Hi Anas,
The first thing I recommend is that you remove the nest box and split the pair up for now. At 11 months old, your birds are much too young to be set up for breeding. Birds will become physically mature at a young age in captivity, but that doesn’t mean they are ready to breed yet. A wild cockatiel would not be breeding when it is this young. Your birds may be physically ready to breed, but they are not mentally ready. A male cockatiel should be at least 18 months old to breed, and the female needs to be at least 2 years old. When you set them up too soon, there are many issues that can come up. A young female is at a high risk of becoming egg bound, which is usually fatal, and if not, can cause damage that prevents her from ever being a breeder. Young birds haven’t settled down yet. They rarely know what to do with the eggs and end up breaking the eggs or eating them. Both of these are bad habits that are nearly impossible to break. In the rare case that an immature pair does hatch chicks, they don’t feed them, or feed them too much or too little, or get bored with them after a few days and kill them or abandon them so they can breed again. They may be ready to mate, but they aren’t ready to raise a family.
If you split them up and let them get a year older, they are more likely to be good breeders for you. When they are old enough, you can reintroduce them and let them bond. But do not give them a nest box until they have bonded again and show signs of mating. Birds only need a nest when they are ready to breed. Once they do breed and raise chicks, you have to take the nest box away and make them rest for about 6 months. You should limit them to no more than 2 clutches per year – in the wild they would only have one, because the weather would change and the breeding season ends. Cockatiels will breed until they die if we allow them to, so we have to take the box away and force them to stop for a few months. I know it seems like a long time, but your birds will have a better chance at success and be healthier overall of you let them get to the correct age for breeding.
As to the curve over the female’s tail, hopefully she isn’t already egg bound. An egg bound hen will sit hunched over and strain, trying to lay the egg. If this is going on, you need to rush her to an avian vet.
Thank you for asking Lafeber,
Brenda
