White-crowned Sparrow subspecies
There are five subspecies of White-crowned Sparrow (Zonotrichia leucophrys) found in North America. Four of the subspecies are migratory but Z.l. pugatensis is considered a short distance migrant based on its primary projection.
Four subspecies are regular visitors to California but our wintering population mostly consists of Gambel’s White-crowned Sparrows - Zonotrichia leucophrys gambelli. Gambel’s White-crowned Sparrows have a white/clear lore and orange bill, and long primary projection. The distinction is clear if you know what to look for as it is the most unique subspecies.
Zonotrichia leucophrys gambelii breeds in Alaska, the northern mainland of Canada to Hudson Bay, eastern British Columbia, and southwestern Alberta. This subspecies has pale lores and an orange bill, grayish coloring, pale brown wash on flanks, , dark reddish centers edged in light gray on back stripes feathering, whitish bend of wing, and long primary projections. The juveniles have reddish crown stripes and pale lores. Z.l. gambelii winters from Washington to California and east in a diagonal line to southern Nebraska to east central Texas.
Zonotrichia leucophrys leucophyrys breeds in northern Ontario, Quebec, Newfoundland, and northeastern Manitoba. This subspecies has dark lores and an reddish pink bill, grayish coloring, pale brown wash on flanks, dark reddish centers edged in light gray on back stripes feathering, whitish bend of wing, and long primary projections. It winters mostly east of the Z.l. gambelii subspecies but can be found together in a narrow strip from SE Nebraska to southern coastal Texas to western Louisiana north to southern Iowa. Its winter territory is contiguous east of the intergrade region it is found from MO south to LA and east to AL then north to Ohio and a small slice from VA to coastal MA. It is absent from most of MI, IL, NY, VT, NH, and ME and the Atlantic coastal plain south of Virginia.
Zonotrichia leucophrys oriantha breeds in mountainous western Alberta and montane areas of the western United States (eastern OR, CA, ID, Western MT and WY, CO, UT, and northern AZ and NM), in California it breeds from the eastern Cascades through the Sierra Nevada south to a small population in the San Jacinto Mtns in southern California. This subspecies has dark lores and an dark pink bill with the upper mandible at times dark gray, grayish coloring, pale brown wash on flanks, dark reddish centers edged in light gray on back stripes feathering, whitish bend of wing, and long primary projections. It normally winters in northern and central Mexico mostly north of Puerto Vallarta.
Z. l. leucophrys and Z. l. oriantha have dark lores and pink to dark reddish pink bills. Only the Z.l. oriantha are seen in California under normal circumstances.
White lored - short primary projection species exclusive to the west coast
Zonotrichia leucophrys pugetensis breeds along the Pacific Coast of North America ranging from Campbell River, Vancouver Island through northwestern California north of Cape Mendocino . It is migratory and can occasionally be found in inland Washington, Oregon, and California. It is most likely found along riparian systems or on the coast. This subspecies has pale/white lores and a dirty yellow bill, it tends toward browner coloring, extensive brown wash on sides and flanks, dusky black centers edged in tan on back stripe feathering, yellowish bend of wing, and short primary projections. In winter along the coast, the only way to really distinguish this subspecies from the non-migratory Z.l. nuttalli is by its lighter weight, shorter bill length, tarsus, and wing. This subspecies averages smaller and slightly lighter than the resident species.
Zonotrichia leucophrys nuttalli is non-migratory and the only subspecies found exclusively in California. It lives along a narrow band on Coast from Cape Mendocino in northwestern California to Santa Barbara County. Z. l. pugatensis and Z. l. nuttalli are virtually indistinguishable, with pale lores and dull yellowish bills. The Z.l. nuttalli average larger and the post ocular stripe averages browner than the Z.l. pugatensis the California subspecies is not found inland.
See Garrett and Dunn's paper for more information found here. http://www.cvbirds.org/wp-content/uploads/2016/10/White-Crowned-Sparrow-Subspecies.-Dunn-Garrett-and-Alderfer.-Birding.pdf