I would guess it was a juv. Western Sandpiper, it appears to have a longer
bill than either RNST or a Semi would have and the bill appears to be
slightly decurved at the tip. It is a little hard to tell from the photos
if these assumptions are correct. It would be wonderful to have a little
sharper photos. I am by no means an expert as I have actually never seen a
any of the eurpoean/asian stints. I have seen my share of Semi's and all
plumages of westerns. I say western because while studying birds on our
coast of washington I have seen birds show that much of an eyeline and
varying abouts of a bright wash on the upper breast area, some as much as
this bird shows. One disclaimer is that while I'm defiently not a
beginner, I am also not nearly as skilled as others with far more stint
experience. I look forward to hearing comments from some of those stint
experts both on lists like tweets and especially on ID-FRONTIERS.
Thanks,

Scott Downes
sdownes at u.washington.edu
Seattle WA

"Birds don't read bird books. (That's why they are seen doing things they
are not supposed to do)." -Mary Wood