Dunlins breed in arctic and subarctic regions, wintering from Massachusetts to central Mexico. These are chunky sandpipers with a thick neck, a long black bill that droops at the very end (seen in this photo), and robust black legs. Non-breeding plumage is fairly drab, with a dun-colored back, some scalloping in the coverts. 

Weskeag Marsh, So. Thomaston, Maine