Lesser goldfinch
The lesser goldfinch (Spinus psaltria) is a very small songbird of the Americas. Together with its relatives the American goldfinch and Lawrence's goldfinch, it forms the New World goldfinch clade in the genus Spinus. As is the case for all three New World goldfinches (and some of their siskin relatives), lesser goldfinch males have a black forehead, which females lack. Males in this species vary strikingly in back color across their range, from green in western North America to black from Texas south to South America. Five subspecies are often recognized.
Taken from: Wikipedia