White-crowned Sparrow, Zonotrichia leucophrys
White-crowned Sparrows are abundant wintering birds throughout most of the San Francisco Bay Area, including my back yard. The Puget Sound (pugetensis) subspecies shown in the picture above and the three immediately below provides most of our wintering birds; it is characterized by a yellow bill, as distinguished from orange or pink; pale feathering on the loral area between the eye and the bill, as distiguished from black lores continuing the crown stripe; and a back pattern of feathers that are dark brown to black in the center bordered with tan, as distinguished from the reddish centered and gray bordered feathers seen further down the page.
The bill of the bird above tends toward orange, but the brown/tan back feathers identify it as of the Puget Sound subspecies.
The bird above is of the Nuttall's subspecies, permanent residents along a narrow strip of land bordering the Pacific Ocean in northern and central California. They closely resemble Puget Sound birds, and are lumped together with them by Sibley as the "Pacific" group of White-crowned Sparrows. Their song is different, however, and they typically have a shorter primary extension and a more blurred pattern in the back feathers. The easiest way to identify a Nuttall's is to see it or hear it singing on its coastal habitat during the summer months, when Puget Sound birds (and Gambel's, see below) have all departed for their northern breeding grounds; the bird above was photographed July 5 on the shore of Monterey Bay. Or, even better, to see an adult White-crowned Sparrow on the nest, or feeding young birds, as below.
The juvenile bird has brown crown stripes, and a heavily streaked breast; compare the plain gray breast of both adults and first-year birds. White-crowned Sparrows hold their juvenal plumage only for about twenty days, then start molting toward the first basic plumage, shown further down the page, which lasts through their first year of life.
The bird above was photographed on the narrow coastal strip which is the habitat of the Nuttall's subspecies, but in October, when birds of the Puget Sound type have returned from the northern breeding grounds and are also found along the coast. This bird is singing, which suggests Nuttall's, but it shows the sharply demarcated brown/tan back pattern characteristic of Puget Sound birds, and is treated as problematic between the two types by Don Roberson here in his discussion of the varieties of White-crowned Sparrow found in central Californa, which includes an excellent guide to the subtle distinctions between Nuttall's and Puget Sound.
The bird shown above, photographed in my back yard on the Stanford campus, is a good example of the third subspecies found in my area, the Gambel's White-crowned Sparrow. These are birds labeled "West Taiga" by Sibley; they breed in Canada and Alaska west of Hudson Bay, and winter in the Pacific States and Mexico. They have the pale lores of the Pacific group, but are distinguished by their dark orange bills and a back pattern of chestnut-centered feathers bordered in gray. They are much less common winterers in the Bay Area than are birds of the Puget Sound subspecies.
The bird above, photographed wintering in southern Arizona in April, is most likely of the oriantha subspecies, called "Interior West" by Sibley, which are characterized by extension of the black crown stripes to the loral area between eye and bill, a bill color tending past orange to pink, and a back pattern with a strong contrast of chestnut and gray. These birds are virtually indistinguishable in appearance from the nominate leucophrys subspecies (Sibley's "East Taiga"), mostly found in winter in the eastern states, but a few of which may stray in winter as far as Arizona. Sibley's discussion of the subspecies of the White-crowned Sparrow is essential, and valuably supplemented by Roberson's discussion of the Pacific group, linked above.
This bird, carrying food to a nest in Montana just west of Yellowstone, is certainly of the Interior West (oriantha) subspecies; they breed in the Mountain West, and winter in the southwest, with the plumage characteristics discussed in the caption to the image immediately above.
Above and below, White-crowned Sparrows in the first basic plumage that follows their briefly held juvenal plumage and persists for their first year of life; they have brown crown stripes like juveniles, but plain breasts like adults. The bird above has a yellow bill and is likely Puget Sound; the one below shows the orange bill of the adult Gambel's, and may be of that subspecies, though I cannot find a definitive treatment of bill color in first-cycle White-crowns, and Gambel's are greatly outnumbered by Puget Sound in the SF Bay Area where this bird was photographed.
