Update Dec 26, 2007: added two more pics at the bottom that show the symmetry of the wing bars, and the worn state of the remiges and retrices (typical of hatching-year juncos)
This Dark-eyed Junco Junco hyemalis was photographed
at the first feeding station in Davis Mountains State Park, Jeff Davis County on December 24, 2007; I believe it to be a first-winter White-winged Junco J. h. aikeni (a TBRC Review taxon with six records to-date); note the following features:-
1) pale gray coloration, with throat and chest being the palest gray.
2) narrow yet obvious white wing bars formed by white tips to outer median and greater coverts.
3) strong whitish-gray edging to the upper two tertials.
very slight brownish tinge to back is okay for first-winter (and some AHY females?) White-winged Junco.
5) slightly elongated bill with darker feathers at base.
6) very slightly darker gray in loral area.
7) extensive white on at least the outer three retrices (see lowermost photo).
See some reference images of White-winged Juncos here:
http://content.ornith.cornell.edu/UEWebApp/images/JWH_012803_100001_L.jpg (adult male)
http://www.kayniyo.com/images/birds/blood5317_09WWJU5319.jpg (adult male)
added Decemer 26, 2007: