Green Singer finch
Serinus Mozambicus

Country of Origin Africa
Compatibility Can be aggressive to others of the same species during the mating season.
Difficulty of breeding The main difficulty is in finding sufficient birds to populate a breeding facility.
Size Length 4" - 4-1/2" (10 - 12 cm)
This is another of the species that is becoming more rare.  While they are not particularly difficult to breed, the lack of available parent stock makes it somewhat of a challenge.  As their name implies, the male of this species is noted for possessing a lovely song. 

In the photo, the hen is in the front.  Notice that she has a necklace while the male does not.  This is the primary means to determine the sex of the birds.

Additional Images