Mutavi - Research & Advice Group
THE
GOULDIAN FINCHES
(Erythrura Gouldiae)
(Part 1)
By Dirk Van den Abeele
MUTAVI, Research & Advice
group
Recently
we were contacted by Daniel Wildemeersch of the BNEC, the Belgian National
Exotic Club. Within this branche of the hobby one had quite a few questions
about certain mutations in Gouldian finches, for us a challenge to look somewhat
closer into this matter.
The
purpose is to do some feather examination but in the first place to have a look
at all mutants step by step.
In
all these investigations it is necessary that we study the wildtype first,
however, here we have the first peculiarity; there is not one wildtype but in
these birds there are actually three “wildtypes” in existance.
There
are specimens with a red head, a black head and an orange head. Therefore it is
important to pay attention to this. The black headed shows a narrow blue zone
between the black head feathering and the back and breast colour. The bill is
ivory coloured, the tip of the bill is red. The colour of the back and the
wingcoverts is green, the rump is blue, the breast is purple and the abdomen
yellow. Legs are horn coloured.
The
“red headed” and the “orange headed” are almost equally coloured, except
for the fact that we find a “red mask” in the “red headed” which
partially spreads over the black head feathering and in the orange headed we
find an orange mask there.
The
red headed has a red tip of the bill and the orange headed a yellow one. Hens
distinguish themselves in these three types by their duller colours and the
almost total lack of the blue transitional zone between the colour of the head
and the rest of the body.
But
where did these three “wildtypes” came from. Well, the answer must lie in
the past. One must know that these birds live in Australia and their main
habitat is about twelve times larger than Belgium. There the first Gouldian
Finches were discovered in 1833 by Hombron and Jacquinot. The birds they
observed first had a red head. Later on specimens were found with a black head
and at last one of them “discovered” the birds with an orange head.
During
the course of the years, they even got three different scientific names and
after many changes they are known as Erythrura gouldiae to day.
However,
it is scientifically spoken very unlikely that there are actually three
“wildtypes” or basic forms in existence. The question remains; what is the
most likely basic form or do we actually have to deal with three different
species or subspecies.
To
know we must have a look at several breeding results and mobilize our basic
knowledge of genetics. If these forms are different species than we should
obtain intermediate offspring out of inter se mating between the different
forms. However, this is not the case because if we mate a black headed cock to a
red headed hen then we obtain black headed hens and red headed cocks split for
black headed.
If
we mate a red headed cock to a black headed hen than all youngsters will be red
headed but the cocks are split for black headed. This is very important to know
because it points out that the factor which is responsible for black headed (or
the factor responsible for the red colour in the head feathering) is situated at
the sex-chromosome and thus inherits sex-linked.
So
if we mate an orange headed cock to a red headed hen or vise versa, than all
offspring will be red headed split for orange headed which indicates that the
orange head factor inherits as an autosomal character and thus is situated at an
autosomal chromosome.
If
we mate an orange headed cock to a black headed hen, than all offspring will be
red headed. All cocks will be split for black headed and orange headed and the
hens will be split for orange headed.
Formulas
Gouldian finches
Black
headed
Xbf
/ Xbf
Orange
headed
of / of
Mating
# 1
----------------------------------------------------------------------
Formula
cock :
of+ / of+ ; Xbf / Xbf (Black
headed)
Formula
hen :
of+ /of+ ; Xbf+ / Y
(Red headed)
Number
of different genotypes : 2
NO.
PERC. NUMB.
GENOTYPES
1
50 % 8
of+ / of+ ; Xbf+ / Xbf
(Red headed / black headed cocks)
2
50 % 8
of+ / of+ ; Xbf / Y
(Black headed hens)
Mating
# 2
-----------------------------------------------------------------
Formula cock :
Xbf+ / Xbf+
(Red headed)
Formula hen :
Xbf
/ Y
(Black headed)
Number
of all possible genotypes : 4
Number
of different genotypes : 2
NO. PERC.
NUMB. GENOTYPES
----------------------------------------------------
1
50 %
2
Xbf+ / Xbf
(Red
headed / black headed cocks)
2
50 %
2
Xbf+ / Y
(Red
headed hens)
Mating
# 3
------------------------------------------------------------------
Formula
cock :
of / of
(Orange headed)
Formula
hen :
of+ / of+ (Red
headed)
Number
of all possible genotypes : 4
Number
of different genotypes : 1
NO. PERC.
NUMB. GENOTYPES
-----------------------------------------------------
1
100 % 4 of+
/ of
(Red headed / orange headed hens and cocks)
-------------------------------------------------------------------
Formula
cock : of / of
; Xbf+ / Xbf+
(Orange headed)
Formula
hen :
of+ / of+ ; Xbf
/ Y (Black
headed)
Number of all possible genotypes : 16
Number
of different genotypes : 2
NO. PERC.
NUMB. GENOTYPES
------------------------------------------------------
1
50 %
8 of+
/ of ; Xbf+
/ Xbf (Red headed / orange headed / blackheaded cocks)
2 50
%
8 of+
/ of ; Xbf+
/ Y (Red headed / orange headed hens)
It
is interesting to know that according to recent valuations in their natural
state, at 1000 Gouldians, 750 black headed, 249 red headed and one orange headed
does excist. The domination of the black headed can be ascribed to their
sex-linked inheritance. The presence of these three forms in their natural
state, without knowing the genetic back ground (genotype) of the birds, conveyed
the impression by their discoverers in those days, that we had to deal with
several forms. However, the fact that we now know that these “phenotypes”
are hereditary factors, gives away that they are mutations.
If
we consider the red headed as the wildtype or basic type, than we are able to
base the genetic symbols at that preposition. This avoids further problems in
the future. We will do this step by
step in connection with breeders, the several societies and the members of the
BNEC. Together we will investigate every colour mutation in Gouldians,
determine the genetic symbols, the loci and where necessary perform feather
investigations.
Several
testmatings will be necessary and in order to do so we will make an appeal to
all breeders and fanciers of Gouldian finches. If you want to cooperate report
it to: Daniël Wildemeersch, Belgium.
Email:
erythrura@gmail.com , homepage:
http://users.skynet.be/fa398872/
Dirk
Van den Abeele
MUTAVI,
Research & Advice Group
05.08.2002
http://www.euronet.nl/users/hnl/
Last changed:
07/03/07 14:45
©2000-2006, Daniël
Wildemeersch, SOFAM
"All rights reserved"