Predictability or Adaptability?
The Controversy of Diversity?
Line-breeding, a form of in-breeding where carefully selected related birds are chosen to breed to each other, has been practiced for centuries, with varying results. The last century has brought much new information to add to the accumulated years of experience, but that has done little to settle the many and often heated discussions on
Go to any bird show and listen, and it will probably not be long before you begin to overhear varied snippets of conversation centering around breeding winning showbirds.
This is a favorite topic at shows, and you will find that there are as many different proponents and systems as there are birds at the show. Yes, I said birds, not people. It’s been my observation that many of the people at these events tend to hold several systems dear.
A newcomer to the Canary Fancy can become incredibly confused in very short order listening to all these (many conflicting) ideas and methods, particularly if they are looking for advice on buying a breeding pair.
I try to tell anybody who asks, to listen to everybody, at least to start with; sort through all the advice and categorize it, then apply that good old yard-stick, common sense. Any one approach or technique that everybody agrees on probably has a lot of validity, for example. On the other hand you always have to watch out for that old boogey-man, the ‘old wives tale.’
Line-breeding is a fairly commonly approach to breeding show-quality canaries. There are various methods for producing the desired goal, but they all have the same aim; to produce a strain of related birds who look and act as much alike as possible.
Ideally, you would choose anywhere from two to six or eight top-quality birds to begin with. These birds should all display the physique, colour, and temperament you wish to propagate. These birds are paired up to produce offspring which will in turn be paired together.
Each generation of offspring is heavily culled of any birds which do not display the desired characteristics before again being bred to each other. Some sell such culled birds as pet stock, others put them down. Many systems also advise crossing back to one of the ‘founder birds’ on a regular basis.
Why this produces more predictable offspring is because of the fact that this approach will directly reduce the diversity of the genes. The birds grow to be more and more reliably similar over the generations because they each carry more and more identical genetic coding.
What many proponents of such a system often forget to mention, or perhaps they do not know, are the problems which can accompany such an approach to breeding.
Genes are composed of an incredible amount of chromosomes, which govern the traits of the living thing which contains them. When the chromosomes are fully diverse, in other words, each is different than its neighbour, the genes are able to carry the codes for a vast number of traits and abilities, some expressed, some not.
It is well known to food-crop husbandrymen that if you reduce the amount of genetic diversity the species is carrying, you will also be losing an unpredictable and unforeseeable amount of adaptability and, often, quite a lot of disease resistance and hardiness.
Canary breeders can often be found who stress the idea that since show stock is so expensive, you will want to see that you get the greatest possible production out of any birds you might buy. Often line-breeding is quoted as proof that the pair will reliably reproduce themselves; the babies will be as similar as possible in size, colour, and type to their parents.
Well, that is true, as far as it goes.
It is at times like this that a basic understanding of genetics and how it works comes in handy. Many’s the person whom I’ve overheard saying, ‘Oh, genetics is too complicated for me, I don’t understand it.’
Well, okay, genetics is a subject with an incredible range of possible complexity, that I will grant you. But if you look at it awhile, it will soon become clear that the basic premises are actually quite simple.
I like to compare genetics with chess.
In chess, there is a finite number of defined moves, possible in limited and qualified ways. It is in combination and in interaction that the moves acquire their complexity.
It is the same with genetics.
Birds who carry many similar chromosomes, as is true of most line-bred stock, will hatch out very similar to each other as well as the parents. It is also usually true that these birds will all tend to be susceptible in the same degree to the same diseases, and that they will all have similar levels of resistance to any other problems which come along – average levels often markedly lower than that of more genetically diverse stock.
Diversity of the gene pool gives rise to higher levels of diversity in the chicks, resulting in more variation in colour, body shape, and expression of personality. The babies from one nest may look and act quite different from their sibs and their parents when adulthood is reached. Often many will not be considered fit for the show-bench.
What I find many people forget to include in their calculations is that many of these birds will tend to be hardy specimens and very good breeders, and will be perfectly acceptable as pets or breeding stock, if carefully mated. Those (admittedly fewer) babies produced which are good enough to show will be as strong and healthy as their less showy siblings, and will usually stand up to the rigors of stress and adversity much better than their ‘hot-house flower’ cousins.
It has been my observation that if careful notation is kept of the ancestry and outstanding characteristics of each chick and its parents, it is possible to get up to 50% predictability of the young a bird will throw when adult, considered in combination with their mates.
Let’s take a simple example. A dark hen bred to an evenly-marked male might throw 2 darks, 3 mottled variegates, an almost evenly-marked variegate, and a clear over two nests. The mates for these babies will come from a clear bird mated to an evenly-marked variegate; the babies were mostly variegate, with one being 3/4ths dark, and two clear.
Pair one takes a clear bird from each nest. (We are pretending for now that they have complementary feather types.) You can reasonably expect to get about 50% clear or lightly ticked babies from this pairing. The rest will be mostly variegates, ranging from lightly ticked to almost fully dark. You may even see a self, or all dark bird, particularly since there is one within two generations of the chicks’ lineage.
Nest two pairs one of the dark birds from pair one with the 3/4 dark from pair two. Here the babies should be about 50% dark, with about 25% of the rest being fairly heavily variegated. Here again, you will see the odd lightly-marked or even a clear bird, but most of the offspring will be dark.
Nest three pairs two of the variegates, and once again the results are fairly predictable. About 50% of the babies will be variegated, and the other 50% will be split fairly evenly between birds that tend to be either heavily dark, or most if not all light.
Nest four pairs a all-dark bird to a all-light bird, a match most will say should not be done. If you are speaking of a inter-breeding two birds from two completely different lines or breeds, this is usually true, but in this case both these birds have both all-dark and all-light birds in their direct ancestry, on both sides.
This is a fun pairing, for me, as I have often found nests of this sort to produce both fully dark and totally light babies in even amounts. I love to show people a nest with two dark babies and two clear babies, and see their faces when they realize that all four babies are full blood siblings.
You can probably imagine enough by now to continue the theoretical matchings by yourself. Besides colour, you can affect song, breeding traits, conformation, and many personality traits.
One delightful result of promoting genetic diversity in your stock is the increased chance of seeing a new mutation, remote though it still is. But with a truly diverse gene-pool, almost anything can (and does) happen.
Remember that percentages are based on averages out of a hundred. Since you will rarely if ever get a hundred babies from a pair, the odds can give you two ‘long-shot’ babies in the first nest. It may be years, however, before you see that particular mutation again if you are not careful to preserve its presence. Take the time to study your birds and their traits, too; that way you will be better able to spot a potential mutation.
The possibilities grow more complex and varied as the diversity of the gene pool is expanded; the sky is literally the limit!
So enjoy your birds, and remember one of the first laws of nature; infinite diversity in infinite combination!
Flock Talk 36
by R C ‘Robirda’ McDonald
copyright (c) 1995-2002
* A version of this article was published in Bird Breeder magazine in spring 1998