Hi Twocrows,
I can understand wanting to keep it dry.
That's really not a problem with our Aviary. It will have a roof that alternates dark and clear fiberglass to let light in and shade some areas.
There is also a 4' square area that has no cover so the birds can get out and play in rain, or soak up sun. That is where I was hoping to put most of the plants. The yard drains well, so that's not really a problem. We did this years ago in this aviary, but I let it all go when we got rid of our birds. (our son being an infant, I gave them up for awhile.)
I have an ornamental grass, and Rosemary for starters, was going to plant a few patches of turf, and areas of bird seed. Starts out grass and then goes to seed, so they will have munchies.
The aviary has a mist system, and i've never had prblems with dampness, and I'm home all the time, so have the time needed for upkeep and cleaning.
I plan to aim and water carefully and am trying to find drought tolerant plants.
I'm thinking maybe a Guava bush would be nice. I can also set up water bottles with a pin hole to water just the base of the plant.