Wikipedia
Sporophila
Sporophila is a genus of Neotropical birds in the family Thraupidae. The seed finches are sometimes also included in this genus.
They are relatively small with stubby, conical bills adapted for feeding on seeds and alike. Most species are strongly sexually dimorphic, and while "typical" adult males often are distinctive, female and immatures of both sexes can be very difficult (in some species virtually impossible) to identify to exact species. Females of at least some of these species have different ultraviolet colours, which can be seen by birds, but not humans. Female-like ( paedomorphic) males apparently also occur, at least in some species.