Thoughts on Clearwings
The October 1996 issue of Budgie Bulletin reproduced a 1979 article summarising the problems then recognized by clearwing breeders. This provided the stimulus to examine the changes that have taken place since 1979 which have affected clearwings. This background will provide the basis for further improvement to this variety and similar principles will be applicable to the other recessive varieties.
Two related events occurred early this decade. These not only drastically affected the future of the Australian clearwing, but impinged upon every other variety of exhibition budgerigar and are having a flow-on effect reaching even the backyard breeder. Firstly, the new budgerigar standard of 1990 challenged the breeder to aim far higher than the previous one of 1962(for the comparison see page 9 of the Standard published by the Australian National Budgerigar Council). Secondly, the arrival of the English imports significantly altered the characteristics of exhibition budgerigars in Australia.
The ideal clearwing should have the outline of the budgerigar(type) as currently depicted in The Standard, directional feather over the eye, clear wings and good body colour accentuating teh contrast in clour between body and wings. Good Australian clearwings have the clear wings and desired body colour but not necessarily the desired type, size or the directional feather. Good English clearwings have, as far as one can tell from photographs in the Budgerigar World, exceptional type and size but not necessarily the clear wings and contrast in body colour. The challenge for cleawing breeders is to add directional feather and combine the best features of teh Australian and English clearwing, especially clarity of teh wing since this is the feature that gives this variety its name. The ideal clearwing has not yet been bred but one is shown in the illustration on the front page of the book entitled The Art of Breeding Clearwings, by Malcolm Freemantle.
Theoretically, Australians could aim to breed this bird in two ways. The English clearwing could be imported and selected for wing clarity and body colour, with the aid of the occasional Australian clearwing outcross to introduce the needed modifier genes. Alternatively, the Australian clearwing could be repeatedly outcrossed to normals of English origin to attain the desired type and directional feather. This will be a painfully slow process since the clearwing gene is recessive and outcrossing to normals will continually introduce undesireable modifier genes adversely affecting wing clarity.
The task of incorporating all of the desired features of the ideal clearwing onto the one bird could even be far more difficult than this. The same genes required for type and feathering may adversely affect wing clarity and body colour and vice versa. This pehgenomenon of the same gene affecting more than one character is known to geneticists as pleiotopy. The breeders of the blackeyed yellows have a similar problem: the big blackeyed yellows have a green suffusion whereas the required buttercup yellow colouration is achieved only on small birds with narrow heads! Neither the large typey buttercup yellow blackeye nor the clearwing shown on the front of the Malcolm Freemantle book have yet been hatched. Perhaps pleiotropy is part of the explanation?
So what are the common faults of the current Australian clearwing? Small size is one fault and this can be corrected by outcrossing or simply breeding numbers and selecting the largest birds as the parents of the next generation. Poor head quality is another problem with manifestations such as protruding beak, narrow head and lack of feather over the eye. These features can be improved by outcrossing to good quality normals of English origin. Finally, heavy wing markings which appear to ba a feature of the English clearwing must be kept out of the Australian clearwing. Although muddy wings are seen on poor representatives of teh Australian bird, the desired clarity can be easily achieved by selection. The basic rules are that at least one member of a pair must have clear wings and the clearwing mated to the normal outcross must have clear wings. A bird with some degree of marking on the wings must be tolerated if it is bred directly from a first generation split. Dark tails seem to be correlated with heavy wing markings so any bird with a dark tail should be culled.
Perhaps this is the time to clarify the relationship between clearwings, greywings and blackeyes. These varieties are genetically allelic, arising from different mutations of the same gene. All are recessive to normals, with carriers(splits) the outcome of crossing to normals. However, clearwings and greywings are dominant to blackeyes(or stated differently, blackeyes are recessive to clearwings and greywings). Clearwings and greywings are co-dominant to each other: intercrossing gives full bodied greywings with features of both varieties(the wing markings of the greywing and the body colour of the clearwing). the three varieties(cleawings, greywings and blackeyes) are upgraded by outcrossing to normals in order to import features that are lacking. I know little about the fourth allelic variety, cinnamonwing yellows(not the same as blackeyed yellows), but do know that there is a light and dark form of greywing marking(with the darker wing dominant to the lighter wing) and there is a dilute gene which is expressed in only clearwings and greywings. Dilutes in either variety should go straight into the petshop and not be presented at shows; however, some say that sizable dilute clearwings crossed back to normal clearwings will clear the wings. The disadvantage of this strategy is that the dilute gene is inherited recessively and will further contribute to wastage in subsequent generations.
Before proceeding further we need to consider som common myths associated with budgie breeding. Myth Number 1 is that splits are necessary to maintain size of the lesser variety(eg., clearwings). Provided sufficient numbers of a given variety are bred and selection of the biggest offspring gives enough parents to maintain numbers in the next generation, then splits will not be necessary to maintain size. They will be necessary to maintain size to counter the loss of vigour associated with inbreeding if only small numbers of a variety are bred. the splits are ESSENTIAL however to IMPROVE a lesser variety by the introduction of genes not already present. this is how directional feather and improvement in type will need to be introduced into the Australian clearwing.
Myth number 2 is that the continual mating together of blues will lead to a loss of size and colour. The genes affecting body size and teh genes acting as colour modifiers would be identical in both blues and greens. There is absolutely no reason why anyone should not establish a stud of entirely blue budgies or even blue clearwings! What must be remembered is that blue is a mutation and therefore, on average, blues might be slightly weaker than greens and have less chance of taking out the major awards when competing with greens in shows. Since the majority of top studs are predominantly green, because they want to win, then it is logical to assume that genetic improvement might be faster in greens and therefore the breeder of blues needs to tap into this genetic resource by using greens from those studs as outcrosses, or paying a hefty price for the odd blue of high quality bred in these studs of predominantly green budgerigars. The astute clearwing breeder might recognize that since the primary faults in the Aussie clearwing are poor head qualities and small size, then chances of success with clearwings on the showbench might be slightly enhanced by breeding green rather than blue clearwings? Furthermore, avoidance of the dark factor, well known for adverse effects on size and head qualities, and loss of wing clarity in clearwings, might further increase chances of success?
Myth number 3 is that dark factor birds need to be used periodically to maintain good depth of colour. This requires some qualification since there is no genetic basis to the belief that the dark factor gene itself(expressed as cobalt or dark green) can impart colour improvement in light green or skyblue offspring. this would be in defiance of the established Menedelian laws of inheritance. The colour variation among sky blues and light greens is subtle by comparison with the variation in colour intensity that is readily observed among cobalts and dark greens(at least to my eyes). Only the use of those cobalts and those dark greens of exceptional colour, which carry the desired modifier genes for colour intensity, is expected to lead to the overall improvement in cloour of the skyblues and light greens in the next generation. this is especially relevant to the clearwing breeder who strives for contrast in colour between the wings and body. Dark factor birds may not take out the top awards as often as the light greens and skys, but their presence in an aviary can aid in selection of the desirable colour modifier genes which ultimately affect the overall quality of the clearwing stud.
Earlier I said that at least one member of a mating pair of cleawings must in fact have CLEAR wings and the clearwing mated to the normal outcross must have CLEAR wings. Despite these precautions there will be numerous clearwings with muddy wings produced from clearwing cross clearwing matings(these should be culled) and there will definitely be clearwings with muddy wings produced from cleawing cross first generation split cleawing matings. The best of these should be retained for mating to clearwings of good wing quality. In this way the features of the outcross will be gradually incorporated into the family of clearwings. Introduction of the desireable features of the outcross nbeeds to be gradual so as not to loose the modifier genes responsible for wing clarity. The improvement in feather and type will be a painfully slow process and it remains to be seen just how far this can go while maintaining the body contrast, and especially the wing clarity.
The existence of both MAJOR GENES and MODIFIER GENES needs to be understood in order to plan a rational breeding strategy for improvement to all varieties. The familiar monogenic traits in budgerigars are controlled by the Mendelian transmission of major genes. These may be sex-linked recessive(eg., opaline, cinnamon, ino), autosomal recessive(eg., clearwing, danish recessive pied, blue, blackeyed self, greywing, fallow) and autosomal dominant(eg., dominant pied, spangle, yellow face, grey factor, dark factor) and this is what many regard as teh genetics of budgerigars. However, the genetics of budgerigars goes far deeper than this. Polygenic traits, determined by the additive action of groups of genes of small effect, include the exhibition traits such as size, deportment, brow, depth of mask and spots, as well as modifications to the expression of the major genes mentioned above. These modifications to expression of major genes include wing clarity in clearwings, intensity of body colour in light greens, skys lutinos and black-eyed yellows, intensity of wing marking in greywings, clarity of the mantle in opalines, markings in spangles, banding pattern in dominant pieds, wing markings on recessive pieds, etc. All of these are controlled by modifiers,the many genes of small effect acting together. Superimposed on this polygenic variation could be additional nongenetic factors eg tendency for wing markings in clearwings to darken with age in the male sex.
Knowledge of the existence of modifiers perhaps can lead to a resolution of the controversy over whether the English Clearwing is the same mutation as the Australian Clearwing. Despite the fact that English Clearwings were originally derived from Australian Clearwings, based on photographic evidence Australians have a tendency to accuse the English Clearwing of being a Greywing. (See Budgerigar World April & July 1996, February & June 1987, March 1988 and October 1994 for further discussion). In actual fact, the two birds probably represent the phenotypic expression of the same major gene in different genetic backgrounds of modifier genes. the divergence was probably driven by different standards: The English judges rewarding type more than wing clarity but wing clarity carrying greater weight in Australia? the European standard for teh clearwing clearly states a dark tail whereas the Australian standard requires a light tail, which alone would acccount for much of the divergence. The additive effect of modifiers tends to blur the phenotypic boundary between the clearwing and the greywing if clearwing breeders fail to select against wing markings and if greywing breeders fail to select for more intense markings.
The crossing of greywing to clearwing is the subject of some controversy. A hypothetical greywing ancestor is often blamed for the loss of clarity of the wings in clearwings but this is rubbish! The greywing and clearwing variants of the same gene cannot somehow combine and cling together for subsequent generations after a mating involving a clearwing and a greywing: this would be in defiance of Mendel’s first law which describes the segregation of alleles. In reality, the loss of wing clarity in a clearwing arises from relaxed selection against the undesireable modifiers affecting wing markings. Although the greywing has nothing to offeer the clearwing breeder, use of the greywing would have no more capacity to pass on these undesireable modifiers than would any well marked normal used as an outcross. However, the clearwing does have something to offer the greywing and that is better colour than that possessed by the pure greywing. I would be interested in the views of greywing specialists bu judging from the sharp drop in quality (eg small dots, narrowing of head) that I observe among the normals which are first generation clearwing splits derived from a Clearwing X quality normal cross, then I would suggest that the clearwing gene would have a detrimental effect on type in any bird which carried it. Perhaps only the heavily marked clearwings should be considered for the production of full body coloured greywings? These represent a major source of frustration for clearwing breeders since they are often of a superior type when compared with the nestmates with the clear wings.
All my clearwings originated from an unrelated pair bought cheaply at an auction in 1993. The small green hen was split for blue with some wing markings and the sky cock was large for a clearwing with nice clean wings, which were slightly heavy in flight feathers. These produced sufficient offspring to begin outcrossing to English normals and to select for wing clarity. Some of the sons of this founder clearwing sky cock produced cinnamon hens, an unwanted complication. The sky founder cockbird was deduced as the source and perhaps this was why he was sold in the first place? the first English normal cock used as an outcross also, in hindsight, introduced more cinnamon! the aims at this stage are increasing the numbers to allow more stringent selection, improving type, improving feather around the face and head ( a major deficiency in my clearwings), maintaining wing clarity, maintaining size, eliminating cinnamon and making sure that the sex linked major genes cinnamone and opaline do not enter this family in the future. This can be guaranteed by outcrossing only to normal hens. Cinnamon clearwings are not sufficiently competitive to be exhibited with cinnamons, and are unattractive compared with normal clearwings. Similarly, opaline clearwings cannot compete with standard or cinnamon opalines, against which opaline clearwings would need to be exhibited. I do breed opaline clearwings but in a separate family of rainbows bred for visual appeal rather than exhibition.
The abovementioned English light green normal cock would be considered by many as a controversial choice for the first outcross (apart from the fact tht later it was evident that he carried cinnamon).He was also split yellow giving offspring when mated to another split yellow which are often erroneously referred to as greywing yellows. I have crossed these yellows on an experimental basis to clearwings and got all clearwings, so I don’t agree that greywing is in any way involved. Remember earlier that I said clearwings and blackeyes are allelic, with clearwing dominant to blackeye, will I think these large yellows with considerable green suffusion are basically big blackeyes(the major gene) but without the modifier genes which give the blackeye yellow that we see on the showbench that desired buttercup yellow. Anyway, this English split yellow crossed to my two best clearwing sky hens allowed me to breed three 50% English clearwings in one step, before he fell off the perch. The wing clarity in one of these birds was fairly good and the other two were retained because of their large size. All three have subsequently produced a proportion of cleawings with good wing clarity when paired to other clearwings with good wing clarity.
Alternatively, I would have needed to breed 50% English splits and then wait another season before backcrossing these to a clearwing to give me 25% English clearwings! I have been asked why anyone would want to cross Australian clearwings to English birds since we don’t want the type of bird which is called a clearwing in England. The answer is that we want the English outcross for type and feather round the face and provided that we do not overlook the need to select for the appropriate modifiers which determine wing clarity then outcrossing to normal English hens is the obvious direction to go if we want improvement to our clearwings.
Realistically, no Australian clearwing breeder expects to produce a grandchampion unless a show was restricted to clearwings and blackeyes. Both varieties represent a challenge to any breeder and the few who try would agree that the difficulties in breeding quality clearwings are second only to theat experienced with blackeyes. Once the odd good specimen is produced the real test is to increase their frequency and to then make further improvement to the variety. There are few sights in an aviary that can surpass that of beautiful sky, cobalt or violet clearwings with snow white wings. Greens or dark greens with the deep buttercup yellow on an unmarked background are not too bad to look at either.