Cute Bird – but what is it??

I need a little help on this one, if anyone can be of help.  I photographed this bird last month down in the Big Bend area of West Texas.   I feel that it is one of the sparrow species, but I am enough of a novice to admit that I may be wrong about that. 🙂

Unknown - un-retouched

You may click on the image to see an enlargement.