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In this issue we will start to see how all the previous preamble relates to our birds. Even if you do not follow my reasoning up to this point you can still make sense of it all as the first two issues are there to explain the background for what is to follow.
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I have included another copy of the Gene Distribution Chart in this issue for your reference. Basically if you recall a bird has two halves: that which it received from its father and that which it received from its mother. These two halves blend in well with each other, and give you a bird that looks a little like the father, and a little like the mother. For example a parent with a large head and a parent with a small head gives you chicks with medium sized heads. Or a large bird and a small bird gives you medium sized birds. The main point is that you do not get half of the chicks small and the other half large but instead the chicks are a blend of the parents.
This cannot be so when we talk about colour. By this I mean that if you breed a blue budgie to a green budgie, you get either blue or green. The whole purpose of this set of articles is to explain how and why. This is what we will be concentrating on in this and all the following issues. As we all know, when two different coloured birds are bred together, we only get one colour or the other in the chick. A normal zebra finch and a pied will give you either normals or pieds or even a colour dissimilar to both parents. A normal cockatiel mated to a white-face gives you either normal or white-faced. This is where the words “Dominant” and “Recessive” come in.
Almost anytime these two get together the dominant one wins. Notice I said “almost,” because there are occasions when the recessive colour wins. This has to be, because if the recessive always lost then we would end up with only dominant colours. Indeed this is exactly what happens in the wild. 99.9% of all wild budgies, zebra finches, cockatiels, peachface lovebirds or any birds are normals. Whenever a new mutation appears out in the wild, and they do regularly, they always lose out to the dominant normal when they breed. This is, of course, if they breed. Nature wants all wild birds to stay normal for uniformity and protection. A yellow budgie in a flock of green birds stands out for the predator to notice.
One other note here is that almost all non-normal birds in the wild are as a result of a mutating gene, and not heredity. There have even been reports of different coloured house sparrows outside in our neighbourhood from time to time. These are a result of a mutation, but because it does not survive, or if it does not have another bird with the same gene, with which to bred with, the colour mutation is hidden in the next generation. Chances are the mutating process will happen on different occasions, but on so few and far between opportunities that two birds never get a chance to meet. Except in captivity.
In captivity it is a different story as we are there to protect the bird. We also can allow it to breed with its parent, or sibling, or its children to give it that help I referred to earlier in this issue. This is where we get into “line breeding” and “inbreeding” (but that is a topic for another series of articles).I would now like to draw your attention to Symbol Legend (Figure #2) to explain the symbol we will be seeing in the remainder of this series. We have two square boxes attached to each other to represent a bird. The box on the left is the dominant half and the box on the right is the recessive. The dominant colour will be the colour that the bird actually shows while the recessive colour is hidden inside.
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Box 1. shows both sides filled in, which means that the dominant colour is on both sides. This bird has no recessive traits.
Box 2. has dominant on one side and recessive on the other. This bird looks identical to the 1st. except that it has the recessive gene hidden inside.
Box 3. has no dominant but both sides have the recessive colour.
This is the only time that you can actually see the recessive colour visually. If the dominant colour is a green budgie and the recessive a blue budgie then box 1 and 2 would be green and box 3 would be blue. Remember to take this series one paragraph at a time.
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We now move on to the Dominant & Recessive Chart and see some results. In this chart you will find parents on the left of the arrow and offspring on the right. Remember from the Key Point to Remember of the last section; that there are only four different ways that the X X genes of the cock and the X Y genes of the hen can combine. That is why we have only four boxes for the offspring.
Row A: Here we have a dominant parent (light green) and a recessive one (sky blue). The offspring are all half dominant light green and half recessive sky blue, but since green is dominant, the chicks will all look green and carry the blue hidden.
Row B: In this scenario, we have two parents both showing green and carrying the blue. When you put the two dominant halves (light green) of each parent together you get a pure green bird with no blue in its makeup. This is the first box. When you put the dominant of each parent with the recessive of the other, you get a green bird carrying blue. There are two different chances for this as shown by the two centre boxes. Notice all the chicks have been green so far. In the last box we find the blue of each parent combining together with no green in the makeup. This would be a visual blue or recessive bird. This bird has no green in it at all, and it is the same as if it was bred from two blue birds. In this row we say that 25% of the chicks are dominant, 50% are dominant/recessive and 25% are recessive. (the “ / " is an international symbol to mean “split for” or you can say “dominant split for recessive”).
Follow the same logic for rows C and D and see what you end up with.
Row E represents two recessives which give you 100% recessive young. An example would be two recessive sky blue budgerigars giving you all sky blue young. This recessive to recessive mating cannot give you a dominant colour.
Row F shows the result of two pure dominants which are 100% dominant. This example would be two pure normal cockatiels giving you all normal young. This pure dominant to pure dominant cannot give you a recessive colour. Please note that in the dominant to recessive relationship, it does not matter which is a cock or which is a hen.
KEY POINTS TO REMEMBER:
1. If a bird has a dominant colour in it, it must show it.
2. Two recessives cannot produce a dominant.
3. Two pure dominants cannot produce a recessive.
4. It does not matter which bird is a cock or which is a hen when considering dominant to recessive relationships.
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Genetics 
