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Descriptions of Head Colors on Gouldians
This page has useful information on the head colors of Gouldians, explained in easy to understand language! Special Thanks to James for breaking it down and for allowing me to use his pictures!! Special Thanks to Gouldian_Preservation_Association_101911.
This is my interpretation of the action of the head colours in the Gouldian Finch, and the results on them, by other genetic actions within the bird.
The pigments found in the head of all Gouldian's are phaeomelanin and eumelanin.
Phaeomelanin is a reddish-brown pigment and is found in small amounts all over the head. Eumelanin is black and is found in the black areas of the head.
In addition, in the red head there is astaxantine, and the yellow/orange head has yellow pigment.
Astaxantine is manufactured from the yellow pigment and is found in the red areas of the head and in the beak.
The yellow pigment is manufactured from lutein which in turn is taken up from the food.
This yellow pigment is found on the yellow head, in the same areas as the red on the red head.
These are the only colour pigments found in the head of the Gouldian Finch and anywhere else in the Gouldian Finch.
The head colours are changed, and influenced, by several of the mutations currently available in the Gouldian Finch, either by removing them, or reducing their intensity.
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First we will look at the Red Head.
The head, or the cheek patch if you prefer, extending up and over the head, is a bright intense red.
The bib and surround of the red area is intense black.
The beak tip is red.
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Now we will put a white breast on this bird.
The action of the white breasted gene is to remove phaeomelanin. It does this from the whole bird, not just the head. The end result is a white breast and the red in the head is just a little brighter and more scarlet in colour. The red head is not reliant on phaeomelanin to produce red, but because there is a fine layer of phaeomelanin, in the head of the normal, it acts on the red to make it just that bit darker. Removing the phaeomelanin has no effect on the black areas because the eumelanin is black and masks any possible effect that phaeomelanin, or the lack of it, would have in these areas.
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Now we will take the white breasted gene out, and put in the mutated eumelanin gene, in a single dose. (Single Factor Yellow or Dilute)
The red has returned to the same colour as it was before we removed the phaeomelanin with the white breasted gene.
Now the black areas have changed.
The gene for production eumelanin is sex linked and carried on the male sex gene.
Each male has two male genes and therefore has two genes for the production of eumelanin.
The SFY or Dilute has one normal gene and one mutated gene. The normal one is producing its share of eumelanin but the mutated one is not producing, so the bird is getting only half the eumelanin of the normal bird. This is seen it the bib, and the surround of the head, which has now become charcoal grey, (a reduction of 50% in eumelanin has caused a reduction of 50% in the black colour, turning it to charcoal)
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Now we will add the second mutated eumelanin gene (Double Factor Yellow)
This photo is hen but it shows you what the double factor cock will look like, the black areas have now turned a pale cream colour. This is because the cock bird now has two mutated eumelanin genes and neither is producing eumelanin. While hens have only one eumelanin producing gene, when it is yellow back, that means it is a mutated gene and is not producing eumelanin, giving the same colour result as the Double Factor Cock. Neither has a normal eumelanin producing gene.There is still the normal amount of phaeomelanin in the head region and this results in the cream colour of the bib and surround.
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Now we go back to the Single factor yellow, but add the white breast.
There is only a slightly more dilution of the black areas, compared to the SFY Purple breast, and the red has returned to the brighter scarlet colour because all the phaeomelanin has been removed once again. (the slight diluting effect of the black area's is achieved, with the removal of the phaeomelanin, in the single factor, because the original eumelanin is already reduced by half by the one mutated eumelanin producing gene, it would show no effect in the normal bird)
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Now we have the double factor white breasted boy
The black bib and the surround of the head are now almost pure white and the red head gives the appearance of a red hood. There are no melanin's at all in the head, only the red pigment.
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The yellow head is the same bird as the red head, with the exception that the yellow gene prevents the bird from turning the yellow pigment to red, so the head colour and the beak tip remain yellow.
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Here we have four yellow/orange heads. The first is a normal followed by a white breasted normal, a double factor purple breast and a single factor purple breast. Notice the difference the white breast makes!! When you remove the phaeomelanin from the head you get a better yellow colour.
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For the black headed bird you can take all the bib colours shown above and this will be the head colour of that bird when it has a genetically black head.
Here we have four black headed birds.
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You will notice the first one, a purple breasted cock, and the last one, a white breasted hen, both have yellow tipped beaks. This indicates that they are double split yellow.(Carry two autosomal modifying genes for yellow head)
I trust this has been of interest,
....James
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