"Small round-headed warbler with small bill and long tail ... M. has bright yellow face and underparts, black eyeline; yellow crescent under eye bordered below by black edge to cheek; dark spot on side of neck ... Similar Pine Warbler is larger, lacks yellow crescent under eye, no black on face ...." (Donald & Lillian Stokes's The Stokes Field Guide to the Birds of North America, p. 619)

"Black or gray semicircle under eye." (Tom Stephenson & Scott Whittle. The Warbler Guide, p. 410)

"Rare to uncommon summer resident in the eastern quarter of the state ... This species is a rare to uncommon migrant in the eastern third and along the coast, becoming very rare to casual elsewhere." (Mark W. Lockwood & Brush Freeman's The TOS Handbook of Texas Birds.)

I am not completely confident of this identification, but the gray on the face under the eye supports this being a Prairie Warbler.

Picture taken with a Nikon D90 using a Nikon 400mm f/5.6.

September 13, 2013.