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Aphriza virgata - Surfbird

Surfbird image

Geographic range:

Alaska to Chile

Key features:

Mostly gray above, white bottom and black speckling below, and short yellow legs. Occurs along rocky shoreline, feeding with a blunt, black bill that has a yellow-orange base.

Similar species:

Arenaria melanocephala -- Black Turnstone
Calidris ptilocnemis -- Rock Sandpiper

Habitat(s):

bay (rocky shore), exposed rocky shore
 

Primary common name:

Surfbird

General grouping:

Seabirds and shorebirds

ITIS code:

176673
 

Geographic Range

Range Description:

The Surfbird has a winter range longer and narrower than any other North American breeding bird, perhaps of any bird in the world. In winter they are found on the west coasts of North and South America, along rocky, coastal shores from Kodiak Island, Alaska, south to the Strait of Magellan, Chile.

During breeding season (spring/summer) they are found in mountains of Alaska and adjacent Yukon Territory, above tree line. They use areas of dry, frequently stony, alpine tundra, characterized by lichens, dwarf shrubs, and mountain plants. At most sites they occupy habitat on summits and upper slopes of steep ridges.

Habitats

bay (rocky shore), exposed rocky shore

Habitat notes:

As their name implies, Surfbirds are usually found in the surf or spray zone and just above the tide line. They range inland only a few meters above the tide line. They are rarely found anywhere without being in a mixed flock with Black Turnstones. Migrants and winter residents occupy rocky shorelines from Pacific Grove south to Big Sur.

Abundance

Relative abundance:

Uncommon

Species Description

General description:

The Surfbird is a plump shorebird with a short (25 mm), plover-like bill, well adapted to prying food off rocks. The stout bill is black above and the base of the lower bill is golden orange. The iris of the eye is dark brown. The short legs are yellow-green as are the feet. Legs of hatchlings are bluish gray. The gray wings show prominent, white wing-stripes in flight. The tail is striking when seen in flight: a prominent black band covers the tip of an otherwise white tail and rump.

In breeding plumage, the Surfbird has salmon/rufous-colored patches on its wings and upperparts. These fade considerably during the breeding season, and may be peach or almost white by the time the birds start their fall migration. Birds in breeding plumage are covered with a wash of dark spots, giving them an overall speckled appearance. The juvenile is gray with white-edged feathers and a breast flecked with white. The adult in non-breeding plumage is also gray, but lacks the white-edged feathers and has no streaks on its breast.

Surfbirds are relatively quiet. Flocks foraging on the shoreline give a constant chatter of high nasal squeaks. Flight song is a nasal, buzzy series of notes: kwii, kwii, kwii, kwir, kwir, kwir, skrii, skrii, skrii, kikrri, kikrri, kikrri. Flight call is a soft iif, iif, iif.

Distinctive features:

Short, blunt bill, golden-orange at the base and black at the tip, which distinguishes this species from the Black Turnstone, Wandering Tattler, and the other rock-piper birds that co-occur with Surfbirds in winter. The Surfbird is mostly gray with a whitish tummy, yellow legs, an overall speckled appearance, and a square, white tail with broad black bar at the tip.

Size:

(Female is larger than male)
Length: 24-26 cm (9.5-10 in)
Wingspan: 59.7-66 cm (23.5–26 in)
Weight: 174.7–197.6 g (6-7 oz) for males and 207.8–225.0 g (7.3-7.9 oz) for females

Natural History

General natural history:

Surfbirds spend their entire lives in rocky areas. They breed in the rocky mountain tundra of Alaska and the Yukon, then migrate to rocky coastal shores of western North and South America. In winter, they are almost always within a few meters of the tidal line. They are often seen with Black Turnstones, Rock Sandpipers, Wandering Tattlers, and occasionally Ruddy Turnstones.

Prince William Sound has recently been identified as the principal spring staging area, where much of the world Surfbird population gathers in May before dispersing directly to mountain breeding sites to the west and north. Only during the short breeding season do Surfbirds occur away from the coast.

Predator(s):

Surfbirds are vulnerable to predation during winter and migration, when raptors, especially falcons (Falco spp.) and probably bald eagles (Haliaeetus leucocephalus) take them. On breeding grounds, adults, young, and eggs are taken by red foxes (Vulpes vulpes) and avian predators such as falcons and jaegers (Stercorarius spp.). Eggs may be eaten by Arctic ground squirrels (Spermophilus parryu).

Prey:

The Surfbird is so named because of its behavior when on its wintering grounds, where it often forages in and around the splash zone as the surf crashes on the rocks, using its short, blunt bill as probe and pry bar. Surfbirds consume mollusks and other intertidal prey, especially bivalve and gastropod mollusks, limpets, barnacles, isopods, crabs, and algae. During breeding season on the dry tundra it eats insects, especially beetles, spiders, flies, and seeds.

Feeding behavior

Omnivore

Feeding behavior notes:

Surfbirds forage in tight flocks and may be aggressive to other birds. They walk or run over rocks to capture prey, on the move almost continually. They use their entire body, not just bill motion, to pull mussels and barnacles from rocks with a sideways tug of the head. They swallow them whole and later regurgitate the shells. They also use rapid pecking and jabbing for small snails and also herring eggs, which are typically still attached to algae or rock. On sandy and muddy surfaces they have been seen running in and out with the waves and probing, much like a Sanderling.

March - May

Migration:

Migration is along the eastern Pacific coast. Flocks consist of >100 Surfbirds. They are also seen, although rarely, in the Central Valley and the Salton Sea during spring migration. Recently Prince William Sound has been identified as the principal staging area where as many as 56,000 Surfbirds gather in May before moving to mountain breeding sites to the west and north. They are gregarious in migration and often associate with Black Turnstones, Ruddy Turnstones, and Rock Sandpipers (all considered to be rock-pipers). Routes of dispersal to breeding sites in western Alaska are not known.

While along the coast, Surfbirds are seldom seen away from rocky shores or jetties. They roost on dry rocks just above the splash zone or on offshore pinnacles.

May - July

Reproduction:

The nest and eggs of Surfbirds were only discovered in the remote mountains breeding grounds of Alaska and the Yukon Territory in 1926. There are many unknowns in the breeding biology of Surfbirds, as their nesting habitat is on remote, rocky ridges above timberline. Pairs form on the breeding ground and are thought to be monogamous. The male performs a long display flight in which he flies on fluttering wings, then glides through the air and gives various calls or a harsh song.

The nest is a natural depression on vegetated or unvegatated ground, frequently on north- or west-facing slopes, and is usually completely exposed. Both parents line the depression with lichen, leaves, and moss. Clutches are usually four eggs, buff colored with brown speckles, and 43 mm x 31 mm each. Males incubate but female incubation has not been confirmed. Incubation is believed to last 22 – 24 days. In areas with grazing sheep or caribou the incubating Surfbird will remain on the nest until the last moment, and then fly up into the face of the intruder, including humans. The young are precocial and leave the nest in a day or two and feed themselves. Again, it is known that the male parent tends the chicks, but not known if the female does. It is unknown at what age the chicks fledge.

June - December

Migration:

It is believed that the first Surfbirds to start to move south are non-breeders or failed breeders, followed by breeders, and finally juveniles. As in the spring migration the route is coastal. The main migration in California spans mid-July through early October, peaking in mid-August. Flocks of coastal migrants often number in the hundreds. Most fall migration is over by mid-September, but smaller, shorter passage migrations are still evident in British Columbia in November and early December. By October adults and juveniles are indistinguishable in the field and it is believed that the young probably mature and breed in their first year.

September - May

Feeding:

Surfbirds winter along rocky coasts and jetties from southeast Alaska to Chile, always close to the surf except when roosting on rocks out of the spray zone or on offshore pinnacles. They may occasionally forage in mudflats or sandy beaches, but generally not for long. They are almost always seen in association with Black Turnstones and Rock Sandpipers.

Listing Status:

The threat of oil spills along the Surfbird’s wintering grounds, together with increased human development along the Pacific Coast, makes the Surfbird a species of high conservation concern.

The U.S. Shorebird Conservation Plan lists Surfbird as a Species of High Concern, based on a suspected population decline and threats on the non-breeding grounds. As with other species that are strictly tied to the rocky shores of the Pacific Coast, the Surfbird is vulnerable to oil spills. The major path of the Exxon Valdez oil spill in Prince William Sound passed within 10 to 15 kilometers of Montague Island, a major migratory stopping point for the Surfbird. A month after the oil spill, Montague Island, which suffered little or no oiling along its shorelines, hosted tens of thousands of Surfbirds and Black Turnstones. Increased human development of the Pacific Coast, especially from Vancouver Island southward, could lead to increased disturbance to Surfbird roosting and feeding habitats.

Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated by the IUCN as one of Least Concern.

Their entire population is estimated to be 70,000.
Click on an image below to view a larger version in the SIMoN Photo Library. You will also be able to view important information on each photo such as photographer, date, caption and more.
Ehrlich, P., D.S. Dobkin, and D. Wheye. 1988. The Birders Handbook: A Field Guide to the Natural History of North American Birds. Simon & Schuster Inc., New York. 785 p.
Paulson, D. 1993. Shorebirds of the Pacific Northwest. University of Washington Press, Seattle, Washington.
Roberson, D. 2002. Monterey Birds 2nd edition. Monterey Peninsula Audubon Society, Carmel, CA. 536 p.
Sibley, D.A. 2000. The Sibley Guide to Bird. Alfred A. Knopf, Inc. 545 p.
WWW
Audubon Society.
http://www.audubon.org
Accessed 02/28/09 for Marbled Godwit
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Accessed 03/15/2009 for Whimbrel
Accessed 06/20/2010 for Black Turnstone

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BirdLife International
http://www.birdlife.org/datazone/speciesfactsheet.php?id=3933
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BirdWeb
http://birdweb.org/birdweb/
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Cornell Lab of Ornithology
All About Birds
http://www.allaboutbirds.org/guide/search
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Planet of Birds
http://www.planetofbirds.com/
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South Dakota Birds and Birding
http://sdakotabirds.com