These shorebirds are feeding “in the mirror.” The mirror is the reflective sheen left on beach sand by receding waves. In the photo above, you can see a nice reflection of each bird; thats the mirror in action. Ornithologists, beachcombers and photographers use this term all the time.
A good mirror occurs when the slope of the beach is shallow, the swell is large and the period between swells is long. It also helps if it’s not too windy and the sun is at a low angle. In the gallery below, you can check out a few more images that illustrate the mirror on theoutershores beaches.
All of the photos above were taken for reasons other than the mirror. In the future I think my eye will be more attuned to the mirror itself. Have you ever noticed an amazing mirror on the beach?
theoutershores 
Beautiful!