Breeding Fostering
Using Foster Parents to Raise Finches
The Ethics of Fostering Finches

Why Foster Finches

Techniques to Successfully Fostering Finches

Gouldian and Zebra chicks being fostering by this Society finch

The Ethics of Fostering Finches
You will not likely find a subject that will raise as much debate in the avicultural world as the subject of fostering. That is the practice of taking eggs or young finches of one species to be raised by another. There are a number of different species that can be used as foster parents, but the most common are the Society finch and Zebra finch. Each has its advantages, but the Society finch is the most widely used. The debate as to whether or not it is right to foster stems from the belief that the fostered young will be imprinted on their foster parents and lose some natural ability, become sexually imprinted on the foster species or learn songs or behaviors that are aberrant to their species.

So that you know before reading on, I believe that fostering is a valuable tool for aviculture if used with a clear understanding of genetics, selection and bird behavior.

Loss of Natural Parenting Ability
Some have argued that those birds that are foster reared will not learn to raise young if they do not have appropriate role models. I do not believe that fostered finches lose the ability to raise the young of their own species if they are raised by another species. Gouldians are often used as an example of this. I dare say that all the Gouldians available in the U.S. today are descendants of birds imported from Japan and Europe which relied heavily on fostering to meet the demand for this species. Then to establish them here in the States, breeders also relied on fostering to help increase the number of young produced. Today, Gouldians can raise their young with great success. If parenting is genetic and not just instinctive, then the type of fostering used by many hobby breeders will do greater damage to the gene pool than the 'mass production' fostering used by commercial breeders. Commercial breeders will foster all the eggs. No selection is taking place other than for hens that will lay eggs. The hobby breeder that says they will only foster 'in case of an emergency' usually only fosters an abandoned clutch or young. If these birds are 'bad' parents and are genetically inferior for raising young, then this line is being perpetuated by fostering the young. In fact, the selection process may actually favor these birds since they are free to start another clutch immediately while the diligent pair is busy raising their clutch of young. At the end of the season, the birds that did not raise their young could conceivably have 2 to 3 times as many offspring as the 'good' parents due to fostering their abandoned eggs and pitched young.

Sexual Imprinting
Klaus Immelmann conducted numerous experiments with Zebra finches and Society finches as well as some other species to see if young birds raised by another species would imprint upon their foster parents. Immelmann's research showed that fostered young did imprint upon their foster parents. His experiments also showed that the degree to which the young imprinted was dependent upon what species of finch was fostered and for how long they were left with the foster parents. His main focus, Zebra finches, would favor the foster species (Society finches were used) over their own species if left with the fosters past 40 days and even more so if left until 90 days old. This imprinting was not reversible as imprinted birds were mated with their own species in breeder cages for several years and raised many clutches of young, but when shown the foster species they began to court them. The key thing for the aviculturist to read there was that the imprinted bird did still raise young of their own species when not in the presence of the foster species. Some species do not seem to be effected by imprinting to the degree that the Zebra finches showed in Immelmann's experiments. Gouldians that I have raised under Society finch fosters showed no interest in Societies. Same would hold true for the Rufous-backed mannikins that I raised under Society finch fosters. They showed no interest at all in the Societies and even when placed in the same cage with many Societies and other Rufous-backed, they always clumped with the other Rufous-backed and repelled the Societies.

Abnormal Learned Behavior or Songs
In some species, the male finch learns certain parts or all of their courtship song and dance from their song tutor which is usually the male bird that feeds them. The Zebra finch has a 'framework' to their song that is instinctive. To this framework they will add notes from their song tutors or occasionally from other sounds in their environment. A Zebra male that is left with a foster Society finch male beyond 40 days old will pick up notes from the Society finch and incorporate them into his framework. This results in a song that has the Zebra finch rhythm, but the Society finch's notes. Other species like the Red Headed finch or Java Sparrow do not have a 'framework' to their courtship song and learn the entire song from their tutor. These birds if left with their foster parents too long will mimic the Society finch's courtship song precisely. I have some Red Headed finches that sound exactly like their Society foster father (which had a slightly unusual song himself) both in sound quality and volume. If hand raised, these mimic birds will accept their human fosters as song tutors and can incorporate even words into their courtship song. Then there are other species such as Gouldians or Rufous-backed mannikins that do not alter their song no matter how long they are left with their foster species. (Of course, I do not know what the wild Gouldian song is like and since all our domestic Gouldians are surely the result of fostering, the natural (wild) song may have been lost generations ago and all Gouldians now sing an altered song.)

To avoid some of the abnormal songs or learned courtship behavior you should move any fostered young, as soon as they can be safely removed, to a cage that contains others of their species (adults preferably). They will then learn the song and behavior that is normal for their species.

Why Foster Finches?
The obvious answer to this question might simply be to raise finches that you otherwise would not be able to. That really is too simple of an answer and there are a number of reasons to foster finches under another species.

Establish a Breeding Strain
This is about raising birds that otherwise might not be produced. The fact of the matter is, no matter how hard we try to reproduce a natural environment, we cannot duplicate all the conditions a species will encounter in the wild. Furthermore, sometimes it is not our intention to try and produce a natural environment, but to entice a pair to breed in smaller cages that are set up for our convenience and enjoyment. some species may only lay eggs and not hatch them or if they do, not raise the young.

Develop a Mutation
Most often when working with a new mutation, a breeder has very few birds to work with. Sometimes only a single bird. While the birds may be capable of raising the offspring on their own, the number of young that can be produced in a season is relatively low. By fostering the eggs, many more of the mutant birds can be produced. This will help ensure that there are sufficient numbers to establish the new variety. The offspring can then be paired to many unrelated lines to help broaden the genetic base for the new color.

Break Chain of Infestation
It has been reported that using the Society finch to foster Gouldians can help break the cycle of the Air Sac Mite in your Gouldian population. It is believed that the Gouldian parents transfer the mites to their young while regurgitating food to feed them. Not much is actually known about the life cycle of the Air Sac Mite, so this is not proven, but it does make some sense. The Society finch is not as susceptible to contracting the mite as the Gouldian or Canary and if used to foster the Gouldians, will not transfer the mites to the young the way the infected Gouldian might. These young should not then be mixed with the old stock as this would expose them to the mites, but if kept isolated, this may help break the cycle.

Techniques to Successfully Fostering Finches
This goes without saying, but like all living things, finches are highly variable as are their abilities to raise young. There are a number of things you can do to increase the likelihood of successfully. These things are general rules that I use, but for each of them I can point to my own exceptions and other breeders never follow my "rules" with great success.

Selecting the Foster Pair
When choosing birds to use as foster parents, if you are using any species other than the Society finch, it is best to select a true pair. That is one male and one female. The reason for this is, nesting and raising young

Timing the Clutch


See how Artificial Incubation can help you in your fostering program

Suggested Reading
Society Finches as Foster Parents
Robert G. Black
ISBN 0--910631-02-6

(1987) A step-by-step guide to fostering finches under Society finches. Covers care of the Society fosters and discusses techniques for fostering 'easy' species such as Gouldians and Tri-colored Nuns to more difficult species such as Red Headed finches and Cordon Blues.

A clutch of mix chicks being raised by Society finch fosters.

Comments and suggestions are always welcome. E-mail me at

Copyright 2000 Roy Beckham