Firstly, study the species of bird you are intending to keep. If keeping any kind of parakeet, cockatiel or other long tailed species then you will require a long aviary to suit your birds needs. If possible it would be ideal if the aviary is suffiently long enough so the bird can actually fly from one side to the other. The birds with a heavyset body, such as the lovebird or a Senegal parrot, gets a good deal of exercise by climbing around in the aviary. These birds require an aviary that is taller rather than it is wide.

You should then consider the size of the aviary. Generall you should buy the largest aviary you can afford for your bird, a newly weaned handfed baby bird may feel lost and terrified in a large aviary. Young birds may also have difficulty locating food and water dishes. If you can afford to, buying a smaller bird aviary while your bird is a baby would be a good idea and then move onto something bigger when it is older.

It is also a good idea to keep in mind the spacing between the aviary bars. A good looking $400 bird aviary will not be very successful if it can fit through the bars! If using an aviary with wire mesh, you should compare the size of the hole in the mesh with the size of your bird's head prior to making your choice. If a bird aviary is built from one inch mesh then it would be the correct size for a cockatiel to put his head through. Cockatiels have been known to bend their necks into a 'U' shape and stick their heads into a different hole when pulling their bodies back through the bars.

When you have determined the aviary size and bar spacing, look at a few other facets of bird aviary design. Seeing the cage tray. When you pull it out to clean it, is there a grate in the aviary to prevent the bird from escaping? The tray will need to be deep enough to catch most of the mess your bird makes? If you still have a deep tray but there is no cage apron you may find the bird will still scatter a lot of seed hulls and feathers on the floor. You can put a plastic apron base on your aviary or have a built in metal apron which is a good option.

As a final point don't forget to have a look at the aviary cups. Ideally there should be an easily accessable opening to get to the cups without gaining access through the main door. If you are buying a bird aviary for a larger bird, the cups should actually bolt to the aviary unless you want to spend every morning and afternoon for the next 50 years reaching for cups that your bird has flung onto the bottom of the bird aviary

If you a replacing a bird aviary for an older parrot type bird, some owners have told me it's crucial to get a bird cage of the same colour. It is assumed that if a bird is used to a coloured painted aviary, it will not adapt easily to a metal cloured aviary.