By Renata Decher-Juden
IFCB Symposium 1983
Foster-parenting Australian finches, the method of letting Society (Bengalese) finches take over or complete the task of hatching and raising another species’ eggs, has been successfully practiced in Europe for decades. It is now becoming increasingly popular in the United States, as commercial and private breeders alike realize its enormous potential to aviculture.
At Behavioral Study of Birds, we presently breed close to 500 pairs of Lady Gouldian (Chloebia gouldiae) and Owl (Stizoptera bichenoyii) finches, with approximately 2,000 pairs of Society finches standing by for fostering. Thus, we are in a good position to study this method in depth. Let me now dispel some of the myths and answer the most-asked questions about foster-breeding.
The most obvious advantage is, of course, that many more babies can be raised out of the same number of exotic finches without ever “overbreeding” the birds. Each bird is given adequate rests between laying cycles, and a full 3-month period is set aside every year to allow for the moulting process and to completely rebuild the birds’ strength before any breeding is resumed. Thus a healthy pair of Lady Gouldians can lay up to 60 eggs per season without undue strain on the female, since she is spared the consuming task of feeding her babies.
As we do not have to rely solely on a good parental instinct in our Gouldians and Owl finches, we can now concentrate on our biggest and strongest specimen birds. This enables us to genetically breed for large size, brilliant color and hardiness, thereby constantly improving the overall appearance and quality of our flock. Species that were once considered difficult to raise, such as the beautiful New Guinea (Noechmia phaeton albiventer) and Australian Blood-finches (Noechmia phaeton phaeton) can now be successfully propagated. New and weak mutations, such as the Fawn Shaftail (fawn mutation of Poephila acuticauda) or White-and Bluebreasted Gouldian, can be strengthened and their survival ensured.
However, one of the most interesting but rarely considered advantages from a purely avicultural standpoint, is the ability to break certain disease and parasite life cycles with the help of foster-breeding. For example, there is, to date, no successful cure for the lung – or air-sack- mite which all too often afflicts the Lady Gouldian finch and can reach epidemic proportions. Tape- and gizzard- worms and certain yeast infections commonly found in Owl finches can prove very hard to eradicate. We have found the incidence of these parasites to be much lower in Society than in Australian finches. Few diseases or parasites are transmitted through the egg, and, since the hatched babies are never exposed to their affected parents, they have less chance of acquiring parental afflictions. If the weaned babies are then kept rigorously apart from their natural parents through adolescence, the entire flock can be replaced with healthy virgin stock.
Another advantage to foster-raising is that Societies require no live food and will successfully raise large healthy babies solely on an egg-based nesting food mixture. We use the following recipe:
To one quart of commercial unseasoned breadcrumbs, add 7-9 hard boiled chicken eggs with their shells liquified in a home-type blender, with one tablespoon powdered multi-vitamins, 1/2 teaspoon di-calcium and one finely ground carrot
The mixture should be crumbly but not soggy. It contains sufficient amounts of animal protein to satisfy any finch baby’s needs and renders the necessity for live food obsolete. At the same time, it provides the breeder with a perfect base in which to administer non-water soluble medications or other supplements should the need arise. The egg food is offered early in the morning and any remains are removed after a maximum of 6 to 7 hours, to avoid contamination by bacteria.
So far, we have discussed the many advantages of foster-breeding. But the question is often asked: “What about imprinting? Will the baby Gouldian not ‘learn’ certain social and mating behaviors from its foster Society parent?” Studies conducted in Germany by Dr. Klaus Immelmann, using Zebra and Society finches, show that a Society-raised Zebra cock will indeed court and attempt to mate a Society hen -IF one is made available. But the same cock, if placed with other Zebra finches without the presence of Societies will successfully mate a hen of his own species and raise a healthy family. Therefore, the only situation where foster-breeding is unadvisable is in a mixed breeding flight that includes Society finches. But since Societies have an annoying habit of “sharing” other bird’s nests, I would discourage their presence altogether in a mixed flight. It has also been established by the same study that the process of imprinting can be partially reversed if the babies, weaned at 6 to 8 weeks, are placed in flights with their own species, out of sight or hearing of their foster-parents. At Behavioral Studies of Birds, we are now successfully raising our third generation of Lady Gouldian and Owl finches, using the foster method exclusively. The original stock was imported from European foster-breeders and other American breeders who have used the method for 10 generations or more and have not encountered any foster-related problems.
Another fear sometimes voiced is the danger of “over-breeding” and depleting the pairs of exotic finches to a point of exhaustion by unscrupulous breeders, thus introducing smaller and smaller specimens to the market. Unfortunately, the same can be true using natural breeding and we must only hope that all breeders will use integrity where the health and well-being of their charges are concerned.
Our method of foster-breeding is herewith presented in detail. All our birds are housed in individual 30″ x 13″ x 12″ cages. These are moulded of white plastic with a removable epoxy-coated wire front, which has several advantages: the cages are well lit, have no sharp corners, are easy to clean and, while still being enclosed from 5 sides, do not present the potential mite problem as as would a comparable wood cage. Seed, water and mineral grit can all be conveniently serviced from the outside, keeping disturbance of the birds to a minimum. Both Lady Gouldian and Owl finches originate from the northern tropical regions of Australia; thus it is essential that an appropriate environment be provided. Ideal temperature range is from 78° to 88°F and a constant relative humidity of 65 to 75% is recommended to keep the birds in good breeding condition. High humidity is also an important factor in helping the chicks hatch. If no natural skylight can be provided, the use of vita-lights is recommended. During the breeding season, the birds received a 12-hour light-cycle. If the lights come on too abruptly out of complete darkness, many birds will be frightened out of their nests, often carrying a baby chick or egg in their clenched claws. To prevent such accidents, we provide low-voltage Christmas lights on a separate timeclock. These come on half an hour before the main lights, to give a smooth transition.
Society finches possess an exceedingly strong breeding desire. It is not necessary to sex the birds, since any combination of two will make a good foster pair, some breeders even preferring two males since no eggs of their own, will require care. Each young pair is first tested with a “trial run” of Society babies to determine just how good a fostering pair they will be, without endangering any Lady Gouldian eggs. If the “pair” shows no nesting desire, or problems arise during incubation and raising, we simply “switch” them with another non-working pair, until we find a compatible team.
We use 5″ x 5″ x 6″ half-open, slide-in wood nestboxes. These can be opened from the back, facilitating nest control, to which, however frequent, the birds do not object. They will accept any kind of nesting material – we have found lawn clippings most satisfactory, though care must be taken to avoid contaminated material (pesticides or dog feces which might carry bacteria.) Almost immediately, the birds will start entering the nestbox. We let them lay a full clutch of their own eggs, or, in the case of two females, 2 or 3 infertile. Specially marked, eggs, placed in the nest will show by their warmth if the birds have started to incubate. They are now ready to accept their foster charges.
Meanwhile, our Lady Gouldian and Owl finches, housed in a separate section of the breeding facility, have been receiving daily rations of our high protein egg food to build up strength and stamina and provide extra calcium. This is continued 3 to 4 days a week throughout breeding season. The same nestboxes are used and additional nesting material, such as long-bladed grasses or 4-5″ long strands of burlap fiber, are placed in the bottom of their cage. This will trigger breeding desire and”coordinate” male and female as they build their nest together insuring against infertile eggs. As long as the eggs are removed, the pair will continue to lay, most hens taking a few days’ rest between each series of 4 to 6 eggs. When the pair has produced approximately 20 eggs, the nestbox is removed, coinciding with the end of a “series.” Deprived of her nest site, the hen will stop laying and enter her 4 to 6 week rest period.
Each egg is recorded so parentage lines can be followed closely and in-breeding avoided. This becomes especially important in small flocks or with mutations such as the Whitebreasted Gouldian. As soon as possible, the eggs are placed with their future foster-pa marked, gently, with a felt-tip pen to differentiate it from any possible Society eggs. These will be removed; they are used as “dummy” eggs or go to the nest of a young, yet unproven, Society pair, thus replenishing our Society flock. We place a maximum of 4 Gouldian or 5 Owl finch eggs per nest. Using a penlight, the eggs are candled for fertility 5 to 7 days after the start of the incubation. Gouldian chicks hatch at 14 to 15 days, Owl finches at 12 to 13 days, each exhibiting the typical oral markings of its species. High protein egg food is now offered daily, starting 2 to 3 days before the expected hatchdate. All egg food cups and water containers must be kept scrupulous clean, as young Goldians especially, are quite susceptible to all kinds of bacteria. Soon the babies can be heard, noisily begging to be fed, a task their foster-parents perform with excellence.
At3 weeks, the babies leave their nest. Gouldian babies will not, as a rule, return to the nest, so the box can be removed at this time to prevent the parents from starting new clutch. Owl finches naturally sleep in the nest, so the box should be left in place another week or so after fledging. The foster-parents continue to feed their charges for another 2 to 3 weeks. The babies can now be observed begging for food each in its own fashion, the Gouldians with their typical “headtwisting” and the Owls with their heads almost touching the cage bottom, lifting the wing farthest removed from the parent into the air.
The babies are fully weaned at 6 to 8 weeks. They are now ready to be transferred into large wire holding flights, out of sight and hearing of their foster-parents. Care is taken to recreate an environment similar to their breeding cage, providing the same or similar feeders and water sources. We cover our weaning flights with a white plastic material to simulate a ceiling, since the sudden “wide open spaces” can prove quite frightening to the fledgling and result in head injuries and shock. A few days prior to fledging sprigs of spray millet are given to the birds; most of them are very fond of this choice food. It is now offered in quantity and can be a big help in smoothing the transition to the flight cage. The babies continue to receive the protein-rich nesting food several times a week all through their first moult — a delicate period in a young Gouldian’s life.
The Society parents, meanwhile, are prepared for their next clutch of foster-babies. This is a good time to clip their nails and give their cage a thorough cleaning. We check for any sign of health problems while holding them. Only choice birds in their prime should be considered for the task of foster-raising – the size and health of future babies mainly depends on them.
We breed our birds nine months out of the year, the 3-month rest coinciding with their natural moulting cycle which occurs approximately from April to June. A ratio of one Gouldian pair to every 4 Society pairs seems to work best for us.
The healthy flocks of beautiful babies raised in this manner speak for themselves. Foster parenting can be an invaluable aid in the ultimate goal of aviculture: to preserve and propagate all bird species in sufficient numbers so that future generations may enjoy them as we are fortunate enough to do today.