Wintering Rock Sandpipers in Homer
Rock Sandpiper Calidris ptilocnemis, probably tschuktschorum, Homer Boat Harbor, 13 November 2009. Click to enlarge.
The winter flock of Rock Sandpipers in Homer (usually 2,500-5,000 birds) is predominately made up of the darker plumaged race tschuktschorum, but may also be contain a few of the Aleutian race couesi (Dan Ruthrauff, USGS, pers. comm.) Banding studies are needed to confirm this. A small number, usually less than three percent, of the Homer flock is made up of nominate ptilocnemis, which breeds on the Pribilof Islands and St. Matthew and Hall Islands. Most ptilocnemis winter on the mudflats of Uppper Cook Inlet. Nominate birds are identified by their paler gray upperparts, more similar in tone to that of winter plumaged Sanderling, and their broader white wingstripe. See photos below. Click on any photo for a larger version.
A typical winter Rock Sandpiper flock in the Homer Boat Harbor, containing mostly dark tschuktschorum (with possibly couesi), small numbers of nominate ptilocnemis, and small numbers of Dunlin C. alpina. Looking closely (click to enlarge) you can see that this flock also harbored the late record Long-billed Dowitcher Limnodromus scolopaceus for the Kenai Peninsula, 13 November 2009.
Rock Sandpiper Calidris ptilocnemis, probably tschuktschorum, Homer Boat Harbor, 13 November 2009.
Rock Sandpiper Calidris ptilocnemis, probably tschuktschorum, Homer Boat Harbor, 13 November 2009.
Dunlin C. alpina and Rock Sandpiper C. ptilocnemis, Homer Boat Harbor, 13 November 2009.
Rock Sandpipers C. p. ptilocnemis (paler bird in center), Homer Boat Harbor, 12 March 2009.
Rock Sandpiper C. p. ptilocnemis (paler bird in center) surrounded by probable tschuktschorum, Homer Boat Harbor, 12 March 2009.
Click here for a photo comparing ptilocnemis, couesi, and tschuktschorum wings patterns. Many thanks to Dan Ruthrauff of the USGS for this very useful pdf.
