Tuesday, October 9, 2012

Undercovert Identification


The striking black-and-white wing pattern of a Willet in flight, photo by Mike Baird
Flash! Upon takeoff, the drab, grey, unnoticed Willet, Catoptrophorus semipalmatus, becomes one of the sharpest dressers around. Black-and-white wings bear a striking, vibrant pattern as the birds move down marsh channels to flight calls of clay-dr-dr. A few Marbled Godwits are usually along for the ride; they keep perfect pace with the willet flock despite being larger shorebirds with different wingspans. Look for their long, straight,  pink bills, ends dipped in black, a godwit signature.

Marbled Godwit with black-dipped beak, photo by Dick Daniels
Winter finds the Western Willet subspecies along Central California coasts, mudflats, and salt marshes. In tidal areas, Willets nab crustaceans, key prey, by sight. But the willet has other feeding strategies too, for example, probing deeply into mud for worms and small mollusks, at times feeding with several inches of water lapping at its grey legs, black and white hidden under dull gray. It's the dull secondary coverts, feathers central in the wings, that conceal the willet's striking wing patterns when the wings are folded.
During breeding season, the Western Willet displays barred patterning across its chest and sides. While shorebirds generally migrate to marshes in western prairies or north into Canada and Alaska, some Western Willets stay further south, many in Great Basin grasslands and deserts just east of the Sierra Nevada. Note that this habitat is quite different from that of the Eastern Willet subspecies, which nests in coastal Atlantic salt marshes.

When not in flight,Willets have a drab appearance, photo by Bruce Tuten
Interestingly, the Western Willet subspecies flies from summer inland breeding areas to wintering grounds both coasts. Meanwhile the slightly smaller Eastern Willet subspecies, rather than remaining on the East Coast where it nests, departs North America in fall for wintering grounds thousands of miles to the south.–Anne M. Rosenthal

Sibley, David Allen. 2000. The Sibley Guide to Birds. Alfred A. Knopf, New York.

Elphick, Chris; Dunning, Jr., John B., and Sibley, David Allen. 2001. The Sibley Guide to Bird Life & Behavior. Alfred A. Knopf, New York.

as well as Personal Observations