On 9/21/2010 11:35 AM, Wayne Baumgartner wrote:
> On another topic, I have been curious about Western Sandpiper plumage for
> our area and this time of year.  Several field guides I have looked at state
> that Western Sandpipers will molt sooner than Semipalmated Sandpipers, which
> are said to not grow into winter plumage until after migration.  Does that
> mean that if a uniform grey adult winter-plumaged Western/Semi-sand is seen
> in our area in fall it is most likely a Western?  Can molt timing be used to
> make this ID?

Yes.  According to Sibley:  "A flock of uniform gray peeps Sep-Oct 
are probably Western Sandpipers; a flock of patchy worn birds 
Sep-Oct are probably Semipalmated."

Good birding!
Jim Moore
Rockville, Maryland
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