Your main issue is having too many birds in the same cage for breeding, as well as having an odd number of birds in the same cage. When you breed birds, you should only have one pair of birds in a cage. It is never a good idea to have an odd number of birds in a cage, even if you don’t set them up to breed. Even if the birds were all the same sex, they will tend to bond in pairs and one bird gets left out. The odd bird is usually bullied, or the birds will constantly fight. In your case, since you gave them a nesting box, you have created a volatile situation. While birds may live in flocks in the wild, this is only for protection from predators. When they are breeding, each pair has their own territory. If another flock member wanders too close, it will be viewed as a rival or intruder and will be attacked and driven away. Your males are fighting over the right to mate with the female and raise the chicks. The fighting will get increasingly more violent until one bird kills the other, since they are trapped in the same cage and the odd bird can’t get away. You need to move the extra male to another cage immediately and put a visual barrier between it and the pair, or put it in a different room. The female is probably less scared of the box and mostly terrified of the fighting males. She is also in danger of being attacked and any eggs she lays may be destroyed or eaten by the rival male. Even if you took the nest box away, you still must remove the extra male. The fighting is not going to stop now that the birds are sexually mature. A lot of owners do like you and cage birds together, which can be fine when the birds are young. But once they become mature, you can’t keep an odd number of birds together. And this doesn’t mean you can add a female. I want to stress, your only option is to remove the extra male, whether you are going to breed them or not.
Now, back to the breeding. Your male needs to be at least 18 months old and the female should be at least two years old. If these birds are younger, then you should not let them have a nest box until they are old enough. They will become sexually mature much sooner than they are actually ready to breed and raise chicks. If they are too young, they end up making mistakes or developing bad breeding habits that will ruin them as breeders in the future. Immature birds are more likely to break or eat eggs and once they start this, it is almost impossible to break the habit. And a young female is at a very high risk of becoming egg bound and dying. If your birds are old enough, then you can set them up to breed – but maybe not now. It depends on how long she has already been laying eggs. If she has laid more than one clutch, then she needs to be rested from breeding for several months, which means removing the nest box. Cockatiels only have one clutch of eggs per year in the wild. In captivity, they will breed year round unless you make them rest between clutches. You should only let them have two clutches per year. Laying eggs is a drain on the female’s health, and she wasn’t intended to keep laying clutch after clutch of eggs. You have to remove the nest box after each clutch, whether they hatched or not, and make the pair rest from breeding for several months. If you do not do this, the female will eventually die from over breeding. And before that, the chicks will start being less healthy, fewer eggs will hatch and you may start seeing physical issues with the chicks. Your birds need to be in prime health in order to breed. They need to be on a nutritionally balanced diet like pellets or our Nutri-Berries, Avi-Cakes and Pellet-Berries – a seed diet will not provide the nutrition they need. In addition you should offer dark leafy greens, chopped veggies, multi grain bread and cooked eggs with the shell cleaned, crushed and cooked with them. The female needs the extra protein and calcium when she is laying eggs and feeding chicks. So you may need to remove that nest box for now and make sure the birds are on a good diet as well as being rested from laying eggs before you set them back up for breeding.
Thank you for asking Lafeber,