You may be thinking “Breeding is natural isn’t it?”. Or maybe one of your question would be, “What can possibly go wrong?”.
I’m here to tell you, if you can think of it going wrong, it’s most likely a potential problem. Breeding cockatiels is often very simple but sometimes it just doesn’t succeed. Some things gone wrong are preventable or correctable, others are not.
To begin with you may have no eggs at all. This may mean that you have set up 2 males or 2 females instead of one of each, that the conditions aren’t triggering breeding, that the birds are too young, the birds are too old, the birds are eating their eggs as they are laid, that the birds aren’t healthy, that they have been overbred, or that your hen is actually incapable of laying eggs due to physical problems. On a rare occassion, maybe your birds just don’t want to have a family but still enjoy the act of breeding.
The eggs you get may be “clear” — infertile. This may mean that your male is an amateur who doesn’t know what to do, your hen is agressive and won’t allow him to mate, they don’t like each other, you have 2 hens set up (especially if there are a lot of eggs and they are laid daily), the perches are loose so they can’t make good contact while mating, The birds might be too young, the birds may be too old, the birds may not be healthy, the birds could have been overbred, your cock may be infertile, you may need to clip the males toenails because they are hurting the female which causes her to try to avoid him, the feathers around the vent of one or both birds may be making it impossible for the male to carry out his responsibilities, or your hen may be infertile.
You may get eggs that begin to develop but die before hatching. This may be due to genetic problems with the chicks, too much humidity, too little humidity, poor sitting or turning of the eggs by one or both parents, an infection either transmitted from parent to chick before the eggs were laid or picked up through the pores of the eggs, a crack in the eggs, mishandling and allowing overheating or chilling during candling, marking the egg with a toxic marker, overheating in the nestbox in summer, cold weather in the winter, or a decline in comodities prices in Japan *grin*. Sorry, that list was getting too depressing.
Your chicks may hatch and develop problems later. The parents may not feed them, the parents may feed them the wrong stuff (bedding, undigestible seed, bits of paper, droppings, etc.), they could get stepped on and killed in the nest, they may refuse handfeeding, they may develop slow crop or sour crop, they may develop spraddle leg, they may have congenital deformities, they may pick up an infection, their parents may pick them bald or even pick them to death, they may get chilled, they may get overheated, or you may have handfeeding troubles such as aspiration or crop burn.
You may have trouble weaning as they determinedly cling to their dependence on that formula long after your schedule says that they should be eating solid foods. They may die close to weaning age due to some problem like Psittacosis, or Polyomavirus. They may not get enough good bacteria to fight off potential problems such as yeast infections. They may have problems with malabsorption.
You may have trouble selling the babies because the market is glutted, because they aren’t properly tamed, because you lack business skills, because people who don’t know better will buy inferior birds in pretty mutations or birds offered at a cheaper price rather then your healthy grey splits, or because you can’t bear to actually part with the little darlings.
You may have one or both of the parents die during incubation or while raising the chicks. You may even have a bird who becomes agressive and injures its mate or its chicks.
I don’t claim that this list is exhaustive. Some of this is likely to happen on your first tries. Most of it is unlikely in future attempts but each of these things has happened to one breeder or another. There is no magic bullet that will ensure sucess. Good nutrition, scrupulous sanitation, and wise choices of breeder birds will go a long way. You may need to re-pair birds who don’t produce fertile eggs together, to ruthlessly cull birds who carry deformities or have bad parenting skills, to wait patiently for birds to mature, to handfeed when you’d rather parent-raise, and to spend a lot of time and money at the vet’s. Sometimes you will get good advice, you will discover the cause of the problem, and correct it easily. Sometimes not. Just because its natural doesn’t meant that its fail-safe.