The Parblue Puzzle

Part 4 — Common Parblue Varieties

The Budgerigar [Melopsittacus undulatus]

The Budgerigar has already been mentioned more than once; and here we go again. In this species three Parblue varieties are usually recognised; the Goldenface (syn. Australian Yellowface), the Yellowface Mutant 2, and the Yellowface Mutant 1. The first two are usually used in double-factor form, in combination with the clearwing and opaline characteristics, to produce the composite Rainbow variety; although in single-factor form a very attractive Seagreen variety is produced. The Yellowface Mutant 1 in single-factor form is familiar as the typical exhibition Yellowface. Every effort is usually made (or should be) to keep these different varieties apart since it can be very difficult to separate them out once mixed.

The genes responsible for these varieties form an extended multiple allelic series comprising the wild-type (green) gene, three mutant parblue alleles, and finally the blue allele. The wild-type allele is dominant to all the others, which are themselves co-dominant with each other. The full series, ranked in the order in which they allow production of yellow psittacin pigment, comprises:

These five alleles can pair to produce 15 genetic types of Budgerigar, which in turn can be mated in 120 different combinations. Far too many to attempt to list!

Since the three varieties are usually kept apart for breeding purposes it is convenient to consider them here separately for the very same reason of avoiding unnecessary complication.

Some doubt as to the separate existence of the goldenface and yellowface mutant 2 alleles has been expressed. Although they produce similar visual types, the Goldenfaces (both SF and DF) show significantly greater psittacin pigment saturation than the corresponding Mutant 2 Yellowfaces. This is sometimes put down to their possessing a different selection of modifying genes due to their differing origins. My own view is that the differences are sufficiently marked, and do not appear to converge with outcrossing, to justify our classifying them separately.

Nevertheless, the inheritance patterns of these two varieties are the same and that for the Goldenface is illustrated below in the by now familiar table:

The SF Goldenface, as already mentioned, has a very attractive and even seagreen body colour which could not possibly be described as turquoise; but would fall within the broader marine category. In the DF Goldenface, the reduction of yellow psittacin is much more pronounced and the greater part of the body colour area is usually a definite blue. However, there is also usually some spillage of yellow down the chest from the head area giving a variable green cast. The head itself is a very bright yellow which, probably because of the colour contrasts, gives the illusion of being even brighter than in the normal Green. There is also bright yellow in the fanned tail feathers.

This differential reduction of psittacin is interesting and shows signs of being echoed in some parblue forms of other species. Is it true differential reduction? Or is it simply that the original pigmentation in some areas is so concentrated that even when reduced it still has the appearance of an almost full yellow? Or is it evidence that two slightly different forms of psittacin are present, one of which shows signs of ultra violet reflectance, and subject to separate genetic control? This is considered in more detail in the section Two Yellow Pigments of Peter Bergman’s article “Gene Function in Yellowface Budgerigars” in these pages.

The Yellowface Mutant 2 follows exactly the same pattern of inheritance but both the single-factor and double-factor forms display a reduction in yellow content in the order of 10-15% compared to the Goldenface.

We can now turn to the Yellowface Mutant 1 which has an unusual breeding pattern that confused early breeders of the variety and still has the capacity to surprise even today. That breeding pattern has been determined to result from the Yellowface Mutant 1 allele being yet another allele of the blue gene, giving the six genetic types listed below:

The surprise, of course, is that the double-factor Yellowface Mutant 1 appears as a visual Blue which is indistinguishable from the true Blue variety. If this is unrecognised for what it is there is a further surprise when, paired to a normal Blue, young are produced which are all SF Yellowface Mutant 1.

Furthermore, paired like to like, a strain of apparent Blues could be established which would not show their true identity until outcrossed to Budgerigars containing the true blue gene. They could even be paired with Greens, and provided those Greens were not split for true blue, the apparent Blues would continue to appear just as would be expected of the real thing.

The most effective early research into the Yellowface varieties was carried out by John Papin of the US and this work was developed by Ken Gray of the UK who is a lifelong breeder of these varieties. (See the article by Ken Gray at Budgerigars Galore.)

The Peach Faced Lovebird [Agapornis roseicollis]

In both the Ringneck Parakeet (Psittacula krameri) and the Budgerigar the (true) Blue varieties were recognised and firmly established before the Parblue varieties. As a consequence they were sensibly named.

The situation with regard to the Peach Faced Lovebird is quite different. Here, two Parblue varieties have existed for many years but, as yet, no true Blue has occurred. In the absence of a true Blue the first Parblue variety, when it was established by Dutch breeders (around 1963), was called the Pastel Blue. To the native English speaker the word pastel immediately implies a pale or diluted colour (a tint) although, on reflection and taking into account artists’ pastels and crayons, it could perhaps also be applied to a muted or less than bright colour (a shade). In no way however does it even hint at a yellow content. In the past our Continental (European) colleagues were no more logical or scientific than we are in naming varieties.

The second Parblue variety is credited as having first occurred in Germany, and in the UK is usually called the Whiteface Blue. Never a satisfactory term, this looks even more inappropriate now that we have a variety of the Splendid Parakeet (Neophema splendida), which is a true Blue, bearing a very similar name.

Jim Hayward, in a welcome attempt to rationalise the names given to parrot colour varieties, created a Universal Naming System in which he introduces the names Marine and Lavender. Marine is an inspired alternative to Pastel Blue and since it covers such a wide spectrum, from greeny-blue to bluey-green, is much preferable to turquoise which is very specific. Lavender, instead of Whiteface Blue, is less satisfactory since it still gives no hint of the (admittedly slight) yellow content of this variety. Even so, it is highly unlikely that anyone will think of anything better and these are the names I shall use in the hope that increased usage will eventually lead to their more general adoption.

More recently, under the auspices of the BVA, European breeders have established a more logical naming system for the Lovebird species. In addition, discussions are taking place between leading breeders and authorities on the Internet to extend similar standardisation to all avicultural species.

So far as I am aware the following is true of the two Parblue varieties in this species:

• Marine and Lavender are both recessive to normal Green.
  
  
• Marine and Lavender always appear to breed true when paired like to like: an indication that each is carrying two identical mutant genes.
  
  
• Breeders report that when Marine is paired to Lavender the progeny are not Green, but yet another (intermediate) Parblue form. This suggests not only that the marine and lavender genes are alleles (different forms) of the same wild-type gene, but also that neither is fully dominant to the other; that they are co-dominant.
  
  

So once again we appear to have a multiple allelic series containing a pair of co-dominant alleles even though there is as yet no true blue allele. To preserve consistency with other species it seems justifiable to label the marine gene b^m and the lavender gene b^l, signifying that both are alleles of a blue gene which we may anticipate will eventually occur. Until such time, the following table sets out the likely genetic structure:

The Splendid (Scarlet Chested) Parakeet [Neophema splendida]

The situation with regard to the Splendid seems to have echoed that of the Peach Faced Lovebird in that two distinct Parblue forms existed for a number of years without a true Blue putting in an appearance. For much of this time, it would seem, UK breeders did not recognise these as two separate varieties and thought of them merely as the two extremes of one very variable colour form. (Does this indicate that intermediate forms blurred the distinction between these two?). Continental breeders were more discerning in recognising them as separate varieties, but do not seem to have unravelled their genetics and have once again saddled us with the name Pastel Blue for the more blue looking bird. The other variety is more aptly known as the Seagreen.

Finally, around 1975/76, a true Blue was established and almost inevitably became known as the Whitebreasted Blue. Reluctantly, to avoid any possible confusion, I will stick with these names.

I have seen no published information which sheds any real light on the relationship between the Parblue and true Blue forms of the Splendid. However, they are probably sufficiently well established for there to be enough sound stock to persuade a number of breeders to consider experimenting with like to like pairings, cross-pairings not involving normal Greens, and pairings of Greens split for the Parblues to Whitebreasted Blue. There can be little doubt that there is information out there which if gathered together could largely resolve the questions surrounding these varieties.

The questions which require answering in respect of the blue series of genes in the Splendid include the following:

• Are the Parblue varieties limited to the Seagreen and Pastel Blue or can other distinct, probably intermediate, forms be reliably identified. (In many species there may be difficulty here due to variation in psittacin concentration brought about by groups of modifying genes [polygenes]; present as a result of selection or because of differences between strains, races, sub-species, or even hybridisation.)
  
  
• Does the Whitebreasted Blue always breed true paired like to like.
  
  
• Which Parblue variety(ies), similarly, always breed true paired like to like.
  
  
• What are the results of pairing each Parblue variety to Whitebreasted Blue.
  
  
• What are the results of pairing dissimilar Parblues; that is, Seagreen to Pastel Blue.
  
  
• What are the results of pairing split Greens to Whitebreasted Blue; do such Greens ever appear to be split for more than one Parblue variety.
  
  
  

We must hope that answers to these and other questions will be forthcoming as the blue series varieties pass into the hands of more and more breeders. No one breeder is likely to know the answer to all these questions but, if only breeders would report their own individual results and observations, these separate pieces of the jigsaw could be assembled to reveal the complete picture.

It might seem perverse to bring up the Cockatiel in a discussion of the Parblue and Blue varieties. But no, remember, the blue series of alleles lie along the biochemical pathway which produces the psittacin pigments. The wild-type gene facilitates full production of psittacin, the parblue allele(s) reduces the amount produced, and the blue allele completely stops production. Although the end result is not a blue or parblue bird, these genes are still present in the Cockatiel and we have varieties which show their influence.

First, and most dramatic, there is the Whiteface variety which is totally devoid of psittacin yellow and orange pigmentation and is analogous to the Blue varieties in other species. Then there is the Paleface (or Pastelface) variety in which psittacin is merely reduced, in the same way as the Parblues in other species. This prompts an interesting thought which might not have occurred to most Cockatiel breeders. Could the two alleles responsible for these varieties form part of a multiple allelic series directly comparable to the blue series we have been discussing?

It is unlikely that many breeders have considered crossing the Whiteface with the Paleface since it is plain they would not combine to produce an interesting composite variety. Nevertheless, in view of the possibility mentioned above, this cross should have an appeal to any Cockatiel breeder interested in genetics. Assuming this possibility, we would have a series of alleles which might be symbolised:

If, as suspected, the two varieties are related many breeders might appreciate pairing them on a regular basis since all the young would be one or the other variety, without the ‘wastage’ associated with producing normal Greys. Additionally, it might emerge that there are two visual forms of the Paleface corresponding to the pure (double-factor or homozygous) Paleface and Paleface split whiteface genetic types.

Note: This article was originally written in 1992. It now seems to be common knowledge that the Paleface (Pastelface) cockatiel is caused by a gene which is an allele of the whiteface gene (see the article New Colour Varieties in the American Cockatiel Society pages). Although the terminology used is suspect, it is clear that in the last two paragraphs a multiple allelic series of three genes is being discussed in which the whiteface is recessive to the paleface, which in turn is recessive to the wild-type. Appropriate symbols (W, w^pf, and w) for these have already been suggested above, which can combine in the following ways:

No difference in appearance between the pure Paleface (double-factor) and the Paleface/whiteface is mentioned so we must assume the paleface allele is fully dominant to the whiteface.

Another couple of points must be made concerning this article. In the Paleface, as we expect from a factor analogous to the parblue, there is a generalised reduction in psittacin pigment which affects both yellow ground colour and the orange cheek patch. The other two newer varieties mentioned, the Sex-linked Yellowcheek and the Dominant Yellowcheek, are rather different in that only the cheekpatch is affected. Here I believe, though I have little knowledge of these varieties, the responsible genes act only to reduce or eliminate the orange (or red) psittacin pigment present in the normal cheekpatch leaving the underlying yellow pigment unaffected.

The writer of the article sidesteps describing these varieties by disingenuously pointing to the lack of a Colour Standard. May I remind him that Mother Nature creates these varieties and the job of a Standards Committee is merely to describe, as accurately as possible, a form of the variety well within its natural range of variation. The more informed and widespread the debate, the less likely the chance of some foolish mistake such as the Opaline standard adopted by the Budgerigar Society (UK) for so many years.

Another article, Cockatiel Genetics, on the National Cockatiel Society (US) pages also makes the association between the Paleface and the Whiteface varieties, but does not consider the implications or use the accepted genetic symbolisation.

End of Part 4

In the concluding section of this article, Part 5, we will consider what conclusions can be drawn from the information so far available.

Copyright: Clive Hesford, 1992 and 1998

Forward to Part 5

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