There are currently 5 subspecies of the Lesser Goldfinch, 2 of which live in western 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 of the USA (California, Arizona) and North West Mexico.
The Black-backed Goldfinch (the other 4 subspecies) occurs mainly east of the Rocky Mountains and south to Peru.

This is Spinus psaltria colombiana which is found in South Mexico south to Colombia and in North Venezuela, Ecuador and North West Peru.

San Benito, Petén, Guatemala, 20 January 2020