The Pied (or Olive-Pied) Redrump Parrot
- a mysterious combination -

by Terry Martin

This mutation is one of the most intriguing to occur in any species of parrot to date. Why do I say this? Not because of it’s outstanding beauty or unusual inheritance. But because of the unusual combination of actions from the one gene.

Olive-Pied Redrump Parrots were imported into Australia from the UK in the early 1990's. In the UK they are known simply as Pied but have been distinguished in Australia partly to indicate greater monetary value and partly because we already had our own pied mutation.

The basic action of pied genes is to inhibit melanin uptake into random areas of plumage. Thus creating a broken appearance to the body colour. Pied genes have no action on psittacin and therefore do not alter the ground colour. And they do not alter the melanin that is deposited in the ‘non pied’ areas. The white or yellow areas on a Pied bird are generally known as the pied areas. The melanin coloured areas appear as they would on the bird if it didn’t exhibit the pied gene. But this is where the Olive Pied Redrump differs. It appears to alter the structural aspect of colour as well as adding the traditional clear patches. To date, no other pied allele alters structural colour. On top of this, it removes the red from the rump of the Cock — an alteration to psittacin pigments; which is not a normal pied trait.

How does a gene that intermittently blocks melanin disposition also effect two other unrelated areas of colour production?

Pied genes in other species

Pied genes are well known in many species of birds and mammals and even reptiles. They occur in many avian families. The familiar yellow canary is a full pied bird. The Canary started as a green bird and the pied gene was selected to remove all melanin from the bird and produce the full yellow. Canary breeders call the effect variegation and look at it in a reverse fashion — from full mutant (yellow) back to the wildtype green (or heavily variegated).

Breeders of other species would call a heavy pied the one that was almost fully yellow, not fully green.

In parrots we have a large number of pieds being established. In Budgerigars for example there are three recognised loci. All of these function in the standard way, by altering melanin distribution and having no effect on psittacin or structural colours. Some pied varieties produce patterns (e.g. Danish Recessive Pied budgerigar) which to my eye appear quite random whilst others have a more consistent pattern (e.g. Australian Dominant Pied). As pieds began to appear in other species, similar effects were expected to occur. And, at first, any discrepancies were overlooked.

Jim Hayward in his book Manual of Colour Breeding, has described the effects of pied alleles in a number of species and noted the loss of red from the rump of the cock Redrump. He has also suggested that psittacin is reduced in distribution in some other species, notably Peachface Lovebirds and Rosellas. I cannot comment on the reduced psittacin in lovebirds or Rosellas, although my mind always questions the validity of this observation. But the loss of the red rump in Redrump cocks is undeniable. There is little discussion of possible causes or significance of these features, or that they conflict with the basic rules for pied genes that occur in other species. I will shortly propose a new explanation for the effects of the Olive-Pied allele in Redrump Parrots.

Grey Green Pied not Olive-Pied

When these birds were first imported into Australia, I quickly expressed locally my belief they were Grey-Greens not Olives in their effect on the structural colour. This is just as hard to explain genetically but has proven significant when breeders have tried to produce a Blue Pied combination. They have been universally disappointed with the appearance of grey pied birds in both cocks and hens. Exactly as I predicted. But, then, as more were produced, reports of blue being visible in some individuals has created a new problem. Whilst reports of blue feathers in these Grey-Pied combinations delighted many, with the hope of a future full Blue Pied being produced, I initially dismissed these reports as fanciful visions. However, I have since seen examples that have obvious blue colours being produced in scattered areas.

For someone like myself, who is interested in gene function rather than simply trying to produce a pretty bird, this new development causes a lot of concern. Grey genes invariably prevent all structural colour production. The gene is absolute in reducing the cloudy cell layer to non-functional status. This means grey alleles do not allow blue colour production to any degree when present in a bird.

So the problem has become not why does a pied gene produce a grey gene effect? But why does the pied gene produce a grey effect that does not work properly. And do not forget the unexplained effects on psittacin red pigments?

A New Type of Gene Action

A possible explanation has occurred to me whilst studying closely some Blue Redrump hens. Such hens have very little blue colour as a result of the dimorphism between the sexes. The wildtype Redrump hen is virtually a greygreen but retains small areas of green feathering, particularly on the edge of the wings. As a result the blue allele creates something close to a grey bird in the hen, but a beautiful blue colour in the cock.

Now consider the appearance of an Olive-Pied hen compared to a wildtype hen. The only effect of the olivepied allele, is the melanin disruption pattern, typical of any pied allele in any species. The areas of green colour evident on a wildtype hen are invariably covered with pied markings. All we see is a greygreen pied hen.

I am therefore going to propose that the true effect of the olivepied allele is not pied and grey, but pied and anti-dimorphism. I have already mentioned that the olivepied allele removes the cock’s red rump. I am now proposing that the greygreen effect is in fact a return to the body colour appearance of the wildtype hen. Along with the occasional scattered area of retained structural colour, which show only when the pied markings allow.

Therefore when we combine the blue allele with the olivepied allele we get a cock with primarily grey plumage and the occasional blue tinge, broken randomly with typical pied markings, no different in appearance to a hen of the same combination. All atypical features of the olivepied allele are explained in one simple answer. And unfortunately for those who see the possibility of Blue Pieds in the combined bird, there is no hope of ever increasing the blue colour beyond the occasional fleeting glimpse.

The Olive Pied Redrump allele is even more fascinating than first thought. It is the first known Anti-Dimorphism Allele.

But Not Alone

Whilst researching for this article, it was pointed out to me that some abnormalities have been described in Pieds by Jim Hayward (as mentioned above). Upon rereading his work, I was reminded about the difficulty that occurs in sexing Pied Cockatiels. Whilst I do not breed many Cockatiels, I am a Veterinarian and Pied Cockatiels are popular pets and therefore frequently presented for treatment at my Clinic. I have always found them difficult to accurately sex but never really thought about it further. Jim Hayward describes the features of pied in this species. Broken melanin pattern, reduced orange in cheeks, extended yellow through body. I will add a fourth - increased melanin in the facial area of cocks, unless broken by the pied gene. But wait, these last three features are not pied features, they are in fact hen features!

So now it is clear that there are at least two species with anti-dimorphism (ADM) pieds. No doubt more will be discovered with time, but obviously only in dimorphic species. I will propose this pied locus be known as ADM Pied locus, for want of a better term and for simplicity in naming across species. I acknowledge that this name is not appealing for the actual birds involved, but it is important that a consistent name be used when discussing the locus in different species so that the true nature of the genes being discussed can be determined. I already use the name UK Pied whenever I discuss the mutation in Australia as we also have an Australian Pied.

We now have a new class of mutation, probably the first in parrots that does not have a clear representative in the common Budgerigar.

Copyright: Terry Martin, February 1999

If you’d like to discuss this article or any other issue with Terry
he may be contacted at:

sbankvet@bigpond.com

Other articles by Terry Martin:

The nature of the Opaline locus

The nature of the Opaline locus - an Update

Defining and classifying Fallow colour morphs

Applying a scientific base to our understanding of Parrot colour morphs

Clive’s first impressions of the Pied Redrump

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