This very common carduelid finch of the southwest breeds in a variety of habitats at different elevations. It is often seen in small flocks feeding along brushy roadsides, particularly where thistle grows. Northern populations migrate south in winter, augmenting resident populations from southern California to southern Texas. It is often detected by its distinctive flight calls. Polytypic. Length 4.5".
A relatively small, sexually dimorphic finch with a short, notched tail and a small, dark, conical bill. Breeding male: differs greatly depending on subspecies. In the “green-backed” hesperophila, the bright yellow underparts and black cap contrast with an olive-green back that can show some fine dark streaking. Narrow pale tips to the lesser coverts and wider white tips to the greater coverts form 2 distinct wing bars on a black wing. The white at the base of the primaries forms a white “tick” on the folded wing. The tertials are broadly edged in white. The mostly white bases to the outer tail feathers form distinctive white tail patches visible from underneath or when in flight. In the “black-backed” psaltria (mexicanus of some authors), bright yellow underparts contrast with entirely black upperparts. The wings and tail are similar to the hesperophila. Female: more uniform yellow-green, often yellower below and greener above, but less contrasting. The head does not have a black cap. The wings are similarly patterned to male, but they are decidedly duller. A distinctive white at base of primaries is present. Some females very dull and drab, mostly gray with some yellowish green wash to body; wings duller, but still with white “tick.” Immature male: It lacks the full black cap of the adult, but it still has black on the forehead (hesperophila) or has some black intermixed with green on the back and crown (psaltria).
There are 2 distinct subspecies in North America. The green-backed hesperophila is more widespread in the Southwest, with black-backed hesperophila breeding from Colorado to southern Texas. Intergradation occurs clinally between Texas and Colorado.
Males are very distinct from other goldfinch species. The female American goldfinch is larger and has white undertail coverts, a wide buffy lower wing bar with very little white at the base for the flight feathers, and a pale pinkish bill. A very pale female lesser can show whitish undertail coverts, but it has a different wing pattern than all Americans and is always greener than the female Lawrence’s.
Calls: includes a plaintive, kittenlike tee-yee. Song: very complex jumble of musical phrases, often mimicking other species.
Status and Distribution
Very common. Breeding: a variety of habitats at different elevations from arid lowlands to high pine forests, often found near water. Winter: northern and high elevation populations migrate to southern United States and Mexico, augmenting resident populations there. Vagrant: casual north and east of mapped range in Great Plains. Accidental in the East.
—From the National Geographic book Complete Birds of North America, 2006