This is an immature. Adults have a more strongly marked chestnut head pattern. Lark Sparrow is the only member of the genus Chondestes. It is a species usually associated with interior grasslands. It is rare along the coast; a first for our yard. Two subspecies are usually recognized. This is presumably the western C. g. strigatus characterized by slightly paler overall coloration, narrower back streaks, and reduced black in the face. Nikon Coolpix P510 through window.
Reference:
Martin, John W. and Jimmie R. Parrish.(2000).Lark Sparrow (Chondestes grammacus), The Birds of North America (P. G. Rodewald, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America: https://birdsna.org/Species-Account/bna/species/larspa