The Western Sandpiper is a very close relative of the Semipalmated Sandpiper, and the two can be very difficult to differentiate between. While many can be found on both U.S. coastlines during the winter, they also migrate southward as far as southern South America. Massive flocks can be found in key migration stopover sites along the West Coast in the Fall.
In South Dakota, Western Sandpipers are rare migrants (recorded sightings in eBird are very sparse), where their similarity in appearance to the much more common Semipalmated Sandpiper may make them an unnoticed visitor.
Habitat
On summer breeding grounds, Western Sandpipers prefer tundra slopes with a low brush and nearby wetlands. In migration and winter, they can be found on mudflats, sandy beaches, and tidal estuaries.
Diet
Primarily east insects, spiders, and small crustaceans on its summer breeding grounds. In winter and in migration, diet varies by location, but may include amphipods, small crustaceans and mollusks, marine worms, insects, and seeds.
Behavior
Forages in shallow water, sandy beaches, or mudflats, walking along and probing in the mud for food, or picking food items directly from the surface.
Breeding
Non-breeder in South Dakota. On their tundra breeding grounds, male Western Sandpipers arrive first, scouting out potential nesting sites as soon as the snow and ice clear. The males will make a shallow scrape on the tundra, typically in a protected area such as at the base of a small shrub, or a clump of herbaceous vegetation. He'll then try to attract a mate, both through display flights, and in courtship displays on the ground where the male will spread his wings, raise the tail, and call to the female. Females eventually follow the chosen mate to the nesting site, where both birds will help construct a small nesting site of mosses, lichen, grasses, and other vegetation. The female lays 2 to 5 buffy colored eggs with dense dark spotting, and both parents help to incubate them. Once the young hatch, both parent initially tend to the young, but the female leaves before the young fledge from the nest, leaving the male to tend to the young until they become independent.
Song
During migration in South Dakota, Western Sandpipers are relatively quiet. They're much more vocal on their breeding grounds, with a variety of calls ranging from thin cheet notes, to a loud, scolding chattering.
