Is there a genetic component to this? Could I start a program to increase the breeding ability of my flock?
Answer: The infertility of the exhibition budgerigar has two possible components:
In your own particular case, since your fertility with smaller wild type budgerigars kept in your aviary has proven almost 100% successful, then one has to say that you have already tested the conditions under which you are keeping budgerigars - you are doing it right. If you now find that exhibition budgerigars, kept in the same conditions, show a marked reduction in fertility, then one must say that the budgerigars themselves have poor fertility. This raises the question: "Why".
The budgerigar is an ancient species which has been in existence with little change for many millions of years. The species admirably lives in harmony with its environment in Australia, and thus its genetic composition has been honed over the years to perfectly satisfy the survival of the species as a whole, through feast and famine. Exceptional fertility is one of the keys to success of the species. I am sure the readiness of the budgerigar to breed in captive conditions, coupled with the many colour mutations which have been developed, were the basis of the popularity which budgerigars had in the past. In seeking to improve the exhibition qualities of the budgerigar, breeders have increased the size of the budgerigar to between 25% - 50% the size of the wild type. It is a fact that as size increases the body volume to surface area ratio increases. eg., a mouse has proportionately more skin than an elephant. Since the body temperature of a budgerigar must be accurately maintained at a specific temperature, small birds need to generate sufficient heat, and this is derived from muscle activity many small animals and birds are more active than their larger cousins. The metabolic rate of small birds is high and they need to feed regularly to supply the energy for muscle activity. As the increase in physical size has been selected by budgerigar breeders, the ample food supply offered to exhibition budgerigar, which are confined to small breeding cages, means that the need or opportunity for much exercise is removed, and most exhibition budgerigars are carrying fat supplies which wild type budgerigars do not possess; fat budgerigars cannot fly well and thus they take even less exercise, this slows down the metabolic rate of such birds. A highly active exhibition type budgerigar is more akin to the wild type and will therefore metabolise at a higher rate than a fat docile specimen and will be more likely to have normal fertility.
With the increase in physical size of the exhibition budgerigar, there has also been an "improvement" in feather "quality" - I use quotation marks because I wonder what the budgerigars themselves might have to say on the subject! The wild type budgerigar has sleek, tight "yellow" feathers, which allows excess heat loss and makes the bird streamline in flight, whereas the "buffquot; feathers are a thick layer of insulation which prevents heat loss and must make flying very difficult. The non-yellow feathered specimens are therefore likely to take as little exercise as possible in order to prevent overheating, which will slow down the naturally high metabolic rate. To be brutally honest, the modern exhibition budgerigar, with all its "improvements" does well to survive, let alone reproduce. (I'm not going to make myself popular with this - but I must admit though, the best specimens do look nice). It seems that poor fertility is now a feature of the modern exhibition budgerigar and the considerable change from the wild type is most likely to be the cause.
However, having said that, there are many good exhibition specimens that are very fertile, and some studs seem to have greater fertility than others. In such cases, I suspect that the stud owner has been quite ruthless in culling specimens which fail to perform in the breeding cage. It amazes me how some breeders will persevere for several seasons with birds which display infertility or low fertility - they are making their own problems for the future. Many breeders use so many additives and hygiene products that their birds must be poisoned to some degree which may also affect fertility.
Trimming the feathers around the vent must help contact between male and female during mating, but the problem of infertility is not necessarily related to the act of copulation, it is more likely to be one of low sperm count. In most mammals, the testes lie outside the body, and as a consequence, they are kept at lower temperature than the core temperature, this maintains sperm viability (as does chilling or freezing sperm). In the case of male birds the testes are within the body, and therefore any slight increase in core body temperature above that normally found in the wild type ancestry, will reduce sperm viability - spermatogenesis is a very delicate process. There is no specific fertility gene, because fertility is determined by the interaction of many different factors; some genetic and some environmental.
It would be possible to commence a programme to improve the fertility of your stud, but since you are relatively new to exhibition budgerigars, and you have not spent many years developing your own strain, it would be far easier to determine which of your birds have the best fertility, besides being the best exhibition specimens; to purchase more birds from the same source(s) and you should then have a good foundation for the future. If you keep good breeding records, you will soon be able to establish which of your foundation birds are the best breeders, and since the best breeders produce the most offspring, you will then have greater choice over which birds you should retain for future breeding.
Many breeders use their birds in the breeding cage for just one season, then dispose of them, using the offspring as the breeding stock for the next season, and so on; htis is folly. It is far better to use a good fertile bird for several seasons, pairing it to several different mates, so that you have many related offspring - you can then select the "cream" of the offspring and either intermate them, or mate them with other birds within your stud. Within a couple of seasons you will have many birds all having very fertile ancestors.
Provided you always ruthlessly cull your stock, you will reap the rewards later, because fertility is as much a feature as is buff feathering, and both features can be selected. On the other hand, if you start out just hoping that your birds will breed, and you get satisfied with poor breeding performance, but at the same time you produce a few nice birds, you will find it soul-destroying when you have just a few gorgeous birds that will not reproduce - because you will have to go back to square one then.
Once you have developed a very fertile strain of exhibition budgerigars, although they may not be good enough to beat the best birds from other breeders, you can then purchase individual birds from other breeders which excel in one or two features. If your selected imports are mated with your own stock in the first season, then the offspring of the imports, which display the features of this bird, are mated back to your own stock, you will quickly improve your stock, whilst at the same time preserving fertility. In this way you will progressively improve the standard of your own stock. When you decide to import new birds, do not introduce more than a couple at a time, so that you can maintain your own gene pool and slowly change it, rather than completely mixing it with many "unknown" genes. I hope I have answered your question, but if I can clarify any more please ask.
Editors' note: I regret that Dr Pilkington is unable to answer any further questions.
Original text Copyright © 1998, Dr John Pilkington
Budgerigars Galore Homepage | Contents Index | Beginners | Breeding | Breeding Charts | Diseases | General Interest | Genetics | Links | Management and Nutrition | New Zealand News | Noonan Aviary | Popular Varieties | Rare Varieties | Show Preparation | Specialist Varieties | Tips
Web page copyright © 1999, Dolores Noonan. All rights reserved.
Designed and created by ArcadiaWebSite Design.