Or maybe he is just stretching. If these are not Sanderlings, I apologize, I am still learning to identify birds. These little guys are fast, skittering all over the place and stopping for a quick peck in the puddles.
Nikon D200, 70 - 200mm lens with 1.7 teleconverter
top image at f4.8 and 1/2000th with a -.67 exposure compensation, ISO 200
bottom image f9 at 1/750th, no exposure compensation, ISO 200