Is it a Pied? – what sort of Pied?

As more and more mutant colour varieties occur in an ever increasing number of species, it is no surprise those varieties we recognise as belonging to the pied category should also rise. In step with this, within the pied category, we notice an widening range of variability and it becomes increasingly difficult in some instances to decide whether a variety should be described as pied. What was once a simple matter becomes more complex and, in the absence of an agreed view of what characteristics define piedness, differences of opinion arise with one ‘authority’ proclaiming a variety to be pied and others begging to differ. Some characteristics which appear to be unique, and are not encountered in other colour forms, add to the confusion.

At one end of the spectrum there lie varieties where loss of melanin produces large clear areas, following a distinctive pattern and making them instantly recognisable as a particular pied form. The clear areas range from yellow in the natural form, through pale yellow or ‘cream’ in the parblues, to white in the true blues. Typical of this type is the Australian Dominant Pied budgerigar. It is important to remember, though, that even these do show quite wide variation and the pied areas are random in their spread and not delineated by any natural patterning of the normal bird. However, pied areas are almost invariably sharp edged and do not blend into adjacent normally coloured areas gradually.

At the other end of the spectrum are those birds where only a few feathers are affected and it may be difficult to decide whether this is inherited, due to disease or environmental deficiencies, or even post-fertilisation genetic change. Sometimes melanin loss is seen in the central region of the feather, but this should not be taken to mean that other forms sharing this feature are pieds.

Random spread

It is the factor of random spread which is the first characteristic to make me doubt whether George Smith, in an article in the Parrot Society Magazine of May 1999, is justified in suggesting that the Clearhead* and Cleartail** Indian Ringnecks should be regarded as pieds. In both these, the clear head is sharply delineated by the neck ring and his view is not widely shared. The essential randomness associated with pieds is not evident in these two varieties in which the patterns of colouration are quite uniform between individuals.

In addition the clear area spreading up from the tail of the Cleartail into the body areas blends quite gradually into the normal body colour. Again, this is not a feature normally associated with piedness.

Although there is no formal definition of what constitutes a pied, this does show that most of us have in our minds eye a ‘picture’ of what is, and what is not, a pied. The criteria may not be articulated but we classify almost by instinct.

As Deon Smith of South Africa has pointed out it is interesting to view the head area of the Ringneck in the context of other members of its genus. In many of these the head, defined by the neck ring, is a different colour to that of the body either in one sex or in both. It is tempting to believe that the capacity to achieve this is, so to speak, ‘hardwired’ into the biochemical pathways of members of this genus; requiring activation of a single genetic ‘switch’ to set in motion a sequence of changes to pigment production that may involve melanin, psittacin, and perhaps even the cloudy layer. Changes which do not affect the rest of the body area and also reflect the sexual environment in which they occur.

In many ways this is reminiscent of the Opaline varieties which have so far only been confirmed in Australian parakeets, pointing to their sharing a common origin, although the new Rose-headed PF Lovebird appears to share some opaline characteristics.

The mere fact of a change in the distribution of colour, an alteration of the distinctive patterns of colour, does not of itself indicate piedness. For this also occurs in Opalines as well as in the Clearbody budgerigar.

Complete melanin suppression

Another factor which appears to be common across all the pied varieties is that there is no melanin at all in the clear pied areas. This is not true of the Ino varieties which, although considered to be pure yellow, or pure white, or somewhere in between, nevertheless do contain remnant traces of melanin giving them a characteristic ‘sheen’ or suffusion of green or blue. I strongly suspect that the clear heads of the Indian Ringneck varieties under discussion also contain these small amounts of melanin and consequently also fail this test.

Avian biologists and others make use of their own classification system for describing aberrant colour forms, or morphs, encountered in the wild. Developed from that originally used for mammals it has grave limitations when applied to birds which, generally speaking, have a more complex array of colour forming pigments and structures. However, as applied to the eumelanin found in parrots, it does distinguish between albinism and what is known as leucism. Albinism, even when complete, is recognised to leave remnant traces of melanin, whereas the different metabolic processes of leucism prevent any melanin at all being produced. Under this system a pied bird would be described as partially leucistic.

These two factors, random spread and complete melanin suppression, are both distinguishing characteristics which could form the basis for an attempt to define the features common across all pied varieties. Below, I put forward a tentative outline of thoughts on the subject and a list of the descriptive terms that might be used to separate the many types of pied birds now being encountered. These descriptive terms are not intended to be mutually exclusive. Any pied form might merit more than one of these descriptions; which should be seen as a quick way of conveying some of the characteristics of that particular pied variety.

Some of the descriptive terms introduce us to a dimension not normally considered in relation to other varieties; the concept of colour change through time. However I do not believe this should be seen as exclusive to pieds for this occurs as part of the maturing process in many species.

Characteristics of piedness

Variably sized, generally sharply edged, clear areas of plumage completely devoid of melanin; coloured only by psittacin pigment where this is present (note that blue, or its derivative green, is only seen where background melanin is also present). The pied areas may be quite large and situated fairly specifically in a recognisable though very variable pattern, or they may tend to be individually much smaller and scattered almost entirely haphazardly. Tissue underlying pied areas lacks melanin and this may also apply to beak and cere, legs, feet and claws.The appearance of the eyes may also be affected in various ways, sometimes becoming plum coloured or losing the typical iris ring.

Certain pied areas, including a variably sized spot at the back of the head, some or all of the flight feathers, and perhaps the central tail feathers, appear very commonly across many pied varieties. Even where pied areas are small and haphazardly placed there is a tendency for those on the body to cluster around and toward the head and neck, the upper chest, and the mantle.

Although piedness typically affects groups of feathers, it may also occur in individual feathers as clear areas on feathers which would otherwise be normally coloured.

Descriptive terms

In view of the wide range of characteristics encountered in the different pied forms it would be useful to have a number of recognised terms to aid in description. The following are either already in limited use or offered as suggestions:

delayed: in an individual; piedness is not apparent in nest feather but becomes evident at the first or a subsequent moult.

progressive: in an individual; the degree of piedness increases over a number of successive moults.

regressive: in an individual; the degree of piedness reduces or even disappears over a number of successive moults.

regular: in an individual or strain; piedness follows a recognisable though variable pattern and is broadly symmetrical.

irregular: in an individual or strain; piedness appears random, is not symmetrical, and it is difficult to discern any pattern.

incremental: in a strain; piedness tends to increase with each subsequent generation even, it is reported, to the extent that completely clear yellow or white individuals may occur. (To what extent this is a natural process or how much it owes to selection, of the most heavily pied or attractively marked individuals, for breeding purposes is not always clear.)

colour enhanced: there is an enhancement or subtle intensification of psittacin colour, or of body colour (green or blue), or of both, leading to an extra brilliance of plumage in those areas not directly affected by piedness. (This is also seen in some other varieties and is not exclusive to pieds.)

anti-dimorphism (ADM): as a separate and distinct process from the pied process, but initiated by the pied gene, males lose their distinctive feather colour or patterning (i.e. the neck ring in the Ringneck, body colour in the English Pied Redrump), and resemble the female. (This process was recognised and the descriptive term suggested by Terry Martin of Brisbane, Australia.)

The neckring

 * Clearhead: commonly known as the ‘Buttercup’.

** Cleartail: commonly known as the ‘Yellow-head Yellow-tail’.

Copyright: Clive Hesford, August 2000

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