tags: Upland Sandpiper, Bartramia longicauda, birds, mystery bird, bird ID quiz
[Mystery bird] Upland Sandpiper, Bartramia longicauda, photographed in Kingsbury County, South Dakota. [I will identify this bird for you in 48 hours]
Image: Terry Sohl, 5 July 2009 [larger view]
Photo taken with a Canon 50D, 400 5.6L.
Please name at least one field mark that supports your identification.

Upland sandpiper, based mainly on the "small head", "thin neck", and "short bill" (Sibley).
Agreed.