This individual is in juvenal plumage characterized by crisp feather edges with light rufous fringing on the upper scapulars. Note also straight rather thick bill, and dark cap contrasting with pale gray nape. It was one of a large congregation of small sandpipers gathered at high tide. This species is an abundant migrant on the East Coast of North America wintering almost entirely in the tropics and South America. Digiscoped with Panasonic DMC-LX5 | hand-held (no adapter)
References:
Chandler, R. (2009). Shorebirds of North America, Europe, and Asia: A photographic guide. Princeton.
Hicklin, Peter and Cheri L. Gratto-Trevor. (2010). Semipalmated Sandpiper (Calidris pusilla), The Birds of North America (P. G. Rodewald, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America: https://birdsna.org/Species-Account/bna/species/semsan