Introduction

The Semipalmated Sandpiper is a small, abundant North American shorebird that breeds near water in low and sub-arctic tundra and winters along the northern and central coasts of South America. Despite numerous studies of this species during migration, comparatively little is known of its wintering biology. Its breeding biology has been examined in only two areas, Alaska and northern Manitoba.

Where its food (small aquatic and marine invertebrates) is abundant, flocks of up to 300,000 Semipalmated Sandpipers may gather in key migration staging areas, and on wintering grounds. Individuals from eastern populations probably undertake nonstop transoceanic flights of 3,000–4,000 km from New England and southern Canada to South America, powered by extensive fat reserves. Less social on the breeding grounds, this species is monogamous and territorial, raising up to four young in just a few weeks of arctic summer. No geographic variation in plumage has been described for this bird, although size, particularly bill length, declines from the eastern part of the breeding range to the west. No subspecies has been named.