The Process of Demonstration
The remarkable progress of domesticating many raptor species in the 1970s and 1980s is a process which will continue to unfold (see 8.5). Currently, in the mid-1990's, most breeders are quite happy to breed what they can. Some state-run projects are deliberately breeding the offspring are wanted for release to the wild. Some breeders are content to breed what they have; the offspring are only wanted for falconry and, once a particular pair are breeding, it is a pity to split them up. Other breeders are selecting for particular traits. For example, certain lines of peregrine which are renowned for waiting-on are selected for game hawking. Physically and genetically they appear standard, bit when flown they have a marked tendency to go up. Some breeders are looking for size; they put together large Aleutian Peale's peregrines or big Finnish goshawks. Others are selecting for speedy bloodlines. This process is bound to continue and in the next twenty years certain bloodlines will come to prominence for these reasons.
Some breeders are taking matters one step further by making intersubspecies hybrids and, in some cases even intergeneric hybrids, such as a Cooper's hawk crossed with a Harris hawk (see 8.4). Most of the wider outcrosses are very different genetically and in the long-term will be sterile. Others, such as the gyr/saker, are very closely related, appear perfectly fertile and perhaps throw new light on our understanding of the taxonomy of these groups. Among falcons, second generation hybrids are now common. For example we fly a lot of gyr/saker x saker. We also fly a gyr/peregrine x New Zealand falcon. The Domestic Falcon Falco domesticus is just around the corner. This is falconry's equivalent of the racing pigeon and the domestic poultry breeds.
Many purists will hold up their hands in horror at all this, but the story is far from finished. Once the breed stage is reached, there is then the question of open and closed stud books. This stage happened in Europe over the last two centuries with many of our horse and dog breeds. It was a somewhat haphazard and very interesting process developing, for example, the thoroughbred horse and the English pointer. Our forebears added a little of this and a bit of that to the recipe until they reached the type they wanted, then they closed the stud book and started breeding true lines. Nowadays one can only alter the English pointer by selecting from registered animals. If one decided to add some setter blood for example, the offspring would be classed as mongrels and would not be registerable. Insofar as this maintains the genetic integrity of the breed, the closed stud book is a good thing. On the other hand it means that the main evolutionary development of the breed is now over and that the breed is restricted now to the limited gene pool it originally started with. If this was large, well and good. But if it was small, the breed will gradually become more inbred through the generations.
It will be some time before this stage is reached will raptors. It has been exciting meeting the challenge of domesticating birds of prey and it will certainly be interesting to watch the bloodlines emerge. For this to happen there has to be selection pressure. In race horses this is competitive racing. In hunting dogs this is fieldwork and competitive Field Trials. In show animals it is Show Standards (some of which are really grim). Field Trials are in many ways a good idea but they suffer from two problems; one is that they measure the training of the dog more than its genes. The other is that they have closed down the uses of the dogs into very tight stereotyped patterns, such as retrieving, based largely on shooting (they are now called gun dogs). This neglects other aspects of the dog such as how long their potential working lives are, how easy they are to train, how good they are with children, how easy they are to live with, and so on.
In raptors, the selection pressures are a little different. The first one is whether or not they will breed at all. For example we have a pair of gyr/sakers here which laid twelve eggs this year and produced twelve chicks. Every fertile egg this female has ever laid has hatched. We have other pairs which have never laid at all. Once the chick has been reared, it then has to be evaluated in various ways before the decision is made to breed from it. We measure it, we train it and evaluate its hunting performance for the type of flight it is intended for, we assess its mental suitability for breeding, we look at its pedigree, and sometimes its DNA profile, then we look for a suitable mate for it and calculate the coefficients of relatedness to see if they will maximize the genes we are selecting for. Most breeders are unable to do this because of the economies of scale. They will be led to some extent by market forces. What sells well is obviously desirable. Unfortunately it is also sold and therefore out of the breeder's hands and not available for breeding. We get round this in two ways: one is that we lend out birds to other falconers and then call them back in once sexually mature. In America, and now in Spain, there are competitive Sky trials which to some extent test the ability of the birds. I am against Sky trials because they degrade the sport of falconry into a competition between raptors between their owners, and because it gives the public and young falconers the idea that falconry is all about releasing bagged game (see 8.9).
At present we don't have Breed Societies. Falconry clubs tend to be based on geographical area rather than breed. But a Harris Hawk Society may not be far away. Harris hawkers tend to be a sociable lot. There will probably never be a Goshawk Society. People who fly goshawk end up antisocial, introverted, stubborn, sensitive, and have generally used up all their patience on their birds . . .
Having looked at breeding from an overall perspective, we are now in a position to look at evaluating the bird, breeding from it and raising good youngsters.
The Genetic Assessment of Pairs
From the start you should have a clear idea of your general breeding plan, based on factors discussed in 8.5 and 8.6. You will know whether you are trying to maintain the widest variety of genes or whether you plan to intensify certain genomes by line-breeding. Therefore you need some information about the genes which your birds carry.
The traditional way to do this is to use a pedigree (figure 2.2.1). This will show the ancestry back several generations, perhaps even to founder stock. It may also give additional information which is useful, such as how the bird was reared and who bred it. The pedigree may also link up to a computer stud book such as SPARKS. Pedigrees are simple and basic to a breeding plan. Surprisingly few people buying a hawk show the remotest interest in its pedigree. This will change in time as purchasers become more discerning.
Fewer people still know how to use a pedigree. It is not enough just to look at the pedigree of your new hawk and say, Oh look! Her grandmother was The Galloping Gourmet - she must be good! What if you are planning to put two birds together as a pair, and you can see that they have one or two shared ancestors in their pedigree? How do you calculate how related they are?
Genetics unfortunately tends to be 90 percent theory and only 10 percent reality. Let's look first of all at what relatedness means. Let's start with two gyrfalcons, one from Alaska and one from Greenland. So they must be unrelated. Wrong. Of course they are related or they wouldn't both be gyrfalcons. The question is: how related are they? Human beings and chimpanzees for example share 95 percent of their genetic material. They are almost the same! We are all related to some extent and so we need to assess what this background level of relatedness is.
When two parents breed together, each donates had its genes. We can say therefore that, on average, the relatedness between parent and child average, is half (or 0.5 or 50 percent). The same applies to siblings: a brother and sister are 50 percent related, (except identical twins, which are 100 percent related.). The background level of relatedness lies somewhere between this close relationship of 50 percent and zero. In a genetically diverse population the background level of relatedness may be as low as 15 percent, but in a bottlenecked population it could be over 40 percent. Therefore we cannot say that our founder birds are unrelated, that they have a coefficient of relatedness of zero.
For the sake of simplicity, SPARKS, and similar studbooks assume that founder birds are unrelated. The only way to find out what the background level of relatedness is, is to profile the DNA and calculate it. This is what we had to do with our New Zealand falcon program. We had to trap wild falcons from all over the breeding range . . . . . |
