I try to get to our local "hot spot" ,Mann Lake, Nez Perce county, Idaho, a couple of times /week during shorebird migration, so I am able to view a lot of shorebirds during their many phases, ages and molts.
These two were part of a group of five same-size birds that I viewed at distances of 15 to 40 feet.
http://www.flickr.com/photos/birddog/9443867825/

With dark caps and cheeks, white supercillium and short blunt bills they appear to be Semipalmated Sandpipers
But what about leg color?
The bird on the left could easily be called a Least based upon yellow-green legs.

Earlier in the week, I posted this photo of very bright maybe Western, maybe Least with dark legs that do not appear to mud covered.
http://www.flickr.com/photos/birddog/9411249454/in/photostream/

This is why shorebird migration time is my favorite time of the birding year.

Keith E. Carlson
Lewiston