Colony breeding in the UK is usually carried out in an outdoor aviary with the flock of budgerigars flying free within the enclosure. However, you can colony breed indoors if you have a large enough flight cage. This method of breeding is more about breeding in quantity than breeding for quality, which cage breeding offers.
You would think that as colony breeding closely follows breeding in the wild it would be the easiest to undertake. However, this is not the case. There are a number of issues which can arise. With the birds being able to select their own partners they do exercise their choice and have preferences. Hens will sometimes also select a new partner during breeding and spare hens will break into nest boxes and destroy eggs and chicks.
Within your colony it is unlikely that all the hens will be in breeding condition (ready to breed) when most of the cocks are, so it is best to have extra females. Once the pairs have selected each other any spare hens and uninterested cocks may be removed from the colony. As a minimum you should start with a least three pairs. You should also ensure that your birds are not over-crowded – an aviary 2 meters high by 3 meters long by 1 meter wide will hold up to six breeding pairs.
You should provide 50% more next boxes than the pairs you have to give them a choice. The boxes should be hung as high in the aviary as possible and all at the same height. The nest site of choice will be the highest and so by removing this situation will reduce the amount of squabbling. Some hens will fight to the death over specific nest boxes.
A gap of around 12 weeks can be expected between rounds of chicks. Taking up to three rounds is acceptable and then the nest boxes should be removed, and breeding activities will cease.