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Calidris virgata (Gmelin)
Surfbird
Family: Scolopacidae

Species account author: Jamie Fenneman
Introduction to the Birds

Photograph

© Tim Zurowski     (Photo ID #7985)

Map

Species Information

Breeding adult
This plumage is held between early spring (March/April) and late summer (July/August). The back is whitish with heavy black mottling and the scapulars are rufous or rufous-buff with white edges and a black subterminal crescent and shaft streak (‘anchor-shaped’ black mark) on each feather; the rufous of the scapulars fades quickly to buff, and can be nearly whitish on post-breeding birds in summer. The lower back and upper rump are blackish or blackish-grey, contrasting with the clean white rump and uppertail coverts. The upperwing coverts are primarily brownish-grey, often with somewhat paler feather edges, and sometimes show irregular blackish spots on the inner secondary coverts. The flight feathers are blackish with a bold white stripe across the bases of the secondaries and primaries; the tertials are brownish-grey, sometimes with irregular black spots. The tail is primarily white, with a broad, sharply-contrasting terminal band across the outer half of the tail. The underparts are whitish with heavy, chevron-shaped black spots across the breast and extending down the sides and flanks; there are usually some chevron-shaped black spots across the belly and undertail coverts as well, but these are not as dense as on the breast and sides. The head and neck are whitish with dense, but fine, blackish streaking throughout, usually with some narrow rufous or buff streaks on the crown. The iris is dark, the relatively short, shout, straight bill is blackish with a yellow-orange or yellow base to the lower mandible, and the sturdy legs and feet are yellow to greenish-yellow.

Non-breeding adult
This plumage is held between late summer (July/August) and early spring (March/April). The back, scapulars, and upperwing coverts are dark grey to brownish-grey and the flight feathers are blackish with a bold white stripe across the bases of the secodaries and primaries (as in breeding plumage). The pattern of the rump and tail is similar to that of the breeding adult. The head, neck, and breast are also dark grey to brownish-grey, breaking into small, relatively sparse chevron-shaped blackish spots that extend onto the white belly, sides, flanks, and undertail coverts. There are usually some areas of pale whitish-grey on the face, especially on the lores, throat, and flecks across the ear coverts. Bare part colouration is similar to that of the breeding-plumaged adult.

Juvenile
This plumage is held throughout the summer and early fall of the first year, occurring as late as September. Juveniles are similar to non-breeding adults, but are somewhat paler grey overall with fine, irregular buffy and whitish streaking and mottling on the head, neck, and breast. The feathers of the back, scapulars, and upperwing coverts are very narrowly edged with whitish-buff, giving the upperparts and finely scaled appearance. Bare part colouration is similar to the adult.

Measurements
Total Length: 25-26 cm
Mass: 155-230 g

Source: Senner and McCaffery (1997); Sibley (2000)


Biology

Identification

This large shorebird is distinctive both in plumage as well as behaviour, and its strict association with rocky shorelines facilitates its identification. No other shorebird combines the size, structure, and bill shape of the Surfbird with the flashy, highly contrasting wing and tail patterns that are visible in flight. The Great Knot, which is strictly a vagrant in North America (including British Columbia), is superficially similar in both breeding and winter plumage to similarly-plumaged Surfbird, but can be easily distinguished by its long, slender bill, dark tail, and lack of a bold white stripe across the base of the primaries and secondaries (wing stripe is very narrow and inconspicuous in Great Knot).
Vocalizations

This species is relatively quiet during winter and migration, and most vocalizations are audible only at close range. Calls include a soft iif iif iif iif, given in flight, as well as a continuous high, nasal chatter given by foraging flocks. Sometimes gives a low, soft chut or ka-chut when flushed.
Source: Paulson (1993); Sibley (2000)

Bird calls (and videos) from Cornell's Lab of Ornithology
Breeding Ecology

This species is a non-breeding migrant and winter visitor to B.C.
Foraging Ecology

The Surfbird belongs to a suite of shorebirds that are adapted to feed on rocky, often wave-swept marine shorelines; this group includes Black and Ruddy Turnstones, Rock Sandpiper, Black Oystercatcher, and Wandering Tattler. This species forages alongside these other species, and regularly forms mixed-species flocks with Rock Sandpipers and turnstones (especially Black Turnstones). It also regularly occurs in small to medium-sized, or occasionally large, single-species flocks, especially during migration or during high-tide roosts. The Surfbird feeds primarily on hard-shelled intertidal invertebrates such as bivalves (especially mussels), snails, crabs, isopods, and barnacles. In some areas, this species also feeds extensively on marine algae in addition to intertidal invertebrates, and spring migrants will consume the eggs of Pacific Herring where they are available. Foraging birds tend to prefer rocks that are as close to the water’s edge as possible, often occurring within the splash zone of waves. When foraging, individuals move rather slowly and methodically among the rocks, inspecting cracks and crevices for hidden prey as well as picking at barnacles, mussels, and other foods that are exposed on the surfaces of the rocks. When prying sessile prey from the surface of the rocks, this species uses its entire body (not just its bill) to wrench the organism from the surface of the rock, often employing a sideways tug of the head. It swallows its prey whole, later regurgitating the shells. The Surfbird is relatively confiding when foraging, often allowing close approach.

Source: Paulson (1993); Senner and McCaffery (1997)

Habitat


Migrants and wintering birds are very closely associated with rocky marine coastlines, especially in areas with significant wave exposure, and usually occur within or just above the splash zone of the intertidal area. Most birds roost and forage on rocky headlands, offshore islets, reefs, breakwaters, jetties, and, to a lesser extent, cobble beaches. Some individuals occasionally occur on log booms, particularly when roosting with other species of shorebird. It very rarely ventures onto sandy beaches or mudflats, and tends to avoid estuaries or other areas of freshwater influence.

Source: Campbell et al. (1990b); Senner and McCaffery (1997)

Distribution

Global Range

Breeds in mountainous areas of Alaska, the Yukon Territory, and the extreme northwestern Northwest Territories. Winters along the Pacific coast of North America, Mexico, Central America, and South America from south-central Alaska south to Tierra del Fuego, Chile.
BC Distribution

Winter
Uncommon to locally fairly common along the entire coast of the province, including all offshore islands, although it is rare or absent from areas of extensive sandy or muddy substrates or where there is a heavy freshwater influence.

Migration and Vagrancy
Fairly common, but local, spring and fall migrant along the entire coast of B.C. Spring migrants first begin to appear in coastal B.C. in February, but are difficult to differentiate from overwintering birds. The population of north-bound migrants continues to build through March and April, peaking in early to mid-April in the Strait of Juan de Fuca and Strait of Georgia and between mid-April and early May on the outer coast of Vancouver Island and the north coast of the province (including the Queen Charlotte Islands); most individuals have left the south coast by mid-May, and even on the north coast the last lingering migrants have typically departed by late May. Barkley Sound, on western Vancouver Island, is a major spring staging area, with flocks often numbering into the thousands of individuals. Occasional non-breeding individuals and small flocks may linger along the coast throughout the first half of June, primarily on the outer coast of Vancouver Island, the Queen Charlotte Islands, and the northern mainland coast.

The first fall migrants arrive along the coast of the province in late June and continue moving south through October and into November. Peak southward-bound movements on the northern and central mainland coast, Queen Charlotte Islands, and the outer coast of Vancouver Island occur between mid-July and mid-August, while peak movements in the sheltered waters of the Strait of Georgia and Strait of Juan de Fuca occur between mid-September and mid-October. Late fall migrants may continue to move through B.C. during November or even into December, but these individuals are difficult to separate from overwintering birds.

Accidental in the southern interior (Shuswap Lake) in early September.

Source: Hatler et al. (1978); Campbell et al. (1990b)

Conservation

Population and Conservation Status

This species is reasonably common and secure in British Columbia, and is not recognized as a species of conservation concern by either the B.C. CDC (Conservation Data Centre) or COSEWIC (Committee on the Status of Endangered Wildlife in Canada). The overall world population appears to be relatively small, however, with an estimated 100,000 birds. With the exception of birds that winter in south-coastal Alaska, the vast majority of the world’s Surfbirds either migrate through or winter in coastal B.C.

Source: Senner and McCaffery (1997)

Taxonomy


This species is monotypic, with no recognized subspecies. It is the only species in the genus Aphriza. Although it is behaviourally and morphologically similar to the turnstones, it is actually more closely related to the Calidrine sandpipers (knots, peeps, stints, etc.).

Source: Senner and McCaffery (1997)

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)		COSEWIC
NativeS4MYellowNot Listed



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