Black-backed Goldfinch

The vast majority of the Lesser Goldfinches in southeast Arizona are green-backed in male plumage, but every once in a while a black-backed male shows up; they seem to be especially frequent at Portal and Paradise feeders in the Chiricahuas, but even here in northwest Tucson we occasionally get a visit. These dark birds seem to show up most often in the winter, but this morning we had a magnificent individual at the thistle seed, shining jet black on the back and auriculars. 

Just what these black-backed birds “are” is still a source of confusion. In the eastern parts of the species’ range, Lesser Goldfinch males tend to be black-backed, though a small minority have green backs; this may be age-related. These birds are generally treated as a distinct subspecies psaltria (sensu Oberholser), while males of the western hesperophila (“our” subspecies) are, according to BNA, “always” green-backed (though sometimes with black streaks on the back and auriculars). If that is true, then the black-backed males we see here are in fact vagrant psaltria from the east. I suspect, though, that Pyle’s quiet suggestion in the Identification Guide is more plausible: namely, that all populations of Lesser Goldfinch are polymorphic, and that green backs and black backs simply appear at different rates in each subspecies.