Pectoral Sandpiper

About the Pectoral Sandpiper

The Pectoral Sandpiper is a medium-sized shorebird, larger than the little "peeps" like Semipalmated or Least Sandpipers but smaller than a Willet, roughly comparable in size to a Dunlin. Its upperparts are patterned in brown, gold, and black, and its most reliable field mark is on the breast: dense, dark brown streaking that covers the chest and then stops abruptly in a sharp line against a clean white belly, almost as if the bird were wearing a vest. The legs are a dull yellowish-green, the bill shows a slight droop near the tip, and in flight the wings show little to no visible stripe, distinguishing it from many other sandpipers.

This species nests on wet, grassy tundra across the Arctic in both North America and Siberia, typically near coastal lowlands. Away from the breeding grounds it is far less picky, turning up in a wide range of grassy, shallow wetlands during migration and winter, including natural marshes as well as human-made habitats like flooded rice fields, sod farms, and wet pastures. Its migration is exceptional: most birds funnel south through the central United States, including Oklahoma, on their way to wintering grounds on the pampas of southern South America, a round-trip journey that ranks among the longest of any shorebird.

Pectoral Sandpipers feed by walking slowly through mud and shallow water, picking and probing for prey using both sight and touch. On the breeding grounds their diet is dominated by insects and their larvae, including crane flies and midges, along with spiders and occasional seeds and algae; during migration and winter they also take small crustaceans and other invertebrates. They tend to forage alone or in loose, scattered groups rather than tight flocks.

Perhaps the species' most remarkable trait is its breeding behavior. Male Pectoral Sandpipers have an inflatable throat and breast sac that they pump up during elaborate courtship flights, swaying and hooting with strange, low calls as they patrol the tundra beneath the Arctic's round-the-clock summer daylight. Males mate with as many females as they can and provide no parental care whatsoever, a mating system biologists call male dominance polygyny. Because competition for mates is so intense during the brief arctic summer, displaying males reportedly forgo most sleep for weeks at a stretch, and individual males have been tracked moving hundreds of miles between breeding sites within a single season to seek out more females. Females alone build the nest, incubate the four-egg clutch, and tend the precocial chicks, which can feed themselves almost immediately after hatching.