This medium-sized, portly sandpiper has the most northerly distribution of all shorebirds in winter, occuring in small groups along exposed, rocky seacoasts of the north Atlantic. Noticeably agile and confident on rocks and near surging waves, the Purple Sandpiper is the commonest wintering shorebird along the eastern coast of Canada, as well as in Iceland and Greenland. The diet of this species varies from marine mollusks and other invertebrates in winter to insects (marine and terrestrial) and seeds in summer. Called “winter snipe” by gunners, Purple Sandpipers were hunted in North America, along with other shorebirds, at the beginning of the twentieth century.
This species has a noticeably dark and uniform plumage in winter, with slate to charcoal upperparts that in some lighting conditions shows a faint purple sheen. In summer, however, Purple Sandpipers are more colorful, with chestnut, buff, and light-brown highlights to otherwise dark back feathers. Usually quiet away from the breeding grounds, individuals are quite approachable in winter, and when flushed, tend to fly only a short distance, low over the water.
On breeding grounds from the high Arctic to the subarctic, Purple Sandpipers perform aerial courtship displays and lure predators away from the nest with a Rodent Run display. Females typically lay 1 clutch of 4 eggs, incubate for 3 weeks, and then leave the area. Males remain behind for several more weeks to tend the precocial young, which fly well within 5–6 weeks.
Most research on Purple Sandpipers has taken place outside of North America, on breeding grounds in the northwestern Palearctic (Arctic Ocean islands and northern Scandinavia) and on wintering grounds in the midwestern Palearctic (for example, Scandinavia, the Netherlands, United Kingdom). Only a few studies have considered this species in North America, so our account draws heavily from studies of populations elsewhere, especially from the eastern part of the species' range.