There are several things to think about before deciding how you are going to get them outside.
Do you want your birds to live outside day and night or do you want to just put them out during the day while you are at home to watch them and bring them into the house at night?
Do you want to attach the aviary to the house with an entrance right into the house so the birds can come and go on their own, but possibly be locked into the house at night?
Do you want to have a stand alone aviary with an attached area to allow them to go inside at night or during storms.
Do you have preditors in the area such as hawks, racoons or foxes and how about rats or mice that would be interested in the bird food, but would also chew on a bird if they could catch one?
If they are just going to be outside during the day while you are there to watch them, you could just bring them outside in their cages or in travel cages. Another option is to get them used to a harness and take them outside this way.
One step further would be to build or purchase an aviary where you can put your birds each day – taking them between the house and the aviary in a travel cage. This is fine for birds that will step up and into their travel cage easily, but not great for birds that would have to be caught with a net.
If you build an aviary attached to the house, with an entrance into a cage or an indoor aviary, you will have to think about the insects that will get into the house through a regular cage wire. That can be solved with a layer of fine screen outside the cage wire that you use. In order to prevent preditors from making holes in this fine screen, you could then add an additional layer of heavy duty wire outside that, making a 3 layer barrier to keep your birds safe.
With a completely detached aviary, you may also want to go with the 3 layers of wire and screen to keep your birds safe. Some birds will enjoy a diet that includes insects though, so you could consider dropping the fine insect mesh from the plans. Every outdoor aviary should have a 2 door safety method of entering and leaving the aviary. If a bird escapes through the first door, he will remain between the doors instead of escaping outdoors.
A good portion of an outdoor aviary should have a roof on it. Otherwise a hawk flying above (or even a plane) will be in view and will scare your birds. Another possibility is that a hawk flying above would be attracted to the colourful birds flying below him and you may find this hawk swooping down to try and catch your birds. Of course he will not catch your birds if you have the heavy duty wire on the outside, but your birds could be injured flying against the wire trying to get away.
The type of wire you use for the inside of the aviary will vary according to the size of birds you will be keeping in it. For instance, finches would need a much smaller screen size than a macaw would. Do not use the bug screen for the inside though because a finches nail could get caught in screen that size and cause injury to the bird.
Whatever you decide to do, I am sure your birds would enjoy some time outdoors when the weather is nice.
