Drawbacks of an aviary include risks of related individuals breeding (colony breeding setup), individuals of different species breeding (mixed aviary setup), not being able to hand pick each breeding pair (colony breeding setup), issues with personality conflicts, territorial issues, risks of overcrowding, and other birds interfering with the breeding behavior of nesting birds, perhaps causing eggs and chicks to be abandoned or tossed.

The advantages of an aviary include better environmental stimulation (there is much more for the birds to do and they seem busier and more natural [in my opinion]), more space for flight - both horizontally and vertically - allowing them to strengthen muscles that might go undeveloped in a cage environment, more places to hide so that they feel more secure, more space for those species that do not breed well in cages. I also find that maintaining an aviary is less work than maintaining many individual cages. Outdoor aviaries have the advantage of natural sunlight, foilage, and food sources, as well as the disadvantages of exposure to the elements, natural pathogens, and predators.

Cages allow you to hand-pick breeding pairs, offer them privacy, and protect them from the interference of other birds, but restrict the space available to them. During breeding periods, the restricted space may not be an issue, because they spend much of their time incubating and rearing the chicks, assuming you are working with a species that is comfortable breeding in a cage (as Gouldians tend to be). Cages will also allow you to house more birds in the same space, as cages can be stacked on on top of another.

I have a mixed aviary in my living room filled with a variety of species. There were times when I had compatibility issues. My zebras straightened themselves out eventually (I don't do zebras anymore, though), but I had to find a new home for a Java Rice finch that just could not get along. I do not allow nests or breeding in the aviary and everyone now gets along fine and it is a very healthy environment for them. When nests were present, there were always issues. I also keep it understocked - ie, each pair has more than the minimal 3 square feet of floor space. It is also easy to clean and maintain - and it provides me with abundant sources of entertainment. For breeding (which I have not yet begun, so this is just speculation) I am interested in breeding waxbills, so I plan to build walk-in aviaries in my birdroom. These will house each 4-5 pairs of waxbills, each pair of a different species, trying to make sure not to house birds together that may hybridize (eg, strawberries and goldbreasts). It is my opinion that waxbills will breed better when offered more space and more privacy. I will try to get each pair to bond in an individual cage before moving them to an aviary. I will have cages on the side for whenever someone needs to be removed for any reason.

Your situation was with Gouldian finches and I have found that my Gouldians have actually been very comfortable in cages. If I were going to breed Gouldian finches, I would probably keep them in a non-breeding community aviary. (I've heard many people recommend keeping hens in one flight and cocks in a separate flight). The aviary environment will help keep them in condition when they are not breeding. When you are ready to put a pair together for breeding, put them into their own private breeding cage. This way, you have direct control over breeding pairs (although this doesn't mean they will like each other, of course), but you can at least prevent inbreeding and you can try to pair birds that you think will produce strong healthy offspring (and perhaps of the colors you want). Of course, I haven't tried this myself, it is just what I would do if I were to go into Gouldians.

On the other hand, I think you can also do just fine with Gouldians in cages year round, but I am an aviary lover, so I would try to house them in a more spacious environment when they are not breeding. Part of the reason you may be experiencing bickering is that you have 12 square feet of floor space. Based on the 3 square feet of floor space per pair, your flight comfortably holds 4 pair and you have 5 pairs of birds in there. So your aviary is pushing full capacity. However, your new flight is plenty large enough and you might see improvement with the additional space.

Good luck with your birds - I am sure you will find the right setup for your particular needs. You have lots of options - pick the one that you are most at home with.

Vonda.