I used to keep budgerigars, about 100 at the highest point.

They bred very well - but it is really important to ensure that the food for the hatchlings is handled with clean hands, put into clean pots and any old food is removed. I used to rear almost every chick which hatched whilst other breeders lost about half or more of each nest - they could not be bothered to be clean.

Don't try to breed in the aviary if you have an odd number of birds - separate the breeding pairs into individual cages or there could be fighting, eggs being destroyed and the like. It is not inevitable, but if there ARE two males and three females it is quite likely.