Tuesday, January 23, 2018

Peeps, Plovers, and Other Notoriously Difficult Shorebirds: Coastal Edition

Last winter, I wrote an identification guide that was intended to help those new to birding differentiate between some of the most commonly encountered small shorebirds that spend winter in the Great Central Valley.  Now, it's time for Part II of the series: small shorebirds of California's central coast.

Shorebirds are found along the coast year-round, with an uptick in numbers during the fall, winter and spring months.  The fewest number of birds occurs in June, as many of these species migrate to northerly breeding grounds, where they spend a short Arctic summer before returning to warmer climes.  Not all birds leave, however, so there is always something to see on the coast!

Peeps (and a Marbled Godwit) at Moss Landing harbor.

"Peeps" is a catchall term for small sandpipers in the genus Calidris, which includes Sanderlings (C. alba), Dunlins (C. alpine), Least Sandpipers (C. minutilla) and Western Sandpipers (C. mauri). 

(Others, like the Semipalmated Sandpiper (C. pusilla), Baird's Sandpiper (C. bairdii) and Pectoral Sandpiper (C. melanotos) are also possible on the coast during the fall migration, but they are considerably more rare.  For now we'll focus on the common species!)

Sanderlings are the most distinct of the coastal peeps.  They are sandpipers of the "swash zone," the part of the sandy beach the waves wash over.  Commonly seen in flocks scuttling up and down the beach, they follow each wave as it washes out, foraging in the sand for small crustaceans and hurrying back up the beach before the next wave comes in.

Sanderlings

Dunlins, or Red-backed Sandpipers as they are less frequently called, are the largest of the peeps - about 2 inches bigger than the Western Sandpiper - with longer, slightly drooping bills.  They also frequent the Central Valley from fall through spring.

Dunlin

Least and Western Sandpipers are both quite small, about the size of a sparrow, and often seen in flocks in estuaries and tidal flats along the coast.  They are also common winter visitors to Central Valley wetlands, with the Least Sandpiper being a little more common inland than the Western.  The photos below show a comparison between the two very similar species.  Notice that the Western Sandpiper (pictured on the left with a Marbled Godwit for scale) has black legs, while the Least Sandpiper has yellow legs. 

Western Sandpiper (with a Marbled Godwit
for scale)


Least Sandpiper

















Plovers can look very similar to sandpipers, especially to beginning birders.  They tend to be stouter and rounder in appearance, with shorter, thicker bills.  Common plovers of the coast include the Snowy Plover Charadrius nivosus), Semipalmated Plover (C. semipalmatus) and the familiar Killdeer (C. vociferous), as well as Black-bellied Plovers (Pluvialis squatarola).  Less common is the Pacific Golden Plover (P. fulva).

Snowy Plovers and Semipalmated Plovers are both very small, between 6 and 7 inches long.  It's not scientific, but I don't know how to describe them without calling them "cute."

Snowy Plovers are most commonly associated with sandy beaches and dune habitat, where they nest (and are extremely vulnerable to disturbance).

Snowy Plover, breeding plumage (May)
 
Snowy Plover, juvenile or non-breeding plumage (August)

Semipalmated Plovers are darker than Snowy Plovers and smaller than Killdeer, common on tidal mudflats and beaches.  (I see them reliably at the Moss Landing harbor during low tide.)

Semipalmated Plover


Semipalmated Plover

Widespread and common, with a distinct call, the Killdeer is our most familiar plover, ranging across North America and often venturing far from water.  Killdeer are relatively tall and slender, considerably larger than Semipalmated Plovers and have two dark collar bands rather than one.

Killdeer

Black-bellied Plover are slightly larger than Killdeer and occur sporadically throughout the year on the coast as well as at inland wetlands.  Like many shorebirds, they are most numerous during the winter when they return from their breeding grounds in the Arctic.  From about August to April, when they are most likely to be seen on our coast, they are in drab nonbreeding plumage.  At the end of summer, you may see Black-bellied Plovers that have just returned from their breeding grounds still dressed in the remains of their striking breeding plumage.

Black-bellied Plover in drab winter or basic plumage (nonbreeding)

One lone Black-bellied Plover showing the remains of his black and white breeding plumage (Moss Landing, September)

This is by no means an exhaustive list of shorebirds you may encounter along California's coast, but hopefully will begin to familiarize you with some of our most common species.  Learning these peeps and plovers will go a long way in aiding your shorebird identification skills and help you more easily pick out the rarities! 

For a primer on larger shorebirds of California's coast, check out this article.

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