Sparrow, Melospiza lincolnii
Lincoln's Sparrows nest in the boreal forests of North America, including the western mountains, and winter in areas near water with the dense underbrush they favor in the west and south of the US and in Mexico and Central America. Their best distinguishing feature, especially from their Melospiza cousins the Song and Swamp Sparrows, is a brown buffy upper breast band crossed by fine dark stripes, sharply demarcated from otherwise plain light underparts and a plain white throat patch above. Lincoln's Sparrows are "highly secretive" and "among the more elusive" birds of the continent (Birds of North America Online), and so not easy to photograph out in the open.
The rear view of a Lincoln's Sparrow, not showing the diagnostic buff breast band;
note the face and side of the neck, more uniformly gray than on related sparrows.