I usually don't go over to that side of the lake, but I just had to see what four killdeer could be doing in one spot.
Here are all four together, the female is on the bottom left. Look at how large and puffed up the males' neckbands are.
The female watches the males battle it out. The two on the right were actually attacking each other. Unfortunately, I couldn't get a photo of the attacks
The male on the left ends up flying off, trying to land near me, then giving up and flying away.
The second male on the right in the bottom photo flew off with the other male and began calling, but when he returned the third male and the female were gone. He was so mad at me and began to yell warning calls even though it didn't bother him that I was standing there before.