Wednesday December 26, 2012 Rock Sandpiper and Dunlins study

Seward Sporadic Bird Report

It has been fascinating to watch the flock of about 38-40 winter DUNLINS and ROCK SANDPIPERS these past few days through the snow showers and light rain. They are ravenous, flipping over beach wrack, probing in the silty mud and cobble, picking up amphipods and tiny clams in their tweezer-like bills. At times, they are quite vocal, chattering away like old friends catching up on the latest gossip. When not feeding, they preen and take baths in the freezing water surrounded by ice floes. Tough birds!

The DUNLINS, numbering at least 3, have long black bills, black legs, and overall appear light brown with a sharp line between their "bib" and their white belly. They are easy to distinguish even without their summertime black belly.

The ROCK SANDPIPERS are more diverse, but all are as round as a grapefruit with short yellowish legs. The light gray rock sands are the Pribilof Island subspecies, Calidris ptilocnemis ptilocnemis, called the nominate species. Most seem to have a yellow-orange at the base of the bill. The slightly smaller, darker birds with much less color are the mainland birds, C. p. tschucktschorum. Thanks to Bob Gill, Project Leader of  USGS Shorebird Research for the verification of these photos.

There's an interesting article on the Winter Ecology of Rock Sandpipers at
According to the article, Rock Sandpipers are unique to the north Pacific with fewer than 100,000 individuals, and at least 4 subspecies (including one in Russia.)

The Pribilof subspecies (Calidris p. ptilocnemis) migrates from those 3 islands a short ways to the Alaska Peninsula, Cook Inlet (and, I should like to add, Seward.) It was surprising to read that the presence of these hardy shorebirds wintering along the frozen coasts was apparently first noted by scientists only within the last 10 years. I guess either no one was looking, or knew who to contact. It is an amazing sight!

The Shorebird Guide by O'Brien, Crossley, and Karlson notes the Pribilof subspecies is larger, distinctly more pale, and has lighter flank streaking than the other races. The mainland subspecies (C. p. tschucktschorum) is slightly smaller with a shorter bill, and breeds on mainland Alaska, wintering south to California.  The Aleutian subspecies, (C. p. couesi) breeds in the Aleutian Islands and is largely resident but may winter to Washington.

Sibley's Guide to Birds cautions that the mainland and Aleutian populations have too much variation to really differentiate them. And then there's the Purple Sandpiper that looks almost identical to Aleutian and mainland subspecies, and if it reads the bird books, knows that it should not be here.

It's all very interesting and provides a lot to think about!

Happy Birding!
Carol Griswold
Seward Sporadic Bird Report Reporter

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