This is the Least Sandpiper, the smallest shorebird in the world. It’s lucky to reach six inches in length.
These Pipers tend to travel in small flocks that put on close-formation aerobatic performances over the water.
The Least Sandpiper often is not noticed on shore because of its size and its habit of not spending time at the water’s edge during low tide; it usually is feeding for insects among the seaweed up at the high tide line, where its markings are good camouflage.
By the way, one of the collective names for any group of Sandpipers is a “contradiction,” as in “There’s a contradiction of Least Sandpipers!” Why that odd name was chosen and by whom seems to be a mystery.