This female nestled in a scrape in an area likely to be inundated by high tide. Apparently females sitting in scrapes are part of courtship and these scrapes are not necessarily chosen for nests. Note the brown on the face meets above the gape. This may help distinguish it from the almost identical Common Ringed Plover (C. hiaticula). Canon PowerShot SX50 HS.
References:
Chandler, R. (2009). Shorebirds of North America, Europe, and Asia: A photographic guide. Princeton.
Dunn, J.L. (1993). The identification of Semipalmated and Common Ringed Plovers in alternate plumage. Birding 25: 238-243
Nol, Erica and Michele S. Blanken.(2014).Semipalmated Plover (Charadrius semipalmatus), 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/semplo
Wiersma, P., Kirwan, G.M. & Boesman, P. (2017). Semipalmated Plover (Charadrius semipalmatus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/53823 on 15 July 2017).