The surfbird (Calidris virgata) is a small stocky wader in the family Scolopacidae. It was once considered to be allied to the turnstones, and placed in the monotypic genus Aphriza, but is now placed in the genus Calidris.
thumb|left|In worn
This bird has a short dark bill, yellow legs and a black band at the end of the white rump. In breeding plumage, it has dark streaks on the brownish head and breast with dark spots on its white underparts; the upperparts are dark with flax or sometimes rust colouring on the wings. Birds in winter plumage and immature birds are mainly grey on the upperparts and breast and white on the underparts with streaking.
Their breeding habitat is rocky tundra areas in Alaska and the Yukon. The female lays 4 eggs in a depression on the ground lined with vegetation. Both parents look after the young birds, who feed themselves.
These birds migrate to the Pacific coasts of North and South America, from southern Alaska to Tierra del Fuego.
On the nesting grounds, these birds mainly eat insects and some seeds. At other times of year, they eat mollusks and crustaceans found along the surf line on rocky coasts and are usually found in small flocks, often with turnstones.
The song is a whistled tee tee tee.
Taxonomy
The surfbird was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with the other sandpipers in the genus Tringa and coined the binomial name Tringa virgata. Gmelin based his description on the "streaked sandpiper" that had been described in 1785 by the English ornithologist John Latham from a specimen collected in 1778 from Sandwich Sound (now Prince William Sound, Alaska) on James Cook's third voyage to the Pacific Ocean. The species was moved to the monotypic genus Aphriza by John James Audubon in 1839. It is now one of 24 species placed in the genus Calidris that was introduced in 1804 by the German naturalist Blasius Merrem. The genus name is from Ancient Greek kalidris or skalidris, a term used by Aristotle for some grey-coloured waterside birds. The specific epithet virgata is from Latin virgatus meaning "striped" or "streaked". The species is treated as monotypic: no subspecies are recognised.
The species was long thought to be allied to the turnstones, and placed in the subfamily Arenariinae. With the turnstones it has even been treated as its own family. Indeed, the great knot looks very much like a larger, longer-billed, and somewhat darker surfbird.
Surfbirds their breeding plumage from March through August, and have white heads, necks breast and belly which are streaked with black, except for the which are rusty.
Breeding
thumb|Surfbird on its nest
The breeding behavior of the surfbird is poorly known. The surfbird arrives in its breeding habitat in early May; due to high winds in their exposed nesting areas the snow has usually cleared by then. Nesting sites are typically on north or west facing slopes. Nests are exposed, and a re simple depressions lined with lichens and, sometimes, Dryas.