Based on size & shape, my original thought was Golden-Plover, but closer inspection showed black-bellied characteristics, viz., breast flanks are streaked rather than barred, cap is light rather than dark, belly white rather than grayish. I sent the photos on to two more knowledgeable birders. The first response pointed out the slight build & smallish bill, and leaned toward golden.
The second verdict mentioned the streaks, also low rather than upright posture, & relatively short primaries all suggest black-bellied.
We heard the sound of thunder as we were studying this bird, so cut off the field inspection to head for shore.....