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Semipalmated Sandpiper

Calidris pusilla
Scolopacidae
Black legs; straight and stout black bill
More of a wader than Least Sandpiper
Easy to overlook even in bright sunlight
Called Semipalmated Sandpiper because of ...
... partially webbed toes
Unwebbed toes and yellow legs of Least Sandpiper
Black legs of Semipalmated (L) and yellow legs of Least (R)
Who's who at the boat launch? Answers at end of text below.
Semipalmated Plover (L), Semipalmated Sandpiper (R)
(L to R) Semipalmated Sandpiper, Lesser, Greater Yellowlegs
Countless birds form flocks to migrate ...
... mostly peaceful until ...
... fights breakout over feeding rights
Usual clutch = four eggs
Chicks just as well camouflaged as eggs
Parenting attentively now ...
... but will fly south a month before offspring
Contrasty plumage of large flock blends into background
Resting birds look just like another layer of stones

The Semipalmated Sandpiper has been recorded five times at Salter Grove during July and August, from 2002 to 2024.  Look for it on mudflats exposed by low tide at the boat launch, and along the shoreline of the causeway and the Marsh Trail.  However, be aware that it can be easily confused with another tiny shorebird, the Least Sandpiper.

A solitary sparrow-size sandpiper with black legs is likely to be a Semipalmated Sandpiper because the smaller Least Sandpiper has yellow legs.  When side-by-side comparisons are possible, the Semipalmated has a stouter and straighter bill, and grayer and less contrasty plumage on its back.

In terms of behavior and posture, the Semipalmated Sandpiper seems in constant motion, stretching its bill for quick jabs into the substrate for aquatic invertebrates.  By comparison, the Least Sandpiper appears hunched on backward-bending legs as it searches for prey near the front of its toes.

The Semipalmated Sandpiper nests close to marshes and ponds in the vegetated tundra of North America.  Parents migrate south a month before their offspring.  It is impressive that naive juveniles migrate up to 2,500 miles to winter along the coasts of South America only to make a return trip the following spring. 

Each year, flocks of hundreds of thousands of birds gather at food-rich staging points like the Bay of Fundy and Delaware Bay to build energy reserves for these long-distance flights.  The relative scarcity of Semipalmated Sandpipers at Salter Grove points to the absence of such expansive mudflats and sandy beaches favored by many shorebirds.

Despite their togetherness, Semipalmated Sandpipers aggressively chase away each other as well as other species as they feed during migration.  A study showed just how much energy is wasted through such aggression.  In areas with large number of predators where birds had to spend time scanning the sky rather than fighting each other, they built up fat reserves in half the usual time.

The Semipalmated Sandpiper is on the decline not because of disturbance to its remote breeding grounds but because human activities have reduced food availability in habitats along its migration route and on its wintering grounds.

[Answer to quiz above in caption:  1) Semipalmated Sandpiper (black legs), 2) Semipalmated Sandpiper (black legs), 3) Least Sandpiper (yellow legs)]