Hawk, Buteo swainsoni
The photo above shows the lightest plumage, all-white underparts, strongly contrasting with a rufous chest, and much white on the face. The other extreme is dark-brown all over, with undertail coverts the only white on the body, and limited or no white on the face; the bird below approaches this end of the spectrum, with underparts mostly brown and some rufous. Traditionally, light, dark, and intermediate color morphs have been recognized, but the recent Birds of North America article reports that "variation is almost continuous from lightest to darkest individuals, making the morph categories convenient but somewhat arbitrary constructs." Males are more likely to be light and females dark, but these are only tendencies.
Swainson's Hawks nest on North American prairies, and most of them migrate to
the pampas of Argentina in our winter, thereby buying themselves summer weather
year round at the cost of a very long migration. This photo and the two below show
birds in Sierra Valley, northeastern California.
View of the underside of an intermediate adult, above; and an intermediate juvenile,
Above and below, a Swainson's Hawk juvenile on the nest and about ready to fledge; this was the first nesting by this species reported in Santa Clara County in decades.