH suddenly spotted this one as we were leaving.