[Mystery bird] Sedge Wren, formerly known as the Short-billed Marsh Wren, Cistothorus platensis, photographed at Attwater Prairie Chicken Refuge, Eagle Lake, Texas. [I will identify this bird for you in 48 hours]
Image: Joseph Kennedy, 7 November 2009 [larger view].
Nikon D200, Kowa 883 telescope with TSN-PZ camera eyepiece 1/350s f/8.0 at 1000.0mm iso400.
If you can ID this species, can you also tell me what its former common name was and how it came by its new common name?
Please name at least one field mark that supports your identification.