Why Foster?
There are many reasons that finch breeders choose to foster eggs or babies under Bengalese finches.
Here are just a few examples:
To increase the quantity of babies, especially for the rare and endangered species
Setting up your Bengalese for Fostering
Bengalese Finches are best parents when set up with 2-3 birds per cage, instead of in a mixed colony. Bengalese in a colony set-up tends to be very inconsistent breeders and foster parents due to their "social" behavior. I have found that one true sexed pair per cage works best, but have been successful housing 2-3 cocks per cage (The advantage of having only males is that there are no hens to lay numerous eggs when they are fostering eggs or babies).
Provide a five inch (12cm) square wooden nest box (with a hinged lid) on the outside of each Bengalese cage. Although Bengalese Finches will take to almost any nest you provide, a nest-box habits advantages, especially when handling delicate eggs and babies. Other nests, such as wicker or millet hanging nests may also be used.
The best nesting material you can provide your Bengalese is hessian strands. Cut the hessian into 2" (5cm) squares and pull out each strand from the squares. Take a handful of the hessian and place inside the nest and push down slightly to make an indentation in the middle of the nest. In a few days, after the Bengalese (mainly the male) has rearranged the nesting material, check to make sure all four corners are filled in to prevent eggs and babies from falling in (also recheck after you have placed eggs in the nest as well).
Eggs
Before handling any newly laid eggs, make sure your hands are clean. Natural oiJs from your skin can easily clog the tiny pores of an egg, causing death of the embryo inside. Keep in mind that finch eggs are very fragile, and should be handled with great care. You may want to carefully use a small spoon to transfer eggs (egg breakage using a spoon can still occur, especially when removing eggs from hanging nests).
Fostered eggs transferred to a pair of Bengalese that includes a hen, should be carefully marked so they won't become confused with any Bengalese eggs that are laid during incubation of the fostered eggs. A permanent marker can be used to GENTLY mark the egg. Larger breeders with many cages usually write the parent cage number on the eggs. A small dot of colored fingernail polish may also be used.
When removing eggs to be fostered from their parents, it’s best to remove them each day they are laid. Place the eggs on their sides in a dish of seed (to prevent movement) and store at room temperature.
It is very important that you rotate the eggs at least twice a day to keep them viable and from drying up on one side. Continue turning the eggs daily until they can be placed under a pair of Bengalese.
Eggs, when turned properly, can be stored up to a week (eggs that have already been incubated must be moved to a foster pair before they are cooled, to keep the embryos from dying when chilled). Ideally, all the eggs in the same clutch should be placed under Bengalese on the same day.
Make sure all Bengalese eggs already in the Bengalese nest have been removed (you can place these under other pairs of Bengalese). For the best results, add between 4- 5 eggs to the Bengalese nest.
Some pairs won't sit when there are fewer than four. Dummy eggs can be added when there are less than three eggs and removed a few days after the babies have hatched. After 4-5 days of incubation, eggs should be candled with a bright pen light to verify that the eggs are fertile.
When held up to a candling light, fertile eggs show tiny red veins near the shell of the egg.
Infertile eggs remain clear, but should be left under the Bengalese for a few more days and rechecked.
If the whole clutch is infertile after two attempts of candling, remove the eggs or replace with another set of eggs that need fostering (if available). The eggs should hatch approximately 13-16 days after the onset of incubation, depending on the species, usually Erdly in the day.
As the chick emerges from the egg, the Bengalese will help the chick out and eat the nutritious shell.
A few days before the projected hatch date, you should provide the foster parents with a nutritious nestling egg food and soaked seed (seed soaked in water for 24 hours, drained and rinsed well) and continue every day until the chicks are eating on their own.
Fostering Problems
Here is a list of problems you may encounter if you foster.
. EGGS: As mentioned earlier, Bengalese may not incubate fostered eggs unless there are at
least 4 eggs. Dummy eggs can be added as needed.