This section is from the book "The American Bird-Keeper's Manual", by James Mann. Also available from Amazon: The American Bird-Keeper's Manual.
On putting your birds in the cage, to pair, give one-third of a hard-boiled egg to a pair, every morning, yolk, white, and shell; add to their portion of hemp and Canary seed, some rape, and put in the cage, or stick in the wires, a piece of old lime plaster, from a ceiling, or wall.* When the female commences laying, she will lay an egg every morning until her complement is laid.
* Some use cuttle fish bone; it is the lime contained in the bone that is useful, therefore the old plaster is superior.
The number is generally five, sometimes six, or four, and some young hens will set upon three. Some females will not set until they have done laying; others will commence setting on laying the first egg, and it has been said by some, that, in this case, the egg should be taken out, and a false one put in its place, until the complement is laid, and then the whole put back into the nest again. This is taking a great deal of trouble, without any necessity for it, and the risk of breaking the eggs into the bargain; for if the young are hatched, one every morning, the one is nourished and fed before the next comes, and so on; and in the other case, where all are hatched together, the male assists in nourishing and feeding them, and all is well. There is very often one bad egg in the nest; when the youngest is two days old, take the box, or basket, which contains the nest,* in your left hand, introduce the little finger of the right gently under the young, and get out the bad egg, as it takes up room in the nest, and if it should get broke is very unpleasant. When I had six young at a hatching, which I have sometimes had, 1 prepared a large nest, and when they were five or six days old removed them gently into it, as the common sized nests, when they grow older, would prove too small for them. When the young are hatched increase the egg to one half, or more; the whole of it as before. Some give only the yolk, this is wrong; when very young the yolk is too heating and rich for them. Add to this a slice of good baker's bread, moistened with pure water; the parents will then feed with the three together.* Be careful that the bread is not sour. If there are four or five young, they may require fresh egg and bread in the afternoon, as they grow older. Give them fresh bread and egg every morning, as soon after sunrise as is convenient; and, if the weather is warm, about noon, remove what may be in the saucer; rinse it with water, and give them fresh egg and bread. The male takes an active part in the feeding of the young whenever they are hatched, but the female alone sits on them; and when they get large, and begin to feather, she will sit by them, or on the side of the nest at night. When they are about ten days old, (as before mentioned,) she will leave the care altogether to the male, and lay again in the other nest. The male will feed them regularly, and also his mate, whenever she calls him, which she will whenever she does not feel disposed to leave her nest. He will attend to his duty diligently, and the young are sometimes safer, under the charge of the male than the female, especially if she is a young mother. I have often gazed with pleasure on the male, after having a fine brood of young left under his charge. He would first hop gently on the nest, and survey them all over, with delight sparkling in his eyes; and when, on his uttering a low note, they would raise their heads and open their mouths, overjoyed he would quickly obey the call, fly down to the bottom of the cage, take two or three mouth-fuls, then fly up and put it into one of two of their little throats, then down again, and when they were all satisfied, and he would take care that there were none unfed, he would hop on his roost, and pour forth strains of melody, which seemed to me to say: "Now I have done my duty I am happy; I will now sing my best song." When the young begin to eat alone, and pick about the bottom of the cage, take an equal part of hemp and rape seed, and bruise it in a mortar, or on a table with a rolling-pin; put it in a saucer, or other shoal vessel, then into the cage. Whenever you think they can eat well enough to be alone, remove them out of the breeding-cage, as they annoy the mother when sitting, by crowding around the nest; and she does not scruple, sometimes, to rob them of a few of their feathers, to keep her eggs warm.
* Both boxes and baskets should be so fixed, that they can be taken down for this purpose; and occasionally to see how the young thrive.
* I have seen a parent bird take a pick of the yolk, of the white, and of the bread, to feed a bird not many hours old.
When you remove your young put them into a pretty large cage, where they can have plenty of room to fly; they will feather better, and be clean. Remove them in the morning; and if they should keep chirping all day, and not eat, in the afternoon take the male out of the breeding cage, and put him in beside them, and he will feed them all. Keep him there until near night; then put him back to his mate again, and they will eat the next day without any trouble. Put in the rape and hemp seed, bruised, as formerly; this I have found very beneficial for young birds. Put in, also, Canary seed, and egg and bread, as formerly; withdraw all the soft food gradually, but as soon as you can, as they will thrive better, and be much more healthy and vigorous, when you get them to live on their seed alone.
 
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