There are 2 distinct subspecies of the Lesser Goldfinch (Spinus psaltria) in North America (and 3 more subspecies living south of the USA).
The colour of the back of the males can either be dull green or solid black depending on the region.
The Green-backed Goldfinch (Spinus psaltria hesperophila) is more widespread in the Southwest (California, Arizona) and North West Mexico.
The Black-backed Spinus psaltria psaltria occurs mainly east of the Rocky Mountains (from Colorado to southern Texas).

This is a male Green-backed Goldfinch (Spinus psaltria hesperophila).

Madera Canyon, Arizona, USA, 25 April 2008

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