Pectoral Sandpiper Life History

Habitat

Habitat Grasslands

Pectoral Sandpipers breed mostly in wet coastal tundra dominated by grasses and sedges. Females build the nest in raised areas such as small ridges, which are drier and also provide better visibility. They avoid dry tundra but sometimes nest in moist areas with cottongrass and small shrubs, mostly away from the coast. After breeding, Pectorals continue to forage in the tundra, especially in ponds with grassy edges. Migrants in North America use similar wet, grassy environments, from sewage ponds, plowed farm fields, sod farms, rice fields, and flooded golf courses to natural freshwater and saltwater marshes with low, grassy cover. In Central and South America, migrants turn up in an even greater variety of habitats, including river banks, ditches, salt lagoons, beaches, estuaries, and even above treeline, in the puna (alpine) zone of the Andes. Wintering birds in South America tend to use freshwater wetlands, wet pastures, and harvested agricultural fields, but those in Australia often forage in brackish and saltwater habitats.

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Food

Food Aquatic invertebrates

Pectoral Sandpipers pick and probe in mud for insects and other invertebrates. They use both sight and touch to find prey as they walk slowly through wetlands. Mostly they forage in or near vegetation rather than in exposed areas of wetlands or tundra. On the breeding grounds, they consume large quantities of insects, including larvae of crane flies, midges, and beetles, along with some spiders, algae, and seeds. Their diet also includes small crustaceans (such as amphipods, rarely small crabs), bugs, bees, wasps, crickets, grasshoppers, and occasionally very small fish.

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Nesting

Nest Placement

Nest Ground

Females select the nest site, a small depression on the ground, usually in a dry, raised area such as a hummock or ridge. The site is sometimes shielded by dwarf willows.

Nest Description

The female molds a nest cup with feet and breast, then lines it with grasses, sedges, lichen, moss, and leaves. Nests average about 4 inches tall, with the interior cup about 3.3 inches across and 2.2 inches deep.

Nesting Facts
Egg Description:

Dull white, cream, buff, or olive, marked with brown, purple, and gray.

Condition at Hatching:

Active and covered with down.

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Behavior

Behavior Probing

In spring, once the tundra is partly clear of snow and ice, male Pectoral Sandpipers claim a territory by displaying vigorously in flight, inflating the air sac beneath their sharply stippled chests and producing odd, mooing calls as they fly with exaggeratedly slow wingbeats. The much smaller females arrive a bit later than the males, usually in small flocks, and displaying males fly directly over them. On the tundra, males approach females and perform even more captivating displays—with wings drooped, tail cocked, breast inflated, the males sway and march, then stretch out the neck, raise and wave the wings, and utter strange-sounding, high-pitched calls. Males do defend their territories against other males on occasion, but they do not guard females after mating. Male Pectoral Sandpipers try to mate with any females they encounter, a mating system called polygyny. Whether females mate with multiple males is unknown. Males and females do not form a pair bond. Females build the nest, incubate the eggs, and tend the young without any help from males, and often far from any male’s territory. By the time the eggs hatch, most males have already migrated away from breeding areas. After the young fledge, females and juveniles gather in flocks, foraging mostly in coastal areas before migrating. When males and females flock together during migration, the size difference between the sexes is striking.

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Conservation

Conservation Declining

As with many species of shorebirds, Pectoral Sandpiper populations have declined sharply since the early 1980s. This species is not covered by the North American Breeding Bird Survey, but migration counts have helped document the decline. Partners in Flight estimates a global breeding population of 1.6 million, rates the species a 13 out of 20 on the Continental Concern Score, and includes it on the Yellow Watch List for its declining population. Pectoral Sandpipers were hunted for food extensively in the nineteenth century, when their populations were much higher, but they are no longer hunted in the United States. The reasons for their population decline are unknown, but loss of freshwater wetlands in migratory corridors or wintering grounds could be part of the problem.

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Credits

Andres, B. A., P. A. Smith, R. I. G. Morrison, C. L. Gratto-Trevor, S. C. Brown, and C. A. Friis (2012). Population estimates of North American shorebirds, 2012. Wader Study Group Bulletin 119:178–194.

Farmer, Adrian, Richard T. Holmes and Frank A. Pitelka. (2013). Pectoral Sandpiper (Calidris melanotos), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

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

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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