There are two sub-species of the Lesser Goldfinch seen in North America. These sub-species or races are the more common Lesser Goldfinch (green-backed) seen from the southern regions of the state of Washington, south into the Baja California Peninsula, east into New Mexico and north into the central states. The Lesser Goldfinch (black-backed) is the least common, usually only seen from eastern Arizona, eastward through southern Texas. Both sub-species are seen deep into Mexico.
The Lesser Goldfinch is a member of the Fringillidae family. These birds are attracted to backyards with bird feeders. It is not uncommon to see them flocking with other types of goldfinches, or for that matter, other types of finches. They are not as hardy as the American Goldfinch which live much farther north.
Avibase - the world bird database This site provides the user with a complete list of bird species, broken down per country, or in the example of the US or Canada, per state and province. Here, bird species names are available in other languages, a great asset to be used as a translation of foreign bird names.
ABA - American Birding Association This site represents an organization that maintains official records of all birds species that have been proven to have been seen inside the perimeters of the North American Continent and the surrounding bodies of water. Regular revised versions are posted to keep the bird list current at all times. This is the list used by all serious birders over their lifetime. You may be aware of the movie called the "Big Year". It was with this list that all the competing birders used in an attempt to set a new record as to how many bird species that could be seen by an individual birder in one calendar year.
I hope you will take advantage of these suggested websites. I have used each of them, in one way or another, throughout the years in my quest to better identify and understand our fine feathered friends.