This is a fairly common sparrow of arid deserts. Only adults have the full black bib as seen here. Unlike most sparrows, the juvenal plumage is retained through the fall and winter and they lack the black throat.
Nine or ten subspecies range from the SW United States through central Mexico and adjacent island. This is presumably A. b. deserticola which is found through most of Arizona and the far Western US. It is sometimes called the "Desert Sparrow" and is more brownish and less grayish above than most subspecies, particularly on back and scapulars.
Digiscoped with Panasonic DMC-LZ5 | Nikon FieldScope III | 30XWA | hand-held (no adapter)