This Great Basin subspecies winters more abundantly in the Colorado River Valley, but is fairly common around the Salton Sea in appropriate habitat. P. g. confinis is larger, grayer above and whiter below than coastal P. g. affinis which is smaller, browner above and buffy below and which winters along the coast of California.
Although the white outer tail feathers are often touted as a key field-mark, they are not easy to see when the bird is perched. I find the white-eyering and pale malar angling up behind the ear coverts to be more useful in identification on perched birds. The reddish lesser coverts are visible here, but are often concealed on the folded wing.
Olympus D-550z / Nikon FieldScope 3 / 30XWA (hand-held - no adapter).