White-rumped Sandpiper Life History

Habitat

Habitat Shorelines

White-rumped Sandpipers breed in moist and wet tundra of the high arctic, from remote northeastern Alaska to Baffin Island. They use areas with low vegetation such as grassy or mossy meadows, or low shrubby areas with arctic willows and clumps of sedges. Common plants include blueberry, water sedge, arctic redtop, narrow-leaved cottongrass, and mosses such as bog, brown, twisted, shining, and gray moss. Most White-rumped Sandpipers nest near freshwater ponds, lakes, or streams, but some nest in higher and drier tundra as well. Pectoral Sandpipers use similar habitats over much the same geographic range. During migration in North America, White-rumped Sandpipers frequent a remarkable variety of freshwater habitats, including wet agricultural fields, sod farms, freshwater impoundments, and marshes with muddy margins. They also use brackish habitats including upper portions of tidal mudflats, lagoons, and estuaries. In South America, migrants occupy similar habitats but also beaches, river banks, and lakes at higher elevation (up to at least 1,500 feet).

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Food

Food Aquatic invertebrates

White-rumped Sandpipers eat mostly invertebrates, which they capture by probing into mud, sometimes deeply, with the entire bill inserted. Less often, they pick prey from the surface. Like many small sandpipers, they probe several times, then walk a short distance and probe again. White-rumped Sandpipers tend to forage in open areas rather than areas within marsh vegetation. They also eat some plant matter, mostly seeds, including those of knotweed and various sedges. Prey items include midges, flies, craneflies, beetles, grasshoppers, leeches, bloodworms, marine worms, ramshorn snails, and tiny crustaceans (amphipods).

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Nesting

Nest Placement

Nest Ground

Females select the nest sites in a male’s territory, on hummocks or other small rises in wet tundra, usually with enough surrounding vegetation to conceal the nests.

Nest Description

Females build a cup of mosses, grasses, sedges, and other plant matter, lined with willow leaves, mosses, and lichens.

Nesting Facts
Egg Description:

Buff or pale green, spotted or blotched with reddish brown.

Condition at Hatching:

Active and covered with down.

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Behavior

Behavior Ground Forager

As soon as they return to the nesting grounds in early June, male White-rumped Sandpipers claim territories and begin displaying, even while the tundra has extensive patches of snow and ice. They fly nearly 100 feet off the ground and begin hovering over the territory, where they extend the neck, distend the throat, and produce their unusual song, which includes low croaks and wiry buzzing (it has been compared to the sound of pig oinks punctuated by a typewriter carriage return). They then drop earthward on upswept wings and land with wings still raised. They also make horizontal flight displays around the territory, using a “butterfly” flight style with deep, exaggerated wing beats as they sing. If a female is present, the male raises a single wing toward her while standing on the ground or executes a more elaborate display in which he opens the wing in a cupped position, cocks the tail, and displays the white uppertail coverts while running around her, stamping his feet, and sometimes dragging the wingtips on the ground. (The first ornithologists to describe this ground display likened it to the dance of the Sharp-tailed Grouse.) Males drive other male White-rumped Sandpipers away from their territories, confronting them on the ground with lowered heads and raised plumage or chasing them in flight. Territories may be 7–15 acres in extent, and males stand guard on hummocks or other raised areas in the territory, alert for intruders.

This species is polygynous in its mating system, meaning that males mate with more than one female. Males display vigorously for just a week or so, courting females that approach and attempting to mate with all that come near. Some even land on the backs of unwilling females and attempt to mate in flight. Once the females in his territory have laid their clutches of 4 eggs, males typically depart the area. Females build the nest, incubate the eggs, and tend the chicks. Females of the same male partner may nest near each other on some territories. When disturbed, females may pretend to have a wing injury, in an attempt to draw a predator away from the nest. Migrating White-rumped Sandpipers are gregarious, often found in small flocks that join other shorebirds. They occasionally chase away other small sandpipers when foraging, and wintering birds defend foraging territories in at least some parts of the range.

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Conservation

Conservation Low Concern

White-rumped Sandpipers are relatively numerous, but very little is known about their past or current population trends. Partners in Flight estimates a global breeding population of 1.7 million and rates the species a 13 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. In some areas, wetlands have been drained or developed along migratory routes and in key stopover areas such as the Great Plains, where depletion of underground aquifers reduces the extent of wetland habitats at the surface. As for many bird species that nest in arctic habitats, climate change may have significant negative impacts on this species.

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Credits

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

Parmelee, David F. (1992). White-rumped Sandpiper (Calidris fuscicollis), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, USA.

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