Though I’m no bird expert I’m totally at a loss as to what was going on here. The bird on the right remained standing and seemed to be foraging, at least it was moving as I’ve normally seen Black-bellied Plovers do. The bird on the left would stand up, walk a couple of paces and then crouch down like this again, then either sit or lay flat on the ground.
My first thought was that it was a threat, alarm, or defensive display, however the large tern colony behind me wasn’t doing anything to indicate a threat near by, nor were there dogs or may people within 100′ or more. My second thought was that the bird may have been injured or tangled up with fishing line. However close inspection though the lens revealed no line, and the bird was certainly capable of moving normally as it did at times. I don’t think it was a territorial display either, as they never strayed far from each other for the 30 minutes or so I was observing them
In any event, if you’re a bird photographer or watcher, and have a clue as to what they were doing please leave a comment.