The colors in the feathers of a bird are formed in two different ways: from pigments and/or from light refraction, which is caused by the structure of the feather. Carotenoids (red and yellow pigments) are responsible for most of the red, orange and yellow colors seen in birds. Pigment melanin which has two forms: eumelanin (black or dark brown) and phaeomelanin (reddish brown) produce colors ranging from the darkest black to reddish browns and pale yellows. The resulting color depends on the combination and concentration of each pigment, and also on the aspects of the feather structure which contribute to the visible coloration.
The process of producing that specific structure and pigmentation is under genetic control. The original gene is called the Wild Type Gene and any change from the wild type is called a Mutation. A mutant can differ in both major and minor ways from the wild type. Mutation is extremely rare event, but while occurred, it can spread in the wild population. So, there is always possibility that captive bird carries some kind of mutation. It is inbreeding, the breeding between close relatives - that allows mutation to be manifested. Inbreeding decreases genetic diversity, which is bad for brood viability in whole but increases the possibility of mutations to pop up. The art of breeding is to select color mutation of interest while keep the descendents healthy and reproductive consistent.

Any mutant being analyzed should be compared with the ancestral wild type, a.k.a. normal or wild type. The wild type adult Shafttail Finch is 7" (18 cm) in length, including the tail feathers. The head (crown) is a silver-gray. The lore, the region on a bird’s head between the eye and the bill, is black. The throat bib, or the vivid patch under a bird’s bill, is also black. The tapering tail is black and rather long, separating into two central shafts. The lower part of the tail is white. The stripes along the leg area, trouser stripes, are black. The back and flight feathers are brownish in coloration. The chest and the belly are a whitish brown. The eyes are black and the legs are bright pink with an orange-red tint. The original population of Shafttail Finches inhabited the north of Australia and was separated by the Kimberley Plateu-Arnhem Land Barrier, resulting in two geographically and morphologically different populations corresponding to the subspecies  Poephila acuticauda acuticauda and Poephila acuticauda hecki. Heck's Shafttail (P.a. hecki) has a remarkable red bill and the P. a. acuticauda has a yellow bill. The subspecies have often been crossbred in captivity, and the bill color of hybrids ranges from orange to coral red. The pure lines of each subspecies are hard to find in US aviculture.

The youth represent a duller version of the adult. The bill is black or very dark gray, the lore is brown. The throat bib is smaller and dark brown. The tail is shorter and does not carry the long central feathers.

We raise four plumage color mutations: Fawn, Isabelle, Creamino, and Albino. The main differences between the color mutations are given in the table below. There are also Pied and Gray shafttail’s color mutations that I would like to keep but they are even more rare.