The Genetics of Colour in the Budgerigar and other Parrots
This page updated 5th August 2001
The Texas Clearbody budgerigar
These two extracts are from articles published in the Newsletter of the Rare Variety and Colour BS in 1995 at a time when the Clearbody budgerigar, originally imported and distrubuted amongst a select band of top exhibition breeders, was becoming more widely available. Not unsurprisingly, little or no worthwhile information had been published by these sources up to that time.
The Genetic Nature of the Texas Clearbody
Rare Variety and Colour BS Newsletter, Spring 1995.
At last an article by one of the leading lights has appeared in Cage and Aviary Birds. Alas, the descriptions were vague and the list of possible pairings incomplete. Worse still, mention of an Ino cock split for Clearbody betrayed a lack of full understanding of the now widely accepted genetic theory involved. Five out of ten for effort!
Fortunately our own later contributors, whether from far distant Australia or a mere hop skip and jump away in Holland, know better though it's never easy to put these fairly technical ideas over in a way that will help the average fancier.
Perhaps, without going into genetic details and schematics I can make a few points useful to the practical breeder:
Breeding the Texas Clearbody
Four possible ways to handle the breeding of Clearbodies come to mind:
As usual in any genetic discussion, the description Normal is used in the sense that such a bird does not show or conceal any of the factors being considered; in this case clearbody and ino. Other factors may well be present in practice and be desirable, dark, grey, violet, etc. Others, particularly diluting factors, may also be present and will in general be undesirable.
American breeders have suggested that Clearbodies produced from pairings with Inos have reduced body colour (green or blue) suffusion.
In the case of hens this could only be due to any differences in genetic background between Normals and Inos and I do not see this as being true as a general and universal rule. Where cocks are concerned there might be more substance in this argument. There could well be differences between doule-factor Clearbody and single-factor Clearbody (split ino) cocks. But, as always, I implore, don't repeat such views unless you are convinced by careful personal observation that they are true. Don't become a myth-monger!
If any of you do breed Clearbodies, I'm sure it would be a great help to the rest of us if you could provide accurate descriptions of straight Clearbodies and the Opaline variant which is so (relatively) commom. In particular, what are the changes to the distribution and colour depth of the markings besides the well-known dilution of the flights? And can you see any difference between double-factor and single-factor cocks?
© Clive Hesford, 1995
The Visual Nature of the Texas Clearbody
Rare Variety and Colour BS Newsletter, October 1995.
No-one has yet responded to my invitation to come up with a description of the Texas Clearbody. In view of this, and even though speaking from a prior position of almost total ignorance, there is nothing for it but to take up my own challenge and venture first where others fear to tread. Then you can tell me where Ive gone wrong!
Back in the days when the Clearbody was just a name, we used to visualise it as having pure yellow or white body colour contrasting with perfectly normal markings. The reality is rather different. Glancing at Clearbodies on the showbenches reveals a wide variation in appearance, made more so by the fact that some carry Opaline in their make-up. This doesnt make it at all easy to decide on the typical appearance of the variety.
However, at the Specialist and Rare Variety Show (Summer 1995) I spotted a couple of Clearbodies exhibited by one of our members, Mrs Dolores Noonan, which it seemed to me best expressed the basic characteristics of the variety. They, a cock and a hen, stood out from the rest for the richness and contrast of their colour. Whether this was the result of their being more typey and tight-feathered than the others, or to the manner of their breeding, I dont pretend to know.
I base the following observations on these birds:
Most breeders of Clearbodies will probably wish to improve their stock by reducing green or blue suffusion. As with other varieties with largely yellow or white body colouration (Dilutes, Lacewing, Fallow, etc.), a certain amount can be done by selection. But the most immediate results will follow from incorporating certain colour modifying factors in a way which by now should perhaps be common practice.
In the blue-series, the addition of the grey gene will replace the objectional (in some instances) blue suffusion with grey suffusion, whilst also tending to intensify the markings. In the green-series, the dark and violet genes will both help to disguise green suffusion and persuade it to blend in with yellow ground colour. They may also slightly deepen the markings. The opaline gene may help to reduce suffusion of the rump, though at the expense of altering the markings.
It seems to me that the challenge which breeders of the Clearbody will increasingly face is that of preserving the pattern and intensity of the markings. Already, there are signs that the exhibition Clearbody will soon be just as nondescript as most Spangles are today. (see The Nondescript Spangle?)
© Clive Hesford, 1995
The Clearbody Phenotype
A peculiarity of the Clearbody or par-ino budgerigar is the unexpected and novel visual form, or phenotype, which it exhibits. It might have been expected that there would be an even overall reduction in melanin in the plumage resulting in an appearance very similar to that of the Lacewing.
As we all know however, whilst this is what does appear to happen in Par-inos of other species, there is more to it than this in the Clearbody budgerigar. Although the processes initiated by the clearbody allele do indeed reduce melanin production, they do so in a selective manner which produces an altogether more interesting phenotype.
The process is fairly subtle with regard to background melanin, and I have not seen it noted by others, but my description above does bring out the fact that there is a noticeable differential reduction in body colour which is most reduced on the breast and deepens outwards from this area. But when it comes to foreground melanin it cannot be missed by even the most casual observer that, rather than there being a general reduction in the intensity of the markings, there is instead a reduction in the total area of those markings resulting in a distinctive pattern possessed by no other variety.
This is most noticeable in the flight feathers which are reduced to a very pale grey though there is just sufficient pigmentation left to reveal the presence of the characteristic white triangular area when the Opaline trait is also expressed in an Opaline Clearbody.
The budgerigar clearbody allele belongs to that class of mutation known as the partial- or par-ino. This means that it is an alternative allele to the ino, and its corresponding wild-type, and acts at the sex-linked ino locus. This is discussed in more detail in another article:
The Par-ino Varieties