The male watched me intently (not sure he’s
the male, but he seemed like the leader of the pair).
Every now and then he would bob up and down like he
had the hiccoughs. I had read earlier that when a Killdeer
notices an intruder (me and my car!), it stops to look
at the intruder and at the same time bobs up and down.
He continued to remain "on alert," eyeing me over his shoulder!
With every click of the camera, he would rotate his head to face me.
Neither of the couple did the classic Injury-feigning Display where the bird will sort of crouch down or flop around on the ground with what seems to be a broken wing trying to lead the intruder away from the nest, so I guess I wasn’t too much of a threat, but the female did slip into the False Brooding display. At first I thought she was exhibiting some sort of courtship behavior and was encouraging the male because she was sitting on the ground with her rufous rump-patch exposed. However, after reading about the False Brooding Display, I realized that was what she was doing. The False Brooding Display is a distraction display, which like the Injury-feigning Display is designed to get the intruder’s mind off the real nest, thus protecting the eggs or nestlings from predation.
The female hunkered down on the ground like she was
sitting on a nest and actively showed her rufous rump-patch.
Every now and then she would look over her shoulder
at me and continue to fluff up those rufous feathers.
Eventually she calmed down and decided I was no
threat, as she got up and walked around with the male.
The Birds of North America Online has a nice description of the distraction displays.