Savannah Sparrow, Passerculus sandwichensis
Savannah Sparrow, adult, 8/20,04, Edwards NWR, Alviso
Savannah Sparrow, adult, 8/20/04, Edwards NWR, Alviso
The bird pictured in the two pictures at the top is an adult of a type sometimes thought typical of residents in the saltmarshes around San Francisco Bay. It shows darker brown striping overall, with some black; the white central crown stripe is indistinct or absent; and the yellow in the lores and supercilium is relatively bright and extensive.
Savannah Sparrow, 10/15/05, Shoreline Park, Mountain View
Savannah Sparrow, 10/23/05, Stevens Creek north of 101
The birds left and above, photographed near San Francisco Bay but not in salt-marsh habitat, have an appearance sometimes associated with Savannah Sparrows found in grassy hillsides in the Bay Area -- paler colors, less extensive and narrower streaking on the chest, broader more distinct central crown stripe, and relatively pale supraloral yellow. It is an open question whether the grass-dwelling and marsh-dwelling Savannah Sparrows of the Bay Area are of different subspecies, and if so, to which they should be assigned. "Belding's," the dark salt-marsh subspecies found in Southern California and Baja, is sometimes considered a possible separate species, and some have thought the Bay Area marsh birds would fall within that group.
Savannah Sparrow, 10/28/06, Sierra Road
Savannah Sparrow, 5/31/08, Radio Road, Redwood Shores, San Mateo Co
Savannah Sparrow, 8/28/04, Shoreline Park, Mountain View
Savannah Sparrow, 11/13/04, Bodega Bay, Sonoma Co
Left, possibly first-winter birds of the salt-marsh type.
Savannah Sparrow, 11/7/07, Mercey Hot Springs, Fresno Co
The bird above has a bill that seems large enough to qualify it as of the Large-billed (Rostratus) subspecies, which is likely to be split off as a separate species. But neither the plumage nor the habitat is right -- these are salt-marsh birds, with dark upperparts similar to Belding's, but (unlike Belding's, and unlike this bird) no yellow in the face. It was found in grassland habitat, and is presumably a typical Savannah with an unusually large bill.
Savannah Sparrow, 5/10/05, First Encounter Beach, Eastham, MA
Here's a Savannah photographed on outer Cape Cod, Massachusetts, in Spring.