[Mystery bird] Least Grebe, also known as the Least Dabchick and the American Dabchick, Tachybaptus dominicus, photographed at Brazos Bend State Park, Needville, Texas. [I will identify this bird for you in 48 hours]
Image: Joseph Kennedy, 27 December 2009 [larger view].
Nikon D200, Kowa 883 telescope with TSN-PZ camera eyepiece 1/320s f/8.0 at 1000.0mm iso400.
Please name at least one field mark that supports your identification.