Semipalmated Sandpiper Life History

Habitat

Semipalmated Sandpipers nest in low tundra, usually not far from marshes or ponds. They use both dry upland habitats and lowland heath, in areas with a mix of sedges, grasses, mosses, willows, birch, and berry plants. They rarely nest in areas devoid of plants. In preparation for migration, they gather into flocks in shallow-water mudflats or lakeshores.

Migrating birds stop over at sewage ponds, ephemeral wetlands (rain pools), beaches, tidal mudflats and sandbars, and freshwater impoundments with shallow margins. On their tropical wintering grounds, they mainly use tidal flats near rivermouths, bays, and estuaries.

Food

Semipalmated Sandpipers eat tiny invertebrate prey including insects and other aquatic animals. They normally feed in sites with very shallow water, rarely more than an inch deep. Most of their food consists of arthropods, small crustaceans (amphipods), mollusks, and marine worms (polychaete and annelid worms especially). They usually feed by touch, pecking and probing rapidly at the surface with repeated jabs of the bill. They also feed visually, especially on insects on top of or near the water’s surface.

Their sharp vision and the sensitivity of their bill tips permit them to forage at night. In the mudflats of the Bay of Fundy, Canada, they feed on “biofilm” (microorganisms that are stuck together) by slurping the material into the bill. Other documented food items include algae, spiders, horseshoe crab eggs, copepods, roundworms, seed shrimp, Baltic clam, periwinkle, tiny snails, midges, crane flies, long-legged flies, drain flies, leaf beetles, water beetles, carabid beetles, and water boatmen. Females have larger bills than males and so take larger prey items than males, but most of their prey measures less than 0.2 inches long.

Nesting

Nest Placement

Males make multiple scrapes, usually near a pond, often along a small hummock or ridge, with low plant cover such as willow, birch, sweet gale, grass, or sedge. The scrape is frequently next to or beneath a small plant.

Nest Description

The female selects one of the male’s nest scrapes for use. She then lines it with grass, sedge, moss, and leaves of cranberry, willow, or birch. The interior cup of the nest measures about 2.2 inches across, 1.8 inches deep.

Nesting Facts

Behavior

In spring, male Semipalmated Sandpipers arrive on the breeding grounds a few days before females and begin establishing and defending territories even before snow has melted completely. They often return to their territory of the previous nesting season. They claim territory with hovering display flights, rapidly flapping the wings and giving a bizarre "motorboating" call.

Semipalmated Sandpipers appear to have a monogamous mating system. When a female shows interest in a male (often the previous year’s mate), a courtship display ensues. The two birds chase each other, call, cock their tails, and make paired flights. Displaying males raise one or both wings, erect the crown feathers, and lead females to nest scrapes. Males guard females until they've laid their clutch, and are highly territorial through the chick-rearing period. Their territory sizes range from 0.6 acres to 2.5 acres.

Semipalmated Sandpipers seem to be among the most territorial of sandpipers year-round: migrants and wintering birds, of all sexes and ages, routinely run off other individuals if they approach too closely. Their dominance hierarchies are ordered by size rather than age: larger individuals dominate smaller ones and put on weight more rapidly at migration stopover sites.

Conservation

Partners in Flight estimates the global breeding population at 2.3 million individuals (all of which breed in Alaska and Canada). The group rates Semipalmated Sandpiper a 14 out of 20 on the Continental Concern Score and places it on the Yellow Watch List for species with declining populations. A 2012 study estimated that populations breeding in western Alaska and the western Canadian Arctic were stable but that populations in eastern Canada were declining. Hunting, mostly in South America, appears to be a source of population declines, followed by destruction or modification of wetlands and by environmental pollutants. Climate change is forecast to have negative effects on nesting areas, migratory stopover habitats, and wintering habitats.

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.

Hicklin, Peter and Cheri L. Gratto-Trevor. (2010). Semipalmated Sandpiper (Calidris pusilla), 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 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.

Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.

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

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