This bird shows substantial contrast between the gray on the head and the rich brown of back and underparts, and also some contrast between the rich brown and the apparent more red of the tail. These features make this a possible candidate for ID as a Fox Sparrow of the Slate-colored group, which breed in the Rockies and certain mountains of the Great Basin, rather than the northwest coastal breeding Sooty group. I've left it identified as Sooty, the normal wintering group for the Bay Area. See Don Roberson's excellent analysis of Fox Sparrow ID, including a discussion of this photo, at http://creagrus.home.montereybay.com/MTYbirdsFOSP.html .