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Shafttail (Long-tailed) Finch Color Mutations |
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The original population
of Shafttail Finches inhabited the north of Australia and was
separated by the Kimberley Plateau - 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.
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 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.
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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 differences between the main
Shafttail Finch color mutations : Fawn,
Creamino,
Isabelle,
and
Albino are given in the
table below. There are also Pied and
Gray shafttail’s color mutations, but
they are even more rare. Please click here for more info. |
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Bird
color |
Normal (wild type) |
Fawn |
Creamino |
Isabelle |
Albino |
| Head (crown) |
silver-gray |
silver-gray |
beige-grayish |
beige-gray |
white |
| Eye |
black |
black |
red |
dark brown |
red |
| Lore |
black |
brown |
beige-rusty |
dark brown |
white |
| Throat bib |
black |
brown |
beige-rusty |
brown |
yellowish white |
| Chest |
grayish brown |
grayish brown |
beige |
beige-rusty |
white |
| Back |
brownish |
brownish |
beige |
brownish |
white |
| Flight
feathers |
brownish |
brownish |
beige |
beige-rusty |
white |
| Trouser stripe |
black |
brown |
beige-rusty |
dark brown |
white |
| Tail feathers |
black |
dark brown |
rusty |
dark brown |
white |
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The fawn mutation within the Shafttail Finches is
a common mutation. It is believed that the fawn variety is a
color mutation qualitatively changing the appearance of eumelanin pigment from black to dark brown as a result of
its incomplete oxidation.
The
inheritance of the fawn mutation is recessively sex-linked.
This means that a fawn mutant from two normally
colored parents will always be a female. Fawn males are rare
because they can only be born from a fawn mother and a normal
father that has been split to this mutation, and of course,
from parents that are both the fawns. |
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The creamino shafttail finch is a bird with
the ino gene, which renders it a soft cream color.
Ino is
defined as a strong qualitative reduction of
eumelanin and phaeomelanin. In this mutation,
phaeomelanin has almost disappeared and there is hardly any
oxidation of the eumelanin. Black feathers will turn a very
pale brown, almost white.
The inheritance of creamino mutation is recessively
sex-linked, see also the
fawn mutation. This means that only males can be
the carriers of the trait and females are either normal or
visual creamino mutant. Creamino males can only be born from a
creamino mother and a normal father that has this hidden
mutation, and of course from parents that are both the creaminos.
For this reason, males showing these two
mutations, Creamino and Fawn, are rarer
than females and therefore command a
higher price. |
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We were lucky enough to have
bought a normal pair of shafttails with a hidden mutation. The
mutation showed during the first hatch when we had one normal male
and our first creamino female.
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In an isabelle mutation, the amount of eumelanin
pigment is reduced. The pigment itself is not changed, but due to a
reduction in the pigment concentration, a diluted color is observed when
compared with the wild type coloration. The isabelle shafttail's
appearance is comprised of soft brown shades.
The
inheritance of isabelle mutation is autosomal recessive. Autosomal genes come
in pairs, and autosomal recessive inheritance means that both genes in a
pair are mutant, which causes an isabelle color. |
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Melanin is the primary
pigment that determines the color of a bird’s feathers,
skin, and eyes.
Albinism is an inherited problem caused by an alteration in
one or more of the genes that are responsible for
melanin
producing or it distributing. Contrary to popular belief, albinos are
therefore not necessarily pure white. In an albino of a
species with
carotenoids
as additional color, these pigments remain present. And
dependent on the natural location of the carotenoids such a
bird will remain completely or partially yellow or red
colors.
Our first
all-white shafttail female is offspring of parents
with normal/wild plumage color. I'm quite sure mother is split to isabelle,
and father is split to
creamino and isabelle. The creamino and isabelle
mutations in their daughter "work" together to remove from the
bird pigment melanin, just as a true albino mutation would.
Albino shafttail finches are extremely rare in aviculture.
To get some genetic
explanation of albino mutation
click here. |
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Sibling birds: albino shafttail female is on the left and
creamino female - on the right hand. |
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