Gouldians - Who? Why? Where to?

Convention dictates that at this stage of an article on Gouldians I should be letting fly with various descriptive adjectives in an attempt to do justice to the bird's obvious visual appeal.  Then perhaps I should divulge the recipe of some special brew guaranteed to induce all your hens to lay double-yolkers.  To prevent the obvious epidemic of egg-binding which would ensue, I'll refrain.  No, this is not your typical feed'n'breed story.  I'm more interested in bigger picture stuff - Who are we? Why are we here? What does the future hold?  I want you to consider these questions from the Gouldian's perspective.

In order to examine these questions we need to first note certain facts regarding the Gouldian's genetic composition and population status.  In relation to head colour, the basic genetic situation is that blacks are recessive (sex-linked) to reds and yellows, and yellows are recessive (autosomal) to reds and blacks.  Given this, one would think that reds should comprise the overwhelming majority of the Gouldian population (wild).  Past accounts of trappers, dealers and breeders of yesteryear indicate that when the wild population was much larger than it is today, the general composition of the species was an overwhelming majority of black-headed birds with a much smaller proportion of reds (about 1 in 10) and a very small proportion of yellows (about 1 in 100 or less).  Given the heritability of the various head colours, these crude population figures tell us that other factors are distorting the population away from what would be expected.

Let's now make some unrealistic assumptions.  Assume we have a population of Gouldians with reasonable numbers of each head colour.  Now assume this population were to breed prolifically over a large number of generations and that each head colour had the same chance of survival.  Under these assumptions, after many generations we would undoubtedly have a population which comprised proportions of the head colours which roughly equated to the genetic heritability of each head colour.  i.e. A dominance of reds, a much smaller proportion of blacks, and an even smaller proportion of yellows.  Given that this is not the case, our assumptions are obviously the key to identifying factors affecting the real population status.

We have assumed that we are starting with a population comprising reasonable numbers of each head colour.  The various head colours are merely mutations of the other head colours, which implies that one colour was the original form from which the others mutated.  We cannot be certain of which was the original one.  For example, to think of the black as a sex-linked recessive mutation of the red may be taking a blinkered approach - it is equally possible that the red is a sex-linked dominant mutation of the black.  In fact, it could plausibly be argued that this is the case given that blacks are more numerous.  It may be that red is a relatively recent mutation of the black which has not yet had sufficient time to breed for the number of generations required to dominate the population.

The yellow is more difficult to place in the order as its low numbers can be attributed to either: (a) It is well established and its breeding over many generations has led to its low heritability translating into a low population; or (b) It is a relatively recent mutation of one of the other colours and this combined with its recessive inheritance led to its low numbers.

In our unrealistic model, we also assumed that each head colour had the same chance of survival.  At least in terms of predation, this is most unlikely.  The population breakup tends to indicate that it is likely that black headed birds may be afforded better camouflage than are reds or yellows.  Another possibility is that there may be some inherent weakness in red or yellow birds compared to blacks.  If the strength of body colour is any indication of physical vigour of the bird then this may be so.  The body colour, on average, of captive blacks is noticeably superior to that of reds and even more so of yellows, although this may simply be proportional to the amount of melanin in the plumage.

After examining all of these points it is difficult to draw any obvious conclusions. But for what its worth I'll have a go.  I believe that the black was the original Gouldian from which the red recently mutated and from the red, the yellow resulted.  A combination of lack of time and some environmental advantages of the blacks led to the disparity between the genetic possibilities and the real population makeup.  I have heard that more recent accounts from Gouldian researchers reveal reds are comprising a higher proportion of the current (diminished) population than was the case 30 - 50 years ago.  Perhaps this is the red's genetic advantage coming to the fore.  We can only hope the species will be around long enough for future generations to document what comes next.

Back to top

GRAHAM AND LEONIE BULL l COFFS HARBOUR, AUSTRALIA